Tag Archives: Geo-engineering

Carbon capture is vital for planet, scientists say

Carbon capture and storage is now proved to work and is essential to prevent global average temperatures exceeding 1.5°C, Norwegian scientists say.

LONDON, 31 October, 2019 − If the world is to avoid dangerous overheating, some climate scientists say, carbon capture and storage (CCS) is essential. But compared with other ways of tackling global heating, it is a method that is developing slowly.

Norway, though, one of the world’s biggest oil producers, has been successfully using carbon capture since 1996. Now, Norwegian scientists say, the rest of the world must learn to do so as quickly as possible, arguing that all large industrial plants could and should capture and store the carbon dioxide they produce before it reaches the atmosphere.

It is a bold claim. Many other scientists insist that CCS − relying on carbon removal and other forms of geo-engineering to bring the temperature down, instead of simply reducing greenhouse gas emissions − can never achieve what is needed, although one US team suggested three years ago that it might well be at least part of the answer.

But the Norwegian researchers, from the independent research organisation Sintef, believe they have the evidence to prove their case. As well as finding how to separate carbon dioxide from electricity production, steel and cement works, they have also developed a separate system, Bio-CCS. This extracts CO2 from the atmosphere and turns it into charcoal before burying it in farmland.

“We cannot manage without CCS. The world must therefore undergo change on a scale we have never seen before, and this is urgent”

Sintef is working with the Norwegian oil industry and some of the other oil majors, including Shell and Total, that are increasingly under pressure to curb their emissions and prevent global average temperatures rising by more than 1.5°C above the pre-industrial level, the internationally agreed limit.

The Norwegians have so far disposed of 23 million tonnes of CO2, pumping it into brine-filled pores in sandstone, called saltwater aquifers, and sealing them with natural caprock, a relatively impervious layer of rock above an oil- or gas-bearing stratum.

The researchers say there is no choice but to adopt carbon capture and storage because turning off the world’s oil supplies immediately is unrealistic: “We cannot manage without CCS. The world must therefore undergo change on a scale we have never seen before, and this is urgent.”

The method of carbon capture developed at the Sintef research facility at Trondheim uses chemicals to bind the CO2 in the flue gases before it reaches the chimney and so prevents it reaching the atmosphere. This means steel, fertiliser and cement factories could reduce emissions to zero.

The next stage of the process is more expensive; the carbon has to be separated from the binding chemicals, a process achieved by heat. Costs are reduced if waste heat is used from the industrial processes that produced the carbon in the first place.

The recovered chemicals are then re-used to capture more carbon, and the carbon captured already is piped to a disposal site. The researchers say they know it works because they tested it at six pilot plants in Norway itself, Germany, Scotland and the US, trying 90 different chemical mixtures before finding the best.

Cost-effective

They also found that the same method can be used to create hydrogen from natural gas, capturing the CO2 in the process. The hydrogen is emission-free.

Part of Sintef’s research has involved calculating the costs to global industry of capturing the carbon it produces – US$97 a tonne for coal-fired power stations. This, Sintef says, is far less than the cost to the planet of releasing the carbon into the atmosphere.

Carbon capture from steel and cement works costs less than this because they use waste heat from the plants.

The team have based their figures on the average cost for 600 coal-fired plants, each capturing one million tonnes of CO2 a year, and includes transport and storage costs. They have also tested and developed the best leak-proof pipelines for taking the gas to where it will be injected into the ground for storage.

Soil improver

The cost varies between plants, depending partly on the distance to a suitable storage place, but the scientists say CCS is getting cheaper all the time because it is getting more efficient, and they expect the price will continue to fall.

Currently much of the research is being directed to finding suitable storage sites and making sure that once the carbon is injected into the storage reservoir it stays put.

The second method, Bio-CCS, is simpler and easier. Biological waste, wood chips or manure can be heated for 20 minutes to a temperature of between 500°C and 700°C in the absence of air and turned into charcoal. Bio-carbon, as it is called, is a good soil improver, and the plan is to produce it in small plants on Norwegian farms and spread it on the land. As long as it is not burned, it stays stored in the soil.

By using their simple methods the Norwegians believe that if 4,000 of their farms used the technology, half their agricultural emissions could be eliminated. − Climate News Network

Carbon capture and storage is now proved to work and is essential to prevent global average temperatures exceeding 1.5°C, Norwegian scientists say.

LONDON, 31 October, 2019 − If the world is to avoid dangerous overheating, some climate scientists say, carbon capture and storage (CCS) is essential. But compared with other ways of tackling global heating, it is a method that is developing slowly.

Norway, though, one of the world’s biggest oil producers, has been successfully using carbon capture since 1996. Now, Norwegian scientists say, the rest of the world must learn to do so as quickly as possible, arguing that all large industrial plants could and should capture and store the carbon dioxide they produce before it reaches the atmosphere.

It is a bold claim. Many other scientists insist that CCS − relying on carbon removal and other forms of geo-engineering to bring the temperature down, instead of simply reducing greenhouse gas emissions − can never achieve what is needed, although one US team suggested three years ago that it might well be at least part of the answer.

But the Norwegian researchers, from the independent research organisation Sintef, believe they have the evidence to prove their case. As well as finding how to separate carbon dioxide from electricity production, steel and cement works, they have also developed a separate system, Bio-CCS. This extracts CO2 from the atmosphere and turns it into charcoal before burying it in farmland.

“We cannot manage without CCS. The world must therefore undergo change on a scale we have never seen before, and this is urgent”

Sintef is working with the Norwegian oil industry and some of the other oil majors, including Shell and Total, that are increasingly under pressure to curb their emissions and prevent global average temperatures rising by more than 1.5°C above the pre-industrial level, the internationally agreed limit.

The Norwegians have so far disposed of 23 million tonnes of CO2, pumping it into brine-filled pores in sandstone, called saltwater aquifers, and sealing them with natural caprock, a relatively impervious layer of rock above an oil- or gas-bearing stratum.

The researchers say there is no choice but to adopt carbon capture and storage because turning off the world’s oil supplies immediately is unrealistic: “We cannot manage without CCS. The world must therefore undergo change on a scale we have never seen before, and this is urgent.”

The method of carbon capture developed at the Sintef research facility at Trondheim uses chemicals to bind the CO2 in the flue gases before it reaches the chimney and so prevents it reaching the atmosphere. This means steel, fertiliser and cement factories could reduce emissions to zero.

The next stage of the process is more expensive; the carbon has to be separated from the binding chemicals, a process achieved by heat. Costs are reduced if waste heat is used from the industrial processes that produced the carbon in the first place.

The recovered chemicals are then re-used to capture more carbon, and the carbon captured already is piped to a disposal site. The researchers say they know it works because they tested it at six pilot plants in Norway itself, Germany, Scotland and the US, trying 90 different chemical mixtures before finding the best.

Cost-effective

They also found that the same method can be used to create hydrogen from natural gas, capturing the CO2 in the process. The hydrogen is emission-free.

Part of Sintef’s research has involved calculating the costs to global industry of capturing the carbon it produces – US$97 a tonne for coal-fired power stations. This, Sintef says, is far less than the cost to the planet of releasing the carbon into the atmosphere.

Carbon capture from steel and cement works costs less than this because they use waste heat from the plants.

The team have based their figures on the average cost for 600 coal-fired plants, each capturing one million tonnes of CO2 a year, and includes transport and storage costs. They have also tested and developed the best leak-proof pipelines for taking the gas to where it will be injected into the ground for storage.

Soil improver

The cost varies between plants, depending partly on the distance to a suitable storage place, but the scientists say CCS is getting cheaper all the time because it is getting more efficient, and they expect the price will continue to fall.

Currently much of the research is being directed to finding suitable storage sites and making sure that once the carbon is injected into the storage reservoir it stays put.

The second method, Bio-CCS, is simpler and easier. Biological waste, wood chips or manure can be heated for 20 minutes to a temperature of between 500°C and 700°C in the absence of air and turned into charcoal. Bio-carbon, as it is called, is a good soil improver, and the plan is to produce it in small plants on Norwegian farms and spread it on the land. As long as it is not burned, it stays stored in the soil.

By using their simple methods the Norwegians believe that if 4,000 of their farms used the technology, half their agricultural emissions could be eliminated. − Climate News Network

Tripled climate cuts needed to fulfil pledge

The gap between the world’s greenhouse gas emissions and countries’ planned reductions is growing, and only tripled climate cuts can reduce global warming enough, researchers say.

LONDON, 28 November, 2018 − The world is not yet living up to its undertaking to tackle global warming, and it will have to make tripled climate cuts − at least − if it is to do so, a report says.

The emissions gap − the difference between the global emissions of greenhouse gases scientists expect in 2030 and the level they need to be at to honour the world’s promises to cut them − is the largest ever.

The 2018 Emissions Gap Report is published by the UN Environment Programme (UNEP). While it is still possible to keep global warming below 2°C, its authors say, the world’s current pace of action to cut emissions must triple for that to happen.

In 2015 almost 200 governments adopted the target of keeping global warming to no more than 2°C above pre-industrial levels, and to try for a lower level, 1.5°C. Their decision is set out in the Paris Agreement.

Inadequate targets

But the Gap Report spells out in detail a criticism scientists have been making since soon after the Agreement was reached, saying the current pace of countries’ plans for reducing emissions − which they decide for themselves − is not enough to meet the Paris targets.

As well as allowing signatories the freedom to cut emissions as savagely or as modestly as they wish, the Agreement is also condemned by those who believe its targets are themselves so unrealistic that they fail to measure up to the scale and urgency of the climate crisis.

The combination of increasing greenhouse gas emissions and increasingly inadequate action to slow them means that the emissions gap is bigger than it has ever been.

