Tag Archives: Volcanoes

Missing heat 'is in the oceans'

FOR IMMEDIATE RELEASE
The recent slow-down in the rate at which the atmosphere is warming may be at least partly explained by European research, which suggests that the heat is going, not into the air, but into the seas.

LONDON, 12 April – Here is the puzzle: humans continue to pump increasing quantities of greenhouse gases into the atmosphere, and the world has warmed accordingly. Eleven of the 12 warmest years ever recorded have fallen in this century – but the rate of warming seems to have slowed rather than increased. So what has been taking the heat?

Climate scientists from Barcelona in Spain and Toulouse in France think they have the answer. They report in Nature Climate Change that instead of going into the near-surface atmosphere where meteorologists could easily measure it, much of the extra heat has been absorbed by the oceans.

This may not be the only explanation. There have also been arguments that volcanic eruptions might have put enough aerosols into the upper atmosphere to dim the sunlight and counter global warming a little. Stratospheric water vapour might also have damped things down, and some say the solar minimum – the spell of least activity in the Sun’s 11-year cycle – has been prolonged.

But Virginie Guemas of the Catalan Institute of Climate Science in Barcelona and colleagues propose more than speculation. They used a technique sometimes called “hindcasting” and in their case labeled “retrospective prediction” to argue what ought to have happened – and then checked the evidence.

This is the basis of science: frame a hypothesis, make a prediction from it and then check the evidence to see if the hypothesis is wrong. The advantage of doing it retrospectively is that it doesn’t take so long to find out whether you are right or wrong.

Trouble ahead

Guemas and her colleagues believe they were right. They argue that they successfully (and retrospectively) predicted the warming slowdown five years before it started around 2000.

And their conclusion is that the extra heat has been absorbed in the top 700 metres of the planet’s oceans below the surface layer, and more than half of this has been concentrated in the tropical Pacific and Atlantic oceans: enough to explain at least a three-year pause in the apparent rate of global warming.

Water in circulating oceans eventually delivers its heat back to the atmosphere, so the logic is that there is more and faster warming to come.

“Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown”, the scientists claim.

“The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions.” – Climate News Network

FOR IMMEDIATE RELEASE
The recent slow-down in the rate at which the atmosphere is warming may be at least partly explained by European research, which suggests that the heat is going, not into the air, but into the seas.

LONDON, 12 April – Here is the puzzle: humans continue to pump increasing quantities of greenhouse gases into the atmosphere, and the world has warmed accordingly. Eleven of the 12 warmest years ever recorded have fallen in this century – but the rate of warming seems to have slowed rather than increased. So what has been taking the heat?

Climate scientists from Barcelona in Spain and Toulouse in France think they have the answer. They report in Nature Climate Change that instead of going into the near-surface atmosphere where meteorologists could easily measure it, much of the extra heat has been absorbed by the oceans.

This may not be the only explanation. There have also been arguments that volcanic eruptions might have put enough aerosols into the upper atmosphere to dim the sunlight and counter global warming a little. Stratospheric water vapour might also have damped things down, and some say the solar minimum – the spell of least activity in the Sun’s 11-year cycle – has been prolonged.

But Virginie Guemas of the Catalan Institute of Climate Science in Barcelona and colleagues propose more than speculation. They used a technique sometimes called “hindcasting” and in their case labeled “retrospective prediction” to argue what ought to have happened – and then checked the evidence.

This is the basis of science: frame a hypothesis, make a prediction from it and then check the evidence to see if the hypothesis is wrong. The advantage of doing it retrospectively is that it doesn’t take so long to find out whether you are right or wrong.

Trouble ahead

Guemas and her colleagues believe they were right. They argue that they successfully (and retrospectively) predicted the warming slowdown five years before it started around 2000.

And their conclusion is that the extra heat has been absorbed in the top 700 metres of the planet’s oceans below the surface layer, and more than half of this has been concentrated in the tropical Pacific and Atlantic oceans: enough to explain at least a three-year pause in the apparent rate of global warming.

Water in circulating oceans eventually delivers its heat back to the atmosphere, so the logic is that there is more and faster warming to come.

“Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown”, the scientists claim.

