Tag Archives: Temperature rise

Rising heat means more methane, warmer nights

Nights are warmer. So are northern lakes. And farm livestock are at greater risk of disease, thanks to rising heat.

LONDON, 20 October, 2020 − Global warming has already begun to alter the world perceptibly, with rising heat changing daily life for millions of people.

Over more than half the planet’s land surface, nights are now warming at a rate faster than the days, with unpredictable consequences for plant and animal life.

Warmer winters now mean that in Europe, Asia and North America, lakes that would once have frozen over are now increasingly sometimes ice-free even at the darkest moments of the year.

And ever-higher temperatures encourage the spread of infectious diseases, and unexpectedly with that, the hazard of yet more warming.

Increasing parasitic activity among farm animals could mean that infected cattle, sheep and goats can produce up to a third more methane. This natural gas is around 30 times more potent, as a greenhouse gas, than the same volume of carbon dioxide.

“There is evidence that climate change, and warming temperatures in particular, are impacting some infectious diseases and increasing their prevalence”

The long-term consequences of any of these changes are difficult to foresee. British scientists report in the journal Global Change Biology that they searched the fine detail of global temperature, cloud cover, humidity and rainfall worldwide from 1983 to 2017 for any significant pattern of change, and found one.

Over more than half the terrestrial surface of the planet, there was a mean annual difference of at least 0.25°C between daytime and night-time warming.

In some places, days warmed more swiftly than nights. But disproportionately greater night-time warming happened over an area more than twice as large.

The agency at work appeared to be cloud cover: more clouds mean a cooler surface in daylight but a more effective blanket to retain warmth at night. Clear skies tend to mean hotter days and colder nights.

“We demonstrate that greater night-time warming is associated with climate becoming wetter, and this been shown to have important consequences for plant growth, and how species such as insects and mammals interact,” said Daniel Cox of Exeter University, UK, who led the research.

More ice-free lakes

“Conversely, we show that greater daytime warming is associated with drier conditions, combined with greater levels of overall warming, which increases vulnerability to heat stress and dehydration. Species that are only active at night or during the day will be particularly affected.”

Freezing winters play a vital role in the life of a northern lake. Canadian scientists report in the journal Geophysical Research Letters that they analysed almost eight decades of data − from 1939 to 2016 − for 122 lakes in Asia, Europe and America: the lakes included Baikal in Siberia, Geneva in Switzerland and Balaton in Hungary, Champlain and Michigan near the US- Canadian border, and Suwa in Japan, where records extend back to 1443.

They found that ice-free years have become three times more frequent since 1978, and 11% experienced at least one completely ice-free year since 1939. The trend was the same, everywhere they looked.

Lake ice is also vulnerable to rising heat. It is important to the winter recreation industry. It also plays a vital role in lake ecology. Without a sheath of winter ice, lakes stay warmer and stratify earlier to become more vulnerable to toxic algal blooms: this in turn is bad for fish, and for swimmers.

“Lake ice is becoming increasingly absent,” said Alessandro Filazzola of York University, Toronto, who led the study. “Even under low-carbon emissions scenarios, we’re going to have ice-free events.”

Methane’s rapid rise

Methane is a relatively short-lived but highly potent greenhouse gas: in the past decade it has increased rapidly in the atmosphere. About half of this increase comes from farm livestock.

US researchers report in the journal Trends in Ecology and Evolution that they looked at sheep studies to find that animals infected with intestinal worms produced up to 33% more methane per kilogram of food than uninfected animals. Dairy cows with mastitis − a bacterial infection − produce 8% more methane per litre of milk than uninfected animals.

Global livestock production could increase at the rate of 2.7% a year, according to UN forecasts. If so, between 2017 and 2050 methane production will soar by more than 20%. Throw parasitic worm infections into the forecasts and methane emissions from livestock could climb by up to 82% in the same period.

“There is evidence that climate change, and warming temperatures in particular, are impacting some infectious diseases and increasing their prevalence,” said Vanessa Ezenwa of the University of Georgia, first author.

“If that’s happening for livestock diseases, and simultaneously higher prevalence is triggering increased methane release, you could end up with what we call a vicious cycle.” − Climate News Network

Nights are warmer. So are northern lakes. And farm livestock are at greater risk of disease, thanks to rising heat.

LONDON, 20 October, 2020 − Global warming has already begun to alter the world perceptibly, with rising heat changing daily life for millions of people.

Over more than half the planet’s land surface, nights are now warming at a rate faster than the days, with unpredictable consequences for plant and animal life.

Warmer winters now mean that in Europe, Asia and North America, lakes that would once have frozen over are now increasingly sometimes ice-free even at the darkest moments of the year.

And ever-higher temperatures encourage the spread of infectious diseases, and unexpectedly with that, the hazard of yet more warming.

Increasing parasitic activity among farm animals could mean that infected cattle, sheep and goats can produce up to a third more methane. This natural gas is around 30 times more potent, as a greenhouse gas, than the same volume of carbon dioxide.

“There is evidence that climate change, and warming temperatures in particular, are impacting some infectious diseases and increasing their prevalence”

The long-term consequences of any of these changes are difficult to foresee. British scientists report in the journal Global Change Biology that they searched the fine detail of global temperature, cloud cover, humidity and rainfall worldwide from 1983 to 2017 for any significant pattern of change, and found one.

Over more than half the terrestrial surface of the planet, there was a mean annual difference of at least 0.25°C between daytime and night-time warming.

In some places, days warmed more swiftly than nights. But disproportionately greater night-time warming happened over an area more than twice as large.

The agency at work appeared to be cloud cover: more clouds mean a cooler surface in daylight but a more effective blanket to retain warmth at night. Clear skies tend to mean hotter days and colder nights.

“We demonstrate that greater night-time warming is associated with climate becoming wetter, and this been shown to have important consequences for plant growth, and how species such as insects and mammals interact,” said Daniel Cox of Exeter University, UK, who led the research.

More ice-free lakes

“Conversely, we show that greater daytime warming is associated with drier conditions, combined with greater levels of overall warming, which increases vulnerability to heat stress and dehydration. Species that are only active at night or during the day will be particularly affected.”

Freezing winters play a vital role in the life of a northern lake. Canadian scientists report in the journal Geophysical Research Letters that they analysed almost eight decades of data − from 1939 to 2016 − for 122 lakes in Asia, Europe and America: the lakes included Baikal in Siberia, Geneva in Switzerland and Balaton in Hungary, Champlain and Michigan near the US- Canadian border, and Suwa in Japan, where records extend back to 1443.

They found that ice-free years have become three times more frequent since 1978, and 11% experienced at least one completely ice-free year since 1939. The trend was the same, everywhere they looked.

Lake ice is also vulnerable to rising heat. It is important to the winter recreation industry. It also plays a vital role in lake ecology. Without a sheath of winter ice, lakes stay warmer and stratify earlier to become more vulnerable to toxic algal blooms: this in turn is bad for fish, and for swimmers.

“Lake ice is becoming increasingly absent,” said Alessandro Filazzola of York University, Toronto, who led the study. “Even under low-carbon emissions scenarios, we’re going to have ice-free events.”

Methane’s rapid rise

Methane is a relatively short-lived but highly potent greenhouse gas: in the past decade it has increased rapidly in the atmosphere. About half of this increase comes from farm livestock.

US researchers report in the journal Trends in Ecology and Evolution that they looked at sheep studies to find that animals infected with intestinal worms produced up to 33% more methane per kilogram of food than uninfected animals. Dairy cows with mastitis − a bacterial infection − produce 8% more methane per litre of milk than uninfected animals.

Global livestock production could increase at the rate of 2.7% a year, according to UN forecasts. If so, between 2017 and 2050 methane production will soar by more than 20%. Throw parasitic worm infections into the forecasts and methane emissions from livestock could climb by up to 82% in the same period.

“There is evidence that climate change, and warming temperatures in particular, are impacting some infectious diseases and increasing their prevalence,” said Vanessa Ezenwa of the University of Georgia, first author.

“If that’s happening for livestock diseases, and simultaneously higher prevalence is triggering increased methane release, you could end up with what we call a vicious cycle.” − Climate News Network

Laughing gas rise leaves climate science anxious

Atmospheric levels of laughing gas are on the increase, thanks to agriculture. This is no joke for climate change.

LONDON, 14 October, 2020 − If humans are to meet the global heating limits set by international agreement in 2015, they will have to think very hard about the effect of the supper table menu on laughing gas, more formally known as nitrous oxide.

That is because food production depends heavily on nitrogen fertilisers. But greenhouse gas emissions driven by agriculture are increasing atmospheric levels of nitrous oxide (N2O).