Meeting the 2°C target will require climate action efforts to triple, the Gap Report says. But to meet the 1.5°C limit, which many governments and scientists are urging, needs nations not just to triple their efforts, but to increase them five-fold.

“The science is clear … governments need to move faster and with greater urgency. We’re feeding this fire while the means to extinguish it are within reach”

Current action to limit emissions suggests that global warming will reach about 3°C above pre-industrial levels by the end of the century, and will continue to rise after that. If the gap is not closed by 2030, the report’s authors say, it is highly unlikely that the 2°C target can be reached.

In 2017 global emissions rose again, after a three-year decrease, as countries’ efforts to combat climate change fell short of what was necessary for global emissions to peak. That year global emissions reached reached 53.5 gigatonnes of carbon dioxide equivalent (GtCO2e), the highest levels yet recorded. Just 57 countries, representing 60% of global emissions, were on track to peak emissions by 2030.

(A gigatonne is a thousand million tonnes. “GtCO2e” is an abbreviation for “gigatonnes of equivalent carbon dioxide” − emissions of various GHGs put on a common footing to express them in terms of the amount of CO2 that would have the same global warming effect.)

The Gap Report has been released just before this year’s UN global climate summit, the 24th Conference of the Parties (COP24) to the UN Framework Convention on Climate Change (UNFCCC) in the Polish city of Katowice.

Critical decade ahead

Two of the contributors are researchers from IIASA, based in Laxenburg, Austria: Joeri Rogelj and Daniel Huppmann.
“This year’s report shows with renewed urgency that emissions reductions in the next decade are critical, and that there are readily available options to achieve this”, said Dr Rogelj.

He is a lead author of the chapter that updated the assessment of the emissions gap, which found that little or no progress had been made in the past year on new policies or more ambitious pledges.

New, more conservative assumptions about the potential contribution of negative emissions technologies (geoengineering) in the future mean that even bigger emissions cuts will be needed.

Dr Huppmann led the year-long effort to compile a large database of emissions scenarios through the IIASA Scenario Explorer. The 2018 Emissions Gap Report draws from this database, first published in Nature Climate Change.

Closing the gap

The report outlines a roadmap which could still meet the Paris Agreement targets and close the emissions gap by 2030. It includes possible contributions by government fiscal policy, the pace of innovation, and a review of climate action by groups other than governments.

If they make commitments to the strongest climate action globally, the authors say, emissions could be cut by 19 GtCO2e, enough to close the 2°C gap.

Governments could subsidise low-emission alternatives and impose higher taxes on fossil fuels. If a carbon price of US$70 a tonne were adopted, emissions could be cut by 40% in some countries.

Removing fossil fuel subsidies would cut global emissions by 10% by 2030, compared with a situation where no climate policies were imposed.

“If the IPCC report represented a global fire alarm, this report is the arson investigation,” said UN Environment’s deputy executive director, Joyce Msuya. “The science is clear; for all the ambitious climate action we’ve seen, governments need to move faster and with greater urgency. We’re feeding this fire while the means to extinguish it are within reach.” − Climate News Network

The gap between the world’s greenhouse gas emissions and countries’ planned reductions is growing, and only tripled climate cuts can reduce global warming enough, researchers say.

LONDON, 28 November, 2018 − The world is not yet living up to its undertaking to tackle global warming, and it will have to make tripled climate cuts − at least − if it is to do so, a report says.

The emissions gap − the difference between the global emissions of greenhouse gases scientists expect in 2030 and the level they need to be at to honour the world’s promises to cut them − is the largest ever.

The 2018 Emissions Gap Report is published by the UN Environment Programme (UNEP). While it is still possible to keep global warming below 2°C, its authors say, the world’s current pace of action to cut emissions must triple for that to happen.

In 2015 almost 200 governments adopted the target of keeping global warming to no more than 2°C above pre-industrial levels, and to try for a lower level, 1.5°C. Their decision is set out in the Paris Agreement.

Inadequate targets

But the Gap Report spells out in detail a criticism scientists have been making since soon after the Agreement was reached, saying the current pace of countries’ plans for reducing emissions − which they decide for themselves − is not enough to meet the Paris targets.

As well as allowing signatories the freedom to cut emissions as savagely or as modestly as they wish, the Agreement is also condemned by those who believe its targets are themselves so unrealistic that they fail to measure up to the scale and urgency of the climate crisis.

The combination of increasing greenhouse gas emissions and increasingly inadequate action to slow them means that the emissions gap is bigger than it has ever been.

Meeting the 2°C target will require climate action efforts to triple, the Gap Report says. But to meet the 1.5°C limit, which many governments and scientists are urging, needs nations not just to triple their efforts, but to increase them five-fold.

“The science is clear … governments need to move faster and with greater urgency. We’re feeding this fire while the means to extinguish it are within reach”

Current action to limit emissions suggests that global warming will reach about 3°C above pre-industrial levels by the end of the century, and will continue to rise after that. If the gap is not closed by 2030, the report’s authors say, it is highly unlikely that the 2°C target can be reached.

In 2017 global emissions rose again, after a three-year decrease, as countries’ efforts to combat climate change fell short of what was necessary for global emissions to peak. That year global emissions reached reached 53.5 gigatonnes of carbon dioxide equivalent (GtCO2e), the highest levels yet recorded. Just 57 countries, representing 60% of global emissions, were on track to peak emissions by 2030.

(A gigatonne is a thousand million tonnes. “GtCO2e” is an abbreviation for “gigatonnes of equivalent carbon dioxide” − emissions of various GHGs put on a common footing to express them in terms of the amount of CO2 that would have the same global warming effect.)

The Gap Report has been released just before this year’s UN global climate summit, the 24th Conference of the Parties (COP24) to the UN Framework Convention on Climate Change (UNFCCC) in the Polish city of Katowice.

Critical decade ahead

Two of the contributors are researchers from IIASA, based in Laxenburg, Austria: Joeri Rogelj and Daniel Huppmann.
“This year’s report shows with renewed urgency that emissions reductions in the next decade are critical, and that there are readily available options to achieve this”, said Dr Rogelj.

He is a lead author of the chapter that updated the assessment of the emissions gap, which found that little or no progress had been made in the past year on new policies or more ambitious pledges.

New, more conservative assumptions about the potential contribution of negative emissions technologies (geoengineering) in the future mean that even bigger emissions cuts will be needed.

Dr Huppmann led the year-long effort to compile a large database of emissions scenarios through the IIASA Scenario Explorer. The 2018 Emissions Gap Report draws from this database, first published in Nature Climate Change.

Closing the gap

The report outlines a roadmap which could still meet the Paris Agreement targets and close the emissions gap by 2030. It includes possible contributions by government fiscal policy, the pace of innovation, and a review of climate action by groups other than governments.

If they make commitments to the strongest climate action globally, the authors say, emissions could be cut by 19 GtCO2e, enough to close the 2°C gap.

Governments could subsidise low-emission alternatives and impose higher taxes on fossil fuels. If a carbon price of US$70 a tonne were adopted, emissions could be cut by 40% in some countries.

Removing fossil fuel subsidies would cut global emissions by 10% by 2030, compared with a situation where no climate policies were imposed.

“If the IPCC report represented a global fire alarm, this report is the arson investigation,” said UN Environment’s deputy executive director, Joyce Msuya. “The science is clear; for all the ambitious climate action we’ve seen, governments need to move faster and with greater urgency. We’re feeding this fire while the means to extinguish it are within reach.” − Climate News Network

New plane can show geoengineering works

With new aircraft, humans could potentially mimic volcanic action, dim the sunlight and slow global warming, showing that geoengineering works. It’s a controversial idea.

LONDON, 26 November, 2018 – Nobody knows for sure whether we shall ever see if geoengineering works. But now somebody knows how to do it.

Engineers have designed an aircraft that could lift a cargo of sulphur dioxide to an altitude of 20 kilometres and spray it into the stratosphere to darken the skies, dim the sunlight and damp down climate change driven by emissions from factory chimneys, power stations and vehicle exhausts.

The aircraft – already dubbed SAIL, or the stratospheric aerosol injection lofter, could cost no more than $2.35 billion a year for airframe and engine, and the first eight could be rolling down the runway 15 years from now to begin flying 4,000 missions a year. By the end of another 15 years, a fleet of 100 high-flying sulphate dumpsters could be in business, making 60,000 high altitude deliveries a year to combat global warming.

US scientists report in the journal Environmental Research Letters that they addressed the costs and practicalities of what is certainly the most-frequently invoked and hotly disputed form of climate engineering on a global scale.

Possible catastrophe

It is considered necessary because, if humans go on burning fossil fuels at the present rates, greenhouse gas build-up in the atmosphere could increase planetary average temperatures to a catastrophic 3°C or more by 2100.

Darkened skies do lower planetary temperatures: violent volcanic eruptions have in recent history injected cubic kilometres of fine ash, smoke and sulphur into the upper atmosphere on scales that lower global average temperatures measurably.

For more than a decade, researchers have argued that – since humankind collectively still shows no great sign of drastically reducing greenhouse gas emissions – some radical form of solar geoengineering might be necessary. Others have opposed the case, citing possible unwelcome consequences.

But the first question was: could it be done at all? The latest answer is that it can, but not with existing hardware.

“This plan is a distraction that may well encourage weaker action on emissions reduction by governments in the hope they will no longer be necessary”

“While we don’t make any judgment about the desirability of SAI, we do show that a hypothetical deployment programme, starting 15 years from now, while both highly uncertain and ambitious, would be technically possible from an engineering perspective,” said Gernot Wagner, of Harvard University.

“It would also be remarkably inexpensive, at an average of around $2 bn to $2.5 bn per year over the first 15 years.”