“The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions.” – Climate News Network

Missing heat ‘is in the oceans’

FOR IMMEDIATE RELEASE The recent slow-down in the rate at which the atmosphere is warming may be at least partly explained by European research, which suggests that the heat is going, not into the air, but into the seas. LONDON, 12 April – Here is the puzzle: humans continue to pump increasing quantities of greenhouse gases into the atmosphere, and the world has warmed accordingly. Eleven of the 12 warmest years ever recorded have fallen in this century – but the rate of warming seems to have slowed rather than increased. So what has been taking the heat? Climate scientists from Barcelona in Spain and Toulouse in France think they have the answer. They report in Nature Climate Change that instead of going into the near-surface atmosphere where meteorologists could easily measure it, much of the extra heat has been absorbed by the oceans. This may not be the only explanation. There have also been arguments that volcanic eruptions might have put enough aerosols into the upper atmosphere to dim the sunlight and counter global warming a little. Stratospheric water vapour might also have damped things down, and some say the solar minimum – the spell of least activity in the Sun’s 11-year cycle – has been prolonged. But Virginie Guemas of the Catalan Institute of Climate Science in Barcelona and colleagues propose more than speculation. They used a technique sometimes called “hindcasting” and in their case labeled “retrospective prediction” to argue what ought to have happened – and then checked the evidence. This is the basis of science: frame a hypothesis, make a prediction from it and then check the evidence to see if the hypothesis is wrong. The advantage of doing it retrospectively is that it doesn’t take so long to find out whether you are right or wrong.

Trouble ahead

Guemas and her colleagues believe they were right. They argue that they successfully (and retrospectively) predicted the warming slowdown five years before it started around 2000. And their conclusion is that the extra heat has been absorbed in the top 700 metres of the planet’s oceans below the surface layer, and more than half of this has been concentrated in the tropical Pacific and Atlantic oceans: enough to explain at least a three-year pause in the apparent rate of global warming. Water in circulating oceans eventually delivers its heat back to the atmosphere, so the logic is that there is more and faster warming to come. “Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown”, the scientists claim. “The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions.” – Climate News Network

FOR IMMEDIATE RELEASE The recent slow-down in the rate at which the atmosphere is warming may be at least partly explained by European research, which suggests that the heat is going, not into the air, but into the seas. LONDON, 12 April – Here is the puzzle: humans continue to pump increasing quantities of greenhouse gases into the atmosphere, and the world has warmed accordingly. Eleven of the 12 warmest years ever recorded have fallen in this century – but the rate of warming seems to have slowed rather than increased. So what has been taking the heat? Climate scientists from Barcelona in Spain and Toulouse in France think they have the answer. They report in Nature Climate Change that instead of going into the near-surface atmosphere where meteorologists could easily measure it, much of the extra heat has been absorbed by the oceans. This may not be the only explanation. There have also been arguments that volcanic eruptions might have put enough aerosols into the upper atmosphere to dim the sunlight and counter global warming a little. Stratospheric water vapour might also have damped things down, and some say the solar minimum – the spell of least activity in the Sun’s 11-year cycle – has been prolonged. But Virginie Guemas of the Catalan Institute of Climate Science in Barcelona and colleagues propose more than speculation. They used a technique sometimes called “hindcasting” and in their case labeled “retrospective prediction” to argue what ought to have happened – and then checked the evidence. This is the basis of science: frame a hypothesis, make a prediction from it and then check the evidence to see if the hypothesis is wrong. The advantage of doing it retrospectively is that it doesn’t take so long to find out whether you are right or wrong.

Trouble ahead

Guemas and her colleagues believe they were right. They argue that they successfully (and retrospectively) predicted the warming slowdown five years before it started around 2000. And their conclusion is that the extra heat has been absorbed in the top 700 metres of the planet’s oceans below the surface layer, and more than half of this has been concentrated in the tropical Pacific and Atlantic oceans: enough to explain at least a three-year pause in the apparent rate of global warming. Water in circulating oceans eventually delivers its heat back to the atmosphere, so the logic is that there is more and faster warming to come. “Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown”, the scientists claim. “The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions.” – Climate News Network

