Tag Archives: Rainfall

Cloud forests risk drying out by 2060

For the world’s cloud forests, the future is overcast. Some face fiercer storm and flood: they could even lose their unique clouds.

LONDON, 23 April, 2019 – Planet Earth may be about to lose a whole ecosystem: the cloud forests – those species-rich, high altitude rainforests found mostly in Central and South America – could be all but gone in 40 years.

Researchers warn that within 25 years, global warming driven by ever increasing use of fossil fuels could dry up 60-80% of the misty mountain forests of Mexico, Puerto Rico, Costa Rica, Ecuador and Peru, simply by dispersing the clouds that keep them ever moist, and rich with plant, insect and bird life.

And as the habitat alters, that could be it for the Monarch butterflies that migrate in their millions to the mountains of Mexico, the elfin woods warbler found only in Puerto Rico, and the other creatures that make their homes in forests so rich and wet that even the trees are home to yet more green habitat: ferns, lichens, mosses and other epiphytes nourished by year-round water and water vapour.

And the reason? The clouds will have dispersed, or moved uphill, or simply been blown away as greenhouse gas ratios in the atmosphere continue to grow and temperatures creep ever higher, according to new research in the Public Library of Science journal PLOS One.

“Maria is more extreme in its precipitation than anything else the island has ever seen. I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years”

And if nations go on burning ever greater quantities of coal, oil and natural gas to power economic growth, then the cloud and frost that keep the equatorial cloud forests unique homes to living things will have gone.

Nine-tenths of the cloud forests in the Western Hemisphere will have been lost by 2060, if the calculations funded by the US Department of Agriculture’s Forest Service are correct.

Researchers mapped cloud forest across the Western Hemisphere with data collected over the last 60 years and then used climate simulations to see how the habitat would change with time.

They found that indeed some regions would become even more immersed in cloud: this however would only add up to perhaps 1%. For the most part the clouds would thin, the steady supply of moisture would thin, and the forests would begin to change inexorably.

Trees head uphill

This is not the first research to suggest that ever higher temperatures would affect cloud patterns. Scientists using a different approach reported earlier this year that tropical cloud formation of the kind that damps down equatorial temperatures could be at risk.

Other researchers have used historic data to record the steady uphill march of characteristic trees in the Andean forests in response to average global temperature increases of 1°C in the past century.

And yet another team has warned that the increasingly violent winds that arrived in Puerto Rico with Hurricane Maria in 2017 would in any case change the make-up of forest species.

Devastating winds that uproot forest giants at all altitudes won’t be the only problem for the climate-hit forests and the region. Hurricane Maria dumped an unprecedented 1.029 mm of rain in a day on Puerto Rico.

Recurrence likely

A second study from the American Geophysical Union has confirmed that the extreme rainfall that accompanied Maria was not only the worst in the last 60 years, but has become much more likely to happen again.

Thanks to global warming, which increased the capacity of the atmosphere to absorb moisture, such floods are now five times more likely, they write in the journal Geophysical Research Letters.

“Maria is more extreme in its precipitation than anything else the island has ever seen,” said David Keellings of the University of Alabama, one of the authors.

“I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years.” – Climate News Network

For the world’s cloud forests, the future is overcast. Some face fiercer storm and flood: they could even lose their unique clouds.

LONDON, 23 April, 2019 – Planet Earth may be about to lose a whole ecosystem: the cloud forests – those species-rich, high altitude rainforests found mostly in Central and South America – could be all but gone in 40 years.

Researchers warn that within 25 years, global warming driven by ever increasing use of fossil fuels could dry up 60-80% of the misty mountain forests of Mexico, Puerto Rico, Costa Rica, Ecuador and Peru, simply by dispersing the clouds that keep them ever moist, and rich with plant, insect and bird life.

And as the habitat alters, that could be it for the Monarch butterflies that migrate in their millions to the mountains of Mexico, the elfin woods warbler found only in Puerto Rico, and the other creatures that make their homes in forests so rich and wet that even the trees are home to yet more green habitat: ferns, lichens, mosses and other epiphytes nourished by year-round water and water vapour.

And the reason? The clouds will have dispersed, or moved uphill, or simply been blown away as greenhouse gas ratios in the atmosphere continue to grow and temperatures creep ever higher, according to new research in the Public Library of Science journal PLOS One.

“Maria is more extreme in its precipitation than anything else the island has ever seen. I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years”

And if nations go on burning ever greater quantities of coal, oil and natural gas to power economic growth, then the cloud and frost that keep the equatorial cloud forests unique homes to living things will have gone.

Nine-tenths of the cloud forests in the Western Hemisphere will have been lost by 2060, if the calculations funded by the US Department of Agriculture’s Forest Service are correct.

Researchers mapped cloud forest across the Western Hemisphere with data collected over the last 60 years and then used climate simulations to see how the habitat would change with time.

They found that indeed some regions would become even more immersed in cloud: this however would only add up to perhaps 1%. For the most part the clouds would thin, the steady supply of moisture would thin, and the forests would begin to change inexorably.

Trees head uphill

This is not the first research to suggest that ever higher temperatures would affect cloud patterns. Scientists using a different approach reported earlier this year that tropical cloud formation of the kind that damps down equatorial temperatures could be at risk.

Other researchers have used historic data to record the steady uphill march of characteristic trees in the Andean forests in response to average global temperature increases of 1°C in the past century.

And yet another team has warned that the increasingly violent winds that arrived in Puerto Rico with Hurricane Maria in 2017 would in any case change the make-up of forest species.

Devastating winds that uproot forest giants at all altitudes won’t be the only problem for the climate-hit forests and the region. Hurricane Maria dumped an unprecedented 1.029 mm of rain in a day on Puerto Rico.

Recurrence likely

A second study from the American Geophysical Union has confirmed that the extreme rainfall that accompanied Maria was not only the worst in the last 60 years, but has become much more likely to happen again.