His co-author Wake Smith, who moved from the aviation business to lecture at Yale College, and who led the study, said he had become intrigued by research that suggested that existing aircraft could be modified to lift huge quantities of sulphur dioxide to great heights, and then release it.

“Turns out that is not so,” he said. “It would indeed take an entirely new plane design to do SAI under reasonable albeit entirely hypothetical parameters. No existing aircraft has the combination of altitude and payload capabilities required.”

Detailed design

The scientists outlined a solution: it had the same weight as a large, narrow-bodied jet passenger aircraft. But to sustain level flight at 20kms, it needed roughly double the wing surface of such an airliner, and double the thrust, with four engines rather than two. “At the same time, its fuselage would be stubby and narrow, sized to accommodate a heavy but dense mass of molten sulphur rather than the large volume of space and air required for passengers,” Mr Smith said.

They then calculated the rate at which such planes could be built, and the numbers needed to make a significant difference to global warming. Global projects on such a scale need international agreement, and the two authors rule out the possibility that any individual nation could hope to secretly operate such a high-flying programme, involving so many flights, without detection. But they do not see it as excessively costly.

“Given the potential benefits of halving average projected increases to radiative forcing from a particular date onward, these numbers invoke the ‘incredible economics’ of solar geoengineering,” Dr Wagner said. “Dozens of countries could fund such a programme, and the required technology is not particularly exotic.”

Political tensions

But solar radiation management or SRM – the catch-all term for any plans to cool the world by dimming the sunlight, rather than reducing greenhouse gas emissions – remains politically fraught, and in any case an incomplete answer: it would, for instance, do nothing to slow the increasing acidification of the world’s oceans, and it could seriously affect rainfall patterns in so far unpredictable ways.

The world has already warmed by 1°C in the last century. In Paris in 2015 the nations of almost the entire world agreed to try to contain global warming to 1.5°C if at all possible. And the world now has only about a dozen years to make this happen.

“Why then set out a plan to implement solar radiation management from a date 15 years hence? This plan is a distraction that may well encourage weaker action on emissions reduction by governments in the hope they will no longer be necessary”, said Joanna Haigh, co-director of the Grantham Institute for Climate Change at Imperial College in the UK.

“Previously, proponents of SRM have suggested that it be used to delay the onset of the inevitable warming arising from human greenhouse gas emissions. This paper, however, seems to suggest that the implementation should be ongoing. Forever?” – Climate News Network

With new aircraft, humans could potentially mimic volcanic action, dim the sunlight and slow global warming, showing that geoengineering works. It’s a controversial idea.

LONDON, 26 November, 2018 – Nobody knows for sure whether we shall ever see if geoengineering works. But now somebody knows how to do it.

Engineers have designed an aircraft that could lift a cargo of sulphur dioxide to an altitude of 20 kilometres and spray it into the stratosphere to darken the skies, dim the sunlight and damp down climate change driven by emissions from factory chimneys, power stations and vehicle exhausts.

The aircraft – already dubbed SAIL, or the stratospheric aerosol injection lofter, could cost no more than $2.35 billion a year for airframe and engine, and the first eight could be rolling down the runway 15 years from now to begin flying 4,000 missions a year. By the end of another 15 years, a fleet of 100 high-flying sulphate dumpsters could be in business, making 60,000 high altitude deliveries a year to combat global warming.

US scientists report in the journal Environmental Research Letters that they addressed the costs and practicalities of what is certainly the most-frequently invoked and hotly disputed form of climate engineering on a global scale.

Possible catastrophe

It is considered necessary because, if humans go on burning fossil fuels at the present rates, greenhouse gas build-up in the atmosphere could increase planetary average temperatures to a catastrophic 3°C or more by 2100.

Darkened skies do lower planetary temperatures: violent volcanic eruptions have in recent history injected cubic kilometres of fine ash, smoke and sulphur into the upper atmosphere on scales that lower global average temperatures measurably.

For more than a decade, researchers have argued that – since humankind collectively still shows no great sign of drastically reducing greenhouse gas emissions – some radical form of solar geoengineering might be necessary. Others have opposed the case, citing possible unwelcome consequences.

But the first question was: could it be done at all? The latest answer is that it can, but not with existing hardware.

“This plan is a distraction that may well encourage weaker action on emissions reduction by governments in the hope they will no longer be necessary”

“While we don’t make any judgment about the desirability of SAI, we do show that a hypothetical deployment programme, starting 15 years from now, while both highly uncertain and ambitious, would be technically possible from an engineering perspective,” said Gernot Wagner, of Harvard University.

“It would also be remarkably inexpensive, at an average of around $2 bn to $2.5 bn per year over the first 15 years.”

His co-author Wake Smith, who moved from the aviation business to lecture at Yale College, and who led the study, said he had become intrigued by research that suggested that existing aircraft could be modified to lift huge quantities of sulphur dioxide to great heights, and then release it.

“Turns out that is not so,” he said. “It would indeed take an entirely new plane design to do SAI under reasonable albeit entirely hypothetical parameters. No existing aircraft has the combination of altitude and payload capabilities required.”

Detailed design

The scientists outlined a solution: it had the same weight as a large, narrow-bodied jet passenger aircraft. But to sustain level flight at 20kms, it needed roughly double the wing surface of such an airliner, and double the thrust, with four engines rather than two. “At the same time, its fuselage would be stubby and narrow, sized to accommodate a heavy but dense mass of molten sulphur rather than the large volume of space and air required for passengers,” Mr Smith said.

They then calculated the rate at which such planes could be built, and the numbers needed to make a significant difference to global warming. Global projects on such a scale need international agreement, and the two authors rule out the possibility that any individual nation could hope to secretly operate such a high-flying programme, involving so many flights, without detection. But they do not see it as excessively costly.

“Given the potential benefits of halving average projected increases to radiative forcing from a particular date onward, these numbers invoke the ‘incredible economics’ of solar geoengineering,” Dr Wagner said. “Dozens of countries could fund such a programme, and the required technology is not particularly exotic.”

Political tensions

But solar radiation management or SRM – the catch-all term for any plans to cool the world by dimming the sunlight, rather than reducing greenhouse gas emissions – remains politically fraught, and in any case an incomplete answer: it would, for instance, do nothing to slow the increasing acidification of the world’s oceans, and it could seriously affect rainfall patterns in so far unpredictable ways.

The world has already warmed by 1°C in the last century. In Paris in 2015 the nations of almost the entire world agreed to try to contain global warming to 1.5°C if at all possible. And the world now has only about a dozen years to make this happen.

“Why then set out a plan to implement solar radiation management from a date 15 years hence? This plan is a distraction that may well encourage weaker action on emissions reduction by governments in the hope they will no longer be necessary”, said Joanna Haigh, co-director of the Grantham Institute for Climate Change at Imperial College in the UK.

“Previously, proponents of SRM have suggested that it be used to delay the onset of the inevitable warming arising from human greenhouse gas emissions. This paper, however, seems to suggest that the implementation should be ongoing. Forever?” – Climate News Network

Geoengineering is no closer to working

Humans cannot expect a safer, cooler world from geoengineering. The only sure way to slow dangerous global warming and climate change is to cut greenhouse gas emissions.

LONDON, 30 October, 2018 – Scientists have established a strategic error in one version of the climate change debate: they still say geoengineering is no guarantee of a cooler world.

There is no practical technology available to cool the Earth, they say – except the obvious one of ceasing to stoke the fires with fossil fuels.

One new study looks at all the tested and yet-to-be-explored mechanisms for either lowering global temperatures by reducing sunlight, or by harnessing new and old ways to capture the extra carbon dioxide released by two centuries of industrial growth.

And, the authors report, the sure way to reduce the dangers of global warming and keep the planetary temperature increase to 2°C or lower by 2100 is to switch to wind and solar energy sources and drastically cut fossil fuel emissions.

A second, separate study looks closely at an often-proposed form of geoengineering – the injection of sulphate aerosols into the stratosphere to intercept sunlight and shade the planet – and delivers a cautious verdict.

“None of the proposed technologies can realistically be implemented on a global scale in the next few decades”

Yes, it might reduce planetary surface warming. But the same technology could lead to continued ocean warming and ever-faster loss of the ice caps.

Geoengineering – the technological fix that would permit humans to go on burning coal, oil and natural gas – has been repeatedly dismissed as an answer by successive teams of researchers: either the outcome is uncertain, or the consequences potentially hazardous or politically dangerous.

European climate scientists report in the journal Nature Communications that they looked at the goals of the Paris Agreement – in which 195 nations in Paris in 2015 vowed to limit global warming to “well below” 2°C and if possible 1.5°C above the average for most of recorded human history – and came to a simple answer: no proposed technological solution could make much difference to global warming, without also the impact of drastic cuts in greenhouse gas emissions.

Plans to sow the soil with biochar as a form of carbon storage were probably impractical on any scale. Massive planting of trees to draw down carbon from the atmosphere might not work as planned. The addition of nutrients to spur phytoplankton blooms in the oceans would disrupt natural nutrient cycles and might increase the emissions of another greenhouse gas, nitrous oxide. Plans to capture carbon directly from the air could be ferociously expensive – because humans released 40 billion tonnes of carbon dioxide from fossil fuels in 2017.

No significant contribution

“None of the proposed technologies can realistically be implemented on a global scale in the next few decades. In other words, we can’t rely on these technologies to make any significant contribution to holding the average temperature increase under the 2°C limit, much less the 1.5°C limit”, said Mark Lawrence, scientific director of the Institute for Advanced Sustainability Studies in Potsdam, Germany, who led the research.