Volcanic fizz could end warming climate

EMBARGOED UNTIL 2300 GMT SATURDAY 6 APRIL The Icelandic volcanio that erupted in 2010 grounded aircraft over a wide area and gave a severe jolt to many people in Europe and North America. But it was small beer compared with what could lie in store, researchers say. LONDON, 7 April – While world leaders dither on taking action about climate change, volcanologists have found that if we are unlucky enough a cloud of volcanic ash from Iceland might solve the problem for us by blotting out the Sun. The eruption in Iceland in 2010 of the volcano Eyjafjallajökull, which caused 100,000 flights to be cancelled and stranded millions of people, was small-scale compared with what could happen (see our story of 21 March, Volcano “did little to lower CO2”.) Not only could Iceland’s eruptions be up to 100 times more powerful, they could shower vast quantities of dust into the atmosphere, not just disrupting air flights but cutting out sunlight. Previous archaeological work on peat bogs and lake beds across Europe has found layers of volcanic ash. The dates of these layers coincide with population crashes in various places, including Scotland. It seems that the lack of sunshine associated with the falls of ash caused crop failures and famine across large swathes of Europe. If blasted high enough, fine ash and volcanic aerosols can take two years to fall out of the atmosphere. A team from the UK’s Open and Lancaster Universities has discovered a “fizzy” magma in Iceland, which increases the likelihood of disruptive ash clouds from future eruptions (magma is molten or partly-molten subterranean rock which is ejected from the Earth as lava.) Published in the journal Geology, the team’s research showed that many of the largest explosive eruptions in Iceland involve a viscous, high-silica magma called rhyolite, and are driven by volcanic gases (mostly water vapour and carbon dioxide). It is these gases that give a volcanic eruption its fizz. At depth they are dissolved within the magma, but as it rises towards the surface during an eruption the gases expand dramatically, causing the magma to froth and accelerate upwards as foam. The viscous rhyolite foam breaks down into tiny ash fragments, which form vast clouds.

Peril far greater

  Drs Jacqui Owen and Hugh Tuffen (Lancaster University) and Dave McGarvie (the Open University) analysed pumice and lava from an eruption at Iceland’s Torfajökull volcano some seventy thousand years ago. Within these samples they found tiny pockets of magma, called melt inclusions, which trapped the original gas. By measuring the gas trapped in the magna they could determine its fizziness. The surprise was just how fizzy this magma was, comparable with the highly explosive volcanoes of the Pacific rim. It means that the Icelandic volcanoes are much more dangerous to life on the planet than was previously thought. Dr Dave McGarvie, senior lecturer, Volcano Dynamics Group at the Open University, said: “We know that large explosive eruptions have occurred at infamous volcanoes such as Hekla and Katla, but it is important also to appreciate that large explosive eruptions are also produced by less well-known Icelandic volcanoes such as Torfajökull and Öraefajökull.” Dr Tuffen, Royal Society University Research Fellow at Lancaster University, said: “The discovery is rather worrying, as it shows that Icelandic volcanoes have the potential to be even more explosive than anticipated. “Added to this is the view of several eminent scientists that Iceland is entering a period of increased volcanic activity. Iceland’s position close to mainland Europe and the north Atlantic flight corridors means air travel could be affected again.” – Climate News Network

EMBARGOED UNTIL 2300 GMT SATURDAY 6 APRIL The Icelandic volcanio that erupted in 2010 grounded aircraft over a wide area and gave a severe jolt to many people in Europe and North America. But it was small beer compared with what could lie in store, researchers say. LONDON, 7 April – While world leaders dither on taking action about climate change, volcanologists have found that if we are unlucky enough a cloud of volcanic ash from Iceland might solve the problem for us by blotting out the Sun. The eruption in Iceland in 2010 of the volcano Eyjafjallajökull, which caused 100,000 flights to be cancelled and stranded millions of people, was small-scale compared with what could happen (see our story of 21 March, Volcano “did little to lower CO2”.) Not only could Iceland’s eruptions be up to 100 times more powerful, they could shower vast quantities of dust into the atmosphere, not just disrupting air flights but cutting out sunlight. Previous archaeological work on peat bogs and lake beds across Europe has found layers of volcanic ash. The dates of these layers coincide with population crashes in various places, including Scotland. It seems that the lack of sunshine associated with the falls of ash caused crop failures and famine across large swathes of Europe. If blasted high enough, fine ash and volcanic aerosols can take two years to fall out of the atmosphere. A team from the UK’s Open and Lancaster Universities has discovered a “fizzy” magma in Iceland, which increases the likelihood of disruptive ash clouds from future eruptions (magma is molten or partly-molten subterranean rock which is ejected from the Earth as lava.) Published in the journal Geology, the team’s research showed that many of the largest explosive eruptions in Iceland involve a viscous, high-silica magma called rhyolite, and are driven by volcanic gases (mostly water vapour and carbon dioxide). It is these gases that give a volcanic eruption its fizz. At depth they are dissolved within the magma, but as it rises towards the surface during an eruption the gases expand dramatically, causing the magma to froth and accelerate upwards as foam. The viscous rhyolite foam breaks down into tiny ash fragments, which form vast clouds.