Thanks to global warming, which increased the capacity of the atmosphere to absorb moisture, such floods are now five times more likely, they write in the journal Geophysical Research Letters.

“Maria is more extreme in its precipitation than anything else the island has ever seen,” said David Keellings of the University of Alabama, one of the authors.

“I just didn’t expect that it was going to be so much more than anything else that has happened in the last 60 years.” – Climate News Network

Half a degree may make heat impact far worse

Half a degree of warming doesn’t sound like much. But there is fresh evidence that it could make a huge difference to rainfall and drought.

LONDON, 4 April, 2019 − Japanese scientists have found new evidence that a global average temperature rise as small as half a degree could have a drastic effect.

They conclude that the world cannot afford to delay action to reduce greenhouse gas emissions and slow global warming to 1.5°C by 2100 – the “ideal target” enshrined in the promise by 195 nations to limit warming to well below 2°C above the long-term average for most of human history.

The evidence is this: a shift of even 0.5°C could make a dramatic difference to the risks of devastating droughts and calamitous floods.

If governments keep to the letter of the Paris Agreement of 2015 but not the spirit, and let warming rise to the maximum of 2°, then there will be more intense rainfall across North America, Europe and Asia, and more intense droughts around the Mediterranean.

And although the average intensity of each flood or drought would increase measurably, the intensity of the most extreme event could be even more intense: 10 times greater. That is: the worst imaginable floods 80 years from now would be ten times worse than the worst today.

“Such drastic changes between flood and drought conditions pose a major challenge . . . risks could be substantially reduced by achieving a 1.5°C target”

At the heart of research like this is a new way of looking at future climate projections devised – by researchers all over the world – on a range of possible outcomes for a planet that has recognised climate change, vowed to respond, but failed to take sufficiently energetic steps.

The planet is already warmer by 1°C on average than it was a century ago. Since the Paris Agreement researchers have warned that on present form, and with the present state of commitment nationally and internationally, global average temperatures will top an increase of at least 3°C by the century’s close.

This would be catastrophic. But since then, a slew of fresh studies has defined fresh shades of potential catastrophe even at 2°C maximum, and delivered evidence that a limit of overall warming to the target of 1.5°C would save not just economic damage but even lost lands.

They have demonstrated that just half a degree more would see sea levels rise by 10cms, to threaten the existence of already vulnerable small island states and low-lying coastal floodplains, to put at risk the survival of the coral reefs, and the Arctic ice.

The latest study simply addressed a phenomenon known in the scientific language as the event-to-event hydrological intensification index. This awkward mouthful of syllables masks the crude consequence of average warming: if the overall temperature rises, then so do the extremes of temperature. That is what is meant by average: the mean of all the extremes.

Harder rain

But if average temperatures rise, so does the capacity of the air to hold moisture, which means that when it does rain, then it will rain harder. And when it doesn’t, the groundwater will evaporate more easily.

So landscapes such as the US south-west, already prone to heat and drought, can expect more heat waves, more forest fires and more intense and prolonged drought, while the northeast could see more flooding.

And the latest study in the journal Scientific Reports, by researchers at the University of Tokyo, looked at the difference of outcomes between 1.5°C and 2°C in an already rapidly-warming world, to find that when it came to rainfall – and the attendant floods, droughts, mudslides, harvest failures and water shortages – even half a degree beyond the ideal could make the very bad 10 times worse.

“The high damage potential of such drastic changes between flood and drought conditions poses a major challenge to adaptation,” the researchers conclude, “and the findings suggest that risks could be substantially reduced by achieving a 1.5°C target.” − Climate News Network

Half a degree of warming doesn’t sound like much. But there is fresh evidence that it could make a huge difference to rainfall and drought.

LONDON, 4 April, 2019 − Japanese scientists have found new evidence that a global average temperature rise as small as half a degree could have a drastic effect.

They conclude that the world cannot afford to delay action to reduce greenhouse gas emissions and slow global warming to 1.5°C by 2100 – the “ideal target” enshrined in the promise by 195 nations to limit warming to well below 2°C above the long-term average for most of human history.

The evidence is this: a shift of even 0.5°C could make a dramatic difference to the risks of devastating droughts and calamitous floods.

If governments keep to the letter of the Paris Agreement of 2015 but not the spirit, and let warming rise to the maximum of 2°, then there will be more intense rainfall across North America, Europe and Asia, and more intense droughts around the Mediterranean.

And although the average intensity of each flood or drought would increase measurably, the intensity of the most extreme event could be even more intense: 10 times greater. That is: the worst imaginable floods 80 years from now would be ten times worse than the worst today.

“Such drastic changes between flood and drought conditions pose a major challenge . . . risks could be substantially reduced by achieving a 1.5°C target”

At the heart of research like this is a new way of looking at future climate projections devised – by researchers all over the world – on a range of possible outcomes for a planet that has recognised climate change, vowed to respond, but failed to take sufficiently energetic steps.

The planet is already warmer by 1°C on average than it was a century ago. Since the Paris Agreement researchers have warned that on present form, and with the present state of commitment nationally and internationally, global average temperatures will top an increase of at least 3°C by the century’s close.

This would be catastrophic. But since then, a slew of fresh studies has defined fresh shades of potential catastrophe even at 2°C maximum, and delivered evidence that a limit of overall warming to the target of 1.5°C would save not just economic damage but even lost lands.

They have demonstrated that just half a degree more would see sea levels rise by 10cms, to threaten the existence of already vulnerable small island states and low-lying coastal floodplains, to put at risk the survival of the coral reefs, and the Arctic ice.

The latest study simply addressed a phenomenon known in the scientific language as the event-to-event hydrological intensification index. This awkward mouthful of syllables masks the crude consequence of average warming: if the overall temperature rises, then so do the extremes of temperature. That is what is meant by average: the mean of all the extremes.

Harder rain

But if average temperatures rise, so does the capacity of the air to hold moisture, which means that when it does rain, then it will rain harder. And when it doesn’t, the groundwater will evaporate more easily.