And scientists at the US National Centre for Atmospheric Research in Boulder, Colorado took a close look at perhaps the most-studied and much-disputed proposal to engineer the climate: the injection of sulphate aerosols into the upper atmosphere to reduce incoming radiation.

This is in one sense nature’s way to cool down the planet a little: it happened, for instance, after the eruption of Mt Pinatubo in the Philippines in 1991 hurled enough ash into the stratosphere to lower planetary temperatures by 0.5°C for about two years.

And, the scientists report in Nature Geoscience, one version of the proposal could be made to work, and computer modelling predicted that it would minimise changes in the planetary surface temperature.

Seas to rise

But it would also accelerate the Atlantic meridional overturning circulation – a powerful force at work in the ocean – and lead to continued warming of the deep, and of the polar oceans.

So the ice caps would go on melting, and sea levels would rise. There would be unpredictable changes in the Indian, South American and African rainy seasons and in hurricane activity.

“Considerable uncertainty therefore surrounds the potential impacts of such shifts, and the relative magnitude of such impacts to those where geoengineering is not implemented”, they write.

They say their study highlights the need to better understand the risks of such actions, along with the sheer complexity of the planetary climate machine and “the need to better develop our understanding of the climate system before the character of a geoengineered climate can be estimated with confidence.” – Climate News Network

Humans cannot expect a safer, cooler world from geoengineering. The only sure way to slow dangerous global warming and climate change is to cut greenhouse gas emissions.

LONDON, 30 October, 2018 – Scientists have established a strategic error in one version of the climate change debate: they still say geoengineering is no guarantee of a cooler world.

There is no practical technology available to cool the Earth, they say – except the obvious one of ceasing to stoke the fires with fossil fuels.

One new study looks at all the tested and yet-to-be-explored mechanisms for either lowering global temperatures by reducing sunlight, or by harnessing new and old ways to capture the extra carbon dioxide released by two centuries of industrial growth.

And, the authors report, the sure way to reduce the dangers of global warming and keep the planetary temperature increase to 2°C or lower by 2100 is to switch to wind and solar energy sources and drastically cut fossil fuel emissions.

A second, separate study looks closely at an often-proposed form of geoengineering – the injection of sulphate aerosols into the stratosphere to intercept sunlight and shade the planet – and delivers a cautious verdict.

“None of the proposed technologies can realistically be implemented on a global scale in the next few decades”

Yes, it might reduce planetary surface warming. But the same technology could lead to continued ocean warming and ever-faster loss of the ice caps.

Geoengineering – the technological fix that would permit humans to go on burning coal, oil and natural gas – has been repeatedly dismissed as an answer by successive teams of researchers: either the outcome is uncertain, or the consequences potentially hazardous or politically dangerous.

European climate scientists report in the journal Nature Communications that they looked at the goals of the Paris Agreement – in which 195 nations in Paris in 2015 vowed to limit global warming to “well below” 2°C and if possible 1.5°C above the average for most of recorded human history – and came to a simple answer: no proposed technological solution could make much difference to global warming, without also the impact of drastic cuts in greenhouse gas emissions.

Plans to sow the soil with biochar as a form of carbon storage were probably impractical on any scale. Massive planting of trees to draw down carbon from the atmosphere might not work as planned. The addition of nutrients to spur phytoplankton blooms in the oceans would disrupt natural nutrient cycles and might increase the emissions of another greenhouse gas, nitrous oxide. Plans to capture carbon directly from the air could be ferociously expensive – because humans released 40 billion tonnes of carbon dioxide from fossil fuels in 2017.

No significant contribution

“None of the proposed technologies can realistically be implemented on a global scale in the next few decades. In other words, we can’t rely on these technologies to make any significant contribution to holding the average temperature increase under the 2°C limit, much less the 1.5°C limit”, said Mark Lawrence, scientific director of the Institute for Advanced Sustainability Studies in Potsdam, Germany, who led the research.

And scientists at the US National Centre for Atmospheric Research in Boulder, Colorado took a close look at perhaps the most-studied and much-disputed proposal to engineer the climate: the injection of sulphate aerosols into the upper atmosphere to reduce incoming radiation.

This is in one sense nature’s way to cool down the planet a little: it happened, for instance, after the eruption of Mt Pinatubo in the Philippines in 1991 hurled enough ash into the stratosphere to lower planetary temperatures by 0.5°C for about two years.

And, the scientists report in Nature Geoscience, one version of the proposal could be made to work, and computer modelling predicted that it would minimise changes in the planetary surface temperature.

Seas to rise

But it would also accelerate the Atlantic meridional overturning circulation – a powerful force at work in the ocean – and lead to continued warming of the deep, and of the polar oceans.

So the ice caps would go on melting, and sea levels would rise. There would be unpredictable changes in the Indian, South American and African rainy seasons and in hurricane activity.

“Considerable uncertainty therefore surrounds the potential impacts of such shifts, and the relative magnitude of such impacts to those where geoengineering is not implemented”, they write.

They say their study highlights the need to better understand the risks of such actions, along with the sheer complexity of the planetary climate machine and “the need to better develop our understanding of the climate system before the character of a geoengineered climate can be estimated with confidence.” – Climate News Network

Underwater walls might avert sea level rise

Could a vast underwater wall in front of an unstable glacier prevent dangerous sea level rise? Or should everyone just move further inland?

LONDON, 10 October, 2018 – Two climate scientists believe they have a long-term solution to dangerous sea level rise by targeting the most vulnerable glaciers, especially those that could trigger a massive collapse of the ice sheets behind them.

A submarine wall big enough and wide enough could halt the flow of increasingly warm ocean water below the front of each glacier. The combination of warmer air temperatures and warmer waters that accompany human-triggered climate change is dangerous: it could for instance accelerate the already alarming retreat of the Thwaites Glacier in West Antarctica, which alone shores up enough ice to raise global sea levels by up to 3 metres.

The scientists don’t propose an immediate start. But they do want to explore ways of halting sea level rise driven by global warming that could soon be costing the world $50 trillion a year in economic losses, that could submerge small island states and turn 1 million people a year into climate migrants.

“We are not advocating that glacial geoengineering be attempted any time soon”, they warn in the journal The Cryosphere.

Their simplest option – a series of pillars to shore up a targeted glacier and keep it “grounded” – would require engineering comparable in scale to the excavation of the Suez canal, would be undertaken in the world’s harshest environment, and would have just a one in three chance of success.

“In the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse”

The researchers – John Moore, of Beijing Normal University in China, who also holds a post at the University of Lapland in Finland, and Michael Wolovick, of Princeton University in the US – have made this case before: they and others argued in March in Nature for what they call “managed collapse.”

In the latest study, they look at the challenge in greater detail. And they warn that even if targeted geoengineering of individual glaciers worked, it would only do so if humans stopped tipping ever more greenhouse gases into the atmosphere to fuel yet more global warming.

Nor do they argue that a submarine curtain wall to halt warming water across the front of the Thwaites glacier – up to 100 kms wide – is currently feasible. “But in the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse.”

And one of these is the Thwaites Glacier in Antarctica: another is the Jakobshaven Isbrae in Greenland. Both could be cases of what the scientists call marine ice sheet instability: as a glacier retreats from its grounding line, the ice lifts off the bedrock and begins to float.

If the bedrock slopes down towards the centre of the ice sheet, and warmer ocean currents wash beneath it, then the ice starts to stretch and thin, and retreat further. At some point, it would become much easier for thawing ice to flow into the sea, and start what could become a runaway collapse. Engineers could devise a way of slowing or halting the process.

Huge impact

The scientists argue that even a rise of 0.6m to 1.2 metres by 2100 could cause up to $50 trillion in economic damage, and the resultant flooding could force up to 200 million to 500 million people out of their homes at least for a few days or weeks: around a million or so every year would never go back.

Climate scientists have been arguing about geoengineering solutions – the so-called technofix – to climate change for more than a decade. Global answers, such as blocking sunlight with stratospheric soot and sulphate aerosols, or whitening the polar ice to make it more reflective, remain contentious.

But the Cryosphere proposals are much more limited, and the immediate dangers of sea level rise are not contested. Ice sheet collapse in Antarctica, for instance, could raise sea levels by more than 3 metres and even by as much as 19 metres over the next two or three centuries.

The researchers’ calculations suggest that in theory an engineering solution that blocked even 50% of the warm water getting under a glacier could offer a 70% chance of delaying or stopping ice sheet collapse.

Left behind

Countries already spend on coastal protection: their solution would require international co-operation at the highest political level, and intensive scientific research.

“Managing sea level rise at the source has the advantage of benefiting the entire world, while a strategy that relies only on local coastal protection is more of an every-nation-for-itself approach that may leave many poor countries behind,” they write.

“Perhaps, after careful consideration, we may conclude that glacial geoengineering is unworkable and the right answer is to invest heavily in coastal protection and retreat inland where that is not practical or economical.

“However, we owe it to the 400 million people who live within 5m of sea level to at least consider the alternatives.” – Climate News Network

Could a vast underwater wall in front of an unstable glacier prevent dangerous sea level rise? Or should everyone just move further inland?

LONDON, 10 October, 2018 – Two climate scientists believe they have a long-term solution to dangerous sea level rise by targeting the most vulnerable glaciers, especially those that could trigger a massive collapse of the ice sheets behind them.

A submarine wall big enough and wide enough could halt the flow of increasingly warm ocean water below the front of each glacier. The combination of warmer air temperatures and warmer waters that accompany human-triggered climate change is dangerous: it could for instance accelerate the already alarming retreat of the Thwaites Glacier in West Antarctica, which alone shores up enough ice to raise global sea levels by up to 3 metres.

The scientists don’t propose an immediate start. But they do want to explore ways of halting sea level rise driven by global warming that could soon be costing the world $50 trillion a year in economic losses, that could submerge small island states and turn 1 million people a year into climate migrants.