Peril far greater

  Drs Jacqui Owen and Hugh Tuffen (Lancaster University) and Dave McGarvie (the Open University) analysed pumice and lava from an eruption at Iceland’s Torfajökull volcano some seventy thousand years ago. Within these samples they found tiny pockets of magma, called melt inclusions, which trapped the original gas. By measuring the gas trapped in the magna they could determine its fizziness. The surprise was just how fizzy this magma was, comparable with the highly explosive volcanoes of the Pacific rim. It means that the Icelandic volcanoes are much more dangerous to life on the planet than was previously thought. Dr Dave McGarvie, senior lecturer, Volcano Dynamics Group at the Open University, said: “We know that large explosive eruptions have occurred at infamous volcanoes such as Hekla and Katla, but it is important also to appreciate that large explosive eruptions are also produced by less well-known Icelandic volcanoes such as Torfajökull and Öraefajökull.” Dr Tuffen, Royal Society University Research Fellow at Lancaster University, said: “The discovery is rather worrying, as it shows that Icelandic volcanoes have the potential to be even more explosive than anticipated. “Added to this is the view of several eminent scientists that Iceland is entering a period of increased volcanic activity. Iceland’s position close to mainland Europe and the north Atlantic flight corridors means air travel could be affected again.” – Climate News Network

Geo-engineering 'could imperil Sahel'

EMBARGOED until 1700 GMT on Sunday 31 March
Attempts to tackle climate change by altering the atmosphere – geo-engineering – may have unpredictable effects. They could even trigger disaster in a drought-prone region of Africa, a study suggests.

LONDON, 31 March – Less than three weeks after two US researchers called for global agreement on the governance of geo-engineering research, British meteorologists have provided a case study in potential geo-engineering disaster.

Jim Haywood from the Met Office Hadley Centre and colleagues report in Nature Climate Change that fine particles concentrated in the stratosphere could precipitate calamitous drought in the Sahel region of Africa.

The team analysed historical observations from 1900 to 2010 and found that substantial volcanic eruptions in the Northern hemisphere – substantial enough to lift huge clouds of aerosols into the upper atmosphere – preceded three of the four driest summers in the region.

Furious volcanic blasts have been historically associated with climate change: an eruption of Mt Tambora in what is now Indonesia in 1815 was followed by Europe’s notorious “year without a summer” in 1816, along with widespread harvest failure, famine and outbreaks of disease.

The eruption of Mt Pinatubo in 1991 was followed by what climate scientists were later to call “the Pinatubo effect” – noticeable global cooling in the following years.

But what concerns Professor Haywood and others is not the random nature of volcanic eruption – difficult to predict and impossible to prevent – but the possibility of deliberate injection of aerosols into the stratosphere to moderate global warming.

The Sahel is the name given to a 1,000-kilometre band of savannah in Africa south of the Sahara, stretching from Mauretania in the west to Eritrea on the Red Sea coast.

The four driest periods in this relatively arid region – these periods bear the deadpan scientific label of negative Sahelian precipitation anomalies – were in 1913, 1972, 1983 and 1984. Three of these dry spells followed an eruption of Katmai in Alaska in 1912 and of El Chichon in Mexico in 1982.

“…a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed…”

The extended drought between 1970 and 1990 in the Sahel region claimed 250,000 lives and created 10 million refugees: it was one of the world’s biggest humanitarian disasters.

All kinds of causes were evoked, including overgrazing, natural variability and industrial exhausts, but Professor Haywood and his colleagues think that volcanic eruptions also strongly influence the sea temperatures in the Atlantic, which are associated with Sahelian drought.

Their conclusions are provisional. Such associations are difficult to prove conclusively. They concede in their paper that “correlation does not prove causality and the sparsity of significant hemispherically asymmetric volcanic eruptions in the recent historical record hampers definitive attribution.” In other words, the jury is still out.

They simulated the impact of continued global warming into the future and found that – provided there was no geoengineering – only 11 of the 50 years between 2020 and 2070 would have negative Sahelian precipitation anomalies. Deliberate geoengineering, however, by loading aerosols into the northern hemisphere stratosphere would cause Sahelian drought.

This could possibly be countered by injecting particles into the southern hemisphere stratosphere, which might have the effect of increasing rainfall in the Sahel countries. But any good there might be countered by a consequent failure of the rains in north-east Brazil.

“Clearly, the juxtaposition of impacts leads us to believe that a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed, and much further research is needed,” they conclude. – Climate News Network

EMBARGOED until 1700 GMT on Sunday 31 March
Attempts to tackle climate change by altering the atmosphere – geo-engineering – may have unpredictable effects. They could even trigger disaster in a drought-prone region of Africa, a study suggests.

LONDON, 31 March – Less than three weeks after two US researchers called for global agreement on the governance of geo-engineering research, British meteorologists have provided a case study in potential geo-engineering disaster.

Jim Haywood from the Met Office Hadley Centre and colleagues report in Nature Climate Change that fine particles concentrated in the stratosphere could precipitate calamitous drought in the Sahel region of Africa.