So landscapes such as the US south-west, already prone to heat and drought, can expect more heat waves, more forest fires and more intense and prolonged drought, while the northeast could see more flooding.

And the latest study in the journal Scientific Reports, by researchers at the University of Tokyo, looked at the difference of outcomes between 1.5°C and 2°C in an already rapidly-warming world, to find that when it came to rainfall – and the attendant floods, droughts, mudslides, harvest failures and water shortages – even half a degree beyond the ideal could make the very bad 10 times worse.

“The high damage potential of such drastic changes between flood and drought conditions poses a major challenge to adaptation,” the researchers conclude, “and the findings suggest that risks could be substantially reduced by achieving a 1.5°C target.” − Climate News Network

Rapidly rising heat will cut maize harvests

Soon the corn could roast on the cob long before the maize harvests are due. That could be far sooner than anyone expects.

LONDON, 3 April, 2019 − European scientists have bad news for the world’s farmers: within a decade, maize harvests will suffer as global temperatures will have reached a level that will turn the once-in-a-decade extremes of heat and drought into the new normal.

That will mean that the worst production losses ever felt by the maize farmers will happen with increasing frequency, if global planetary temperatures reach 1.5°C above the long-term average for almost all human history.

The world is already 1°C hotter on average than it was before the Industrial Revolution and its increasing dependence on fossil fuels to power the global economies.

And if the temperature reaches 2°C, researchers warn, farmlands where maize once flourished will be hit by heat and drought events never before experienced. The big agribusiness giants will be hurt – and so will the small subsistence farmers who depend on their crop to keep their families alive.

“At the 2°C warning level . . . our projections suggest that global maize production will suffer from unprecedented losses”

Already the warming in the last few decades has begun to hit yields: the scientists reckon that maize yield within the 28 European member states is 290,000 tonnes a year lower than it would have been without global warming.

Significantly, 195 nations met in Paris in 2015 to agree to co-operate to keep average global warming down to if possible “well below” 2°C by 2100. Their target was a rise of no more than 1.5°C.

At the present rate of action – to switch to solar and wind power, to restore the world’s forests – the planet is on course to warm by 3°C by the close of the century.

But a new study by the European Union’s Joint Research Centre in Ispra, Italy, published in the journal Earth’s Future, is not worried about the average, but about the extremes that, over the course of a year, make up that average, and drive up the loss of one particular crop: maize.

Vulnerabilities

Maize is now the world’s biggest single crop: the US is the most important producer but the EU ranks fourth in the world, producing an average of 65 million tonnes a year for food and cattle fodder. This warm climate crop is at certain points in its growing season vulnerable to heat stress and to drought. And heat stress seems increasingly  certain.

Researchers have warned, repeatedly, that higher average planetary or regional temperatures will mean increasingly intense, frequent, prolonged and potentially dangerous extremes of heat. And those areas already vulnerable to drought are likely to see much more of it, while other regions will become more at risk of catastrophic flood.

Agricultural scientists have already confirmed that untimely spells of heat and drought have started to slash cereal yields as measured across whole regions, or per field.

Hunger warning

And although the US has increased production, this too will be vulnerable to further warming. The World Meteorological Organisation has just warned of an already warmer, hungrier world.

The European researchers report that their analysis of past and future maize production surveys a range of outcomes: in one of these, the worst could start to happen as early as 2020. They suggest greater efforts to meet the goals set in Paris but even with those, farmers and agriculture ministries will need to find ways to adapt.

Their report ends bluntly. “We found that global warming will substantially increase the risk of maize production losses in most world regions, including the United States. The climatic events affecting historical global maize production once every 10 years will become normal at the 1.5°C global warming level, which is reached in the 2020s in most of the analysed climate model simulations,” they write.

“At the 2°C warning level (approximately late 2030s) our projections suggest that global maize production will suffer from unprecedented losses.” − Climate News Network

Soon the corn could roast on the cob long before the maize harvests are due. That could be far sooner than anyone expects.

LONDON, 3 April, 2019 − European scientists have bad news for the world’s farmers: within a decade, maize harvests will suffer as global temperatures will have reached a level that will turn the once-in-a-decade extremes of heat and drought into the new normal.

That will mean that the worst production losses ever felt by the maize farmers will happen with increasing frequency, if global planetary temperatures reach 1.5°C above the long-term average for almost all human history.

The world is already 1°C hotter on average than it was before the Industrial Revolution and its increasing dependence on fossil fuels to power the global economies.

And if the temperature reaches 2°C, researchers warn, farmlands where maize once flourished will be hit by heat and drought events never before experienced. The big agribusiness giants will be hurt – and so will the small subsistence farmers who depend on their crop to keep their families alive.

“At the 2°C warning level . . . our projections suggest that global maize production will suffer from unprecedented losses”

Already the warming in the last few decades has begun to hit yields: the scientists reckon that maize yield within the 28 European member states is 290,000 tonnes a year lower than it would have been without global warming.

Significantly, 195 nations met in Paris in 2015 to agree to co-operate to keep average global warming down to if possible “well below” 2°C by 2100. Their target was a rise of no more than 1.5°C.

At the present rate of action – to switch to solar and wind power, to restore the world’s forests – the planet is on course to warm by 3°C by the close of the century.

But a new study by the European Union’s Joint Research Centre in Ispra, Italy, published in the journal Earth’s Future, is not worried about the average, but about the extremes that, over the course of a year, make up that average, and drive up the loss of one particular crop: maize.

Vulnerabilities

Maize is now the world’s biggest single crop: the US is the most important producer but the EU ranks fourth in the world, producing an average of 65 million tonnes a year for food and cattle fodder. This warm climate crop is at certain points in its growing season vulnerable to heat stress and to drought. And heat stress seems increasingly  certain.

Researchers have warned, repeatedly, that higher average planetary or regional temperatures will mean increasingly intense, frequent, prolonged and potentially dangerous extremes of heat. And those areas already vulnerable to drought are likely to see much more of it, while other regions will become more at risk of catastrophic flood.