“We are not advocating that glacial geoengineering be attempted any time soon”, they warn in the journal The Cryosphere.

Their simplest option – a series of pillars to shore up a targeted glacier and keep it “grounded” – would require engineering comparable in scale to the excavation of the Suez canal, would be undertaken in the world’s harshest environment, and would have just a one in three chance of success.

“In the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse”

The researchers – John Moore, of Beijing Normal University in China, who also holds a post at the University of Lapland in Finland, and Michael Wolovick, of Princeton University in the US – have made this case before: they and others argued in March in Nature for what they call “managed collapse.”

In the latest study, they look at the challenge in greater detail. And they warn that even if targeted geoengineering of individual glaciers worked, it would only do so if humans stopped tipping ever more greenhouse gases into the atmosphere to fuel yet more global warming.

Nor do they argue that a submarine curtain wall to halt warming water across the front of the Thwaites glacier – up to 100 kms wide – is currently feasible. “But in the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse.”

And one of these is the Thwaites Glacier in Antarctica: another is the Jakobshaven Isbrae in Greenland. Both could be cases of what the scientists call marine ice sheet instability: as a glacier retreats from its grounding line, the ice lifts off the bedrock and begins to float.

If the bedrock slopes down towards the centre of the ice sheet, and warmer ocean currents wash beneath it, then the ice starts to stretch and thin, and retreat further. At some point, it would become much easier for thawing ice to flow into the sea, and start what could become a runaway collapse. Engineers could devise a way of slowing or halting the process.

Huge impact

The scientists argue that even a rise of 0.6m to 1.2 metres by 2100 could cause up to $50 trillion in economic damage, and the resultant flooding could force up to 200 million to 500 million people out of their homes at least for a few days or weeks: around a million or so every year would never go back.

Climate scientists have been arguing about geoengineering solutions – the so-called technofix – to climate change for more than a decade. Global answers, such as blocking sunlight with stratospheric soot and sulphate aerosols, or whitening the polar ice to make it more reflective, remain contentious.

But the Cryosphere proposals are much more limited, and the immediate dangers of sea level rise are not contested. Ice sheet collapse in Antarctica, for instance, could raise sea levels by more than 3 metres and even by as much as 19 metres over the next two or three centuries.

The researchers’ calculations suggest that in theory an engineering solution that blocked even 50% of the warm water getting under a glacier could offer a 70% chance of delaying or stopping ice sheet collapse.

Left behind

Countries already spend on coastal protection: their solution would require international co-operation at the highest political level, and intensive scientific research.

“Managing sea level rise at the source has the advantage of benefiting the entire world, while a strategy that relies only on local coastal protection is more of an every-nation-for-itself approach that may leave many poor countries behind,” they write.

“Perhaps, after careful consideration, we may conclude that glacial geoengineering is unworkable and the right answer is to invest heavily in coastal protection and retreat inland where that is not practical or economical.

“However, we owe it to the 400 million people who live within 5m of sea level to at least consider the alternatives.” – Climate News Network

Forests cut warming better than technology

Biofuels are no easy answer to climate change. Nor is storing captured carbon dioxide. The world’s great forests cut warming better than engineered solutions can.

LONDON, 11 September, 2018 – Simple solutions are often the best, and British and European climate scientists have identified one: forests cut warming better than the technological solutions now being widely canvassed.

They have established some simple ground rules for limiting global warming to the international target of an average rise of no more than 1.5°C by 2100.

Rule one: do not try to generate electric power with biofuels made from harvested crops, trees or grasses, and do not spend even more money trying to capture the carbon dioxide emissions, liquefy them and bury them deep underground. To do so successfully would require at least 380 million and maybe up to 700 million hectares of farmland.

This is about half of the space already needed to grow food for more than 7 billion humans.

Rule two: do preserve and regenerate the world’s forests. They already capture the greenhouse gas carbon dioxide and preserve it as root and branch. Yet more intact forest would be even more effective.

“We need to both drastically reduce emissions and employ a mix of technologies to remove carbon dioxide from the atmosphere. There is no single get-out-of-jail-free card.”

In effect, the scientists have told the Intergovernmental Panel on Climate Change (IPCC), and the 195 governments that agreed in Paris in 2015 on a target to contain climate change to “well below 2°C” that one favoured strategy – biomass energy matched with carbon capture and storage, or BECCS in shorthand – would be in many cases a waste of time and, even more importantly, space.

“The vast majority of IPCC scenarios for how we can limit global warming to less than 2°C include BECCS,” said Anna Harper, a mathematician at the University of Exeter in the UK. “But the land required to grow biomass in these scenarios would be twice the size of India.”

She and colleagues report in the journal Nature Communications that they used a computer simulation of the world’s vegetation and soil and tested it with a series of scenarios that might keep global average temperatures to either 2°C or 1.5°C above pre-industrial levels. Since the start of the Industrial Revolution two centuries ago, global average temperatures have already risen about 1°C.

The computer models delivered an answer: to switch to crop biomass and carbon capture on a global scale would actually lead to an increase of carbon in the atmosphere, to ramp up global warming even further, and precipitate what could be, for many, catastrophic climate change.

The researchers don’t dismiss the biofuel technology entirely: in some cases it might be an effective solution. But, overall, it would be better simply to protect and restore the world’s forests.

Forests at risk

That forests are vital components of climate stability is already accepted: the Paris Agreement recognised the need, and repeated research has confirmed the logic.

But global studies have also confirmed that the world’s intact forests are threatened with accelerating destruction both through human degradation and through climate extremes of heat, drought and flood.

Biofuels – generated from fields of sugar cane, maize, trees or grasses such as miscanthus – are already big agribusiness, but both environmental campaigners and climate scientists are concerned about their effectiveness in reducing greenhouse gas emissions and about their potential impact on food prices.

Carbon capture and storage is a technology that has yet to prove itself.

“To meet the climate change targets from the Paris Agreement, we need to both drastically reduce emissions and employ a mix of technologies to remove carbon dioxide from the atmosphere,” said Dr Harper. “There is no single get-out-of-jail-free card.” – Climate News Network

Biofuels are no easy answer to climate change. Nor is storing captured carbon dioxide. The world’s great forests cut warming better than engineered solutions can.

LONDON, 11 September, 2018 – Simple solutions are often the best, and British and European climate scientists have identified one: forests cut warming better than the technological solutions now being widely canvassed.

They have established some simple ground rules for limiting global warming to the international target of an average rise of no more than 1.5°C by 2100.

Rule one: do not try to generate electric power with biofuels made from harvested crops, trees or grasses, and do not spend even more money trying to capture the carbon dioxide emissions, liquefy them and bury them deep underground. To do so successfully would require at least 380 million and maybe up to 700 million hectares of farmland.

This is about half of the space already needed to grow food for more than 7 billion humans.

Rule two: do preserve and regenerate the world’s forests. They already capture the greenhouse gas carbon dioxide and preserve it as root and branch. Yet more intact forest would be even more effective.

“We need to both drastically reduce emissions and employ a mix of technologies to remove carbon dioxide from the atmosphere. There is no single get-out-of-jail-free card.”

In effect, the scientists have told the Intergovernmental Panel on Climate Change (IPCC), and the 195 governments that agreed in Paris in 2015 on a target to contain climate change to “well below 2°C” that one favoured strategy – biomass energy matched with carbon capture and storage, or BECCS in shorthand – would be in many cases a waste of time and, even more importantly, space.

“The vast majority of IPCC scenarios for how we can limit global warming to less than 2°C include BECCS,” said Anna Harper, a mathematician at the University of Exeter in the UK. “But the land required to grow biomass in these scenarios would be twice the size of India.”

She and colleagues report in the journal Nature Communications that they used a computer simulation of the world’s vegetation and soil and tested it with a series of scenarios that might keep global average temperatures to either 2°C or 1.5°C above pre-industrial levels. Since the start of the Industrial Revolution two centuries ago, global average temperatures have already risen about 1°C.

The computer models delivered an answer: to switch to crop biomass and carbon capture on a global scale would actually lead to an increase of carbon in the atmosphere, to ramp up global warming even further, and precipitate what could be, for many, catastrophic climate change.

The researchers don’t dismiss the biofuel technology entirely: in some cases it might be an effective solution. But, overall, it would be better simply to protect and restore the world’s forests.

Forests at risk

That forests are vital components of climate stability is already accepted: the Paris Agreement recognised the need, and repeated research has confirmed the logic.

But global studies have also confirmed that the world’s intact forests are threatened with accelerating destruction both through human degradation and through climate extremes of heat, drought and flood.

Biofuels – generated from fields of sugar cane, maize, trees or grasses such as miscanthus – are already big agribusiness, but both environmental campaigners and climate scientists are concerned about their effectiveness in reducing greenhouse gas emissions and about their potential impact on food prices.

Carbon capture and storage is a technology that has yet to prove itself.

“To meet the climate change targets from the Paris Agreement, we need to both drastically reduce emissions and employ a mix of technologies to remove carbon dioxide from the atmosphere,” said Dr Harper. “There is no single get-out-of-jail-free card.” – Climate News Network

Carbon removal is not enough to save climate

Carbon removal from the atmosphere cannot match reducing emissions of greenhouse gases as a way of slowing global warming, US analysts say.

LONDON, 10 September, 2018 – New studies from the US provide an answer to one of the thorniest questions facing climate policymakers: carbon removal will not replace stringent reductions in greenhouse gas emissions enough, they say, to avert the threat of global warming.

In a world making (so far) only halting progress to cut the pollutants that heat the planet through reducing emissions there is support for a different approach, using carbon removal and other forms of geo-engineering rather than emission cuts to remove the pollution already in the atmosphere, the oceans and the biosphere.

