Tag Archives: Warming

Global heating means a wetter and warmer world

A wetter and even warmer world will result from faster global warming. The evidence is in the sands of time.

LONDON, 14 May, 2020 – A warmer world may not be just a wetter one. It may get even warmer as well. New studies suggest the heavier rain that will accompany ever-higher global average atmospheric temperatures is in itself likely to trigger ever more carbon dioxide release from tropical soils.

This is what engineers call positive feedback. The very symptoms of a warming world become part of the fuel for accelerating global temperature change.

And the warning is derived not just from models of climate change, but once again from evidence from the past.

Scientists from the US, Canada and Switzerland report in the journal Nature that for the past 18,000 years, the “time of residence” of carbon in the soils of the Ganges-Brahmaputra river basin has been controlled by India’s summer monsoon rainfall.

The lower the rainfall, the higher the length of stored carbon. But as levels of downpour go up, so does the activity of the microbes that turn vegetable matter back into carbon dioxide, and the levels of stored soil carbon go down.

“Climate change is likely to increase rainfall in tropical regions, further accelerating respiration of soil carbon, and adding even more CO2 to the atmosphere”

Right now, global atmospheric concentrations of carbon dioxide have risen from 285 parts per million – the average for most of human history – to 416 ppm as humans clear ever more forest and burn ever more fossil fuels. This 416ppm adds up to about 750 billion tonnes of carbon. The planet’s soils are home to an estimated 3,500 bn tonnes: more than four times as much.

“Our results suggest that future hydroclimate changes in tropical regions are likely to accelerate soil carbon destabilisation, further increasing carbon dioxide concentrations,” the scientists warn.

As temperatures rise, the atmosphere’s capacity to absorb moisture also increases. As temperatures rise, so does direct evaporation from oceans, lakes, rivers and soils. This water vapour will eventually fall as rain, but unevenly: those regions already rainy will become rainier, while drylands are likely to become increasingly arid.

The Ganges and Brahmaputra carry more than a billion tonnes of sediment – most of it eroded from the Himalayan mountain chain – into the Bay of Bengal each year, and cores of sediment taken from the sea floor provide a good record of climate conditions for the last 18,000 years, as the Ice Age began to wane, and the glaciers retreated to permit a hunter-gatherer species to cultivate cereals, domesticate animals, build permanent settlements and found human civilisation.

Radiocarbon readings mean that researchers can date the sediments, and preserved organic molecules from land plants provide an indicator of conditions at those dates.

Methane adds speed

Scientists have repeatedly warned that climate change in the Arctic – the fastest-warming zone of all – is likely to be matched by the release of soil carbon in the form of the greenhouse gas methane from the thawing permafrost, to accelerate yet more warming.

As the once-frozen ground warms up, and vegetation moves further and further north, an estimated 600 million tonnes of carbon is released into the atmosphere every year.

Now, and for different reasons, the same could be true of the tropics, and the evidence is in the sands of time, deposited by one of the world’s great river systems. As the Ice Age ended, monsoon rains began to increase and in 2,600 years soil respiration – and therefore carbon release – doubled. Since then, monsoon rainfall has increased threefold.

“We found that shifts toward a warmer and wetter climate in the drainage basin of the Ganges and Brahmaputra rivers over the last 18,000 years enhanced rates of soil respiration and decreased stocks of soil carbon,” said Christopher Hein, of the Virginia Institute of Marine Science, who led the study.

“This has direct implications for the Earth’s future, as climate change is likely to increase rainfall in tropical regions, further accelerating respiration of soil carbon, and adding even more CO2 to the atmosphere than that directly added by humans.” – Climate News Network

A wetter and even warmer world will result from faster global warming. The evidence is in the sands of time.

LONDON, 14 May, 2020 – A warmer world may not be just a wetter one. It may get even warmer as well. New studies suggest the heavier rain that will accompany ever-higher global average atmospheric temperatures is in itself likely to trigger ever more carbon dioxide release from tropical soils.

This is what engineers call positive feedback. The very symptoms of a warming world become part of the fuel for accelerating global temperature change.

And the warning is derived not just from models of climate change, but once again from evidence from the past.

Scientists from the US, Canada and Switzerland report in the journal Nature that for the past 18,000 years, the “time of residence” of carbon in the soils of the Ganges-Brahmaputra river basin has been controlled by India’s summer monsoon rainfall.

The lower the rainfall, the higher the length of stored carbon. But as levels of downpour go up, so does the activity of the microbes that turn vegetable matter back into carbon dioxide, and the levels of stored soil carbon go down.

“Climate change is likely to increase rainfall in tropical regions, further accelerating respiration of soil carbon, and adding even more CO2 to the atmosphere”

Right now, global atmospheric concentrations of carbon dioxide have risen from 285 parts per million – the average for most of human history – to 416 ppm as humans clear ever more forest and burn ever more fossil fuels. This 416ppm adds up to about 750 billion tonnes of carbon. The planet’s soils are home to an estimated 3,500 bn tonnes: more than four times as much.

“Our results suggest that future hydroclimate changes in tropical regions are likely to accelerate soil carbon destabilisation, further increasing carbon dioxide concentrations,” the scientists warn.

As temperatures rise, the atmosphere’s capacity to absorb moisture also increases. As temperatures rise, so does direct evaporation from oceans, lakes, rivers and soils. This water vapour will eventually fall as rain, but unevenly: those regions already rainy will become rainier, while drylands are likely to become increasingly arid.

The Ganges and Brahmaputra carry more than a billion tonnes of sediment – most of it eroded from the Himalayan mountain chain – into the Bay of Bengal each year, and cores of sediment taken from the sea floor provide a good record of climate conditions for the last 18,000 years, as the Ice Age began to wane, and the glaciers retreated to permit a hunter-gatherer species to cultivate cereals, domesticate animals, build permanent settlements and found human civilisation.

Radiocarbon readings mean that researchers can date the sediments, and preserved organic molecules from land plants provide an indicator of conditions at those dates.

Methane adds speed

Scientists have repeatedly warned that climate change in the Arctic – the fastest-warming zone of all – is likely to be matched by the release of soil carbon in the form of the greenhouse gas methane from the thawing permafrost, to accelerate yet more warming.

As the once-frozen ground warms up, and vegetation moves further and further north, an estimated 600 million tonnes of carbon is released into the atmosphere every year.

Now, and for different reasons, the same could be true of the tropics, and the evidence is in the sands of time, deposited by one of the world’s great river systems. As the Ice Age ended, monsoon rains began to increase and in 2,600 years soil respiration – and therefore carbon release – doubled. Since then, monsoon rainfall has increased threefold.

“We found that shifts toward a warmer and wetter climate in the drainage basin of the Ganges and Brahmaputra rivers over the last 18,000 years enhanced rates of soil respiration and decreased stocks of soil carbon,” said Christopher Hein, of the Virginia Institute of Marine Science, who led the study.

“This has direct implications for the Earth’s future, as climate change is likely to increase rainfall in tropical regions, further accelerating respiration of soil carbon, and adding even more CO2 to the atmosphere than that directly added by humans.” – Climate News Network

Heatwaves too hot and wet for human life are here

Lethal heatwaves carrying air turned too hot and wet to survive are a threat which has arrived, thanks to climate change.

LONDON, 11 May, 2020 – Scientists who have repeatedly warned of future lethal conditions of temperature and humidity caused by heatwaves in a world of climate change have grim news: that future has already arrived.

They have combed through local records to identify thousands of episodes in which the dangerous combination of high temperatures and high humidity has risen to levels at which humans could not in theory survive for long. These have happened in Asia, Africa, South and North America and Australia.

More than a dozen such episodes have already been recorded around the Persian Gulf, a region that – researchers warned years ago – could one day become deadly for outdoor workers.

These outbreaks of both sweltering heat and stifling humidity have, researchers report in the journal Science Advances, so far been confined to localised areas and have lasted only hours, but they are now increasing in frequency and intensity.

There are many ways in which extreme heat can lead to death – one group has identified as many as 27 – but at its simplest, a species adapted to maintain a stable temperature by shivering when cold and perspiring when too hot can be overwhelmed by very high temperatures, or in conditions in which the body can no longer lose heat because the air is too moist for perspiration to evaporate.

“Previous studies projected that this would happen several decades from now, but this shows it’s happening right now”

Scientists measure such hazards by what they call a “wet bulb” temperature, and even the strongest and best adapted humans cannot work safely outdoors when this hits 32°C.

Potentially fatal readings identified in hourly reports from 7,877 weather stations between 1979 and 2017 confirm that such temperatures have already reached dangerous levels – and even as high as 35°C – in Saudi Arabia, Doha in Qatar, in the United Arab Emirates, in Texas, Louisiana, Mississippi, Alabama and Florida in the US, India and Bangladesh, south China, northwest Australia and Iran.