Agricultural scientists have already confirmed that untimely spells of heat and drought have started to slash cereal yields as measured across whole regions, or per field.

Hunger warning

And although the US has increased production, this too will be vulnerable to further warming. The World Meteorological Organisation has just warned of an already warmer, hungrier world.

The European researchers report that their analysis of past and future maize production surveys a range of outcomes: in one of these, the worst could start to happen as early as 2020. They suggest greater efforts to meet the goals set in Paris but even with those, farmers and agriculture ministries will need to find ways to adapt.

Their report ends bluntly. “We found that global warming will substantially increase the risk of maize production losses in most world regions, including the United States. The climatic events affecting historical global maize production once every 10 years will become normal at the 1.5°C global warming level, which is reached in the 2020s in most of the analysed climate model simulations,” they write.

“At the 2°C warning level (approximately late 2030s) our projections suggest that global maize production will suffer from unprecedented losses.” − Climate News Network

The day the Earth’s climate went berserk

The day in 1815 when the world’s climate went berserk was only the start of months and years of global climate disruption and social unrest.

LONDON, 19 March, 2019 − If you had been in what were then called the Dutch East Indies on 10 April 1815, the day would have been etched indelibly on your memory: it was the day the global climate went berserk.

Many parts of the world are already feeling the effects of a changing climate. Island nations in the Pacific are seeing their lands eaten away by rising sea levels.

Whole communities of people in Arctic regions are threatened by rapidly expanding ice melt. The foundations of houses are being swept away. Traditional hunting grounds are being lost.

Wolfgang Behringer is a climate historian who seeks to draw parallels between what is going on now and events long ago. In particular Behringer, a professor of early modern history at Saarland University in Germany, looks at how changes in climate can influence and shape events – political, economic and social.

In a new book he focuses on the 1815 volcanic explosion of Tambora, on the island of Sumbawa in present-day Indonesia. The eruption still rates as the largest in human history; the cloud that burst from the volcano reached a height of 45 kilometres.

“Apparently minor changes in temperature and humidity suffice to shake up entrenched ecosystems, but above all entrenched agricultural systems”

Many thousands of people were killed on Sumbawa and adjoining islands, including Lombok and Bali. Dust clouds from Tambora were swept around the globe; the world’s climate went berserk, says Behringer.

“The dimensions of the Tambora crisis were so extraordinary because its roots lay in nature, in processes of geology, atmospheric physics and meteorology. These forces of nature respect no borders.”

The suspended particles from the volcano reduced solar radiation and led to global cooling. What scientists call a dry fog enveloped much of Asia. A blue sun appeared in Latin America. Snow that fell in Italy was red and yellow.

The winter of 1815/16 in much of the world was one of the coldest of the century. In Europe, 1816 became known as the year without summer. In North America what was described as the “Yankee chill” resulted in the worst harvest ever recorded.

Global upset

Torrential rains caused floods and thousands of deaths in China and India. Famine was widespread.

Behringer says the changes in climate provoked social unrest on a worldwide scale.

“The reactions to the crisis offer an example of how societies and individuals respond to climate change, what risks emerge and what opportunities may be associated with it”, he writes.

Epidemics broke out. In 1817 the cholera pathogen appeared for the first time. In India alone it’s believed 1.25 million died of the disease each year for more than a decade following the Tambora explosion. The suffering led to uprisings against British colonial rule in India and Ceylon, today’s Sri Lanka.

Simmering revolution

In Ireland, Scotland and Wales people rioted as grain prices soared. In England the authorities became concerned at a rise in revolutionary activity. Prisons filled up.

The years following 1815 were a time of mass migration. Hundreds of thousands of people in Europe, in an effort to escape hunger, travelled across the Atlantic to the US and Canada. Within the US there was a movement westwards towards California, which had largely escaped the more severe effects of the eruption.

There were other, less dramatic consequences. Behringer says Tambora inspired a new-found preoccupation with weather and climate phenomena. Not surprisingly, it spurred the emergence of the science of volcanology.

Establishing the cause and effect of changes in climate – whether caused by volcanic eruptions or by the burning of fossil fuels and the increasing amounts of greenhouse gases in the atmosphere in consequence – is an extremely tricky business.

Temporary influence

Behringer makes the point that not all of the events of 1815 and subsequent years can be directly attributed to Tambora. But the explosion did act as a catalyst.

The eruption was a single event and its after-effects were not permanent though, for a limited period, the world’s ecological framework was altered.

“Apparently minor changes in temperature and humidity sufficed (and still suffice today) to shake up entrenched ecosystems, but above all entrenched agricultural systems.

“And without their daily bread, people can very quickly become angry. In such situations it is clear – even in absolutist monarchies or dictatorships – who the sovereign is.” − Climate News Network

* * *

Tambora and the Year without a Summer, Polity Books, £25.00: to be published on 26 April, 2019.

The day in 1815 when the world’s climate went berserk was only the start of months and years of global climate disruption and social unrest.

LONDON, 19 March, 2019 − If you had been in what were then called the Dutch East Indies on 10 April 1815, the day would have been etched indelibly on your memory: it was the day the global climate went berserk.

Many parts of the world are already feeling the effects of a changing climate. Island nations in the Pacific are seeing their lands eaten away by rising sea levels.

Whole communities of people in Arctic regions are threatened by rapidly expanding ice melt. The foundations of houses are being swept away. Traditional hunting grounds are being lost.

Wolfgang Behringer is a climate historian who seeks to draw parallels between what is going on now and events long ago. In particular Behringer, a professor of early modern history at Saarland University in Germany, looks at how changes in climate can influence and shape events – political, economic and social.

In a new book he focuses on the 1815 volcanic explosion of Tambora, on the island of Sumbawa in present-day Indonesia. The eruption still rates as the largest in human history; the cloud that burst from the volcano reached a height of 45 kilometres.