This is a greenhouse gas − popularly known as “laughing gas” − that is 300 times more potent than carbon dioxide, and it tends to stay in the atmosphere, driving up the thermometer, for at least 100 years. And in the 200 years since the start of the Industrial Revolution, atmospheric levels of nitrous oxide have risen by 20%, and are still rising.

Nitrous oxide is one of the six greenhouse gases identified in the Kyoto Protocol, the pioneering global climate agreement, as a danger whose emissions should be reduced by all its signatories.

The ratio of N2O to other gases is tiny, a thousand times lower than carbon dioxide, for instance, but an increase can still make a significant difference. In 1750 the ratio stood at 270 parts per billion. In 2018 it had reached 331 ppb, with the fastest growth all in the last 50 years, thanks to humankind’s demand for food.

“There is a conflict between the way we are feeding people and stabilising the climate”

And this, say 57 scientists from 14 nations in a report in the journal Nature, now threatens to eliminate any hope of containing global heating to “well below” 2°C by the year 2100. This is the target set in the Paris Agreement in 2015 by 195 nations.

Right now, the world has already warmed by 1°C in the last century and on all the evidence so far it is heading by the end of the century to be at least 3°C hotter than the average for most of the last 10,000 years of human history.

“The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,” said Hanqin Tian, of Auburn University’s School of Forestry and Wildlife Sciences in Alabama in the US. “There is a conflict between the way we are feeding people and stabilising the climate.”

He and his colleagues call their research an inventory of the traffic in nitrous oxide from human and from natural sources. The most significant human source is the fertiliser added to croplands.

They found that the highest growth in nitrous oxide emissions came from emerging economies in East Asia, South Asia, Africa and South America, from synthetic fertilisers and from livestock manure. In the course of the next few decades global population will soar, and so will the demand for food.

Total rethink

Researchers have consistently argued for a new approach to agriculture,  with ever-greater emphasis on plant-based diets, as a way to help contain climate change on a scale that is likely to actually threaten global food security.

“Europe is the only region in the world that has successfully reduced nitrous oxide emissions over the past two decades,” said Robert Jackson,  of Stanford University in the US, who chairs the Global Carbon Project.

“Industrial and agricultural policies to reduce greenhouse gases and air pollution and to optimise fertiliser use efficiencies have proven to be effective. Still, further efforts are required, in Europe as well as globally.”

And another author, Josep Canadell of Australia’s Commonwealth Scientific and Industrial Research Organisation, said: “This new analysis calls for a full rethink in the ways we use and abuse nitrogen fertilisers globally and urges us to adopt more sustainable practices in the way we produce food,  including the reduction of food waste.” − Climate News Network

Atmospheric levels of laughing gas are on the increase, thanks to agriculture. This is no joke for climate change.

LONDON, 14 October, 2020 − If humans are to meet the global heating limits set by international agreement in 2015, they will have to think very hard about the effect of the supper table menu on laughing gas, more formally known as nitrous oxide.

That is because food production depends heavily on nitrogen fertilisers. But greenhouse gas emissions driven by agriculture are increasing atmospheric levels of nitrous oxide (N2O).

This is a greenhouse gas − popularly known as “laughing gas” − that is 300 times more potent than carbon dioxide, and it tends to stay in the atmosphere, driving up the thermometer, for at least 100 years. And in the 200 years since the start of the Industrial Revolution, atmospheric levels of nitrous oxide have risen by 20%, and are still rising.

Nitrous oxide is one of the six greenhouse gases identified in the Kyoto Protocol, the pioneering global climate agreement, as a danger whose emissions should be reduced by all its signatories.

The ratio of N2O to other gases is tiny, a thousand times lower than carbon dioxide, for instance, but an increase can still make a significant difference. In 1750 the ratio stood at 270 parts per billion. In 2018 it had reached 331 ppb, with the fastest growth all in the last 50 years, thanks to humankind’s demand for food.

“There is a conflict between the way we are feeding people and stabilising the climate”

And this, say 57 scientists from 14 nations in a report in the journal Nature, now threatens to eliminate any hope of containing global heating to “well below” 2°C by the year 2100. This is the target set in the Paris Agreement in 2015 by 195 nations.

Right now, the world has already warmed by 1°C in the last century and on all the evidence so far it is heading by the end of the century to be at least 3°C hotter than the average for most of the last 10,000 years of human history.

“The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,” said Hanqin Tian, of Auburn University’s School of Forestry and Wildlife Sciences in Alabama in the US. “There is a conflict between the way we are feeding people and stabilising the climate.”

He and his colleagues call their research an inventory of the traffic in nitrous oxide from human and from natural sources. The most significant human source is the fertiliser added to croplands.

They found that the highest growth in nitrous oxide emissions came from emerging economies in East Asia, South Asia, Africa and South America, from synthetic fertilisers and from livestock manure. In the course of the next few decades global population will soar, and so will the demand for food.

Total rethink

Researchers have consistently argued for a new approach to agriculture,  with ever-greater emphasis on plant-based diets, as a way to help contain climate change on a scale that is likely to actually threaten global food security.

“Europe is the only region in the world that has successfully reduced nitrous oxide emissions over the past two decades,” said Robert Jackson,  of Stanford University in the US, who chairs the Global Carbon Project.

“Industrial and agricultural policies to reduce greenhouse gases and air pollution and to optimise fertiliser use efficiencies have proven to be effective. Still, further efforts are required, in Europe as well as globally.”

And another author, Josep Canadell of Australia’s Commonwealth Scientific and Industrial Research Organisation, said: “This new analysis calls for a full rethink in the ways we use and abuse nitrogen fertilisers globally and urges us to adopt more sustainable practices in the way we produce food,  including the reduction of food waste.” − Climate News Network

Plant world feels effect of growing climate heat

From Hudson Bay to Tierra del Fuego, the plant world is beginning to change. Blame it on global heating.

LONDON, 28 August, 2020 – From one end of the Americas to the other, climate heating is subjecting the plant world to radical change, with cold-resistant species increasingly yielding place to those that welcome the rising warmth.

That badge of Canadian identity, the sugar maple, may one day turn sour. As global temperatures, driven by profligate human use of fossil fuels, continue to soar, Acer saccharum could simply lose its habitat and no longer sweeten the forests from Novia Scotia to the Appalachians.

And the southern live oak, so associated with Florida that a city there preserves its name, may find life too hot for comfort: in the south of the state, Quercus virginiana could one day be replaced by trees from the Caribbean or even further south, such as the already present Cuban mahogany Swietenia mahogani or the Gumbo limbo Bursera simaruba.

And in what was once the reliably wintry city of New York, that marvel of old Mississippi the southern magnolia, Magnolia grandiflora, has begun to multiply and bloom ever earlier each year.

These species shifts are just part of a larger trend in the Americas, from Hudson Bay to Tierra del Fuego, according to new research in the journal Nature Climate Change.

“If we lose some plants, we may also lose the insects, birds and many other forms of wildlife that are critical to our ways of life”

Researchers analysed 60 million records of 17,000 plant species in almost 200 New World eco-regions, from 1970 to 2011, to identify a pattern of change in response to heat: a phenomenon called thermophilisation.

“Almost anywhere you go, the types of species that you encounter now are different than what you would have found in the same spot 40 years ago, and we believe that this pattern is the direct result of rising temperatures and climate change,” said Ken Feeley, a biologist at the University of Miami, who led the research.

The study – two continents, and a range of temperature regimes from near-Arctic to equatorial and onwards, almost to the edge of the Southern Ocean – confirms the big picture, but dozens of earlier studies had already built up a mosaic of observations that told much the same story.

As temperatures rise, and precipitation patterns shift, plants respond. The forests of the northern hemisphere everywhere are vulnerable to heat and drought, and even species considered resistant to drought could be about to succumb.

In the lowland tropics, researchers have warned that conditions could become so intemperate that some species may fail to germinate and renew their tenure in the forest. Researchers have observed tropical species moving uphill to find more equable temperature regimes, while others have warned that those upland species that are comfortable at height may soon find it so hot there could be nowhere left to go.

Worldwide effects

The northern tundra is already beginning to host new plant life, but rising temperatures and shifting climate regimes could also damage forests and fuel even more global warming.

The latest study shows once again that, in any ecosystem, those species that are more likely to cope with colder temperatures are being replaced by others that just like it hot.

“Some of these changes can be so dramatic that we are shifting entire habitat types from forests to grasslands or vice versa – by looking at all types of plants over long periods of time and over huge areas, we were able to observe those changes,” said Professor Feeley.

“All animals – including humans – depend on the plants around them. If we lose some plants, we may also lose the insects, birds and many other forms of wildlife that we are used to seeing in our communities and that are critical to our ways of life.