Researchers began warning years ago of the notional threat of extreme heat and extreme humidity in a world in which humans continue to burn fossil fuels and increase greenhouse gases’ concentrations in the atmosphere, and repeated studies have confirmed the reality of the hazard.

Humans cannot survive outdoor “wet bulb” conditions of 35°C for long. The number of readings beyond 30°C has doubled since 1979. There have been 1,000 readings of 31°C and 80 of 33°C.

“Previous studies projected that this would happen several decades from now, but this shows it’s happening right now,” said Colin Raymond, who completed the research at the Lamont-Doherty Earth Observatory at Columbia University, but who is now at Nasa’s Jet Propulsion Laboratory.

“The times these events last will increase, and the areas they affect will grow, in direct correlation with global warming.” – Climate News Network

Lethal heatwaves carrying air turned too hot and wet to survive are a threat which has arrived, thanks to climate change.

LONDON, 11 May, 2020 – Scientists who have repeatedly warned of future lethal conditions of temperature and humidity caused by heatwaves in a world of climate change have grim news: that future has already arrived.

They have combed through local records to identify thousands of episodes in which the dangerous combination of high temperatures and high humidity has risen to levels at which humans could not in theory survive for long. These have happened in Asia, Africa, South and North America and Australia.

More than a dozen such episodes have already been recorded around the Persian Gulf, a region that – researchers warned years ago – could one day become deadly for outdoor workers.

These outbreaks of both sweltering heat and stifling humidity have, researchers report in the journal Science Advances, so far been confined to localised areas and have lasted only hours, but they are now increasing in frequency and intensity.

There are many ways in which extreme heat can lead to death – one group has identified as many as 27 – but at its simplest, a species adapted to maintain a stable temperature by shivering when cold and perspiring when too hot can be overwhelmed by very high temperatures, or in conditions in which the body can no longer lose heat because the air is too moist for perspiration to evaporate.

“Previous studies projected that this would happen several decades from now, but this shows it’s happening right now”

Scientists measure such hazards by what they call a “wet bulb” temperature, and even the strongest and best adapted humans cannot work safely outdoors when this hits 32°C.

Potentially fatal readings identified in hourly reports from 7,877 weather stations between 1979 and 2017 confirm that such temperatures have already reached dangerous levels – and even as high as 35°C – in Saudi Arabia, Doha in Qatar, in the United Arab Emirates, in Texas, Louisiana, Mississippi, Alabama and Florida in the US, India and Bangladesh, south China, northwest Australia and Iran.

Researchers began warning years ago of the notional threat of extreme heat and extreme humidity in a world in which humans continue to burn fossil fuels and increase greenhouse gases’ concentrations in the atmosphere, and repeated studies have confirmed the reality of the hazard.

Humans cannot survive outdoor “wet bulb” conditions of 35°C for long. The number of readings beyond 30°C has doubled since 1979. There have been 1,000 readings of 31°C and 80 of 33°C.

“Previous studies projected that this would happen several decades from now, but this shows it’s happening right now,” said Colin Raymond, who completed the research at the Lamont-Doherty Earth Observatory at Columbia University, but who is now at Nasa’s Jet Propulsion Laboratory.

“The times these events last will increase, and the areas they affect will grow, in direct correlation with global warming.” – Climate News Network

North Pole may be clear water by mid-century

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

Within 30 years, there could be clear blue water over the North Pole – not good news for most of the planet.

LONDON, 25 April, 2020 – Within three decades, the North Pole could be free of sea ice in the late summer. The latest and most advanced climate simulations, tested by 21 research institutes from around the world, predict that if humans go on emitting ever-greater volumes of carbon dioxide from fossil fuel combustion and other actions, then before 2050, for the first time in human history, there could be no ice over the North Pole.

And a team of research scientists aboard a ship intent on spending a year observing the drift of sea ice across the Arctic Ocean has been warned that they may have to finish early: the ice supposed to hold the ship fast could melt too soon.

The loss of sea ice promises devastating consequences for the rich life in the most northern waters. The ice reflects sunlight back into space and keeps the Arctic cool. It also provides space for seals on which to haul out, and hunting grounds for blubber-hungry polar bears.

And although human inaction in the climate emergency makes the loss of polar ice ever more probable, so much greenhouse gas has already built up in the planetary atmosphere that it could happen anyway.

Taken aback

“If we reduce global emissions rapidly and substantially, and thus keep our warming below 2°C relative to pre-industrial levels, sea ice will nevertheless likely disappear occasionally in summer even before 2050,” said Dirk Notz, of the University of Hamburg in Germany, who led the study. “This really surprised us.”

Climate scientists first warned of the accelerating loss of Arctic sea ice two decades ago, and have repeatedly re-examined the climate predictions, each time with much the same outcome.

The loss of ice promises new trade routes between Atlantic and Pacific Oceans, but the cost of a warming Arctic could have catastrophic economic consequences.

The pattern of the northern hemisphere climate is driven by the temperature difference between the Arctic and the tropics, and rapid polar warming both disturbs temperate climate regimes and brings ever higher sea levels, with accelerating ice loss from Greenland, which right now bears enough ice to raise global sea levels by more than seven metres.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today”

Dr Notz and his co-authors report in the journal Geophysical Research Letters that they used the very latest climate model developed for the Intergovernmental Panel on Climate Change and tested it on a range of 40 possible climate outcomes.

In most simulations, the Arctic sea ice was reduced to less than a million square kilometres – polar researchers call this “practically sea-ice free” – in the month of September for the first time before 2050. Even if human fossil fuel use was sharply reduced, the ocean could be free of ice some years; if not, the pole could become open water most years.

And a second study, in the journal The Cryosphere, offers a measure of the sea ice loss even now. More than a century ago, the great explorer Fridtjof Nansen sailed his ship the Fram into the polar ice, became fast, and travelled with the floe across the Arctic Ocean.

His became the first scientific observation of a phenomenon called the trans-Polar drift, which takes algae, sediments and nutrients – and increasingly, plastic pollution – across the Arctic from Siberia to Canada and Greenland.

Melted out

In October a team of international researchers boarded a vessel called Polarstern with the intention of measuring the ice movement in the modern Arctic in more detail. They had planned for a year fast in the ice. Their project even has a name: Mosaic, or Multidisciplinary drifting Observatory for the Study of Arctic Climate.

But climate simulations by the US scientists reveal that in every sense, the project is on thin ice and could end prematurely. The flow of ice could be faster, and carry the ship further, than expected: nearly one in five of the simulations also predicted that the ship could melt out of the ice in less than a year.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today,” said one of the authors, Marika Holland of the US National Center for Atmospheric Research.

“Now there is thinner ice, which moves more quickly, and there is less snow cover. It is a totally different ice regime.” – Climate News Network

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

Within 30 years, there could be clear blue water over the North Pole – not good news for most of the planet.

LONDON, 25 April, 2020 – Within three decades, the North Pole could be free of sea ice in the late summer. The latest and most advanced climate simulations, tested by 21 research institutes from around the world, predict that if humans go on emitting ever-greater volumes of carbon dioxide from fossil fuel combustion and other actions, then before 2050, for the first time in human history, there could be no ice over the North Pole.

And a team of research scientists aboard a ship intent on spending a year observing the drift of sea ice across the Arctic Ocean has been warned that they may have to finish early: the ice supposed to hold the ship fast could melt too soon.

The loss of sea ice promises devastating consequences for the rich life in the most northern waters. The ice reflects sunlight back into space and keeps the Arctic cool. It also provides space for seals on which to haul out, and hunting grounds for blubber-hungry polar bears.

And although human inaction in the climate emergency makes the loss of polar ice ever more probable, so much greenhouse gas has already built up in the planetary atmosphere that it could happen anyway.

Taken aback

“If we reduce global emissions rapidly and substantially, and thus keep our warming below 2°C relative to pre-industrial levels, sea ice will nevertheless likely disappear occasionally in summer even before 2050,” said Dirk Notz, of the University of Hamburg in Germany, who led the study. “This really surprised us.”

Climate scientists first warned of the accelerating loss of Arctic sea ice two decades ago, and have repeatedly re-examined the climate predictions, each time with much the same outcome.

The loss of ice promises new trade routes between Atlantic and Pacific Oceans, but the cost of a warming Arctic could have catastrophic economic consequences.

The pattern of the northern hemisphere climate is driven by the temperature difference between the Arctic and the tropics, and rapid polar warming both disturbs temperate climate regimes and brings ever higher sea levels, with accelerating ice loss from Greenland, which right now bears enough ice to raise global sea levels by more than seven metres.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today”

Dr Notz and his co-authors report in the journal Geophysical Research Letters that they used the very latest climate model developed for the Intergovernmental Panel on Climate Change and tested it on a range of 40 possible climate outcomes.

In most simulations, the Arctic sea ice was reduced to less than a million square kilometres – polar researchers call this “practically sea-ice free” – in the month of September for the first time before 2050. Even if human fossil fuel use was sharply reduced, the ocean could be free of ice some years; if not, the pole could become open water most years.