“Apparently minor changes in temperature and humidity suffice to shake up entrenched ecosystems, but above all entrenched agricultural systems”

Many thousands of people were killed on Sumbawa and adjoining islands, including Lombok and Bali. Dust clouds from Tambora were swept around the globe; the world’s climate went berserk, says Behringer.

“The dimensions of the Tambora crisis were so extraordinary because its roots lay in nature, in processes of geology, atmospheric physics and meteorology. These forces of nature respect no borders.”

The suspended particles from the volcano reduced solar radiation and led to global cooling. What scientists call a dry fog enveloped much of Asia. A blue sun appeared in Latin America. Snow that fell in Italy was red and yellow.

The winter of 1815/16 in much of the world was one of the coldest of the century. In Europe, 1816 became known as the year without summer. In North America what was described as the “Yankee chill” resulted in the worst harvest ever recorded.

Global upset

Torrential rains caused floods and thousands of deaths in China and India. Famine was widespread.

Behringer says the changes in climate provoked social unrest on a worldwide scale.

“The reactions to the crisis offer an example of how societies and individuals respond to climate change, what risks emerge and what opportunities may be associated with it”, he writes.

Epidemics broke out. In 1817 the cholera pathogen appeared for the first time. In India alone it’s believed 1.25 million died of the disease each year for more than a decade following the Tambora explosion. The suffering led to uprisings against British colonial rule in India and Ceylon, today’s Sri Lanka.

Simmering revolution

In Ireland, Scotland and Wales people rioted as grain prices soared. In England the authorities became concerned at a rise in revolutionary activity. Prisons filled up.

The years following 1815 were a time of mass migration. Hundreds of thousands of people in Europe, in an effort to escape hunger, travelled across the Atlantic to the US and Canada. Within the US there was a movement westwards towards California, which had largely escaped the more severe effects of the eruption.

There were other, less dramatic consequences. Behringer says Tambora inspired a new-found preoccupation with weather and climate phenomena. Not surprisingly, it spurred the emergence of the science of volcanology.

Establishing the cause and effect of changes in climate – whether caused by volcanic eruptions or by the burning of fossil fuels and the increasing amounts of greenhouse gases in the atmosphere in consequence – is an extremely tricky business.

Temporary influence

Behringer makes the point that not all of the events of 1815 and subsequent years can be directly attributed to Tambora. But the explosion did act as a catalyst.

The eruption was a single event and its after-effects were not permanent though, for a limited period, the world’s ecological framework was altered.

“Apparently minor changes in temperature and humidity sufficed (and still suffice today) to shake up entrenched ecosystems, but above all entrenched agricultural systems.

“And without their daily bread, people can very quickly become angry. In such situations it is clear – even in absolutist monarchies or dictatorships – who the sovereign is.” − Climate News Network

* * *

Tambora and the Year without a Summer, Polity Books, £25.00: to be published on 26 April, 2019.

Greenland’s winter rain melts icecap faster

Its huge icecap is thawing faster because Greenland’s winter rain means its snows are being washed away, or falling at higher altitudes.

LONDON, 8 March, 2019 − The largest body of ice in the northern hemisphere faces a problem scientists had not identified before: Greenland’s winter rain is accelerating the loss of its vast store of ice.

Two new studies have identified mechanisms for ever-faster melting of the ice. One is that the snowline keeps shifting, to alter the levels of radiation absorbed by the ice sheet that masks the Greenland bedrock.

The other is that ever more snow and ice is simply washed away by the rainfall – even in the Arctic winter. That is because global warming has raised Greenland’s summer temperatures as much as 1.8°C, and by up to 3°C in the winter months.

Reports of winter rain over an icecap large enough – if it were all washed into the ocean – to raise global sea levels by more than seven metres are a surprise: glaciologists expect some melting of the polar ice caps each summer, to be replaced each winter by snowfall that insulates the ice below and then endures for much of the following summer.

Meltwater matters more

Such icecaps are thought to shed most of their mass as glaciers deliver ice downstream to the coast, and icebergs calve and float south.

But research in the journal The Cryosphere tells a different and unexpected story: direct meltwater now running off Greenland into the sea accounts for seven-tenths of the 270 billion tonnes of ice that Greenland loses each year. And increasingly, rainy weather is the trigger that sets off the rivulets of meltwater streaming to the coast.

German and US researchers took data from 20 Greenland weather stations between 1979 and 2012, and matched this with satellite imagery that could distinguish snow from liquid water. In the data they identified more than 300 episodes of melting in which the initial trigger was the arrival of rain.

And during the 33 years of data, they found that melting associated with rainfall doubled during the summer months, and tripled in winter. Nearly a third of all the flow of water from Greenland was initiated by rainfall.

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet”

Warm air can melt ice but, more potently, warming air can turn what might have been snow into rain. Liquid water carries considerable heat, to soak into the snow and melt it. And the clouds that bring the rain have a way of conserving the warmth in the air.

Some of the meltwater will refreeze as surface ice, darkened by dust and colonised by algae, to absorb solar radiation more efficiently than snow, and to melt more easily and much earlier in the summer.

“If it rains in the winter, that preconditions the ice to be more vulnerable in the summer,” said Marco Tedesco of Columbia University’s Lamont-Doherty Earth Observatory, one of the authors. “We are starting to realise you have to look at all the seasons.”

Most of the winter rainfall is in the island’s south and southwest, spilled by warm ocean winds from the south, and these may have become more common because warming has been linked to changes in the stratospheric jet stream.

Loss not gain

Marilena Oltmanns, of Germany’s Geomar Centre for Ocean Research, called the discovery “a surprise to see. The ice should be gaining mass in winter when it snows, but an increasing part of the mass gain from precipitation is lost by melt.”

But research in the journal Science Advances in the same week pinpoints another related factor in setting the rate of melting in Greenland: the snowline.

This varies significantly from year to year. Once again, snow tends to reflect radiation, and with darker ice to absorb it the new study suggests that even Greenland’s icy mountains conform to simple physics.

Researchers flew drones inland across the bare ice to identify the snowline. A pause during a few days of high winds brought a big surprise.