“When people think of climate change, they need to realise that it’s not just about losing ice in Antarctica, or rising sea levels – climate change affects almost every natural system in every part of the planet.” – Climate News Network

From Hudson Bay to Tierra del Fuego, the plant world is beginning to change. Blame it on global heating.

LONDON, 28 August, 2020 – From one end of the Americas to the other, climate heating is subjecting the plant world to radical change, with cold-resistant species increasingly yielding place to those that welcome the rising warmth.

That badge of Canadian identity, the sugar maple, may one day turn sour. As global temperatures, driven by profligate human use of fossil fuels, continue to soar, Acer saccharum could simply lose its habitat and no longer sweeten the forests from Novia Scotia to the Appalachians.

And the southern live oak, so associated with Florida that a city there preserves its name, may find life too hot for comfort: in the south of the state, Quercus virginiana could one day be replaced by trees from the Caribbean or even further south, such as the already present Cuban mahogany Swietenia mahogani or the Gumbo limbo Bursera simaruba.

And in what was once the reliably wintry city of New York, that marvel of old Mississippi the southern magnolia, Magnolia grandiflora, has begun to multiply and bloom ever earlier each year.

These species shifts are just part of a larger trend in the Americas, from Hudson Bay to Tierra del Fuego, according to new research in the journal Nature Climate Change.

“If we lose some plants, we may also lose the insects, birds and many other forms of wildlife that are critical to our ways of life”

Researchers analysed 60 million records of 17,000 plant species in almost 200 New World eco-regions, from 1970 to 2011, to identify a pattern of change in response to heat: a phenomenon called thermophilisation.

“Almost anywhere you go, the types of species that you encounter now are different than what you would have found in the same spot 40 years ago, and we believe that this pattern is the direct result of rising temperatures and climate change,” said Ken Feeley, a biologist at the University of Miami, who led the research.

The study – two continents, and a range of temperature regimes from near-Arctic to equatorial and onwards, almost to the edge of the Southern Ocean – confirms the big picture, but dozens of earlier studies had already built up a mosaic of observations that told much the same story.

As temperatures rise, and precipitation patterns shift, plants respond. The forests of the northern hemisphere everywhere are vulnerable to heat and drought, and even species considered resistant to drought could be about to succumb.

In the lowland tropics, researchers have warned that conditions could become so intemperate that some species may fail to germinate and renew their tenure in the forest. Researchers have observed tropical species moving uphill to find more equable temperature regimes, while others have warned that those upland species that are comfortable at height may soon find it so hot there could be nowhere left to go.

Worldwide effects

The northern tundra is already beginning to host new plant life, but rising temperatures and shifting climate regimes could also damage forests and fuel even more global warming.

The latest study shows once again that, in any ecosystem, those species that are more likely to cope with colder temperatures are being replaced by others that just like it hot.

“Some of these changes can be so dramatic that we are shifting entire habitat types from forests to grasslands or vice versa – by looking at all types of plants over long periods of time and over huge areas, we were able to observe those changes,” said Professor Feeley.

“All animals – including humans – depend on the plants around them. If we lose some plants, we may also lose the insects, birds and many other forms of wildlife that we are used to seeing in our communities and that are critical to our ways of life.

“When people think of climate change, they need to realise that it’s not just about losing ice in Antarctica, or rising sea levels – climate change affects almost every natural system in every part of the planet.” – Climate News Network

Annual planetary temperature continues to rise

More than 500 scientists from 61 countries have again measured the annual planetary temperature. The diagnosis is not good.

LONDON, 17 August, 2020 – Despite global promises to act on climate change, the Earth continues to warm. The annual planetary temperature confirms that the last 10 years were on average 0.2°C warmer than the first 10 years of this century. And each decade since 1980 has been warmer than the decade that preceded it.

The year 2019 was also one of the three warmest years since formal temperature records began in the 19th century. The only warmer years – in some datasets but not all – were 2016 and 2015. And all the years since 2013 have been warmer than all other years in the last 170.

The link with fossil fuel combustion remains unequivocal: carbon dioxide levels in the atmosphere increased by 2.5 parts per million (ppm) in 2019 alone. These now stand at 409 ppm. The global average for most of human history has hovered around 285 ppm.

Two more greenhouse gases – nitrous oxide and methane, both of them more short-lived – also increased measurably.

“This millennium has been warmer than any comparable period since the Industrial Revolution”

The study, in the Bulletin of the American Meteorological Society, is a sobering chronicle of the impact of climate change in the decade 2010-2019 and the year 2019 itself. It is the 30th such report, it is signed by 528 experts from 61 countries, and it is a catalogue of unwelcome records achieved and uncomfortable extremes surpassed.

July 2019 was the hottest month on record. Record high temperatures were measured in more than a dozen nations across Africa, Europe, Asia and the Caribbean. In North America, Alaska scored its hottest year on record.

The Arctic as a whole was warmer than in any year except 2016. Australia achieved a new nationally average daily temperature high of 41.9°C on 18 December, breaking the previous 2013 record by 1.6°C. But even Belgium and the Netherlands saw temperatures higher than 40°C.

For the 32nd consecutive year, the world’s alpine glaciers continued to get smaller and retreat further uphill. For the first time on record in inland Alaska, when measured at 26 sites, the active layer of permafrost failed to freeze completely. In September, sea ice around the Arctic reached a minimum that tied for the second lowest in the 41 years of satellite records.

Catalogue of extremes

Global sea levels set a new high for the eighth consecutive year and are now 87.6mm higher than the 1993 average, when satellite records began. At a depth of 700 metres, ocean temperatures reached new records, and the sea surface temperatures on average were the highest since 2016.

Drought conditions led to catastrophic wildfires in Australia, in Indonesia, Siberia and in the southern Amazon forests of Bolivia, Brazil and Peru. And around the equator, meteorologists catalogued 96 named tropical storms: the average for 1981 to 2010 was 82. In the North Atlantic, just one storm, Hurricane Dorian, killed 70 people and caused $3.4bn (£2.6bn) in damage in the Bahamas.

“This millennium has been warmer than any comparable period since the Industrial Revolution. A number of extreme events, such as wildfires, heatwaves and droughts, have at least part of their root linked to the rise in global temperature,” said Robert Dunn, of the UK Met Office, one of the contributors.

“And of course the rise in global temperature is linked to another climate indicator, the ongoing rise in emissions in greenhouse gases, notably carbon dioxide, nitrous oxide and methane.” – Climate News Network

More than 500 scientists from 61 countries have again measured the annual planetary temperature. The diagnosis is not good.

LONDON, 17 August, 2020 – Despite global promises to act on climate change, the Earth continues to warm. The annual planetary temperature confirms that the last 10 years were on average 0.2°C warmer than the first 10 years of this century. And each decade since 1980 has been warmer than the decade that preceded it.

The year 2019 was also one of the three warmest years since formal temperature records began in the 19th century. The only warmer years – in some datasets but not all – were 2016 and 2015. And all the years since 2013 have been warmer than all other years in the last 170.

The link with fossil fuel combustion remains unequivocal: carbon dioxide levels in the atmosphere increased by 2.5 parts per million (ppm) in 2019 alone. These now stand at 409 ppm. The global average for most of human history has hovered around 285 ppm.

Two more greenhouse gases – nitrous oxide and methane, both of them more short-lived – also increased measurably.

“This millennium has been warmer than any comparable period since the Industrial Revolution”

The study, in the Bulletin of the American Meteorological Society, is a sobering chronicle of the impact of climate change in the decade 2010-2019 and the year 2019 itself. It is the 30th such report, it is signed by 528 experts from 61 countries, and it is a catalogue of unwelcome records achieved and uncomfortable extremes surpassed.

July 2019 was the hottest month on record. Record high temperatures were measured in more than a dozen nations across Africa, Europe, Asia and the Caribbean. In North America, Alaska scored its hottest year on record.

The Arctic as a whole was warmer than in any year except 2016. Australia achieved a new nationally average daily temperature high of 41.9°C on 18 December, breaking the previous 2013 record by 1.6°C. But even Belgium and the Netherlands saw temperatures higher than 40°C.

For the 32nd consecutive year, the world’s alpine glaciers continued to get smaller and retreat further uphill. For the first time on record in inland Alaska, when measured at 26 sites, the active layer of permafrost failed to freeze completely. In September, sea ice around the Arctic reached a minimum that tied for the second lowest in the 41 years of satellite records.

Catalogue of extremes

Global sea levels set a new high for the eighth consecutive year and are now 87.6mm higher than the 1993 average, when satellite records began. At a depth of 700 metres, ocean temperatures reached new records, and the sea surface temperatures on average were the highest since 2016.