And a second study, in the journal The Cryosphere, offers a measure of the sea ice loss even now. More than a century ago, the great explorer Fridtjof Nansen sailed his ship the Fram into the polar ice, became fast, and travelled with the floe across the Arctic Ocean.

His became the first scientific observation of a phenomenon called the trans-Polar drift, which takes algae, sediments and nutrients – and increasingly, plastic pollution – across the Arctic from Siberia to Canada and Greenland.

Melted out

In October a team of international researchers boarded a vessel called Polarstern with the intention of measuring the ice movement in the modern Arctic in more detail. They had planned for a year fast in the ice. Their project even has a name: Mosaic, or Multidisciplinary drifting Observatory for the Study of Arctic Climate.

But climate simulations by the US scientists reveal that in every sense, the project is on thin ice and could end prematurely. The flow of ice could be faster, and carry the ship further, than expected: nearly one in five of the simulations also predicted that the ship could melt out of the ice in less than a year.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today,” said one of the authors, Marika Holland of the US National Center for Atmospheric Research.

“Now there is thinner ice, which moves more quickly, and there is less snow cover. It is a totally different ice regime.” – Climate News Network

Cloudless skies hasten Greenland’s ice loss

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

The bad news about Greenland’s ice loss has just got even worse. Blame it on mischief by blue skies all day long.

LONDON, 22 April, 2020 – Greenland’s ice loss reached record levels in 2019, and scientists think they’ve identified the culprit: the good weather which normally brings the snow-bearing clouds to the High Arctic.

The huge island, the biggest bank of ice in the northern hemisphere, has been losing ice at an ever-increasing rate in a rapidly warming world. Last year it shed more ice than ever, and this time because the skies were unusually clear.

There is enough ice on Greenland to raise global sea levels by more than seven metres. A recent study established that in the years between 1992 and 2018, rates of polar ice loss have risen six-fold, and so much water has flowed off the Greenland ice surface that sea levels have risen by more than 10mm everywhere.

Now a new study by US and Belgian scientists in the journal The Cryosphere confirms that 2019 was even worse. Because of good weather and cloudless skies, only enough snow fell to deposit 50 billion tonnes of ice into the island’s profit-and-loss ice account. The average annual deposit between 1981 and 2010 was about 375bn tonnes.

But glaciers still flowed towards the sea at an ever-increasing rate, summer snow melt continued to flow off the ice sheet, and icebergs continued to calve, so on balance the island lost 600 billion tonnes of ice: enough to raise global sea levels by 1.5mm. This is the biggest overall loss of ice since records in Greenland began in 1948.

“These atmospheric conditions are becoming more and more frequent over the past few decades. It is very likely that this is due to the waviness of the jet stream”

The cause: unusual spells of high atmospheric pressure over the island for unusually long periods of time. That stopped the formation of clouds, and that meant less precipitation, in the form of snow. Snow reflects solar radiation more effectively than ice, so the surface absorbed more heat and melting also accelerated.

The pattern of warm moist clouds trapped over northern Greenland by the heat that would normally radiate off the ice, instead of releasing snow, also emitted their own heat, to make things worse. The worst year for surface melting remains 2012, but the summer of 2019 was a good second.

The implication is that things could get worse, and losses of Greenland ice could accelerate.

“These atmospheric conditions are becoming more and more frequent over the past few decades,” said Marco Tedesco, of the Lamont-Doherty Earth Observatory at the University of Columbia in the US, the lead author.

“It is very likely that this is due to the waviness of the jet stream, which we think is related to, among other things, the disappearance of snow cover in Siberia, the disappearance of sea ice, and the difference in the rate at which temperature is increasing in the Arctic versus the mid-latitudes.” – Climate News Network

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

The bad news about Greenland’s ice loss has just got even worse. Blame it on mischief by blue skies all day long.

LONDON, 22 April, 2020 – Greenland’s ice loss reached record levels in 2019, and scientists think they’ve identified the culprit: the good weather which normally brings the snow-bearing clouds to the High Arctic.

The huge island, the biggest bank of ice in the northern hemisphere, has been losing ice at an ever-increasing rate in a rapidly warming world. Last year it shed more ice than ever, and this time because the skies were unusually clear.

There is enough ice on Greenland to raise global sea levels by more than seven metres. A recent study established that in the years between 1992 and 2018, rates of polar ice loss have risen six-fold, and so much water has flowed off the Greenland ice surface that sea levels have risen by more than 10mm everywhere.

Now a new study by US and Belgian scientists in the journal The Cryosphere confirms that 2019 was even worse. Because of good weather and cloudless skies, only enough snow fell to deposit 50 billion tonnes of ice into the island’s profit-and-loss ice account. The average annual deposit between 1981 and 2010 was about 375bn tonnes.

But glaciers still flowed towards the sea at an ever-increasing rate, summer snow melt continued to flow off the ice sheet, and icebergs continued to calve, so on balance the island lost 600 billion tonnes of ice: enough to raise global sea levels by 1.5mm. This is the biggest overall loss of ice since records in Greenland began in 1948.

“These atmospheric conditions are becoming more and more frequent over the past few decades. It is very likely that this is due to the waviness of the jet stream”

The cause: unusual spells of high atmospheric pressure over the island for unusually long periods of time. That stopped the formation of clouds, and that meant less precipitation, in the form of snow. Snow reflects solar radiation more effectively than ice, so the surface absorbed more heat and melting also accelerated.

The pattern of warm moist clouds trapped over northern Greenland by the heat that would normally radiate off the ice, instead of releasing snow, also emitted their own heat, to make things worse. The worst year for surface melting remains 2012, but the summer of 2019 was a good second.

The implication is that things could get worse, and losses of Greenland ice could accelerate.

“These atmospheric conditions are becoming more and more frequent over the past few decades,” said Marco Tedesco, of the Lamont-Doherty Earth Observatory at the University of Columbia in the US, the lead author.

“It is very likely that this is due to the waviness of the jet stream, which we think is related to, among other things, the disappearance of snow cover in Siberia, the disappearance of sea ice, and the difference in the rate at which temperature is increasing in the Arctic versus the mid-latitudes.” – Climate News Network

Tree rings and weather data warn of megadrought

Farmers in the US West know they have a drought, but may not yet realise these arid years could become a megadrought.

LONDON, 17 April, 2020 – Climate change could be pushing the US west and northern Mexico towards the most severe and most extended period of drought observed in a thousand years of US history, a full-blown megadrought.

Natural atmospheric forces have always triggered prolonged spells with little rain. But warming driven by profligate human use of fossil fuels could now be making a bad situation much worse.

The warning of what climate scientists call a megadrought – outlined in the journal Science – is based not on computer simulations but on direct testimony from more than a century of weather records and the much longer story told by 1200 consecutive years of evidence preserved in the annual growth rings of trees that provide a record of changing levels of soil moisture.

“Earlier studies were largely model projections of the future. We are no longer looking at projections, but at where we are now,” said Park Williams, a bioclimatologist at the Lamont Doherty Earth Observatory of Columbia University in the US.

“We now have enough observations of current drought and tree ring records of past drought to say we’re on the same trajectory as the worst prehistoric droughts.”

Repeating the past

Previous research has already linked catastrophic drought to turmoil among pre-Columbian civilisations in the American Southwest.

Studies by other groups have also warned that what happened in the past could happen again, as carbon dioxide emissions from fossil fuel combustion enrich the atmosphere, raise temperatures and parch the soils of the US West.

Global heating has been repeatedly linked to the last devastating drought in California, and to the possible return of Dust Bowl conditions in the Midwestern grain belt.

The latest study delivers a long-term analysis of conditions across nine US states, from Oregon and Montana in the north down to California, New Mexico and part of northern Mexico.

With the evidence preserved in old tree trunks, the scientists identified dozens of droughts in the region from 800 AD. They found four megadroughts – periods in which the conditions became extreme – between 800 and 1600. Since then there have been no droughts that could be matched with these – so far.

And then the researchers matched the megadrought tree ring evidence with soil moisture records collected in the first 19 years of this century, and compared this with any 19-year period in the prehistoric droughts.

“We’ll need more and more good luck to break out of drought, and less and less bad luck to get into drought”

They found that the current prolonged dry spell is already more pronounced than the three earliest records of megadrought. The fourth megadrought – it ran from 1575 to 1603 – may still have been the worst of all, but the match with the present years is so close that nobody can be sure.

But the team behind the Science study is sure of one thing. This drought right now is affecting wider stretches of landscape more consistently than any of the earlier megadroughts, and this, they say, is a signature of global heating. All the ancient megadroughts lasted longer, and sometimes much longer, than 19 years, but all began in a way very similar to the present.

The snowpack in the western high mountains has fallen dramatically, the flow of the rivers has dwindled, lake levels have fallen, farmers have been  hit and the wildfires have become more prolonged and more intense.