No specific studies

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet and was now out of the range of our drones.

“That was the first moment we thought we should investigate the effects of snowline movement on melt,” said Jonathan Ryan, of Brown University in Rhode Island, who led the study.

And Laurence Smith, a researcher based at Brown University, and one of the authors, said: “People who study alpine glaciers have recognised the importance of snowlines for years, but no one has explicitly studied them in Greenland before.

“This study shows for the first time that simple partitioning between bare ice and snow matters more when it comes to melting than a whole host of other processes that receive more attention.” − Climate News Network

Its huge icecap is thawing faster because Greenland’s winter rain means its snows are being washed away, or falling at higher altitudes.

LONDON, 8 March, 2019 − The largest body of ice in the northern hemisphere faces a problem scientists had not identified before: Greenland’s winter rain is accelerating the loss of its vast store of ice.

Two new studies have identified mechanisms for ever-faster melting of the ice. One is that the snowline keeps shifting, to alter the levels of radiation absorbed by the ice sheet that masks the Greenland bedrock.

The other is that ever more snow and ice is simply washed away by the rainfall – even in the Arctic winter. That is because global warming has raised Greenland’s summer temperatures as much as 1.8°C, and by up to 3°C in the winter months.

Reports of winter rain over an icecap large enough – if it were all washed into the ocean – to raise global sea levels by more than seven metres are a surprise: glaciologists expect some melting of the polar ice caps each summer, to be replaced each winter by snowfall that insulates the ice below and then endures for much of the following summer.

Meltwater matters more

Such icecaps are thought to shed most of their mass as glaciers deliver ice downstream to the coast, and icebergs calve and float south.

But research in the journal The Cryosphere tells a different and unexpected story: direct meltwater now running off Greenland into the sea accounts for seven-tenths of the 270 billion tonnes of ice that Greenland loses each year. And increasingly, rainy weather is the trigger that sets off the rivulets of meltwater streaming to the coast.

German and US researchers took data from 20 Greenland weather stations between 1979 and 2012, and matched this with satellite imagery that could distinguish snow from liquid water. In the data they identified more than 300 episodes of melting in which the initial trigger was the arrival of rain.

And during the 33 years of data, they found that melting associated with rainfall doubled during the summer months, and tripled in winter. Nearly a third of all the flow of water from Greenland was initiated by rainfall.

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet”

Warm air can melt ice but, more potently, warming air can turn what might have been snow into rain. Liquid water carries considerable heat, to soak into the snow and melt it. And the clouds that bring the rain have a way of conserving the warmth in the air.

Some of the meltwater will refreeze as surface ice, darkened by dust and colonised by algae, to absorb solar radiation more efficiently than snow, and to melt more easily and much earlier in the summer.

“If it rains in the winter, that preconditions the ice to be more vulnerable in the summer,” said Marco Tedesco of Columbia University’s Lamont-Doherty Earth Observatory, one of the authors. “We are starting to realise you have to look at all the seasons.”

Most of the winter rainfall is in the island’s south and southwest, spilled by warm ocean winds from the south, and these may have become more common because warming has been linked to changes in the stratospheric jet stream.

Loss not gain

Marilena Oltmanns, of Germany’s Geomar Centre for Ocean Research, called the discovery “a surprise to see. The ice should be gaining mass in winter when it snows, but an increasing part of the mass gain from precipitation is lost by melt.”

But research in the journal Science Advances in the same week pinpoints another related factor in setting the rate of melting in Greenland: the snowline.

This varies significantly from year to year. Once again, snow tends to reflect radiation, and with darker ice to absorb it the new study suggests that even Greenland’s icy mountains conform to simple physics.

Researchers flew drones inland across the bare ice to identify the snowline. A pause during a few days of high winds brought a big surprise.

No specific studies

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet and was now out of the range of our drones.

“That was the first moment we thought we should investigate the effects of snowline movement on melt,” said Jonathan Ryan, of Brown University in Rhode Island, who led the study.

And Laurence Smith, a researcher based at Brown University, and one of the authors, said: “People who study alpine glaciers have recognised the importance of snowlines for years, but no one has explicitly studied them in Greenland before.

“This study shows for the first time that simple partitioning between bare ice and snow matters more when it comes to melting than a whole host of other processes that receive more attention.” − Climate News Network

Early rain as Arctic warms means more methane

As spring advances, so does the rain to warm the permafrost. It means more methane can get into the atmosphere to accelerate global warming.

LONDON, 18 February, 2019 − As the global temperature steadily rises, it ensures that levels of one of the most potent greenhouse gases are increasing in a way new to science: the planet will have to reckon with more methane than expected.

Researchers who monitored one bog for three years in the Alaskan permafrost have identified yet another instance of what engineers call positive feedback. They found that global warming meant earlier springs and with that, earlier spring rains.

And as a consequence, the influx of warm water on what had previously been frozen ground triggered a biological frenzy that sent methane emissions soaring.

One stretch of wetland in a forest of black spruce in the Alaskan interior stepped up its emissions of natural gas (another name for methane) by 30%. Methane is a greenhouse gas at least 30 times more potent than carbon dioxide.

“The microbes in this bog on some level are like ‘Oh man, we’re stuck making methane because that’s all this bog is allowing us to do’”

As a consequence, climate scientists may have to return yet again to the vexed question of the carbon budget, in their calculations of how fast the world will warm as humans burn more fossil fuels, to set up ever more rapid global warming and climate change, which will in turn accelerate the thawing of the permafrost.

The evidence so far comes from a detailed study of water, energy and carbon traffic from just one wetland. But other teams of scientists have repeatedly expressed concern about the integrity of the northern hemisphere permafrost and the vast stores of carbon preserved in the frozen soils, beneath the shallow layer that comes to life with each Arctic spring.

“We saw the plants going crazy and methane emissions going bonkers,” said Rebecca Neumann, an environmental engineer at the University of Washington in Seattle, who led the study. “2016 had above average rainfall, but so did 2014. So what was different about this year?”