Drought conditions led to catastrophic wildfires in Australia, in Indonesia, Siberia and in the southern Amazon forests of Bolivia, Brazil and Peru. And around the equator, meteorologists catalogued 96 named tropical storms: the average for 1981 to 2010 was 82. In the North Atlantic, just one storm, Hurricane Dorian, killed 70 people and caused $3.4bn (£2.6bn) in damage in the Bahamas.

“This millennium has been warmer than any comparable period since the Industrial Revolution. A number of extreme events, such as wildfires, heatwaves and droughts, have at least part of their root linked to the rise in global temperature,” said Robert Dunn, of the UK Met Office, one of the contributors.

“And of course the rise in global temperature is linked to another climate indicator, the ongoing rise in emissions in greenhouse gases, notably carbon dioxide, nitrous oxide and methane.” – Climate News Network

Climate science’s worst case is today’s reality

Climate science’s worst case scenario isn’t just an awful warning. It describes what is already happening right now.

LONDON, 10 August, 2020 – A trio of US researchers has grim news for people worried about climate science’s worst case outcome. Forget about the other options. The worst case is already happening.

Christopher Schwalm and colleagues at the Woods Hole Research Center in Massachusetts report in the Proceedings of the National Academy of Sciences that they took a closer look at the evidence for climate change in terms of carbon dioxide emissions and climate models.

This is the kind of research that assesses the future under a number of possible scenarios. These scenarios are based on mathematical models and global assumptions about economic growth, carbon budgets and land use changes, and they are couched in language arcane enough to make even committed followers of climate science reach for the aspirin.

The most optimistic of these is one in which the world makes a determined, drastic and concerted effort to contain global heating to well below 2°C above the average for most of human history. At the other end of the scale is one notoriously called “business as usual”, in which the nations of the world carry on burning ever more fossil fuels, while sea levels rise ever higher, and the thermometer readings get ever higher. It has been intended from the start as an awful warning rather than as a guide to what is most likely to happen.

“RCP8.5 has continued utility … if RCP8.5 did not exist, we’d have to create it”

Since 195 nations met in Paris in 2015 and vowed to take action to keep global heating if possible to well below 2°C, and ideally no higher than 1.5°C, there has been an assumption that the “worst case”, or “business as usual” scenario – known in climate science shorthand as Representative Concentration Pathway 8.5, or RCP8.5 – was no more than that: the worst case.

Under the terms of the Paris Agreement, nations accepted commitments to plans to reduce emissions. Researchers have repeatedly warned that such plans as have been announced were not ambitious enough, and not being implemented fast enough.

The US has announced that it will abandon the Paris promise. Other nations have maintained their willingness to act, but have gone on opening coal mines and prospecting for more oil.

Even so, after Paris, it became clear there would surely be change. The world had been alerted, the worst could indeed be averted. The RCP8.5 scenario was, some said, of no great help. It has even been described as “extreme, alarmist and ‘misleading’.”

Implications for 2100

Sadly, it may not be. Dr Schwalm and his colleagues looked at cumulative greenhouse gas emissions since 2005. By 2020, the emissions matched the “business as usual” or RCP8.5 predictions very closely.

They then extended the trends to 2030, and to 2050, with the same outcome. That means that – by the end of the century – the planet could be 3.3°C to 5.4°C warmer than it was at the launch of the Industrial Revolution and the worldwide switch to fossil fuels. In which case, the worst-case scenario would remain on the table as a useful risk assessment tool.

“The implied probability of occurrence similar to RCP8.5 even at the end of the century is large enough to merit its continued use,” the scientists write.

“RCP8.5 has continued utility, both as an instrument to explore mean outcomes as well as risk. Indeed, if RCP8.5 did not exist, we’d have to create it.” – Climate News Network

Climate science’s worst case scenario isn’t just an awful warning. It describes what is already happening right now.

LONDON, 10 August, 2020 – A trio of US researchers has grim news for people worried about climate science’s worst case outcome. Forget about the other options. The worst case is already happening.

Christopher Schwalm and colleagues at the Woods Hole Research Center in Massachusetts report in the Proceedings of the National Academy of Sciences that they took a closer look at the evidence for climate change in terms of carbon dioxide emissions and climate models.

This is the kind of research that assesses the future under a number of possible scenarios. These scenarios are based on mathematical models and global assumptions about economic growth, carbon budgets and land use changes, and they are couched in language arcane enough to make even committed followers of climate science reach for the aspirin.

The most optimistic of these is one in which the world makes a determined, drastic and concerted effort to contain global heating to well below 2°C above the average for most of human history. At the other end of the scale is one notoriously called “business as usual”, in which the nations of the world carry on burning ever more fossil fuels, while sea levels rise ever higher, and the thermometer readings get ever higher. It has been intended from the start as an awful warning rather than as a guide to what is most likely to happen.

“RCP8.5 has continued utility … if RCP8.5 did not exist, we’d have to create it”

Since 195 nations met in Paris in 2015 and vowed to take action to keep global heating if possible to well below 2°C, and ideally no higher than 1.5°C, there has been an assumption that the “worst case”, or “business as usual” scenario – known in climate science shorthand as Representative Concentration Pathway 8.5, or RCP8.5 – was no more than that: the worst case.

Under the terms of the Paris Agreement, nations accepted commitments to plans to reduce emissions. Researchers have repeatedly warned that such plans as have been announced were not ambitious enough, and not being implemented fast enough.

The US has announced that it will abandon the Paris promise. Other nations have maintained their willingness to act, but have gone on opening coal mines and prospecting for more oil.

Even so, after Paris, it became clear there would surely be change. The world had been alerted, the worst could indeed be averted. The RCP8.5 scenario was, some said, of no great help. It has even been described as “extreme, alarmist and ‘misleading’.”

Implications for 2100

Sadly, it may not be. Dr Schwalm and his colleagues looked at cumulative greenhouse gas emissions since 2005. By 2020, the emissions matched the “business as usual” or RCP8.5 predictions very closely.

They then extended the trends to 2030, and to 2050, with the same outcome. That means that – by the end of the century – the planet could be 3.3°C to 5.4°C warmer than it was at the launch of the Industrial Revolution and the worldwide switch to fossil fuels. In which case, the worst-case scenario would remain on the table as a useful risk assessment tool.

“The implied probability of occurrence similar to RCP8.5 even at the end of the century is large enough to merit its continued use,” the scientists write.

“RCP8.5 has continued utility, both as an instrument to explore mean outcomes as well as risk. Indeed, if RCP8.5 did not exist, we’d have to create it.” – Climate News Network

Earth cooled naturally long before human heating

Once again the past shows the role of greenhouse gases in climate change. It also confirms human heating as the main cause of global warmth.

LONDON, 8 July, 2020 – A new reconstruction of the history of global temperatures for the last 12,000 years supports an argument often put forward by climate sceptics: that global climate is subject to natural cycles driven by astronomical forces and planet Earth might be in one, with human heating not responsible.

It is. But the latest finding offers no evidence for scepticism. For the last 6,500 years the global mean surface of the planet has slowly and  naturally been getting cooler, as lower levels of summer sunlight hit the northern hemisphere.

And this gradual cooling came to a sudden end only in the 19th century as human cities and industries switched increasingly to coal, and then to oil and gas, to return ever-higher levels of ancient carbon to the atmosphere.

The rate of natural cooling would be imperceptible in any human lifespan: less than 0.1°C per thousand years.

This slow, subtle lowering of the temperature began 4,500 years before the beginning of the Christian era, in a Neolithic world of perhaps only 40 million people, at a time when Chinese villagers began to grow rice on terraces along the Yellow River and civilisation began to flourish in the Tigris-Euphrates valley.

“This past decade was likely cooler than what the average temperatures will be for the rest of this century and beyond”

This was a time when the first agricultural and pastoral settlements spread across Europe, along with the first pottery; when the Sahara was still grassland, and when most of Europe spoke just one language, now called Proto-Indo-European.

Researchers from the US and Europe report in the journal Scientific Data that they used the most comprehensive collection of palaeo-climatic evidence – 1,319 data sets based on tree rings, fossil pollen samples, ice cores and so on, collected from 679 sites worldwide – to establish that this must have been, for humans in prehistory, the moment of what they call “peak warmth.” From then on, the thermometer began to drop, at an average of 0.08C per millennium.

“The rate of cooling that followed the peak warmth was subtle, only around 0.01°C per 1,000 years. This cooling seems to be driven by slow cycles in the Earth’s orbit, which reduced the amount of summer sunlight in the Northern Hemisphere, culminating in the Little Ice Age of recent centuries,” said Michael Erb of Northern Arizona University.