The team analysed historical observations from 1900 to 2010 and found that substantial volcanic eruptions in the Northern hemisphere – substantial enough to lift huge clouds of aerosols into the upper atmosphere – preceded three of the four driest summers in the region.

Furious volcanic blasts have been historically associated with climate change: an eruption of Mt Tambora in what is now Indonesia in 1815 was followed by Europe’s notorious “year without a summer” in 1816, along with widespread harvest failure, famine and outbreaks of disease.

The eruption of Mt Pinatubo in 1991 was followed by what climate scientists were later to call “the Pinatubo effect” – noticeable global cooling in the following years.

But what concerns Professor Haywood and others is not the random nature of volcanic eruption – difficult to predict and impossible to prevent – but the possibility of deliberate injection of aerosols into the stratosphere to moderate global warming.

The Sahel is the name given to a 1,000-kilometre band of savannah in Africa south of the Sahara, stretching from Mauretania in the west to Eritrea on the Red Sea coast.

The four driest periods in this relatively arid region – these periods bear the deadpan scientific label of negative Sahelian precipitation anomalies – were in 1913, 1972, 1983 and 1984. Three of these dry spells followed an eruption of Katmai in Alaska in 1912 and of El Chichon in Mexico in 1982.

“…a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed…”

The extended drought between 1970 and 1990 in the Sahel region claimed 250,000 lives and created 10 million refugees: it was one of the world’s biggest humanitarian disasters.

All kinds of causes were evoked, including overgrazing, natural variability and industrial exhausts, but Professor Haywood and his colleagues think that volcanic eruptions also strongly influence the sea temperatures in the Atlantic, which are associated with Sahelian drought.

Their conclusions are provisional. Such associations are difficult to prove conclusively. They concede in their paper that “correlation does not prove causality and the sparsity of significant hemispherically asymmetric volcanic eruptions in the recent historical record hampers definitive attribution.” In other words, the jury is still out.

They simulated the impact of continued global warming into the future and found that – provided there was no geoengineering – only 11 of the 50 years between 2020 and 2070 would have negative Sahelian precipitation anomalies. Deliberate geoengineering, however, by loading aerosols into the northern hemisphere stratosphere would cause Sahelian drought.

This could possibly be countered by injecting particles into the southern hemisphere stratosphere, which might have the effect of increasing rainfall in the Sahel countries. But any good there might be countered by a consequent failure of the rains in north-east Brazil.

“Clearly, the juxtaposition of impacts leads us to believe that a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed, and much further research is needed,” they conclude. – Climate News Network

Geo-engineering ‘could imperil Sahel’

EMBARGOED until 1700 GMT on Sunday 31 March Attempts to tackle climate change by altering the atmosphere – geo-engineering – may have unpredictable effects. They could even trigger disaster in a drought-prone region of Africa, a study suggests. LONDON, 31 March – Less than three weeks after two US researchers called for global agreement on the governance of geo-engineering research, British meteorologists have provided a case study in potential geo-engineering disaster. Jim Haywood from the Met Office Hadley Centre and colleagues report in Nature Climate Change that fine particles concentrated in the stratosphere could precipitate calamitous drought in the Sahel region of Africa. The team analysed historical observations from 1900 to 2010 and found that substantial volcanic eruptions in the Northern hemisphere – substantial enough to lift huge clouds of aerosols into the upper atmosphere – preceded three of the four driest summers in the region. Furious volcanic blasts have been historically associated with climate change: an eruption of Mt Tambora in what is now Indonesia in 1815 was followed by Europe’s notorious “year without a summer” in 1816, along with widespread harvest failure, famine and outbreaks of disease. The eruption of Mt Pinatubo in 1991 was followed by what climate scientists were later to call “the Pinatubo effect” – noticeable global cooling in the following years. But what concerns Professor Haywood and others is not the random nature of volcanic eruption – difficult to predict and impossible to prevent – but the possibility of deliberate injection of aerosols into the stratosphere to moderate global warming. The Sahel is the name given to a 1,000-kilometre band of savannah in Africa south of the Sahara, stretching from Mauretania in the west to Eritrea on the Red Sea coast. The four driest periods in this relatively arid region – these periods bear the deadpan scientific label of negative Sahelian precipitation anomalies – were in 1913, 1972, 1983 and 1984. Three of these dry spells followed an eruption of Katmai in Alaska in 1912 and of El Chichon in Mexico in 1982.