Drought and even the chance of megadrought may be a fact of life in the US West. During occasional natural atmospheric cycles, the tropical Pacific cools and storm tracks shift further north, taking rainfall away from the US drylands.

But since 2000, average air temperatures in the western states have risen by more than 1.2°C above the normal over earlier centuries. So soils already starved of rain began to lose their stored moisture at an ever-increasing rate.

Worsened by heating

Without the additional global heating, this drought might have happened anyway, and perhaps even been the 11th worst ever recorded, rather than almost the worst ever in human experience.

“It doesn’t matter if this is exactly the worst drought ever,” said Benjamin Cook, a co-author, from Nasa’s Goddard Institute for Space Studies. “What matters is that it has been made much worse than it could have been because of climate change.”

The researchers also found that the 20th century was the wettest century in the entire 1200 year record, and this relatively plentiful supply of water must have helped enrich the US West and make California, for instance, become the Golden State, the most populous in the US.

“Because the background is getting warmer, the dice are increasingly loaded towards longer and more severe droughts,” Professor Williams said. “We may get lucky, and natural variability will bring more precipitation for a while.

“But going forward, we’ll need more and more good luck to break out of drought, and less and less bad luck to get into drought.” – Climate News Network

Farmers in the US West know they have a drought, but may not yet realise these arid years could become a megadrought.

LONDON, 17 April, 2020 – Climate change could be pushing the US west and northern Mexico towards the most severe and most extended period of drought observed in a thousand years of US history, a full-blown megadrought.

Natural atmospheric forces have always triggered prolonged spells with little rain. But warming driven by profligate human use of fossil fuels could now be making a bad situation much worse.

The warning of what climate scientists call a megadrought – outlined in the journal Science – is based not on computer simulations but on direct testimony from more than a century of weather records and the much longer story told by 1200 consecutive years of evidence preserved in the annual growth rings of trees that provide a record of changing levels of soil moisture.

“Earlier studies were largely model projections of the future. We are no longer looking at projections, but at where we are now,” said Park Williams, a bioclimatologist at the Lamont Doherty Earth Observatory of Columbia University in the US.

“We now have enough observations of current drought and tree ring records of past drought to say we’re on the same trajectory as the worst prehistoric droughts.”

Repeating the past

Previous research has already linked catastrophic drought to turmoil among pre-Columbian civilisations in the American Southwest.

Studies by other groups have also warned that what happened in the past could happen again, as carbon dioxide emissions from fossil fuel combustion enrich the atmosphere, raise temperatures and parch the soils of the US West.

Global heating has been repeatedly linked to the last devastating drought in California, and to the possible return of Dust Bowl conditions in the Midwestern grain belt.

The latest study delivers a long-term analysis of conditions across nine US states, from Oregon and Montana in the north down to California, New Mexico and part of northern Mexico.

With the evidence preserved in old tree trunks, the scientists identified dozens of droughts in the region from 800 AD. They found four megadroughts – periods in which the conditions became extreme – between 800 and 1600. Since then there have been no droughts that could be matched with these – so far.

And then the researchers matched the megadrought tree ring evidence with soil moisture records collected in the first 19 years of this century, and compared this with any 19-year period in the prehistoric droughts.

“We’ll need more and more good luck to break out of drought, and less and less bad luck to get into drought”

They found that the current prolonged dry spell is already more pronounced than the three earliest records of megadrought. The fourth megadrought – it ran from 1575 to 1603 – may still have been the worst of all, but the match with the present years is so close that nobody can be sure.

But the team behind the Science study is sure of one thing. This drought right now is affecting wider stretches of landscape more consistently than any of the earlier megadroughts, and this, they say, is a signature of global heating. All the ancient megadroughts lasted longer, and sometimes much longer, than 19 years, but all began in a way very similar to the present.

The snowpack in the western high mountains has fallen dramatically, the flow of the rivers has dwindled, lake levels have fallen, farmers have been  hit and the wildfires have become more prolonged and more intense.

Drought and even the chance of megadrought may be a fact of life in the US West. During occasional natural atmospheric cycles, the tropical Pacific cools and storm tracks shift further north, taking rainfall away from the US drylands.

But since 2000, average air temperatures in the western states have risen by more than 1.2°C above the normal over earlier centuries. So soils already starved of rain began to lose their stored moisture at an ever-increasing rate.

Worsened by heating

Without the additional global heating, this drought might have happened anyway, and perhaps even been the 11th worst ever recorded, rather than almost the worst ever in human experience.

“It doesn’t matter if this is exactly the worst drought ever,” said Benjamin Cook, a co-author, from Nasa’s Goddard Institute for Space Studies. “What matters is that it has been made much worse than it could have been because of climate change.”

The researchers also found that the 20th century was the wettest century in the entire 1200 year record, and this relatively plentiful supply of water must have helped enrich the US West and make California, for instance, become the Golden State, the most populous in the US.

“Because the background is getting warmer, the dice are increasingly loaded towards longer and more severe droughts,” Professor Williams said. “We may get lucky, and natural variability will bring more precipitation for a while.

“But going forward, we’ll need more and more good luck to break out of drought, and less and less bad luck to get into drought.” – Climate News Network

Entire wild systems at risk from rising global heat

Rising global heat raises risks to the creatures and ecosystems that sustain human society. Collapse could be sudden and near-total.

LONDON, 14 April, 2020 – Worldwide, entire ecosystems could collapse as the planetary thermometer soars: rising global heat could see the Earth’s average temperature rise by 4°C (right now the world is heading for a rise of more than three degrees).

And then one in six of the complex communities of plants and animals in wetlands, grasslands, forests or oceans could drastically alter or fail.

That is because at such temperatures more than one in five of the creatures in that network of co-dependencies would in the same decade experience temperatures beyond their normal tolerance levels.

The prediction is based on data that pinpoint the geographical ranges of 30,652 birds, mammals, reptiles, amphibians, fish and plants, and climate data from 1850 to 2005.

“We found that climate change risks to biodiversity don’t increase gradually,” said Alex Pigot of Imperial College London, in the UK, who led the research.

Abrupt change

“Instead, as the climate warms, within a certain area most species will be able to cope for a while, before crossing a temperature threshold, when a large proportion of the species will suddenly face conditions they’ve never experienced before.

“It’s not a slippery slope, but a series of cliff edges, hitting different areas at different times.”

The finding – published in the journal Nature – should come as no great surprise to the world’s zoologists, botanists, ecologists, foresters, marine scientists and conservationists.

They have repeatedly warned that as global temperatures rise, and climate patterns become increasingly unstable, in response to ever-higher greenhouse gas emissions from power stations and car exhausts, and forest destruction, both individual species and even whole habitats could be exposed to loss and species extinction.

Such threats can be prefigured even in subtle changes in species behaviour. Within this month, Spanish ornithologists who have studied the nightingale Luscinia megarhynchos since 1995 report in the journal The Auk: Ornithological Advances that in two decades, as Spanish summers became hotter and more parched, the wings of each new generation of birds have become progressively shorter.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction”

A shorter wingspan in proportion to body length creates potential survival problems for a species that breeds in Europe but prefers to fly to sub-Saharan Africa for the winter.

And across the Atlantic, another species, the American robin Turdus migratorius now takes wing 12 days earlier each spring in Mexico and the US to fly to its summer breeding grounds in Canada and Alaska.

The ornithologists report in the journal Environmental Research Letters that GPS tracking of 55 individual birds confirms that the bird may be timing its migration to the snow melt and the first arrival of insects in the high latitudes nearer the fast-warming Arctic.

So far, the planet on average has warmed around only 1°C above the long-term average for most of human history. But Dr Pigot and colleagues in the US and South Africa wanted to look at the big picture of potential change in species everywhere as global heating reaches 2°C – the upper limits that the world’s nations promised in a key international agreement reached in Paris in 2015 – and then goes on soaring.

So they took their species data, and mapped it onto a global grid divided into 100-km-square cells, and then fine-tuned the temperature predicted by climate scientists to see where species and their habitats would experience ever-rising heat beyond their comfort zone.

Unprecedented ocean heat

Any ecosystem is a network of interdependencies: insects pollinate flowers, animals disperse seed and prey upon pests and each other in an intricate set of arrangements that have evolved over tens of thousands of years in a particular pattern of temperature and precipitation. Any disturbance ripples through the entire habitat.

The scientists’ atlas of potential ecological disruption included isolated bits of the world such as the Cayman Islands in the Caribbean and the Gobi Desert in Mongolia as well as the Amazon basin and the forests and clearings in the Congo, and one of the world’s richest marine habitats, the so-called Coral Triangle bounded by the Philippines, Malaysia, Papua New Guinea and the islands of the Western Pacific.

They found that if warming could be contained to 2°C or less, only about one community in 50 would be faced with exposure to such disruption: they warn however that even this 2% includes some of the richest habitats on the planet.