More than a century of observation has shown that tiny cyclic changes in the Earth’s elliptical orbit can explain some of the patterns of climate change in the past, and confirm the lengths of the more recent Ice Ages, and the role of other planets in these periodic shifts.

Big picture unchanged

It is an article of faith among geologists that the present is key to the past, and the rocks and fossils preserve enduring evidence of the ups and downs of global temperatures.

It is now four years since European scientists proposed that climate change driven by greenhouse gas emissions from fossil fuels might have begun to delay the next Ice Age.

So the latest look at more recent data doesn’t change the big picture. In the last 100 or more years, global temperatures have risen by at least 1°C, and the average temperature of the last decade has been the warmest for 12,000 years, thanks to increasing concentrations of carbon dioxide in the atmosphere, as a consequence of human action.

“On the other hand, this past decade was likely cooler than what the average temperatures will be for the rest of this century and beyond, which are very likely to continue to exceed 1°C above pre-industrial temperatures,” said Nicholas McKay, one of the authors from Flagstaff, Arizona.

And his colleague Darrell Kaufman, who led the study, said: “It’s possible that the last time the sustained average global temperature was 1°C above the 19th century was prior to the last Ice Age, back around 125,000 years ago when sea level was around 20 feet (6 metres) higher than today.” – Climate News Network

Once again the past shows the role of greenhouse gases in climate change. It also confirms human heating as the main cause of global warmth.

LONDON, 8 July, 2020 – A new reconstruction of the history of global temperatures for the last 12,000 years supports an argument often put forward by climate sceptics: that global climate is subject to natural cycles driven by astronomical forces and planet Earth might be in one, with human heating not responsible.

It is. But the latest finding offers no evidence for scepticism. For the last 6,500 years the global mean surface of the planet has slowly and  naturally been getting cooler, as lower levels of summer sunlight hit the northern hemisphere.

And this gradual cooling came to a sudden end only in the 19th century as human cities and industries switched increasingly to coal, and then to oil and gas, to return ever-higher levels of ancient carbon to the atmosphere.

The rate of natural cooling would be imperceptible in any human lifespan: less than 0.1°C per thousand years.

This slow, subtle lowering of the temperature began 4,500 years before the beginning of the Christian era, in a Neolithic world of perhaps only 40 million people, at a time when Chinese villagers began to grow rice on terraces along the Yellow River and civilisation began to flourish in the Tigris-Euphrates valley.

“This past decade was likely cooler than what the average temperatures will be for the rest of this century and beyond”

This was a time when the first agricultural and pastoral settlements spread across Europe, along with the first pottery; when the Sahara was still grassland, and when most of Europe spoke just one language, now called Proto-Indo-European.

Researchers from the US and Europe report in the journal Scientific Data that they used the most comprehensive collection of palaeo-climatic evidence – 1,319 data sets based on tree rings, fossil pollen samples, ice cores and so on, collected from 679 sites worldwide – to establish that this must have been, for humans in prehistory, the moment of what they call “peak warmth.” From then on, the thermometer began to drop, at an average of 0.08C per millennium.

“The rate of cooling that followed the peak warmth was subtle, only around 0.01°C per 1,000 years. This cooling seems to be driven by slow cycles in the Earth’s orbit, which reduced the amount of summer sunlight in the Northern Hemisphere, culminating in the Little Ice Age of recent centuries,” said Michael Erb of Northern Arizona University.

More than a century of observation has shown that tiny cyclic changes in the Earth’s elliptical orbit can explain some of the patterns of climate change in the past, and confirm the lengths of the more recent Ice Ages, and the role of other planets in these periodic shifts.

Big picture unchanged

It is an article of faith among geologists that the present is key to the past, and the rocks and fossils preserve enduring evidence of the ups and downs of global temperatures.

It is now four years since European scientists proposed that climate change driven by greenhouse gas emissions from fossil fuels might have begun to delay the next Ice Age.

So the latest look at more recent data doesn’t change the big picture. In the last 100 or more years, global temperatures have risen by at least 1°C, and the average temperature of the last decade has been the warmest for 12,000 years, thanks to increasing concentrations of carbon dioxide in the atmosphere, as a consequence of human action.

“On the other hand, this past decade was likely cooler than what the average temperatures will be for the rest of this century and beyond, which are very likely to continue to exceed 1°C above pre-industrial temperatures,” said Nicholas McKay, one of the authors from Flagstaff, Arizona.

And his colleague Darrell Kaufman, who led the study, said: “It’s possible that the last time the sustained average global temperature was 1°C above the 19th century was prior to the last Ice Age, back around 125,000 years ago when sea level was around 20 feet (6 metres) higher than today.” – Climate News Network

Ocean sensitivity may lower carbon emissions cuts

Ocean sensitivity to atmospheric change is well established. But just how sensitive the oceans are remains a surprise to science.

LONDON, 30 June, 2020 – As greenhouse gas emissions soar, ocean sensitivity has quietly helped humanity to slow global heating: the seas have responded by absorbing more and more carbon dioxide from the atmosphere.

But should humans come to grips with the challenge of looming climate catastrophe and start to reduce emissions, the oceans could respond again – by absorbing less and slightly slowing the fall of the mercury in the global thermometer.

And there is even an immediate chance to test this proposal: if so, then oceans that have been each year absorbing more and more carbon from the atmosphere as greenhouse gas ratios rise will go into brief reverse, because of the global economic shutdown and fall in emissions triggered by the global pandemic of Covid-19.

For the first time in decades, the oceans could take up less carbon dioxide in 2020, according to a new study by US scientists in the American Geophysical Union journal AGU Advances.

“We didn’t realise until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That’s a real surprise,” said Galen McKinley, of Columbia University’s Lamont-Doherty Earth Observatory.

Feedback in action

“As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it’s important to realise that the ocean carbon sink will respond by slowing down.”

The research should not be interpreted as an invitation to go on burning fossil fuels. It is another lesson in the intricacy of the traffic between atmosphere, rocks, oceans, and living things in an evolving world. And it is more immediately an exquisite example of what engineers call feedback.

In cases of negative feedback, the agency of change also triggers a way of slowing that change. Since 1750 – the birth of the Industrial Revolution – human economies have added 440 billion tonnes of carbon to the planetary atmosphere.

For most of human history carbon dioxide ratios in the atmosphere had hovered around 285 parts per million. They have now gone beyond 400 ppm, and global average temperatures have already risen by more than 1°C.

They’d be even higher but for the oceans, which have responded by absorbing around 39% of all that extra carbon from coal, oil and gas combustion. So the oceans are sensitive to atmospheric change, and respond.

“There will be a time when the ocean will limit the effectiveness of mitigation actions, and this should be accounted for in policymaking”

The latest study is a lesson in how sensitive: Professor McKinley and her colleagues used computer models to try to understand better why the ocean uptake of carbon varies.

In the early 1990s, the ocean absorption of carbon dioxide varied: dramatically at first, because a devastating volcanic eruption of Mt Pinatubo in the Philippines in 1991 that darkened the stratosphere also accelerated ocean uptake.

And then the ocean uptake started to slow, as the skies cleared but also as the collapse of the Soviet Union and its satellite nations changed the global pattern of fuel use. It went on declining until 2001, when fossil fuel use started to accelerate. And then the ocean sink started once again to become more absorbent.

Such research is a reminder of how much scientists still don’t know about the machinery of the planet. That greenhouse gas from fossil fuel combustion drives global heating is not now in doubt. But the precise speed, and the drivers and brakes of positive and negative feedback, remain less certain.

Many feedbacks are positive: as the Arctic warms, carbon plant remains frozen in the permafrost will start to decay, release more methane and carbon dioxide, and accelerate warming.

Forest concern

As the sea ice retreats, and the ice reflects less sunlight, the exposed blue seas will absorb ever more radiation, to turn up the planetary temperatures. A warner world will be a wetter one, which may also mean a rise in the rate of warming.

But the ocean is not the only example of negative feedback. More carbon dioxide seems to mean more vigorous plant growth, and there is clear evidence that the world’s great forests are an important carbon sink: an example of negative feedback. That is why almost all governments recognise the importance of forest conservation.

Action however is uneven, forests are still being degraded, and there is alarming evidence that at some point, as temperatures get too high, the tropical forests could start surrendering the carbon they have for millennia absorbed, and become agents of positive feedback.

Professor McKinley warns that – as global emissions are cut – there will be a phase during which ocean uptake slows. If so, then planetary temperature rise will not slow as fast as hoped: extra carbon dioxide will linger, to contribute to warming.