“…a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed…”

The extended drought between 1970 and 1990 in the Sahel region claimed 250,000 lives and created 10 million refugees: it was one of the world’s biggest humanitarian disasters. All kinds of causes were evoked, including overgrazing, natural variability and industrial exhausts, but Professor Haywood and his colleagues think that volcanic eruptions also strongly influence the sea temperatures in the Atlantic, which are associated with Sahelian drought. Their conclusions are provisional. Such associations are difficult to prove conclusively. They concede in their paper that “correlation does not prove causality and the sparsity of significant hemispherically asymmetric volcanic eruptions in the recent historical record hampers definitive attribution.” In other words, the jury is still out. They simulated the impact of continued global warming into the future and found that – provided there was no geoengineering – only 11 of the 50 years between 2020 and 2070 would have negative Sahelian precipitation anomalies. Deliberate geoengineering, however, by loading aerosols into the northern hemisphere stratosphere would cause Sahelian drought. This could possibly be countered by injecting particles into the southern hemisphere stratosphere, which might have the effect of increasing rainfall in the Sahel countries. But any good there might be countered by a consequent failure of the rains in north-east Brazil. “Clearly, the juxtaposition of impacts leads us to believe that a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed, and much further research is needed,” they conclude. – Climate News Network

EMBARGOED until 1700 GMT on Sunday 31 March Attempts to tackle climate change by altering the atmosphere – geo-engineering – may have unpredictable effects. They could even trigger disaster in a drought-prone region of Africa, a study suggests. LONDON, 31 March – Less than three weeks after two US researchers called for global agreement on the governance of geo-engineering research, British meteorologists have provided a case study in potential geo-engineering disaster. Jim Haywood from the Met Office Hadley Centre and colleagues report in Nature Climate Change that fine particles concentrated in the stratosphere could precipitate calamitous drought in the Sahel region of Africa. The team analysed historical observations from 1900 to 2010 and found that substantial volcanic eruptions in the Northern hemisphere – substantial enough to lift huge clouds of aerosols into the upper atmosphere – preceded three of the four driest summers in the region. Furious volcanic blasts have been historically associated with climate change: an eruption of Mt Tambora in what is now Indonesia in 1815 was followed by Europe’s notorious “year without a summer” in 1816, along with widespread harvest failure, famine and outbreaks of disease. The eruption of Mt Pinatubo in 1991 was followed by what climate scientists were later to call “the Pinatubo effect” – noticeable global cooling in the following years. But what concerns Professor Haywood and others is not the random nature of volcanic eruption – difficult to predict and impossible to prevent – but the possibility of deliberate injection of aerosols into the stratosphere to moderate global warming. The Sahel is the name given to a 1,000-kilometre band of savannah in Africa south of the Sahara, stretching from Mauretania in the west to Eritrea on the Red Sea coast. The four driest periods in this relatively arid region – these periods bear the deadpan scientific label of negative Sahelian precipitation anomalies – were in 1913, 1972, 1983 and 1984. Three of these dry spells followed an eruption of Katmai in Alaska in 1912 and of El Chichon in Mexico in 1982.

“…a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed…”

The extended drought between 1970 and 1990 in the Sahel region claimed 250,000 lives and created 10 million refugees: it was one of the world’s biggest humanitarian disasters. All kinds of causes were evoked, including overgrazing, natural variability and industrial exhausts, but Professor Haywood and his colleagues think that volcanic eruptions also strongly influence the sea temperatures in the Atlantic, which are associated with Sahelian drought. Their conclusions are provisional. Such associations are difficult to prove conclusively. They concede in their paper that “correlation does not prove causality and the sparsity of significant hemispherically asymmetric volcanic eruptions in the recent historical record hampers definitive attribution.” In other words, the jury is still out. They simulated the impact of continued global warming into the future and found that – provided there was no geoengineering – only 11 of the 50 years between 2020 and 2070 would have negative Sahelian precipitation anomalies. Deliberate geoengineering, however, by loading aerosols into the northern hemisphere stratosphere would cause Sahelian drought. This could possibly be countered by injecting particles into the southern hemisphere stratosphere, which might have the effect of increasing rainfall in the Sahel countries. But any good there might be countered by a consequent failure of the rains in north-east Brazil. “Clearly, the juxtaposition of impacts leads us to believe that a global governance agreement for geo-engineering is essential before any practical geo-engineering system is deployed, and much further research is needed,” they conclude. – Climate News Network

Volcanoes may mask 'lost' warming

EMBARGOED until 0001 GMT on Monday 4 March
Scientists believe that emissions of sulphur dioxide from erupting volcanoes may be masking the effect of greenhouse gases and so keeping temperature rises artificially low.

LONDON, 4 March – Climate scientists think they may have found at least part of the answer to a conundrum which has been puzzling them recently – why the atmosphere has not warmed as much as expected over the last decade or so.