What mattered was when the rain fell: it fell earlier, when the ground was still colder than the air. The warmer water saturated the frozen forest, flowed into the bog, and created a local permafrost thaw in anoxic conditions: the subterranean microbial communities responded by converting the once-frozen organic matter into a highly effective greenhouse gas.

Alarm rises

“It’d be the bottom of the barrel in terms of energy production for them,” Dr Neumann said. “The microbes in this bog on some level are like ‘Oh man, we’re stuck making methane because that’s all this bog is allowing us to do’.”

As global average temperature levels creep up, so does alarm about the state of the vast tracts of permafrost, home to huge stores of frozen carbon in the form of semi-decayed plant material that could be released into the atmosphere to fuel further global warming, with devastating consequences.

Spring has been arriving earlier everywhere in the northern hemisphere, including the Arctic, with unpredictable impacts on high latitude ecosystems.

The permafrost itself has been identified as a vulnerable region, change in which could tip the planet into a new and unpredictable climate regime, and geographers only this year have started to assess the direct hazard to the communities that live in the high latitudes as once-solid ground turns to slush under their feet.

More evaporation

Much more difficult to assess is how the steady attrition of the permafrost plays out in terms of the traffic of carbon between rocks, ocean, atmosphere and living things: researchers are still teasing out the roles of all the agencies at work, including subterranean microbes.

In a warmer world, evaporation will increase. Warmer air has a greater capacity for water vapour. In the end, it means more rain will fall. If it falls in spring or early summer, the research from one marshland in Alaska seems to suggest, more methane will escape into the atmosphere.

Right now, the rewards of the study are academic. They throw just a little more light on the subtle machinery of weather and climate. The test is whether what happens in one instance is likely to happen in other, similar terrain around the high latitudes.

“The ability of rain to transport thermal energy into soils has been under-appreciated,” Dr Neumann said. “Our study shows that by affecting soil temperature and methane emissions, rain can increase the ability of thawing permafrost to warm the climate.” − Climate News Network

As spring advances, so does the rain to warm the permafrost. It means more methane can get into the atmosphere to accelerate global warming.

LONDON, 18 February, 2019 − As the global temperature steadily rises, it ensures that levels of one of the most potent greenhouse gases are increasing in a way new to science: the planet will have to reckon with more methane than expected.

Researchers who monitored one bog for three years in the Alaskan permafrost have identified yet another instance of what engineers call positive feedback. They found that global warming meant earlier springs and with that, earlier spring rains.

And as a consequence, the influx of warm water on what had previously been frozen ground triggered a biological frenzy that sent methane emissions soaring.

One stretch of wetland in a forest of black spruce in the Alaskan interior stepped up its emissions of natural gas (another name for methane) by 30%. Methane is a greenhouse gas at least 30 times more potent than carbon dioxide.

“The microbes in this bog on some level are like ‘Oh man, we’re stuck making methane because that’s all this bog is allowing us to do’”

As a consequence, climate scientists may have to return yet again to the vexed question of the carbon budget, in their calculations of how fast the world will warm as humans burn more fossil fuels, to set up ever more rapid global warming and climate change, which will in turn accelerate the thawing of the permafrost.

The evidence so far comes from a detailed study of water, energy and carbon traffic from just one wetland. But other teams of scientists have repeatedly expressed concern about the integrity of the northern hemisphere permafrost and the vast stores of carbon preserved in the frozen soils, beneath the shallow layer that comes to life with each Arctic spring.

“We saw the plants going crazy and methane emissions going bonkers,” said Rebecca Neumann, an environmental engineer at the University of Washington in Seattle, who led the study. “2016 had above average rainfall, but so did 2014. So what was different about this year?”

What mattered was when the rain fell: it fell earlier, when the ground was still colder than the air. The warmer water saturated the frozen forest, flowed into the bog, and created a local permafrost thaw in anoxic conditions: the subterranean microbial communities responded by converting the once-frozen organic matter into a highly effective greenhouse gas.

Alarm rises

“It’d be the bottom of the barrel in terms of energy production for them,” Dr Neumann said. “The microbes in this bog on some level are like ‘Oh man, we’re stuck making methane because that’s all this bog is allowing us to do’.”

As global average temperature levels creep up, so does alarm about the state of the vast tracts of permafrost, home to huge stores of frozen carbon in the form of semi-decayed plant material that could be released into the atmosphere to fuel further global warming, with devastating consequences.

Spring has been arriving earlier everywhere in the northern hemisphere, including the Arctic, with unpredictable impacts on high latitude ecosystems.

The permafrost itself has been identified as a vulnerable region, change in which could tip the planet into a new and unpredictable climate regime, and geographers only this year have started to assess the direct hazard to the communities that live in the high latitudes as once-solid ground turns to slush under their feet.

More evaporation

Much more difficult to assess is how the steady attrition of the permafrost plays out in terms of the traffic of carbon between rocks, ocean, atmosphere and living things: researchers are still teasing out the roles of all the agencies at work, including subterranean microbes.

In a warmer world, evaporation will increase. Warmer air has a greater capacity for water vapour. In the end, it means more rain will fall. If it falls in spring or early summer, the research from one marshland in Alaska seems to suggest, more methane will escape into the atmosphere.

Right now, the rewards of the study are academic. They throw just a little more light on the subtle machinery of weather and climate. The test is whether what happens in one instance is likely to happen in other, similar terrain around the high latitudes.

“The ability of rain to transport thermal energy into soils has been under-appreciated,” Dr Neumann said. “Our study shows that by affecting soil temperature and methane emissions, rain can increase the ability of thawing permafrost to warm the climate.” − Climate News Network

Melting polar ice sheets will alter weather

Sea level rise and melting polar ice sheets may not cause a climate catastrophe, but they will certainly change weather patterns unpredictably.

LONDON, 15 February, 2019 – The global weather is about to get worse. The melting polar ice sheets will mean rainfall and windstorms could become more violent, and hot spells and ice storms could become more extreme.