They also warn that by 2030, the tropical oceans will start to experience temperature regimes that have no precedent in human history. The tropical forests could be at risk by 2050. Ominously, almost three-fourths of all the species to face unprecedented temperatures before the end of this century will all do so more or less at the same time.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction,” Dr Pigot said. – Climate News Network

Rising global heat raises risks to the creatures and ecosystems that sustain human society. Collapse could be sudden and near-total.

LONDON, 14 April, 2020 – Worldwide, entire ecosystems could collapse as the planetary thermometer soars: rising global heat could see the Earth’s average temperature rise by 4°C (right now the world is heading for a rise of more than three degrees).

And then one in six of the complex communities of plants and animals in wetlands, grasslands, forests or oceans could drastically alter or fail.

That is because at such temperatures more than one in five of the creatures in that network of co-dependencies would in the same decade experience temperatures beyond their normal tolerance levels.

The prediction is based on data that pinpoint the geographical ranges of 30,652 birds, mammals, reptiles, amphibians, fish and plants, and climate data from 1850 to 2005.

“We found that climate change risks to biodiversity don’t increase gradually,” said Alex Pigot of Imperial College London, in the UK, who led the research.

Abrupt change

“Instead, as the climate warms, within a certain area most species will be able to cope for a while, before crossing a temperature threshold, when a large proportion of the species will suddenly face conditions they’ve never experienced before.

“It’s not a slippery slope, but a series of cliff edges, hitting different areas at different times.”

The finding – published in the journal Nature – should come as no great surprise to the world’s zoologists, botanists, ecologists, foresters, marine scientists and conservationists.

They have repeatedly warned that as global temperatures rise, and climate patterns become increasingly unstable, in response to ever-higher greenhouse gas emissions from power stations and car exhausts, and forest destruction, both individual species and even whole habitats could be exposed to loss and species extinction.

Such threats can be prefigured even in subtle changes in species behaviour. Within this month, Spanish ornithologists who have studied the nightingale Luscinia megarhynchos since 1995 report in the journal The Auk: Ornithological Advances that in two decades, as Spanish summers became hotter and more parched, the wings of each new generation of birds have become progressively shorter.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction”

A shorter wingspan in proportion to body length creates potential survival problems for a species that breeds in Europe but prefers to fly to sub-Saharan Africa for the winter.

And across the Atlantic, another species, the American robin Turdus migratorius now takes wing 12 days earlier each spring in Mexico and the US to fly to its summer breeding grounds in Canada and Alaska.

The ornithologists report in the journal Environmental Research Letters that GPS tracking of 55 individual birds confirms that the bird may be timing its migration to the snow melt and the first arrival of insects in the high latitudes nearer the fast-warming Arctic.

So far, the planet on average has warmed around only 1°C above the long-term average for most of human history. But Dr Pigot and colleagues in the US and South Africa wanted to look at the big picture of potential change in species everywhere as global heating reaches 2°C – the upper limits that the world’s nations promised in a key international agreement reached in Paris in 2015 – and then goes on soaring.

So they took their species data, and mapped it onto a global grid divided into 100-km-square cells, and then fine-tuned the temperature predicted by climate scientists to see where species and their habitats would experience ever-rising heat beyond their comfort zone.

Unprecedented ocean heat

Any ecosystem is a network of interdependencies: insects pollinate flowers, animals disperse seed and prey upon pests and each other in an intricate set of arrangements that have evolved over tens of thousands of years in a particular pattern of temperature and precipitation. Any disturbance ripples through the entire habitat.

The scientists’ atlas of potential ecological disruption included isolated bits of the world such as the Cayman Islands in the Caribbean and the Gobi Desert in Mongolia as well as the Amazon basin and the forests and clearings in the Congo, and one of the world’s richest marine habitats, the so-called Coral Triangle bounded by the Philippines, Malaysia, Papua New Guinea and the islands of the Western Pacific.

They found that if warming could be contained to 2°C or less, only about one community in 50 would be faced with exposure to such disruption: they warn however that even this 2% includes some of the richest habitats on the planet.

They also warn that by 2030, the tropical oceans will start to experience temperature regimes that have no precedent in human history. The tropical forests could be at risk by 2050. Ominously, almost three-fourths of all the species to face unprecedented temperatures before the end of this century will all do so more or less at the same time.

“Our findings highlight the urgent need for climate change mitigation, by immediately and drastically reducing emissions, which could help save thousands of species from extinction,” Dr Pigot said. – Climate News Network

Northern Europe’s warm water flow may falter

Global heating can stop the flow of Europe’s warm water from the tropics. Happening often during the Ice Ages, it could soon recur.

LONDON, 1 April, 2020 – Oceanographers have confirmed once again that global heating could slow or shut down the flow of currents such as the Gulf Stream, ending northern Europe’s warm water supply with an unexpected and prolonged cold snap.

This time the confidence is based neither on ocean measurements made now, nor complex computer simulations of the future. There is fresh evidence from the sea floor that such an ocean shutdown happened many times in the last half a million years of Ice Ages.

The Gulf Stream is part of a much larger flow of water called the Atlantic Meridional Overturning Circulation, an ocean recycling system that both nourishes marine life and moderates the climate in two hemispheres.

For the last 10,000 years of human history, tropical water has flowed north from the Caribbean and equatorial regions and washed the shores of Europe as far north as Norway, bringing equatorial heat to soften the impact of European winters.

A former UK chief scientist once calculated that the Gulf Stream delivered the warmth of 27,000 power stations and kept Britain about 5°C warmer than its citizens had any right to expect, given the latitude at which they lived.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions”

But as that stretch of the Gulf Stream known to oceanographers as the North Atlantic drift current reaches the Greenland Sea it becomes increasingly colder and saltier and thus more dense, and sinks to the ocean floor, loaded with dissolved atmospheric carbon dioxide and oxygen, to become a southward flow called the North Atlantic Deepwater formation.

And it also mingles with fresh water melting each summer from the Greenland ice sheet. But as the rate of Arctic melting accelerates, more fresh water will plunge into the same sea, with an increasing probability that it will disrupt the ocean cycle, turn off the flow of warm tropical water, and plunge Europe into a prolonged cold spell.

In its most dramatic form, this hypothesis was the basis for a 2004 Hollywood disaster movie called The Day After Tomorrow. Climate scientists are fairly sure that such an event would not mean the sudden advance of glacial ice over much of Europe and North America. But they have repeatedly identified evidence that the flow of the northward current is beginning to weaken.

And the journal Science now carries additional evidence that the ocean circulation was repeatedly interrupted for periods of a century or more during the warm spells or interglacials that have happened during the last 450,000 years.

Shells’ signatures

The signature of ocean change is there in the tiny sea shells from marine creatures called foraminifera that rain down onto the ocean floor to form annual layers of silent testimony to past climates.

When the mix of carbon isotope ratios preserved in them is high, that is a sign that the Atlantic circulation was once vigorous. When it is low, then this overturning circulation is feeble, or has stopped altogether.

The signal from the deep ocean is that when they happen, these disruptions seem to happen very swiftly, and to linger for 100 years or more. And, the scientists say, these interruptions in the flow of the ocean – and with it, the transport of heat from the tropics – happen more easily than previously appreciated, and they occurred in past climate conditions similar to those the world may soon face.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions,” said Yair Rosenthal of Rutgers University in the US, one of the authors.

“Although the disruptions in circulation and possible coolings may be relatively short-lived – lasting maybe a century or more – the consequences might be large.” – Climate News Network

Global heating can stop the flow of Europe’s warm water from the tropics. Happening often during the Ice Ages, it could soon recur.

LONDON, 1 April, 2020 – Oceanographers have confirmed once again that global heating could slow or shut down the flow of currents such as the Gulf Stream, ending northern Europe’s warm water supply with an unexpected and prolonged cold snap.

This time the confidence is based neither on ocean measurements made now, nor complex computer simulations of the future. There is fresh evidence from the sea floor that such an ocean shutdown happened many times in the last half a million years of Ice Ages.

The Gulf Stream is part of a much larger flow of water called the Atlantic Meridional Overturning Circulation, an ocean recycling system that both nourishes marine life and moderates the climate in two hemispheres.

For the last 10,000 years of human history, tropical water has flowed north from the Caribbean and equatorial regions and washed the shores of Europe as far north as Norway, bringing equatorial heat to soften the impact of European winters.

A former UK chief scientist once calculated that the Gulf Stream delivered the warmth of 27,000 power stations and kept Britain about 5°C warmer than its citizens had any right to expect, given the latitude at which they lived.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions”

But as that stretch of the Gulf Stream known to oceanographers as the North Atlantic drift current reaches the Greenland Sea it becomes increasingly colder and saltier and thus more dense, and sinks to the ocean floor, loaded with dissolved atmospheric carbon dioxide and oxygen, to become a southward flow called the North Atlantic Deepwater formation.