“We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking.” – Climate News Network

Ocean sensitivity to atmospheric change is well established. But just how sensitive the oceans are remains a surprise to science.

LONDON, 30 June, 2020 – As greenhouse gas emissions soar, ocean sensitivity has quietly helped humanity to slow global heating: the seas have responded by absorbing more and more carbon dioxide from the atmosphere.

But should humans come to grips with the challenge of looming climate catastrophe and start to reduce emissions, the oceans could respond again – by absorbing less and slightly slowing the fall of the mercury in the global thermometer.

And there is even an immediate chance to test this proposal: if so, then oceans that have been each year absorbing more and more carbon from the atmosphere as greenhouse gas ratios rise will go into brief reverse, because of the global economic shutdown and fall in emissions triggered by the global pandemic of Covid-19.

For the first time in decades, the oceans could take up less carbon dioxide in 2020, according to a new study by US scientists in the American Geophysical Union journal AGU Advances.

“We didn’t realise until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That’s a real surprise,” said Galen McKinley, of Columbia University’s Lamont-Doherty Earth Observatory.

Feedback in action

“As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it’s important to realise that the ocean carbon sink will respond by slowing down.”

The research should not be interpreted as an invitation to go on burning fossil fuels. It is another lesson in the intricacy of the traffic between atmosphere, rocks, oceans, and living things in an evolving world. And it is more immediately an exquisite example of what engineers call feedback.

In cases of negative feedback, the agency of change also triggers a way of slowing that change. Since 1750 – the birth of the Industrial Revolution – human economies have added 440 billion tonnes of carbon to the planetary atmosphere.

For most of human history carbon dioxide ratios in the atmosphere had hovered around 285 parts per million. They have now gone beyond 400 ppm, and global average temperatures have already risen by more than 1°C.

They’d be even higher but for the oceans, which have responded by absorbing around 39% of all that extra carbon from coal, oil and gas combustion. So the oceans are sensitive to atmospheric change, and respond.

“There will be a time when the ocean will limit the effectiveness of mitigation actions, and this should be accounted for in policymaking”

The latest study is a lesson in how sensitive: Professor McKinley and her colleagues used computer models to try to understand better why the ocean uptake of carbon varies.

In the early 1990s, the ocean absorption of carbon dioxide varied: dramatically at first, because a devastating volcanic eruption of Mt Pinatubo in the Philippines in 1991 that darkened the stratosphere also accelerated ocean uptake.

And then the ocean uptake started to slow, as the skies cleared but also as the collapse of the Soviet Union and its satellite nations changed the global pattern of fuel use. It went on declining until 2001, when fossil fuel use started to accelerate. And then the ocean sink started once again to become more absorbent.

Such research is a reminder of how much scientists still don’t know about the machinery of the planet. That greenhouse gas from fossil fuel combustion drives global heating is not now in doubt. But the precise speed, and the drivers and brakes of positive and negative feedback, remain less certain.

Many feedbacks are positive: as the Arctic warms, carbon plant remains frozen in the permafrost will start to decay, release more methane and carbon dioxide, and accelerate warming.

Forest concern

As the sea ice retreats, and the ice reflects less sunlight, the exposed blue seas will absorb ever more radiation, to turn up the planetary temperatures. A warner world will be a wetter one, which may also mean a rise in the rate of warming.

But the ocean is not the only example of negative feedback. More carbon dioxide seems to mean more vigorous plant growth, and there is clear evidence that the world’s great forests are an important carbon sink: an example of negative feedback. That is why almost all governments recognise the importance of forest conservation.

Action however is uneven, forests are still being degraded, and there is alarming evidence that at some point, as temperatures get too high, the tropical forests could start surrendering the carbon they have for millennia absorbed, and become agents of positive feedback.

Professor McKinley warns that – as global emissions are cut – there will be a phase during which ocean uptake slows. If so, then planetary temperature rise will not slow as fast as hoped: extra carbon dioxide will linger, to contribute to warming.

“We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking.” – Climate News Network

Forest trees are growing shorter and dying younger

Temperatures could get too high for tropical forests, and forest trees everywhere are changing in response to human action.

LONDON, 9 June, 2020 – There are limits to what forest trees will tolerate; many tropical forests, for instance, can cope with climate change – but only up to a point. Again, they will go on storing carbon from human greenhouse gas emissions – but only to a degree.

But at around the 32°C threshold, tree growth halts and trees start to die more frequently, putting carbon back into the atmosphere, to accelerate more global heating, according to a detailed study of trees in more than 800 tropical forests.

And a second, unrelated study of forests worldwide finds separate evidence of the impact of climate change. Thanks to human action, forest trees are now younger – and shorter.

The point of the first study is that, in their natural and undisturbed state, the world’s tropical forests can take the heat, but there may be a limit to their capacity for change, and that limit is a daytime maximum of 32.2°C.

A collective of 225 researchers in South America, Africa and Asia report in the journal Science that they made 2 million measurements of 10,000 tropical tree species in sample plots in 24 countries to examine the capacity of forests to absorb atmospheric carbon in a rapidly heating world.

Safety zone

“Our analysis reveals that up to a certain point of heating, tropical forests are surprisingly resistant to small temperature differences. If we limit climate change they can continue to store a large amount of carbon in a warmer world,” said Martin Sullivan, a geographer at the University of Leeds, and at Manchester Metropolitan University, who led the study.

“The 32-degree threshold highlights the critical importance of cutting our emissions to avoid pushing too many forests beyond the safety zone.

“For example, if we limit global average temperatures to a 2°C increase above pre-industrial levels, this pushes nearly three-quarters of tropical forests above the heat threshold we identified. Any further increases in temperature will lead to rapid losses of forest carbon.”

The finding suggests that overall, and independently of species of tree, tropical forest carbon declines with higher temperatures. In all forests, trees flourish and absorb carbon, die back and release it again. But at their best, forests on balance absorb and store away for centuries more carbon than they release – until the thermometer starts to rise and goes on rising.

“Reductions in forest age and height are already happening, and they’re likely to continue to happen”

A co-author, Beatriz Marimon of the State University of Matto Grosso in Brazil, said: “Each degree increase above this 32-degree threshold releases four times as much carbon as would have been released below the threshold.”

The message is that tropical forests need to be protected from climate change, deforestation and wildlife exploitation: that way, they protect  biodiversity, protect themselves, and protect humankind, for future generations. They can adapt to warming temperatures, but this takes decades, perhaps centuries.

But according to another study, also in Science, forest trees the world over are now changing. They are responding to ever higher levels of atmospheric carbon – in effect, they are being fertilised – but also wildfire, drought, windstorm damage, insect attack and disease have become more frequent and more severe with climate change.

And then there has been the direct impact of human economic demand: clearance, disturbance and economic exploitation.

In consequence, US and European scientists conclude, from detailed satellite data and from reviews of more than 160 previous studies, that there has been a “pervasive shift” in forest dynamics, and a dramatic decrease in the age and stature of the forests. The world’s trees on average are younger, and shorter.

Drastic change

“This trend is likely to continue with global warming,” said Nate McDowell,  of the Pacific Northwest National Laboratory, who led the research.

“A future planet with fewer large, old forests will be very different than what we have grown accustomed to. Older forests often host much higher biodiversity than young forests, and they store more carbon than young forests.”

So direct and indirect human action have – in the big picture – affected the way forests shelter new seedlings, the growth of all trees, and the rate of death of those trees. Mortality is going up, while recruitment and growth are faltering.

“Unfortunately, mortality drivers like rising temperature and disturbances are on the rise and are expected to continue increasing in frequency over the next century,” Dr McDowell said.

“So reductions in forest age and height are already happening, and they’re likely to continue to happen.” – Climate News Network

Temperatures could get too high for tropical forests, and forest trees everywhere are changing in response to human action.

LONDON, 9 June, 2020 – There are limits to what forest trees will tolerate; many tropical forests, for instance, can cope with climate change – but only up to a point. Again, they will go on storing carbon from human greenhouse gas emissions – but only to a degree.

But at around the 32°C threshold, tree growth halts and trees start to die more frequently, putting carbon back into the atmosphere, to accelerate more global heating, according to a detailed study of trees in more than 800 tropical forests.

And a second, unrelated study of forests worldwide finds separate evidence of the impact of climate change. Thanks to human action, forest trees are now younger – and shorter.

The point of the first study is that, in their natural and undisturbed state, the world’s tropical forests can take the heat, but there may be a limit to their capacity for change, and that limit is a daytime maximum of 32.2°C.

A collective of 225 researchers in South America, Africa and Asia report in the journal Science that they made 2 million measurements of 10,000 tropical tree species in sample plots in 24 countries to examine the capacity of forests to absorb atmospheric carbon in a rapidly heating world.