A team led by the University of Colorado-Boulder (CU-Boulder) thinks the reason may be emissions of sulphur dioxide (SO2), a known inhibitor of atmospheric warming, from many of the world’s volcanoes.

The puzzle is why the global average temperature has not increased as expected in step with rising greenhouse gas emissions. This has led some to suggest that global warming itself is faltering, and with it the entire scientific justification for action to stabilise the climate.

The chair of the Intergovernmental Panel on Climate Change, Dr R K Pachauri, was reported in The Australian on 22 February as having acknowledged “a 17-year pause in global temperature rises, confirmed recently by Britain’s Met Office”, but “said it would need to last ’30 to 40 years at least’ to break the long-term global warming trend”.

Most SO2 emissions are from fossil fuel burning at power plants and in industry, with smaller amounts coming from railways, large vessels and some industrial processes.

Volcanoes downplayed

 

Small quantities of the emissions eventually rise into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulphuric acid and water particles that reflect sunlight back into space, cooling the planet.

Scientists have known for years that this cooling mechanism from a range of aerosols is helping to prevent global average temperatures rising as much as they otherwise would under the influence of greenhouse gases, but it appears they have underestimated the effect of volcanic SO2.

India and China are estimated to have increased their industrial SO2 emissions by about 60% between 2000 and 2010 through coal burning.

But the study, published online in Geophysical Research Letters, suggests it is volcanic eruptions, not Asia’s emissions, that are largely responsible for the warming slowdown.

The study’s lead author, Ryan Neely, said previous observations had suggested that increases in stratospheric aerosols as a whole since 2000 had cancelled out as much as 25% of the warming from greenhouse gases.

“This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet”, said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration (NOAA).

Negligible overall effect

 

The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely. Since 2000 the optical depth in the layer has increased by about 4 to 7%, meaning it is slightly more opaque now than it was.

“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate”,  said Professor Brian Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences.

“But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”

“This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.”

While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tonnes of SO2 that cooled the Earth slightly for the next few years. – Climate News Network

EMBARGOED until 0001 GMT on Monday 4 March
Scientists believe that emissions of sulphur dioxide from erupting volcanoes may be masking the effect of greenhouse gases and so keeping temperature rises artificially low.

LONDON, 4 March – Climate scientists think they may have found at least part of the answer to a conundrum which has been puzzling them recently – why the atmosphere has not warmed as much as expected over the last decade or so.

A team led by the University of Colorado-Boulder (CU-Boulder) thinks the reason may be emissions of sulphur dioxide (SO2), a known inhibitor of atmospheric warming, from many of the world’s volcanoes.

The puzzle is why the global average temperature has not increased as expected in step with rising greenhouse gas emissions. This has led some to suggest that global warming itself is faltering, and with it the entire scientific justification for action to stabilise the climate.

The chair of the Intergovernmental Panel on Climate Change, Dr R K Pachauri, was reported in The Australian on 22 February as having acknowledged “a 17-year pause in global temperature rises, confirmed recently by Britain’s Met Office”, but “said it would need to last ’30 to 40 years at least’ to break the long-term global warming trend”.

Most SO2 emissions are from fossil fuel burning at power plants and in industry, with smaller amounts coming from railways, large vessels and some industrial processes.

Volcanoes downplayed

 

Small quantities of the emissions eventually rise into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulphuric acid and water particles that reflect sunlight back into space, cooling the planet.

Scientists have known for years that this cooling mechanism from a range of aerosols is helping to prevent global average temperatures rising as much as they otherwise would under the influence of greenhouse gases, but it appears they have underestimated the effect of volcanic SO2.

India and China are estimated to have increased their industrial SO2 emissions by about 60% between 2000 and 2010 through coal burning.

But the study, published online in Geophysical Research Letters, suggests it is volcanic eruptions, not Asia’s emissions, that are largely responsible for the warming slowdown.

The study’s lead author, Ryan Neely, said previous observations had suggested that increases in stratospheric aerosols as a whole since 2000 had cancelled out as much as 25% of the warming from greenhouse gases.

“This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet”, said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration (NOAA).

Negligible overall effect

 

The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely. Since 2000 the optical depth in the layer has increased by about 4 to 7%, meaning it is slightly more opaque now than it was.

“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate”,  said Professor Brian Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences.

“But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”

“This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.”