And it also mingles with fresh water melting each summer from the Greenland ice sheet. But as the rate of Arctic melting accelerates, more fresh water will plunge into the same sea, with an increasing probability that it will disrupt the ocean cycle, turn off the flow of warm tropical water, and plunge Europe into a prolonged cold spell.

In its most dramatic form, this hypothesis was the basis for a 2004 Hollywood disaster movie called The Day After Tomorrow. Climate scientists are fairly sure that such an event would not mean the sudden advance of glacial ice over much of Europe and North America. But they have repeatedly identified evidence that the flow of the northward current is beginning to weaken.

And the journal Science now carries additional evidence that the ocean circulation was repeatedly interrupted for periods of a century or more during the warm spells or interglacials that have happened during the last 450,000 years.

Shells’ signatures

The signature of ocean change is there in the tiny sea shells from marine creatures called foraminifera that rain down onto the ocean floor to form annual layers of silent testimony to past climates.

When the mix of carbon isotope ratios preserved in them is high, that is a sign that the Atlantic circulation was once vigorous. When it is low, then this overturning circulation is feeble, or has stopped altogether.

The signal from the deep ocean is that when they happen, these disruptions seem to happen very swiftly, and to linger for 100 years or more. And, the scientists say, these interruptions in the flow of the ocean – and with it, the transport of heat from the tropics – happen more easily than previously appreciated, and they occurred in past climate conditions similar to those the world may soon face.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions,” said Yair Rosenthal of Rutgers University in the US, one of the authors.

“Although the disruptions in circulation and possible coolings may be relatively short-lived – lasting maybe a century or more – the consequences might be large.” – Climate News Network

A second US Dust Bowl would hit world food stocks

When the US Great Plains are hit again by sustained drought, the world’s food stocks will feel the heat.

LONDON, 27 March, 2020 – The next time the fertile soils of North America turn to dust, the consequences will hit food stocks worldwide.

Within four years of a climate crisis of the kind that fired John Steinbeck’s 1939 masterpiece The Grapes of Wrath, the US would have consumed almost all its grain reserves.

And the ripple effects would be felt in all those countries to which America normally exports grain. That is because America feeds much of the world: in a good year, the US exports wheat with an energy value of more than 90 trillion kilocalories. The collapse of farmland into wasteland on the scale that inspired John Steinbeck could reduce this over a four-year period to around 50 trillion kcal.

Worldwide, global wheat reserves would fall by 31% in the first year, and four years on somewhere between 36 and 52 countries would have consumed three-fourths of their own reserves. Food prices would rise around the planet.

“In today’s system of global food trade, disruptions are not bound by borders. Shocks to production are expected to affect trade partners who depend on imports for their domestic food supply,” said Alison Heslin, a climate scientist at Columbia University in the US.

“Accessing food reserves can, for a time, buffer populations from trade-induced supply shortages, but as reserves deplete, people are at risk of food shortages”

“Our results remind us that mitigating climate risks requires accounting not only for the direct effects of climate change, like local extreme weather events, but also the climate impacts which travel through our interconnected system of global trade.”

By some time in the mid-century, most of the US will be between 1.5°C to 2°C warmer. Researchers have already warned that the border between the arid western states and the more fertile mid-western plains has shifted to the east.

There have been repeated warnings that as global average temperatures rise, in response to ever greater use of fossil fuels, the US will become increasingly vulnerable to climate extremes, including megadroughts. Drought is already becoming the “new normal” for Californians, and the fertility of the Great Plains is in any case vulnerable to human changes to a natural landscape.

A succession of droughts of the kind that turned the farmland of Kansas and Oklahoma into a devastated landscape, and turned thousands of Americans into climate refugees, would not necessarily now mean the onset of regional famine.

Dr Heslin and her colleagues report in the journal Frontiers in Sustainable Food Systems that they contemplated the likelihood of a four-year drought of the kind that created the notorious 1930s Dust Bowl, and then examined the possible impact on world trade systems.

Yields and nutrition affected

Just one such climate event could hit hard those nations that rely on food imports, but even the other great grain-producing countries – among them China, India, Iran, Canada, Russia, Morocco, Australia and Egypt – would see their reserves fall.

The climate crisis is in any case a threat to the world’s supper tables. There has been repeated evidence that food output will inevitably be at risk in a warming world. With higher temperatures, yields will be reduced and with higher atmospheric levels of carbon dioxide that warm the planet, nutrition levels of many staples are expected to fall.

The researchers factored in none of these things. They supposed that a climate catastrophe that paralleled the Dust Bowl era would occur only in the US, and found that, despite strain, the world’s markets could probably cope.

But other studies have repeatedly found that the potential for climate catastrophe and massive crop failure to strike in more than one region at any one time are increasing, with ominous consequences for world food security.

“In the context of food security, we show that accessing food reserves can, for a time, buffer populations from trade-induced supply shortages,” said Dr Heslin, “but as reserves deplete, people are at risk of food shortages.” – Climate News Network

When the US Great Plains are hit again by sustained drought, the world’s food stocks will feel the heat.

LONDON, 27 March, 2020 – The next time the fertile soils of North America turn to dust, the consequences will hit food stocks worldwide.

Within four years of a climate crisis of the kind that fired John Steinbeck’s 1939 masterpiece The Grapes of Wrath, the US would have consumed almost all its grain reserves.

And the ripple effects would be felt in all those countries to which America normally exports grain. That is because America feeds much of the world: in a good year, the US exports wheat with an energy value of more than 90 trillion kilocalories. The collapse of farmland into wasteland on the scale that inspired John Steinbeck could reduce this over a four-year period to around 50 trillion kcal.

Worldwide, global wheat reserves would fall by 31% in the first year, and four years on somewhere between 36 and 52 countries would have consumed three-fourths of their own reserves. Food prices would rise around the planet.

“In today’s system of global food trade, disruptions are not bound by borders. Shocks to production are expected to affect trade partners who depend on imports for their domestic food supply,” said Alison Heslin, a climate scientist at Columbia University in the US.

“Accessing food reserves can, for a time, buffer populations from trade-induced supply shortages, but as reserves deplete, people are at risk of food shortages”

“Our results remind us that mitigating climate risks requires accounting not only for the direct effects of climate change, like local extreme weather events, but also the climate impacts which travel through our interconnected system of global trade.”

By some time in the mid-century, most of the US will be between 1.5°C to 2°C warmer. Researchers have already warned that the border between the arid western states and the more fertile mid-western plains has shifted to the east.

There have been repeated warnings that as global average temperatures rise, in response to ever greater use of fossil fuels, the US will become increasingly vulnerable to climate extremes, including megadroughts. Drought is already becoming the “new normal” for Californians, and the fertility of the Great Plains is in any case vulnerable to human changes to a natural landscape.

A succession of droughts of the kind that turned the farmland of Kansas and Oklahoma into a devastated landscape, and turned thousands of Americans into climate refugees, would not necessarily now mean the onset of regional famine.

Dr Heslin and her colleagues report in the journal Frontiers in Sustainable Food Systems that they contemplated the likelihood of a four-year drought of the kind that created the notorious 1930s Dust Bowl, and then examined the possible impact on world trade systems.

Yields and nutrition affected

Just one such climate event could hit hard those nations that rely on food imports, but even the other great grain-producing countries – among them China, India, Iran, Canada, Russia, Morocco, Australia and Egypt – would see their reserves fall.

The climate crisis is in any case a threat to the world’s supper tables. There has been repeated evidence that food output will inevitably be at risk in a warming world. With higher temperatures, yields will be reduced and with higher atmospheric levels of carbon dioxide that warm the planet, nutrition levels of many staples are expected to fall.

The researchers factored in none of these things. They supposed that a climate catastrophe that paralleled the Dust Bowl era would occur only in the US, and found that, despite strain, the world’s markets could probably cope.

But other studies have repeatedly found that the potential for climate catastrophe and massive crop failure to strike in more than one region at any one time are increasing, with ominous consequences for world food security.

“In the context of food security, we show that accessing food reserves can, for a time, buffer populations from trade-induced supply shortages,” said Dr Heslin, “but as reserves deplete, people are at risk of food shortages.” – Climate News Network

Vegetation holds key to climate control

New studies shine a light on the intricate relationship in which climate affects vegetation, which in turn impacts on the global climate.

LONDON, 23 March, 2020 − Here’s an easy way to warm the tropics even further: just fell some rainforest, and the local temperatures will soar by at least a degree Celsius, showing the role played by vegetation.

There is also a good way to temper the summer heat of temperate Europe: just abandon some farmland, leave it to go wild and leafy, and the thermometer will drop by perhaps as much as 1°C.

And, paradoxically, there is even a leafy way to warm the Arctic: burn lots of fossil fuels, precipitate a climate crisis, advance the growth of spring foliage by three weeks or so, and check the thermometer. The region will be even warmer, just because the Arctic has become greener.