Safety zone

“Our analysis reveals that up to a certain point of heating, tropical forests are surprisingly resistant to small temperature differences. If we limit climate change they can continue to store a large amount of carbon in a warmer world,” said Martin Sullivan, a geographer at the University of Leeds, and at Manchester Metropolitan University, who led the study.

“The 32-degree threshold highlights the critical importance of cutting our emissions to avoid pushing too many forests beyond the safety zone.

“For example, if we limit global average temperatures to a 2°C increase above pre-industrial levels, this pushes nearly three-quarters of tropical forests above the heat threshold we identified. Any further increases in temperature will lead to rapid losses of forest carbon.”

The finding suggests that overall, and independently of species of tree, tropical forest carbon declines with higher temperatures. In all forests, trees flourish and absorb carbon, die back and release it again. But at their best, forests on balance absorb and store away for centuries more carbon than they release – until the thermometer starts to rise and goes on rising.

“Reductions in forest age and height are already happening, and they’re likely to continue to happen”

A co-author, Beatriz Marimon of the State University of Matto Grosso in Brazil, said: “Each degree increase above this 32-degree threshold releases four times as much carbon as would have been released below the threshold.”

The message is that tropical forests need to be protected from climate change, deforestation and wildlife exploitation: that way, they protect  biodiversity, protect themselves, and protect humankind, for future generations. They can adapt to warming temperatures, but this takes decades, perhaps centuries.

But according to another study, also in Science, forest trees the world over are now changing. They are responding to ever higher levels of atmospheric carbon – in effect, they are being fertilised – but also wildfire, drought, windstorm damage, insect attack and disease have become more frequent and more severe with climate change.

And then there has been the direct impact of human economic demand: clearance, disturbance and economic exploitation.

In consequence, US and European scientists conclude, from detailed satellite data and from reviews of more than 160 previous studies, that there has been a “pervasive shift” in forest dynamics, and a dramatic decrease in the age and stature of the forests. The world’s trees on average are younger, and shorter.

Drastic change

“This trend is likely to continue with global warming,” said Nate McDowell,  of the Pacific Northwest National Laboratory, who led the research.

“A future planet with fewer large, old forests will be very different than what we have grown accustomed to. Older forests often host much higher biodiversity than young forests, and they store more carbon than young forests.”

So direct and indirect human action have – in the big picture – affected the way forests shelter new seedlings, the growth of all trees, and the rate of death of those trees. Mortality is going up, while recruitment and growth are faltering.

“Unfortunately, mortality drivers like rising temperature and disturbances are on the rise and are expected to continue increasing in frequency over the next century,” Dr McDowell said.

“So reductions in forest age and height are already happening, and they’re likely to continue to happen.” – Climate News Network

Pandemic and climate extremes hit India together

A fearsome cyclone, other climate extremes, Covid-19 and now locust swarms – Indians may think life could hardly get worse.

DELHI, 2 June, 2020 – India is no stranger to coping with climate extremes and natural emergencies, but this year is likely to lodge in the national memory as one of the most challenging in recent history.

The Covid-19 pandemic is a global scourge, but India also has many regional and national afflictions to make 2020 a year to forget – a massive heatwave, its strongest recorded cyclone, thunderstorms bringing huge hailstones, and floods. Now it is being assailed by all-devouring locust swarms, the worst in 25 years, leaving the land scarred.

Government figures showed more than 5,000 Covid-19 deaths by the end of May. The pandemic is causing a humanitarian crisis as well, with a huge reverse migration of penniless unskilled labourers who have lost their jobs in the cities and are now returning to their rural homes.

Five states – Rajasthan, Gujarat, Punjab, Madhya Pradesh and parts of Maharashtra – have been invaded by the locusts. The swarms normally arrive to breed in June or July but this year the first flew in in mid-April, helped to spread by a strong west wind. Climate scientists say warmer waters in the western Indian Ocean also worsened the problem.

The only saving grace is that there are not many standing crops in many of the affected districts, as the monsoon sowing is yet to begin. “It is only the vegetables, orchards and trees that are the victims of this attack,” an official said.

“This is an emergency situation. These desert locusts will not only leave a severe impact on India’s food production but also deal a double whammy to the farmers, who are already reeling from the economic lockdown”

As the locust threat developed, a range of devastating climate events hit the country in May, starting with heavy rain and hail which killed 29 people in Uttar Pradesh, India’s most populous state. Next came Cyclone Amphan, bringing sustained windspeeds of 270 kms per hour.

It was the strongest storm ever recorded in the Bay of Bengal. When it hit the coast on 20 May more than 80 people died. West Bengal, on the eastern coast bordering Bangladesh, suffered a trail of destruction. The winds even damaged the tiger stronghold of the Sundarbans, the islands  whose mangrove forests in the delta of three major rivers normally give Bengal some protection from the storms.

Amphan’s rampage caused the evacuation of 300,000 people to shelter. Many acres of agricultural land near the coast were flooded by salty water and are now unusable. The government estimated the initial losses caused by the cyclone at one trillion rupees (US$13.2 billion).

Amphan’s storm surge was among its most dangerous threats. Global sea levels have already increased by about 23 cm as a result of human carbon emissions – dramatically increasing the distance that the surges can reach. Sea levels in the North Indian Ocean have risen more quickly than in many oceans elsewhere in recent years.

Assam struck

Amphan’s tail also left its mark on the northeastern state of Assam, which experienced heavy rainfall and flooding in low-lying areas, and then several days later a massive thunderstorm. On 27 May, as the Brahmaputra and its tributaries rose above danger point at several places, over 300 villages experienced heavy flooding.

Nor was that all. The same week maximum temperatures reached 40-45C° in much of northern and central India. While Delhi sizzled at 45-46°, Churu in Rajasthan touched 50°C. Fortunately, there have been no deaths reported this year of farm workers and street vendors, as many people remain locked in their homes because of the virus.

As India braces for the annual monsoon, the government is claiming that it has contained much of the locust threat. But Devinder Sharma, an agriculture and trade policy expert, said: “The government’s preparedness has been too slow to keep pace with this rapid increase in locust swarms.

“This is an emergency situation and requires emergency measures. These desert locusts will not only leave a severe impact on India’s food production but also deal a double whammy to the farmers, who are already reeling from the economic lockdown caused by Covid-19.” – Climate News Network

* * * * * * *

Nivedita Khandekar is an independent journalist based in Delhi. She writes on environmental and developmental issues. She can be reached at nivedita_him@rediffmail.com or @nivedita_Him

A fearsome cyclone, other climate extremes, Covid-19 and now locust swarms – Indians may think life could hardly get worse.

DELHI, 2 June, 2020 – India is no stranger to coping with climate extremes and natural emergencies, but this year is likely to lodge in the national memory as one of the most challenging in recent history.

The Covid-19 pandemic is a global scourge, but India also has many regional and national afflictions to make 2020 a year to forget – a massive heatwave, its strongest recorded cyclone, thunderstorms bringing huge hailstones, and floods. Now it is being assailed by all-devouring locust swarms, the worst in 25 years, leaving the land scarred.

Government figures showed more than 5,000 Covid-19 deaths by the end of May. The pandemic is causing a humanitarian crisis as well, with a huge reverse migration of penniless unskilled labourers who have lost their jobs in the cities and are now returning to their rural homes.

Five states – Rajasthan, Gujarat, Punjab, Madhya Pradesh and parts of Maharashtra – have been invaded by the locusts. The swarms normally arrive to breed in June or July but this year the first flew in in mid-April, helped to spread by a strong west wind. Climate scientists say warmer waters in the western Indian Ocean also worsened the problem.

The only saving grace is that there are not many standing crops in many of the affected districts, as the monsoon sowing is yet to begin. “It is only the vegetables, orchards and trees that are the victims of this attack,” an official said.

“This is an emergency situation. These desert locusts will not only leave a severe impact on India’s food production but also deal a double whammy to the farmers, who are already reeling from the economic lockdown”

As the locust threat developed, a range of devastating climate events hit the country in May, starting with heavy rain and hail which killed 29 people in Uttar Pradesh, India’s most populous state. Next came Cyclone Amphan, bringing sustained windspeeds of 270 kms per hour.

It was the strongest storm ever recorded in the Bay of Bengal. When it hit the coast on 20 May more than 80 people died. West Bengal, on the eastern coast bordering Bangladesh, suffered a trail of destruction. The winds even damaged the tiger stronghold of the Sundarbans, the islands  whose mangrove forests in the delta of three major rivers normally give Bengal some protection from the storms.