While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tonnes of SO2 that cooled the Earth slightly for the next few years. – Climate News Network

Volcanoes may mask ‘lost’ warming

EMBARGOED until 0001 GMT on Monday 4 March Scientists believe that emissions of sulphur dioxide from erupting volcanoes may be masking the effect of greenhouse gases and so keeping temperature rises artificially low. LONDON, 4 March – Climate scientists think they may have found at least part of the answer to a conundrum which has been puzzling them recently – why the atmosphere has not warmed as much as expected over the last decade or so. A team led by the University of Colorado-Boulder (CU-Boulder) thinks the reason may be emissions of sulphur dioxide (SO2), a known inhibitor of atmospheric warming, from many of the world’s volcanoes. The puzzle is why the global average temperature has not increased as expected in step with rising greenhouse gas emissions. This has led some to suggest that global warming itself is faltering, and with it the entire scientific justification for action to stabilise the climate. The chair of the Intergovernmental Panel on Climate Change, Dr R K Pachauri, was reported in The Australian on 22 February as having acknowledged “a 17-year pause in global temperature rises, confirmed recently by Britain’s Met Office”, but “said it would need to last ’30 to 40 years at least’ to break the long-term global warming trend”. Most SO2 emissions are from fossil fuel burning at power plants and in industry, with smaller amounts coming from railways, large vessels and some industrial processes.

Volcanoes downplayed

  Small quantities of the emissions eventually rise into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulphuric acid and water particles that reflect sunlight back into space, cooling the planet. Scientists have known for years that this cooling mechanism from a range of aerosols is helping to prevent global average temperatures rising as much as they otherwise would under the influence of greenhouse gases, but it appears they have underestimated the effect of volcanic SO2. India and China are estimated to have increased their industrial SO2 emissions by about 60% between 2000 and 2010 through coal burning. But the study, published online in Geophysical Research Letters, suggests it is volcanic eruptions, not Asia’s emissions, that are largely responsible for the warming slowdown. The study’s lead author, Ryan Neely, said previous observations had suggested that increases in stratospheric aerosols as a whole since 2000 had cancelled out as much as 25% of the warming from greenhouse gases. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet”, said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration (NOAA).

Negligible overall effect

  The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely. Since 2000 the optical depth in the layer has increased by about 4 to 7%, meaning it is slightly more opaque now than it was. “The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate”,  said Professor Brian Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences. “But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.” “This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.” While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tonnes of SO2 that cooled the Earth slightly for the next few years. – Climate News Network

EMBARGOED until 0001 GMT on Monday 4 March Scientists believe that emissions of sulphur dioxide from erupting volcanoes may be masking the effect of greenhouse gases and so keeping temperature rises artificially low. LONDON, 4 March – Climate scientists think they may have found at least part of the answer to a conundrum which has been puzzling them recently – why the atmosphere has not warmed as much as expected over the last decade or so. A team led by the University of Colorado-Boulder (CU-Boulder) thinks the reason may be emissions of sulphur dioxide (SO2), a known inhibitor of atmospheric warming, from many of the world’s volcanoes. The puzzle is why the global average temperature has not increased as expected in step with rising greenhouse gas emissions. This has led some to suggest that global warming itself is faltering, and with it the entire scientific justification for action to stabilise the climate. The chair of the Intergovernmental Panel on Climate Change, Dr R K Pachauri, was reported in The Australian on 22 February as having acknowledged “a 17-year pause in global temperature rises, confirmed recently by Britain’s Met Office”, but “said it would need to last ’30 to 40 years at least’ to break the long-term global warming trend”. Most SO2 emissions are from fossil fuel burning at power plants and in industry, with smaller amounts coming from railways, large vessels and some industrial processes.

Volcanoes downplayed

  Small quantities of the emissions eventually rise into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulphuric acid and water particles that reflect sunlight back into space, cooling the planet. Scientists have known for years that this cooling mechanism from a range of aerosols is helping to prevent global average temperatures rising as much as they otherwise would under the influence of greenhouse gases, but it appears they have underestimated the effect of volcanic SO2. India and China are estimated to have increased their industrial SO2 emissions by about 60% between 2000 and 2010 through coal burning. But the study, published online in Geophysical Research Letters, suggests it is volcanic eruptions, not Asia’s emissions, that are largely responsible for the warming slowdown. The study’s lead author, Ryan Neely, said previous observations had suggested that increases in stratospheric aerosols as a whole since 2000 had cancelled out as much as 25% of the warming from greenhouse gases. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet”, said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration (NOAA).

Negligible overall effect

  The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely. Since 2000 the optical depth in the layer has increased by about 4 to 7%, meaning it is slightly more opaque now than it was. “The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate”,  said Professor Brian Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences. “But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.” “This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.” While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tonnes of SO2 that cooled the Earth slightly for the next few years. – Climate News Network