If we can be certain the gains will exceed the risks, then geoengineering might even let us avoid any need to cut fossil fuel emissions at all, its enthusiasts say. Could it really be the future?

Among all the uncertainties, few have stuck their necks out decisively either for or against carbon removal as the answer to warming – until now. But reports by a group of US analysts have changed that.

Carbon removal, they say, cannot on its own provide the answer, nor is it likely to do so. It may have a part to play in tackling the climate crisis, but there is no evidence that it will ever be able to replace emission reductions.

“There is no evidence that carbon removal could serve as a viable alternative to emissions reduction”

On 8 October the Intergovernmental Panel on Climate Change (IPCC) is due to publish a report, Global Warming of 1.5ºC (the Paris Agreement on climate change calls for the temperature increase caused by climate change to be kept to a maximum of 1.5°C).

The IPCC is expected to say that to avoid dangerous levels of global warming the world must couple a rapid shift to a low carbon economy with efforts to capture and store some of the carbon already released.

So the analysts, from the World Resources Institute, are making a significant contribution to the debate. Their language is judicious, many of their judgments are carefully hedged, but their conclusion that simply trying to engineer our way out of trouble is not an option will carry considerable weight.

They explain their thinking in three research papers, focused on the US. One tackles what WRI calls “the big foundational questions” (for example, is carbon removal mission-critical, or simply a distraction?).

Other approaches

Another examines land management approaches and implications for forests and agriculture, while the third explores emerging technological solutions designed to remove billions of tonnes of carbon dioxide a year from the  atmosphere.

This paper also explores other possible ,approaches for carbon removal in the US, including bioenergy with carbon capture and storage (BECCS); direct air capture and storage (DACS); and several emerging technologies, including biochar, plant selection or engineering, enhanced weathering, and seawater capture.

The land management paper explores possible approaches for US carbon removal. The authors say there is untapped potential to increase removal in America’s forests and farms. But using these approaches on a large scale will mean addressing issues such as scientific uncertainty, and ways to encourage landowners to adopt new methods.

The paper on foundational questions says many possible approaches to large-scale carbon removal hold promise “but also face challenges and limitations”.

New resources

More widely, the authors write: “Although carbon removal has raised some concerns about the degree to which it might detract from ongoing efforts to reduce emissions, it has the potential to broaden the public policy agenda on climate change in ways that bring additional stakeholders and resources to the table”.

One concern they address is the question of who would control the technologies which some approaches   would need, a conundrum preoccupying many scientists. Others make the point that carbon removal may often prove a double-edged sword, offering both benefits and risks. For all that, some studies show that, in principle anyway, the concept works. And at least one group of scientists has found that carbon dioxide can yield a new fuel able to slow climate change.

But the WRI team’s conclusion appears definitive in a way few previous analysts have been able to reach. They say that emissions cuts must remain the main way humans tackle the climate crisis.

“For carbon removal to play a meaningful role in stabilising the climate, it must supplement, not become a substitute for, deep decarbonisation of the economy. There is no evidence that carbon removal could serve as a viable alternative to emissions reduction.” – Climate News Network

Carbon removal from the atmosphere cannot match reducing emissions of greenhouse gases as a way of slowing global warming, US analysts say.

LONDON, 10 September, 2018 – New studies from the US provide an answer to one of the thorniest questions facing climate policymakers: carbon removal will not replace stringent reductions in greenhouse gas emissions enough, they say, to avert the threat of global warming.

In a world making (so far) only halting progress to cut the pollutants that heat the planet through reducing emissions there is support for a different approach, using carbon removal and other forms of geo-engineering rather than emission cuts to remove the pollution already in the atmosphere, the oceans and the biosphere.

If we can be certain the gains will exceed the risks, then geoengineering might even let us avoid any need to cut fossil fuel emissions at all, its enthusiasts say. Could it really be the future?

Among all the uncertainties, few have stuck their necks out decisively either for or against carbon removal as the answer to warming – until now. But reports by a group of US analysts have changed that.

Carbon removal, they say, cannot on its own provide the answer, nor is it likely to do so. It may have a part to play in tackling the climate crisis, but there is no evidence that it will ever be able to replace emission reductions.

“There is no evidence that carbon removal could serve as a viable alternative to emissions reduction”

On 8 October the Intergovernmental Panel on Climate Change (IPCC) is due to publish a report, Global Warming of 1.5ºC (the Paris Agreement on climate change calls for the temperature increase caused by climate change to be kept to a maximum of 1.5°C).

The IPCC is expected to say that to avoid dangerous levels of global warming the world must couple a rapid shift to a low carbon economy with efforts to capture and store some of the carbon already released.

So the analysts, from the World Resources Institute, are making a significant contribution to the debate. Their language is judicious, many of their judgments are carefully hedged, but their conclusion that simply trying to engineer our way out of trouble is not an option will carry considerable weight.

They explain their thinking in three research papers, focused on the US. One tackles what WRI calls “the big foundational questions” (for example, is carbon removal mission-critical, or simply a distraction?).

Other approaches

Another examines land management approaches and implications for forests and agriculture, while the third explores emerging technological solutions designed to remove billions of tonnes of carbon dioxide a year from the  atmosphere.

This paper also explores other possible ,approaches for carbon removal in the US, including bioenergy with carbon capture and storage (BECCS); direct air capture and storage (DACS); and several emerging technologies, including biochar, plant selection or engineering, enhanced weathering, and seawater capture.

The land management paper explores possible approaches for US carbon removal. The authors say there is untapped potential to increase removal in America’s forests and farms. But using these approaches on a large scale will mean addressing issues such as scientific uncertainty, and ways to encourage landowners to adopt new methods.

The paper on foundational questions says many possible approaches to large-scale carbon removal hold promise “but also face challenges and limitations”.

New resources

More widely, the authors write: “Although carbon removal has raised some concerns about the degree to which it might detract from ongoing efforts to reduce emissions, it has the potential to broaden the public policy agenda on climate change in ways that bring additional stakeholders and resources to the table”.

One concern they address is the question of who would control the technologies which some approaches   would need, a conundrum preoccupying many scientists. Others make the point that carbon removal may often prove a double-edged sword, offering both benefits and risks. For all that, some studies show that, in principle anyway, the concept works. And at least one group of scientists has found that carbon dioxide can yield a new fuel able to slow climate change.

But the WRI team’s conclusion appears definitive in a way few previous analysts have been able to reach. They say that emissions cuts must remain the main way humans tackle the climate crisis.

“For carbon removal to play a meaningful role in stabilising the climate, it must supplement, not become a substitute for, deep decarbonisation of the economy. There is no evidence that carbon removal could serve as a viable alternative to emissions reduction.” – Climate News Network

Geo-engineered crops may help – and harm

To cool the world and also boost plant growth, geo-engineered crops might do the trick. But if they work by dimming the sunlight, the plants will suffer.

LONDON, 13 August, 2018 – Proposals to tackle climate change that rely on geo-engineered crops show neatly the double bind that can await remedies which try to do too much.

US researchers have cast yet another shadow over the hopes of those who think global technology could damp down global warming. A worldwide manmade sunscreen might limit distress to crops from heat extremes, but on the other hand the drop in solar radiation would be just as damaging.

The message: there is still no easy technological answer to the challenge of global warming and climate change.

Scientists report in the journal Nature that they studied two well-documented events in which nature itself conducted a form of geoengineering. One was the eruption of El Chichon in Mexico in 1982, and the other was the explosion of Pinatubo in the Philippines in 1991.

Suggesting a remedy

Pinatubo ejected a spectacular 20 million tons of sulphate aerosols into the upper atmosphere to reduce sunlight by 2.5% and to lower global average temperatures by around 0.5 C.

Such eruptions seemed to suggest a possible method for managing global warming, The deliberate release of aerosols into the stratosphere could, some scientists argued, counter the threat of global warming from ever greater emissions of greenhouse gases as a consequence of the ever more extensive combustion of fossil fuels.

And global warming certainly presents a global danger to food supplies: researchers have repeatedly shown that, as temperatures soar, crop yields suffer.

The researchers then asked the question: what happens to crops when sunlight is scattered back into space? They analysed the levels of aerosols, all the available data for solar irradiation, and the statistics for crop yields for 105 countries from 1979 to 2009, to find that as the sunlight bounced back into space in 1982 and 1991, yields from rice, soy, wheat and maize all suffered.

“Sunlight powers everything on the planet, so we must understand the possible outcomes if we are going to try to manage it”

A bit more work with computer simulations showed them that losses from reductions in sunlight would match any benefits crops might gain from a cooler climate. Intentional geo-engineering would fail to deliver the hoped-for extra food on the global table.

“Shading the planet keeps things cooler, which helps crops grow better. But plants also need sunlight to grow, so blocking sunlight can affect growth. For agriculture, the unintended impacts of solar geo-engineering are equal in magnitude to the benefits,” said lead author Jonathan Proctor, a doctoral candidate at the University of California, Berkeley.

“It’s a bit like performing an experimental surgery; the side-effects of treatment appear to be as bad as the illness.”

Researchers have repeatedly examined
geo-engineering solutions to the challenge of climate change. Humans have inadvertently warmed the planet. So surely they could intentionally cool it again with some ambitious technology, the reasoning goes.

Recurrent snags

But almost every examination of the potential benefits and handicaps of such an approach has been discouraging: either the technology won’t deliver benefits, or it could prove harmful in unexpected ways.

Partners in the latest study include Solomon Hsiang of UC Berkeley and Marshall Burke of Stanford University. In the past few years the two have looked closely at the economic and social consequences of global warming, to find that temperature increases are likely to affect many people’s incomes; that as the thermometer rises, so does the danger of social conflict, and even of depression and suicide.