Amphan’s rampage caused the evacuation of 300,000 people to shelter. Many acres of agricultural land near the coast were flooded by salty water and are now unusable. The government estimated the initial losses caused by the cyclone at one trillion rupees (US$13.2 billion).

Amphan’s storm surge was among its most dangerous threats. Global sea levels have already increased by about 23 cm as a result of human carbon emissions – dramatically increasing the distance that the surges can reach. Sea levels in the North Indian Ocean have risen more quickly than in many oceans elsewhere in recent years.

Assam struck

Amphan’s tail also left its mark on the northeastern state of Assam, which experienced heavy rainfall and flooding in low-lying areas, and then several days later a massive thunderstorm. On 27 May, as the Brahmaputra and its tributaries rose above danger point at several places, over 300 villages experienced heavy flooding.

Nor was that all. The same week maximum temperatures reached 40-45C° in much of northern and central India. While Delhi sizzled at 45-46°, Churu in Rajasthan touched 50°C. Fortunately, there have been no deaths reported this year of farm workers and street vendors, as many people remain locked in their homes because of the virus.

As India braces for the annual monsoon, the government is claiming that it has contained much of the locust threat. But Devinder Sharma, an agriculture and trade policy expert, said: “The government’s preparedness has been too slow to keep pace with this rapid increase in locust swarms.

“This is an emergency situation and requires emergency measures. These desert locusts will not only leave a severe impact on India’s food production but also deal a double whammy to the farmers, who are already reeling from the economic lockdown caused by Covid-19.” – Climate News Network

* * * * * * *

Nivedita Khandekar is an independent journalist based in Delhi. She writes on environmental and developmental issues. She can be reached at nivedita_him@rediffmail.com or @nivedita_Him

South Asia’s twin threat: extreme heat and foul air

Climate change means many health risks. Any one of them raises the danger. What happens when extreme heat meets bad air?

LONDON, 29 May, 2020 – Extreme heat can kill. Air pollution can seriously shorten human lives. By 2050, extreme summer heat will threaten about 2 billion people on and around the Indian sub-continent for around 78 days every year. And the chances of unbearable heat waves and choking atmospheric chemistry at the same time will rise by 175%.

Climate scientists have been warning for decades that what were once rare events – for instance the 2003 heat wave that claimed tens of thousands of lives in Europe – will, as global average temperatures rise, become the new normal.

And they have repeatedly warned that in step with extreme summer temperatures, extreme humidity is also likely to increase in some regions, and to levels that could prove potentially fatal for outdoor workers and people in crowded cities.

The link between air pollution and ill health was established 60 or more years ago and has been confirmed again and again with mortality statistics.

Risk to megacities

Now a team from China and the US confirms once more in the journal  AGU Advances, published by the American Geophysical Union, that the danger is real, and that they can tell where it is becoming immediate: in seven nations that stretch from Afghanistan to Myanmar, and from Nepal to the tip of southern India.

Around 1.5bn people live there now, and they are already learning to live with around 45 days of extreme heat every year. By 2050, there will be 2bn people, most of them crammed into megacities in Afghanistan, Bangladesh, Bhutan, India, Myanmar, Nepal and Pakistan, and climate models confirm that the number of days of extreme heat could rise to 78 a year.

The number of days on which cities – already blighted by air pollution – reach health-threatening levels of high particulate matter will also rise. When heat and choking air chemistry become too much, lives will be at risk.

That extremes of summer heat are on the increase is now a given. That the intensity, duration and frequency of heat waves will go on rising has also been established. Extremes of heat are a threat to crops and a particular hazard in cities already much hotter than their surrounding landscapes.

“South Asia is a hotspot for future climate change impacts. Much research is needed over other parts of the world on  the risks they pose, and their potential human health effects”

One research group has identified 27 ways in which high temperatures can kill. Others have repeatedly warned of the dangerous mix of high temperatures and high humidity (climate scientists call it the “wet bulb” temperature), and one team of scientists has already argued that such conditions have already arrived, albeit so far for short periods and in limited locations.

The researchers chose the so-called wet-bulb temperature of 25°C as their threshold for an unhealthy extreme, and then worked out the number of days a year that such conditions happened in South Asia: between 1994 and 2006, these arrived at an average of between 40 and 50 days a year.

They then looked at the likely rise with forecast increases in average planetary temperature, depending on how vigorously or feebly the world’s nations tried to switch from fossil fuels to renewable energy sources. The probability increased by 75%.

They then chose widely-agreed dangerous thresholds for air pollution with soot, and sulphate aerosols, usually from fossil fuel combustion, to find that extremes of pollution would happen by 2050 on around 132 days a year.

Tenfold risk increase

Then they tried to estimate the probabilities that extreme pollution and extreme heat would coincide. They judged that the frequency of these more than usually hazardous days would rise by 175%, and they would last an estimated 79% longer. The area of land exposed to this double assault on human health would by then have increased tenfold.

Scientific publications usually avoid emotional language, but the researchers call their own finding “alarming.”

“South Asia is a hotspot for future climate change impacts,” said Yangyang Xu, of Texas A&M University, the first author.

“I think this study raises a lot of important concerns, and much research is needed over other parts of the world on these compounded extremes, the risks they pose, and their potential human health effects.” – Climate News Network

Climate change means many health risks. Any one of them raises the danger. What happens when extreme heat meets bad air?

LONDON, 29 May, 2020 – Extreme heat can kill. Air pollution can seriously shorten human lives. By 2050, extreme summer heat will threaten about 2 billion people on and around the Indian sub-continent for around 78 days every year. And the chances of unbearable heat waves and choking atmospheric chemistry at the same time will rise by 175%.

Climate scientists have been warning for decades that what were once rare events – for instance the 2003 heat wave that claimed tens of thousands of lives in Europe – will, as global average temperatures rise, become the new normal.

And they have repeatedly warned that in step with extreme summer temperatures, extreme humidity is also likely to increase in some regions, and to levels that could prove potentially fatal for outdoor workers and people in crowded cities.

The link between air pollution and ill health was established 60 or more years ago and has been confirmed again and again with mortality statistics.

Risk to megacities

Now a team from China and the US confirms once more in the journal  AGU Advances, published by the American Geophysical Union, that the danger is real, and that they can tell where it is becoming immediate: in seven nations that stretch from Afghanistan to Myanmar, and from Nepal to the tip of southern India.

Around 1.5bn people live there now, and they are already learning to live with around 45 days of extreme heat every year. By 2050, there will be 2bn people, most of them crammed into megacities in Afghanistan, Bangladesh, Bhutan, India, Myanmar, Nepal and Pakistan, and climate models confirm that the number of days of extreme heat could rise to 78 a year.

The number of days on which cities – already blighted by air pollution – reach health-threatening levels of high particulate matter will also rise. When heat and choking air chemistry become too much, lives will be at risk.

That extremes of summer heat are on the increase is now a given. That the intensity, duration and frequency of heat waves will go on rising has also been established. Extremes of heat are a threat to crops and a particular hazard in cities already much hotter than their surrounding landscapes.

“South Asia is a hotspot for future climate change impacts. Much research is needed over other parts of the world on  the risks they pose, and their potential human health effects”

One research group has identified 27 ways in which high temperatures can kill. Others have repeatedly warned of the dangerous mix of high temperatures and high humidity (climate scientists call it the “wet bulb” temperature), and one team of scientists has already argued that such conditions have already arrived, albeit so far for short periods and in limited locations.

The researchers chose the so-called wet-bulb temperature of 25°C as their threshold for an unhealthy extreme, and then worked out the number of days a year that such conditions happened in South Asia: between 1994 and 2006, these arrived at an average of between 40 and 50 days a year.

They then looked at the likely rise with forecast increases in average planetary temperature, depending on how vigorously or feebly the world’s nations tried to switch from fossil fuels to renewable energy sources. The probability increased by 75%.

They then chose widely-agreed dangerous thresholds for air pollution with soot, and sulphate aerosols, usually from fossil fuel combustion, to find that extremes of pollution would happen by 2050 on around 132 days a year.

Tenfold risk increase

Then they tried to estimate the probabilities that extreme pollution and extreme heat would coincide. They judged that the frequency of these more than usually hazardous days would rise by 175%, and they would last an estimated 79% longer. The area of land exposed to this double assault on human health would by then have increased tenfold.

Scientific publications usually avoid emotional language, but the researchers call their own finding “alarming.”

“South Asia is a hotspot for future climate change impacts,” said Yangyang Xu, of Texas A&M University, the first author.

“I think this study raises a lot of important concerns, and much research is needed over other parts of the world on these compounded extremes, the risks they pose, and their potential human health effects.” – Climate News Network