These apparently contradictory findings are, more than anything else, a reminder that the pas de deux of vegetation and atmosphere is complex, intricate and finely balanced. Nor are they inconsistent, as each study simply takes the measure of vegetation change on local or regional climate.

Reducing heating

In sum, and for the time being, the big picture remains that forests absorb carbon, and more vigorous growth absorbs more carbon to significantly reduce the average rates of global heating across the entire planet.

In effect, all three studies demonstrate that vegetation moderates extremes of temperature in three climate zones.

Brazilian scientists report in the Public Library of Science journal
PLOS One that they subdivided a tract of the Atlantic rainforest in the southeast of the nation into 120-metre squares, measured those segments that had been part-felled or clear-felled, and read the local land surface temperatures.

If even one fourth of a hectare had been cleared, the local temperature went up by 1°C. If the entire hectare had been razed, the rise could be as high as 4°C.

Risk to trees

The Atlantic rainforest is one of the world’s richest ecosystems: it covers 15% of Brazil, but 72% of the population lives there. It holds seven of Brazil’s nine largest drainage basins, delivers water to 130 million people and its dams provide 60% of the nation’s hydroelectric power.

Between 2017 and 2018, around 113 square kilometres of this forest was cleared. As temperatures continue to rise, some tree species could be at risk.

“We don’t have enough data to predict how long it will take, but in the long run, rising temperatures in Atlantic rainforest fragments could certainly influence the survival of tree species in the forest, albeit some species more than others,” says one of the report’s authors, Carlos Joly, professor of plant biology at the University of Campinas in Brazil.

“The forest is extremely important to maintaining milder temperatures on the local and regional scale. Changes in its function could disrupt this type of ecosystem service.

“Abandoned cropland – or land cover change more generally – and its role in regional climate can help us adapt to and mitigate the effects of climate change”

“The Atlantic rainforest doesn’t produce water but it protects the springs and permits the storage of water in reservoirs for consumption, power generation, agricultural irrigation and fishing, among other activities.”

By contrast, Europeans have achieved a local 1°C cooling simply by abandoning farmland that was no longer sufficiently productive.

Between 1992 and 2014, the European Space Agency satellites compiled detailed maps of the continents, measuring the extents of evergreen needle-leaf forest, deciduous broadleaf woodland, open shrubland, crop fields, urban and built-up areas, wetlands, peatlands, grassland and mosaic areas of crops and wilderness.

In those 24 years – partly because of dramatic political changes that followed the collapse of the Soviet Union – around 25 million hectares of farmland was abandoned.

Drying wetlands

Although farmland was colonised elsewhere, the continent was left with 5 million hectares – an area the size of Switzerland – to be colonised by trees and other natural foliage, European scientists report in the journal Nature Communications.

Overall, the loss of cropland in Western Europe was associated with a drop of 1° in spring and summer. In eastern and northeastern Europe, however, temperatures rose by as much as 1°C, partly because what had once been wetlands began to dry.

“We are already at a mean warming of about 1.8°C on the land, and we will be about 3°C on the land even if we are successful at stabilising the average global temperature at 1.5°C,” says one of the report’s authors, Francesco Cherubini, director of the Industrial Ecology Programme at the Norwegian University of Science and Technology.

“That means we take action to adapt to a warming climate, and land use planning is one action that can bring local cooling benefits.”

The Arctic greens

“The message is quite clear. Abandoned cropland – or land cover change more generally – and its role in regional climate can help us adapt to and mitigate the effects of climate change. And by improving agricultural systems, we can free up land for multiple uses.”

But while Europe is changing, and forest in the tropics is being lost, the Arctic is becoming greener: as temperatures rise, vegetation has moved northwards and spring has arrived ever earlier, and growing seasons have lasted longer.

The science of measurement of seasonal change in plant and animal behaviour is called phenology. Chinese and US scientists report in Nature Climate Change that they looked at computer models of vegetation change and factored in the numbers: on average, in the last four decades, leaf-out has advanced by an average of more than four days a decade, and in some cases up to 12 days a decade.

That means snow-covered ground has retreated, and green leaves have moved northwards, and become denser.

Climate feedback

Snow reflects solar radiation, and darker colours absorb it. That means that local landscapes in the north have tended to become even warmer with each decade.

In the Canadian archipelago, the air has been measured at 0.7°C warmer, and parts of Siberia and the Tibetan plateau − far from any leafy canopy − have warmed by 0.4°C and 0.3°C respectively because advanced leaf-out further south means more water vapour, which moves north to change patterns of cloud cover and snowfall.

Climate scientists see this as positive feedback: climate change begets even faster climate change. Global heating tends to accelerate. Climate change affects vegetation, which in turn affects climate yet further.

“Positive feedback loops between climate and spring leaf phenology is likely to amplify in the northern high latitudes,” says Gensuo Jia, one of the researchers from the Chinese Academy of Sciences. “The impact of vegetation change on climate is profound in spring.” − Climate News Network

New studies shine a light on the intricate relationship in which climate affects vegetation, which in turn impacts on the global climate.

LONDON, 23 March, 2020 − Here’s an easy way to warm the tropics even further: just fell some rainforest, and the local temperatures will soar by at least a degree Celsius, showing the role played by vegetation.

There is also a good way to temper the summer heat of temperate Europe: just abandon some farmland, leave it to go wild and leafy, and the thermometer will drop by perhaps as much as 1°C.

And, paradoxically, there is even a leafy way to warm the Arctic: burn lots of fossil fuels, precipitate a climate crisis, advance the growth of spring foliage by three weeks or so, and check the thermometer. The region will be even warmer, just because the Arctic has become greener.

These apparently contradictory findings are, more than anything else, a reminder that the pas de deux of vegetation and atmosphere is complex, intricate and finely balanced. Nor are they inconsistent, as each study simply takes the measure of vegetation change on local or regional climate.

Reducing heating

In sum, and for the time being, the big picture remains that forests absorb carbon, and more vigorous growth absorbs more carbon to significantly reduce the average rates of global heating across the entire planet.

In effect, all three studies demonstrate that vegetation moderates extremes of temperature in three climate zones.

Brazilian scientists report in the Public Library of Science journal
PLOS One that they subdivided a tract of the Atlantic rainforest in the southeast of the nation into 120-metre squares, measured those segments that had been part-felled or clear-felled, and read the local land surface temperatures.

If even one fourth of a hectare had been cleared, the local temperature went up by 1°C. If the entire hectare had been razed, the rise could be as high as 4°C.

Risk to trees

The Atlantic rainforest is one of the world’s richest ecosystems: it covers 15% of Brazil, but 72% of the population lives there. It holds seven of Brazil’s nine largest drainage basins, delivers water to 130 million people and its dams provide 60% of the nation’s hydroelectric power.

Between 2017 and 2018, around 113 square kilometres of this forest was cleared. As temperatures continue to rise, some tree species could be at risk.

“We don’t have enough data to predict how long it will take, but in the long run, rising temperatures in Atlantic rainforest fragments could certainly influence the survival of tree species in the forest, albeit some species more than others,” says one of the report’s authors, Carlos Joly, professor of plant biology at the University of Campinas in Brazil.

“The forest is extremely important to maintaining milder temperatures on the local and regional scale. Changes in its function could disrupt this type of ecosystem service.

“Abandoned cropland – or land cover change more generally – and its role in regional climate can help us adapt to and mitigate the effects of climate change”

“The Atlantic rainforest doesn’t produce water but it protects the springs and permits the storage of water in reservoirs for consumption, power generation, agricultural irrigation and fishing, among other activities.”

By contrast, Europeans have achieved a local 1°C cooling simply by abandoning farmland that was no longer sufficiently productive.

Between 1992 and 2014, the European Space Agency satellites compiled detailed maps of the continents, measuring the extents of evergreen needle-leaf forest, deciduous broadleaf woodland, open shrubland, crop fields, urban and built-up areas, wetlands, peatlands, grassland and mosaic areas of crops and wilderness.

In those 24 years – partly because of dramatic political changes that followed the collapse of the Soviet Union – around 25 million hectares of farmland was abandoned.

Drying wetlands

Although farmland was colonised elsewhere, the continent was left with 5 million hectares – an area the size of Switzerland – to be colonised by trees and other natural foliage, European scientists report in the journal Nature Communications.

Overall, the loss of cropland in Western Europe was associated with a drop of 1° in spring and summer. In eastern and northeastern Europe, however, temperatures rose by as much as 1°C, partly because what had once been wetlands began to dry.

“We are already at a mean warming of about 1.8°C on the land, and we will be about 3°C on the land even if we are successful at stabilising the average global temperature at 1.5°C,” says one of the report’s authors, Francesco Cherubini, director of the Industrial Ecology Programme at the Norwegian University of Science and Technology.

“That means we take action to adapt to a warming climate, and land use planning is one action that can bring local cooling benefits.”