“Unknown unknowns make everybody nervous when it comes to global policies, as they should,” Professor Hsiang said. “The problem in figuring out the consequences of solar geo-engineering is that we can’t do a planetary-scale experiment without actually deploying the technology.

Learning from nature

“The breakthrough here was realising that we could learn something by studying the effects of giant volcanic eruptions that geo-engineering tries to copy.”

Sunscreen by sulphate aerosol is not the only possible geo-engineering solution; and food security is not the only thing threatened by rising temperatures. The latest study is unlikely to be the end of the debate. The authors suggest more research into the human and ecological consequences of geo-engineering, both good and bad.

“The most certain way to reduce damages to crops and, in turn, people’s livelihood and well-being, is reducing carbon emissions,” Proctor said. And Professor Hsiang said: “Perhaps what is most important is that we have respect for the potential scale, power and risks of geo-engineering technologies.

“Sunlight powers everything on the planet, so we must understand the possible outcomes if we are going to try to manage it.” – Climate News Network

To cool the world and also boost plant growth, geo-engineered crops might do the trick. But if they work by dimming the sunlight, the plants will suffer.

LONDON, 13 August, 2018 – Proposals to tackle climate change that rely on geo-engineered crops show neatly the double bind that can await remedies which try to do too much.

US researchers have cast yet another shadow over the hopes of those who think global technology could damp down global warming. A worldwide manmade sunscreen might limit distress to crops from heat extremes, but on the other hand the drop in solar radiation would be just as damaging.

The message: there is still no easy technological answer to the challenge of global warming and climate change.

Scientists report in the journal Nature that they studied two well-documented events in which nature itself conducted a form of geoengineering. One was the eruption of El Chichon in Mexico in 1982, and the other was the explosion of Pinatubo in the Philippines in 1991.

Suggesting a remedy

Pinatubo ejected a spectacular 20 million tons of sulphate aerosols into the upper atmosphere to reduce sunlight by 2.5% and to lower global average temperatures by around 0.5 C.

Such eruptions seemed to suggest a possible method for managing global warming, The deliberate release of aerosols into the stratosphere could, some scientists argued, counter the threat of global warming from ever greater emissions of greenhouse gases as a consequence of the ever more extensive combustion of fossil fuels.

And global warming certainly presents a global danger to food supplies: researchers have repeatedly shown that, as temperatures soar, crop yields suffer.

The researchers then asked the question: what happens to crops when sunlight is scattered back into space? They analysed the levels of aerosols, all the available data for solar irradiation, and the statistics for crop yields for 105 countries from 1979 to 2009, to find that as the sunlight bounced back into space in 1982 and 1991, yields from rice, soy, wheat and maize all suffered.

“Sunlight powers everything on the planet, so we must understand the possible outcomes if we are going to try to manage it”

A bit more work with computer simulations showed them that losses from reductions in sunlight would match any benefits crops might gain from a cooler climate. Intentional geo-engineering would fail to deliver the hoped-for extra food on the global table.

“Shading the planet keeps things cooler, which helps crops grow better. But plants also need sunlight to grow, so blocking sunlight can affect growth. For agriculture, the unintended impacts of solar geo-engineering are equal in magnitude to the benefits,” said lead author Jonathan Proctor, a doctoral candidate at the University of California, Berkeley.

“It’s a bit like performing an experimental surgery; the side-effects of treatment appear to be as bad as the illness.”

Researchers have repeatedly examined
geo-engineering solutions to the challenge of climate change. Humans have inadvertently warmed the planet. So surely they could intentionally cool it again with some ambitious technology, the reasoning goes.

Recurrent snags

But almost every examination of the potential benefits and handicaps of such an approach has been discouraging: either the technology won’t deliver benefits, or it could prove harmful in unexpected ways.

Partners in the latest study include Solomon Hsiang of UC Berkeley and Marshall Burke of Stanford University. In the past few years the two have looked closely at the economic and social consequences of global warming, to find that temperature increases are likely to affect many people’s incomes; that as the thermometer rises, so does the danger of social conflict, and even of depression and suicide.

“Unknown unknowns make everybody nervous when it comes to global policies, as they should,” Professor Hsiang said. “The problem in figuring out the consequences of solar geo-engineering is that we can’t do a planetary-scale experiment without actually deploying the technology.

Learning from nature

“The breakthrough here was realising that we could learn something by studying the effects of giant volcanic eruptions that geo-engineering tries to copy.”

Sunscreen by sulphate aerosol is not the only possible geo-engineering solution; and food security is not the only thing threatened by rising temperatures. The latest study is unlikely to be the end of the debate. The authors suggest more research into the human and ecological consequences of geo-engineering, both good and bad.

“The most certain way to reduce damages to crops and, in turn, people’s livelihood and well-being, is reducing carbon emissions,” Proctor said. And Professor Hsiang said: “Perhaps what is most important is that we have respect for the potential scale, power and risks of geo-engineering technologies.

“Sunlight powers everything on the planet, so we must understand the possible outcomes if we are going to try to manage it.” – Climate News Network

Solar geoengineering ‘too uncertain to go ahead yet’

The world must urgently agree controls on solar geoengineering to weigh up its possible risks and benefits before deciding to go ahead, one expert says.

LONDON, 6 April, 2018 – Progress to deploy solar engineering, experimental technology designed to protect the world against the impact of the changing climate, must pause, a former United Nations climate expert says, arguing that governments need to create “effective guardrails” against any unforeseen risks.

Janos Pasztor, who served as a UN assistant secretary-general on climate change, is using a speech to Arizona State University, broadast via Facebook Live by ASU LightWorks, 6:30-8pm Arizona time (9:30pm EDT – US Eastern Daylight Time) today, to warn the world that governments are largely ignoring the fundamental question of who should control geoengineering, and how.

There are widespread misgivings, both among scientists and more widely, about geoengineering, with many regarding it as at best a strategy of last resort to help to avoid calamitous climate change.

Mr Pasztor’s warning comes as researchers prepare for what is thought to be the world’s first outdoor experiment on stratospheric aerosol injection (SAI), one type of solar geoengineering. The test is due to take place later this year over Arizona.

Pasztor heads the Carnegie Climate Geoengineering Governance Initiative (C2G2),  an initiative of the New York-based Carnegie Council for Ethics in International Affairs. The Initiative wants solar geoengineering deployment to be delayed until the risks and potential benefits are better known and governance frameworks are agreed.

“Getting this right is a challenge that affects all humanity . . . It’s critical the world addresses this issue as soon as possible”

“Some time within the next year, we may see the world’s first outdoor experiment on stratospheric aerosol injection take place here in the skies above Arizona, yet for the most part governments are not aware of, nor addressing, the profound governance issues this poses,” Mr Pasztor says.

“We urgently need an open, inclusive discussion on how the world will research and govern solar geoengineering. Otherwise we could be in danger of events overtaking society’s capacity to respond prudently and effectively.”

Solar geoengineering does not remove carbon from the atmosphere, and so it can be used only to supplement action to reduce greenhouse gas emissions: it can never replace that action. Many risks and unknowns remain, Pasztor says, including possible harm to the environment, and to justice, geopolitical concerns and governance.

With SAI aerosols are sprayed into the stratosphere to reflect the sun’s radiation and cool the earth fast. It is still in its early stages, and scientists say it will take another 15 to 20 years for the technology to be developed fully.

Too soon to decide

Any eventual full-scale deployment of technology of this sort would have planet-wide effects and pose profound ethical and governance challenges, C2G2 says. Pasztor says the risks and potential benefits of SAI are not yet understood well enough for policymakers to reach informed decisions.

This year’s planned experiment, called SCoPEx (Stratospheric Controlled Perturbation Experiment) is run by a Harvard University research group, which says the physical risks posed by the quantity of aerosols to be released during SCoPEx will be hundreds of times smaller than during a transatlantic flight by a commercial airliner.

Even so, Pasztor says, the governance of SCoPEx will probably set important precedents. “As solar geoengineering moves from the lab to outdoor experiments, crucial questions remain unanswered,” he argues.

“How does this experiment acquire legitimacy from other scientists? Do civil society groups and the public, including those located in the area of the experiment, have a say? What are the ramifications for other proposed experiments in this country or in other countries?”

Priority for cuts

So far, he says, many governments and civil society groups have shied away from the need to create governance for the new technology, or have not been aware of it. One common concern is that discussing geoengineering could distract society from concentrating on cutting carbon dioxide emissions.

Other geoengineering ideas, which may be nearing testing, include proposals to refreeze parts of the Arctic and to brighten clouds at sea.

“There’s no question we must accelerate efforts to rapidly reduce global emissions, whilst at the same time remaining open to the possibility that other approaches may also be needed if we are to limit some of the adverse impacts of global warming”, Pasztor says.

“Public policy needs to address very legitimate safety, human rights and accountability issues, as well as concern for future generations.

“Getting this right is a challenge that affects all humanity, and needs to be addressed through discussions that include all sectors of society. It’s critical the world addresses this issue as soon as possible.” – Climate News Network

The world must urgently agree controls on solar geoengineering to weigh up its possible risks and benefits before deciding to go ahead, one expert says.

LONDON, 6 April, 2018 – Progress to deploy solar engineering, experimental technology designed to protect the world against the impact of the changing climate, must pause, a former United Nations climate expert says, arguing that governments need to create “effective guardrails” against any unforeseen risks.

Janos Pasztor, who served as a UN assistant secretary-general on climate change, is using a speech to Arizona State University, broadast via Facebook Live by ASU LightWorks, 6:30-8pm Arizona time (9:30pm EDT – US Eastern Daylight Time) today, to warn the world that governments are largely ignoring the fundamental question of who should control geoengineering, and how.