The Arctic greens

“The message is quite clear. Abandoned cropland – or land cover change more generally – and its role in regional climate can help us adapt to and mitigate the effects of climate change. And by improving agricultural systems, we can free up land for multiple uses.”

But while Europe is changing, and forest in the tropics is being lost, the Arctic is becoming greener: as temperatures rise, vegetation has moved northwards and spring has arrived ever earlier, and growing seasons have lasted longer.

The science of measurement of seasonal change in plant and animal behaviour is called phenology. Chinese and US scientists report in Nature Climate Change that they looked at computer models of vegetation change and factored in the numbers: on average, in the last four decades, leaf-out has advanced by an average of more than four days a decade, and in some cases up to 12 days a decade.

That means snow-covered ground has retreated, and green leaves have moved northwards, and become denser.

Climate feedback

Snow reflects solar radiation, and darker colours absorb it. That means that local landscapes in the north have tended to become even warmer with each decade.

In the Canadian archipelago, the air has been measured at 0.7°C warmer, and parts of Siberia and the Tibetan plateau − far from any leafy canopy − have warmed by 0.4°C and 0.3°C respectively because advanced leaf-out further south means more water vapour, which moves north to change patterns of cloud cover and snowfall.

Climate scientists see this as positive feedback: climate change begets even faster climate change. Global heating tends to accelerate. Climate change affects vegetation, which in turn affects climate yet further.

“Positive feedback loops between climate and spring leaf phenology is likely to amplify in the northern high latitudes,” says Gensuo Jia, one of the researchers from the Chinese Academy of Sciences. “The impact of vegetation change on climate is profound in spring.” − Climate News Network

Record Antarctic temperatures fuel sea level worry


Sea levels may threaten coastal cities sooner than expected, scientists say, as ice loss speeds up and Antarctic temperatures rise.

LONDON, 20 February, 2020 − Across the world, people now alive in coastal areas may face dangerously rising seas within their lifetimes, as record Antarctic temperatures and rapid melting of the continent’s ice drive global sea levels upwards.

Temperatures on the Antarctic Peninsula reached more than 20°C for the first time in history earlier this month, the Guardian reported: “The 20.75C logged by Brazilian scientists at Seymour Island on 9 February was almost a full degree higher than the previous record of 19.8C, taken on Signy Island in January 1982.”

The Antarctic Peninsula has warmed by almost 3°C since the start of the Industrial Revolution around 200 years ago − faster than almost anywhere else on Earth. But scientists are increasingly concerned not only about the Peninsula, but with the possibility that the entire southern continent may be heating up much faster than current estimates suggest.

Among evidence of increasing scientific effort to determine what is happening is a joint UK-US collaboration, due to report in 2023 on the chances of the collapse of the huge Thwaites glacier in West Antarctica, where from 1992 to 2017 the annual rate of ice loss rose threefold.

Big speed-up

Now a study by scientists co-ordinated by Germany’s Potsdam Institute for Climate Impact Research (PIK) says sea level rise caused by Antarctica’s ice loss could become a major risk for coastal protection in the near future.

After what they call “an exceptionally comprehensive comparison of state-of-the-art computer models from around the world”, they conclude that Antarctica alone could cause global sea level to rise by 2100 by up to three times more than it did in the last century.

“The ‘Antarctica Factor’ turns out to be the greatest risk, and also the greatest uncertainty, for sea levels around the globe,” says the lead author, Anders Levermann of PIK and Columbia University’s Lamont-Doherty Earth Observatory (LDEO) in New York.

“While we saw about 19 centimetres of sea level rise in the past 100 years, Antarctic ice loss could lead to up to 58 centimetres within this century”, he said.

“We know for certain that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai”

“Coastal planning cannot merely rely on the best guess. It requires a risk analysis. Our study provides exactly that. The sea level contribution of Antarctica is very likely not going to be more than 58 centimetres.”

Thermal expansion of the oceans by global warming and the melting of glaciers, which so far have been the most important factors in sea level rise, will add to the contribution from Antarctic ice loss, making the overall sea level rise risk even bigger. But the ‘Antarctica Factor’ is about to become the most important element, according to the study, published in the journal Earth System Dynamics.

The range of sea-level rise estimates the scientists have come up with is fairly large. Assuming that humanity keeps on emitting greenhouse gases as before, they say, the range they call “very likely” to describe the future is between 6 and 58 cms for this century.

If greenhouse gas emissions were reduced rapidly, it would be between 4 and 37 cms. Importantly, the difference between a business-as-usual scenario and one of emissions reductions becomes substantially greater as time passes.

More robust insights

Sixteen ice sheet modelling groups consisting of 36 researchers from 27 institutes contributed to the new study. A similar study six years ago had to rely on the output of only five ice sheet models.

“The more computer simulation models we use, all of them with slightly different dynamic representations of the Antarctic ice sheet, the wider the range of results that we yield − but also the more robust the insights that we gain”, said co-author Sophie Nowicki of the NASA Goddard Space Flight Center.

“There are still large uncertainties, but we are constantly improving our understanding of the largest ice sheet on Earth. Comparing model outputs is a forceful tool to provide society with the necessary information for rational decisions.”

Over the long term, the Antarctic ice sheet has the potential ultimately to raise sea levels by many tens of metres. “What we know for certain”, said Professor Levermann, “is that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai.” − Climate News Network


Sea levels may threaten coastal cities sooner than expected, scientists say, as ice loss speeds up and Antarctic temperatures rise.

LONDON, 20 February, 2020 − Across the world, people now alive in coastal areas may face dangerously rising seas within their lifetimes, as record Antarctic temperatures and rapid melting of the continent’s ice drive global sea levels upwards.

Temperatures on the Antarctic Peninsula reached more than 20°C for the first time in history earlier this month, the Guardian reported: “The 20.75C logged by Brazilian scientists at Seymour Island on 9 February was almost a full degree higher than the previous record of 19.8C, taken on Signy Island in January 1982.”

The Antarctic Peninsula has warmed by almost 3°C since the start of the Industrial Revolution around 200 years ago − faster than almost anywhere else on Earth. But scientists are increasingly concerned not only about the Peninsula, but with the possibility that the entire southern continent may be heating up much faster than current estimates suggest.

Among evidence of increasing scientific effort to determine what is happening is a joint UK-US collaboration, due to report in 2023 on the chances of the collapse of the huge Thwaites glacier in West Antarctica, where from 1992 to 2017 the annual rate of ice loss rose threefold.

Big speed-up

Now a study by scientists co-ordinated by Germany’s Potsdam Institute for Climate Impact Research (PIK) says sea level rise caused by Antarctica’s ice loss could become a major risk for coastal protection in the near future.

After what they call “an exceptionally comprehensive comparison of state-of-the-art computer models from around the world”, they conclude that Antarctica alone could cause global sea level to rise by 2100 by up to three times more than it did in the last century.

“The ‘Antarctica Factor’ turns out to be the greatest risk, and also the greatest uncertainty, for sea levels around the globe,” says the lead author, Anders Levermann of PIK and Columbia University’s Lamont-Doherty Earth Observatory (LDEO) in New York.

“While we saw about 19 centimetres of sea level rise in the past 100 years, Antarctic ice loss could lead to up to 58 centimetres within this century”, he said.

“We know for certain that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai”

“Coastal planning cannot merely rely on the best guess. It requires a risk analysis. Our study provides exactly that. The sea level contribution of Antarctica is very likely not going to be more than 58 centimetres.”

Thermal expansion of the oceans by global warming and the melting of glaciers, which so far have been the most important factors in sea level rise, will add to the contribution from Antarctic ice loss, making the overall sea level rise risk even bigger. But the ‘Antarctica Factor’ is about to become the most important element, according to the study, published in the journal Earth System Dynamics.

The range of sea-level rise estimates the scientists have come up with is fairly large. Assuming that humanity keeps on emitting greenhouse gases as before, they say, the range they call “very likely” to describe the future is between 6 and 58 cms for this century.

If greenhouse gas emissions were reduced rapidly, it would be between 4 and 37 cms. Importantly, the difference between a business-as-usual scenario and one of emissions reductions becomes substantially greater as time passes.

More robust insights

Sixteen ice sheet modelling groups consisting of 36 researchers from 27 institutes contributed to the new study. A similar study six years ago had to rely on the output of only five ice sheet models.

“The more computer simulation models we use, all of them with slightly different dynamic representations of the Antarctic ice sheet, the wider the range of results that we yield − but also the more robust the insights that we gain”, said co-author Sophie Nowicki of the NASA Goddard Space Flight Center.

“There are still large uncertainties, but we are constantly improving our understanding of the largest ice sheet on Earth. Comparing model outputs is a forceful tool to provide society with the necessary information for rational decisions.”

Over the long term, the Antarctic ice sheet has the potential ultimately to raise sea levels by many tens of metres. “What we know for certain”, said Professor Levermann, “is that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai.” − Climate News Network