There are widespread misgivings, both among scientists and more widely, about geoengineering, with many regarding it as at best a strategy of last resort to help to avoid calamitous climate change.

Mr Pasztor’s warning comes as researchers prepare for what is thought to be the world’s first outdoor experiment on stratospheric aerosol injection (SAI), one type of solar geoengineering. The test is due to take place later this year over Arizona.

Pasztor heads the Carnegie Climate Geoengineering Governance Initiative (C2G2),  an initiative of the New York-based Carnegie Council for Ethics in International Affairs. The Initiative wants solar geoengineering deployment to be delayed until the risks and potential benefits are better known and governance frameworks are agreed.

“Getting this right is a challenge that affects all humanity . . . It’s critical the world addresses this issue as soon as possible”

“Some time within the next year, we may see the world’s first outdoor experiment on stratospheric aerosol injection take place here in the skies above Arizona, yet for the most part governments are not aware of, nor addressing, the profound governance issues this poses,” Mr Pasztor says.

“We urgently need an open, inclusive discussion on how the world will research and govern solar geoengineering. Otherwise we could be in danger of events overtaking society’s capacity to respond prudently and effectively.”

Solar geoengineering does not remove carbon from the atmosphere, and so it can be used only to supplement action to reduce greenhouse gas emissions: it can never replace that action. Many risks and unknowns remain, Pasztor says, including possible harm to the environment, and to justice, geopolitical concerns and governance.

With SAI aerosols are sprayed into the stratosphere to reflect the sun’s radiation and cool the earth fast. It is still in its early stages, and scientists say it will take another 15 to 20 years for the technology to be developed fully.

Too soon to decide

Any eventual full-scale deployment of technology of this sort would have planet-wide effects and pose profound ethical and governance challenges, C2G2 says. Pasztor says the risks and potential benefits of SAI are not yet understood well enough for policymakers to reach informed decisions.

This year’s planned experiment, called SCoPEx (Stratospheric Controlled Perturbation Experiment) is run by a Harvard University research group, which says the physical risks posed by the quantity of aerosols to be released during SCoPEx will be hundreds of times smaller than during a transatlantic flight by a commercial airliner.

Even so, Pasztor says, the governance of SCoPEx will probably set important precedents. “As solar geoengineering moves from the lab to outdoor experiments, crucial questions remain unanswered,” he argues.

“How does this experiment acquire legitimacy from other scientists? Do civil society groups and the public, including those located in the area of the experiment, have a say? What are the ramifications for other proposed experiments in this country or in other countries?”

Priority for cuts

So far, he says, many governments and civil society groups have shied away from the need to create governance for the new technology, or have not been aware of it. One common concern is that discussing geoengineering could distract society from concentrating on cutting carbon dioxide emissions.

Other geoengineering ideas, which may be nearing testing, include proposals to refreeze parts of the Arctic and to brighten clouds at sea.

“There’s no question we must accelerate efforts to rapidly reduce global emissions, whilst at the same time remaining open to the possibility that other approaches may also be needed if we are to limit some of the adverse impacts of global warming”, Pasztor says.

“Public policy needs to address very legitimate safety, human rights and accountability issues, as well as concern for future generations.

“Getting this right is a challenge that affects all humanity, and needs to be addressed through discussions that include all sectors of society. It’s critical the world addresses this issue as soon as possible.” – Climate News Network

More reflectivity can cool the world

Think of reflectivity as down-to-earth geoengineering. Some simple actions could make a big difference to city life in the long hot summer.

LONDON, 14 February, 2018 – Engineering reflectivity can be a way to protect human safety during dangerous heatwaves: in the baking rural regions, put off ploughing those freshly-harvested wheat fields. And in the sweltering cities, paint the houses white, fit shiny roofs and plant pale-leafed tree species

In a word, increase reflectivity. Bounce more sunlight back into space to save lives, tempers and energy costs. It would, in effect, be local geoengineering, but without the unimaginable costs of spraying aerosols into the stratosphere, or placing solar reflectors in orbit; and without unwelcome side effects.

And it is based on the simple observation that a harvested wheat field is brighter than ploughed croplands, and that reflective roofs are less likely to absorb sunlight than dark tiles or slates.

“These measures could help to lower extreme temperatures in agricultural regions and densely populated areas by up to two to three degrees Celsius,” said Sonia Seneviratne, professor of land-climate dynamics at ETH Zurich, the Swiss federal institute of technology.

“Even this climate technique is no silver bullet; it’s just one potential tool among several others in the battle against climate change”

And her co-author Andy Pitman, of the University of New South Wales, who directs the Australian research council’s Centre of Excellence for Climate Extremes, said: “Extreme temperatures are where human and natural systems are most vulnerable. Changing the radiative properties of land helps address this issue with fewer side effects.

“This research suggests that by taking the regional approach, at least in temperate zones, policy and investment decisions can be pragmatically and affordably focused on areas of greatest need.”

The Swiss and Australian scientists report in the journal Nature Geoscience that they worked with computer models to simulate changes in the albedo of the land and the cities: albedo is the climate scientist’s word for the reflectivity of ocean, ice, desert or forest.

What the researchers found was that the higher the temperatures, the stronger the effect of enhanced albedo, or reflectivity.

Growing problem

And the big heat is on the way. Researchers have repeatedly confirmed that heat extremes pose increasing threats, especially to the megacities, urban centres with more than 10 million people.

They have also confirmed that such extremes of heat can be lethal,  especially when matched with rising humidity.

Cities in any case are more at hazard, because of the notorious urban heat island effect. Greater investment in air conditioning plant is not the answer, because it could only increase energy demand driven by fossil fuel combustion and thus raise urban temperatures even higher and increase long-term global warming even more.

So there has been more emphasis on natural responses, such as greater investment in the “urban forest” of park, garden and avenue trees to keep the urban population a little cooler.

Reducing extremes

The latest study found that large scale alteration of rural and urban albedo had no significant effect on average temperatures, and made hardly any difference to rainfall in Europe and North America. But as the thermometer soared, so did the effect: it did significantly reduce the extremes of heat.

In Asia, this form of what might be called grassroots geoengineering may not suit: monsoon rainfall fell in the simulation, and the monsoons are crucial to the economies of China and India.

“Regional radiation management can be effective, but even here we have to consider any potential effects on food production, biodiversity, CO2 absorption, recreation areas and much more,” said Professor Seneviratne.

“Even this climate technique is no silver bullet; it’s just one potential tool among several others in the battle against climate change.” – Climate News Network

Think of reflectivity as down-to-earth geoengineering. Some simple actions could make a big difference to city life in the long hot summer.

LONDON, 14 February, 2018 – Engineering reflectivity can be a way to protect human safety during dangerous heatwaves: in the baking rural regions, put off ploughing those freshly-harvested wheat fields. And in the sweltering cities, paint the houses white, fit shiny roofs and plant pale-leafed tree species

In a word, increase reflectivity. Bounce more sunlight back into space to save lives, tempers and energy costs. It would, in effect, be local geoengineering, but without the unimaginable costs of spraying aerosols into the stratosphere, or placing solar reflectors in orbit; and without unwelcome side effects.

And it is based on the simple observation that a harvested wheat field is brighter than ploughed croplands, and that reflective roofs are less likely to absorb sunlight than dark tiles or slates.

“These measures could help to lower extreme temperatures in agricultural regions and densely populated areas by up to two to three degrees Celsius,” said Sonia Seneviratne, professor of land-climate dynamics at ETH Zurich, the Swiss federal institute of technology.

“Even this climate technique is no silver bullet; it’s just one potential tool among several others in the battle against climate change”

And her co-author Andy Pitman, of the University of New South Wales, who directs the Australian research council’s Centre of Excellence for Climate Extremes, said: “Extreme temperatures are where human and natural systems are most vulnerable. Changing the radiative properties of land helps address this issue with fewer side effects.

“This research suggests that by taking the regional approach, at least in temperate zones, policy and investment decisions can be pragmatically and affordably focused on areas of greatest need.”

The Swiss and Australian scientists report in the journal Nature Geoscience that they worked with computer models to simulate changes in the albedo of the land and the cities: albedo is the climate scientist’s word for the reflectivity of ocean, ice, desert or forest.

What the researchers found was that the higher the temperatures, the stronger the effect of enhanced albedo, or reflectivity.

Growing problem

And the big heat is on the way. Researchers have repeatedly confirmed that heat extremes pose increasing threats, especially to the megacities, urban centres with more than 10 million people.

They have also confirmed that such extremes of heat can be lethal,  especially when matched with rising humidity.

Cities in any case are more at hazard, because of the notorious urban heat island effect. Greater investment in air conditioning plant is not the answer, because it could only increase energy demand driven by fossil fuel combustion and thus raise urban temperatures even higher and increase long-term global warming even more.

So there has been more emphasis on natural responses, such as greater investment in the “urban forest” of park, garden and avenue trees to keep the urban population a little cooler.

Reducing extremes

The latest study found that large scale alteration of rural and urban albedo had no significant effect on average temperatures, and made hardly any difference to rainfall in Europe and North America. But as the thermometer soared, so did the effect: it did significantly reduce the extremes of heat.

In Asia, this form of what might be called grassroots geoengineering may not suit: monsoon rainfall fell in the simulation, and the monsoons are crucial to the economies of China and India.

“Regional radiation management can be effective, but even here we have to consider any potential effects on food production, biodiversity, CO2 absorption, recreation areas and much more,” said Professor Seneviratne.

“Even this climate technique is no silver bullet; it’s just one potential tool among several others in the battle against climate change.” – Climate News Network