This is because the ice sheets of Greenland and Antarctica are melting, to affect what were once stable ocean currents and airflow patterns around the globe.

Planetary surface temperatures could rise by 3°C or even 4°C by the end of the century. Global sea levels will rise in ways that would “enhance global temperature variability”, but this might not be as high as earlier studies have predicted. That is because the ice cliffs of Antarctica might not be so much at risk of disastrous collapse that would set the glaciers accelerating to the sea.

The latest revision of evidence from the melting ice sheets in two hemispheres – and there is plenty of evidence that melting is happening at ever greater rates – is based on two studies of what could happen to the world’s greatest reservoirs of frozen freshwater if nations pursue current policies, fossil fuel combustion continues to increase, and global average temperatures creep up to unprecedented levels.

“Even if we do include ice-cliff instability … the most likely contribution to sea level rise would be less than half a metre by 2100”

“Under current global government policies, we are heading towards 3 or 4 degrees of warming above pre-industrial levels, causing a significant amount of melt water from the Greenland and Antarctic ice sheets to enter Earth’s oceans. According to our models, this melt water will cause significant disruptions to ocean currents and change levels of warming around the world,” said Nick Golledge, a south polar researcher at Victoria University, in New Zealand.

He and colleagues from Canada, the US, Germany and the UK report in Nature that they matched satellite observations of what is happening to the ice sheets with detailed simulations of the complex effects of melting over time, and according to the human response so far to warnings of climate change.

In Paris in 2015, leaders from 195 nations vowed to contain global warming to “well below” an average rise of 2°C by 2100. But promises have yet to become concerted and coherent action, and researchers warn that on present policies, a 3°C rise seems inevitable.

Sea levels have already risen by about 14 cms in the last century: the worst scenarios have proposed a devastating rise of 130 cms by 2100. The fastest increase in the rise of sea levels is likely to happen between 2065 and 2075.

Gulf Stream weakens

As warmer melt water gets into the North Atlantic, that major ocean current the Gulf Stream is likely to be weakened. Air temperatures are likely to rise over eastern Canada, central America and the high Arctic. Northwestern Europe – scientists have been warning of this for years – will become cooler.

In the Antarctic, a lens of warm fresh water will form over the surface, allowing uprising warm ocean water to spread and cause what could be further Antarctic melting.

But how bad this could be is re-examined in a second, companion paper in Nature. Tamsin Edwards, now at King’s College London, Dr Golledge and others took a fresh look at an old scare: that the vast cliffs of ice – some of them 100 metres above sea level – around the Antarctic could become unstable and collapse, accelerating the retreat of the ice behind them.

They used geophysical techniques to analyse dramatic episodes of ice loss that must have happened 3 million years ago and 125,000 years ago, and they went back to the present patterns of melt. These losses, in their calculations, did not cause unstoppable ice loss in the past, and may not affect the future much either.

Instability less important

“We’ve shown that ice-cliff instability doesn’t appear to be an essential mechanism in reproducing past sea level changes and so this suggests ‘the jury’s still out’ when it comes to including it in future predictions,” said Dr Edwards.

“Even if we do include ice-cliff instability, our more thorough assessment shows the most likely contribution to sea level rise would be less than half a metre by 2100.”

At worst, there is a one in 20 chance that enough of Antarctica’s glacial burden will melt to raise sea levels by 39 cms. More likely, both studies conclude, under high levels of greenhouse gas concentrations, south polar ice will only melt to raise sea levels worldwide by about 15 cms. – Climate News Network

Sea level rise and melting polar ice sheets may not cause a climate catastrophe, but they will certainly change weather patterns unpredictably.

LONDON, 15 February, 2019 – The global weather is about to get worse. The melting polar ice sheets will mean rainfall and windstorms could become more violent, and hot spells and ice storms could become more extreme.

This is because the ice sheets of Greenland and Antarctica are melting, to affect what were once stable ocean currents and airflow patterns around the globe.

Planetary surface temperatures could rise by 3°C or even 4°C by the end of the century. Global sea levels will rise in ways that would “enhance global temperature variability”, but this might not be as high as earlier studies have predicted. That is because the ice cliffs of Antarctica might not be so much at risk of disastrous collapse that would set the glaciers accelerating to the sea.

The latest revision of evidence from the melting ice sheets in two hemispheres – and there is plenty of evidence that melting is happening at ever greater rates – is based on two studies of what could happen to the world’s greatest reservoirs of frozen freshwater if nations pursue current policies, fossil fuel combustion continues to increase, and global average temperatures creep up to unprecedented levels.

“Even if we do include ice-cliff instability … the most likely contribution to sea level rise would be less than half a metre by 2100”

“Under current global government policies, we are heading towards 3 or 4 degrees of warming above pre-industrial levels, causing a significant amount of melt water from the Greenland and Antarctic ice sheets to enter Earth’s oceans. According to our models, this melt water will cause significant disruptions to ocean currents and change levels of warming around the world,” said Nick Golledge, a south polar researcher at Victoria University, in New Zealand.

He and colleagues from Canada, the US, Germany and the UK report in Nature that they matched satellite observations of what is happening to the ice sheets with detailed simulations of the complex effects of melting over time, and according to the human response so far to warnings of climate change.

In Paris in 2015, leaders from 195 nations vowed to contain global warming to “well below” an average rise of 2°C by 2100. But promises have yet to become concerted and coherent action, and researchers warn that on present policies, a 3°C rise seems inevitable.

Sea levels have already risen by about 14 cms in the last century: the worst scenarios have proposed a devastating rise of 130 cms by 2100. The fastest increase in the rise of sea levels is likely to happen between 2065 and 2075.

Gulf Stream weakens

As warmer melt water gets into the North Atlantic, that major ocean current the Gulf Stream is likely to be weakened. Air temperatures are likely to rise over eastern Canada, central America and the high Arctic. Northwestern Europe – scientists have been warning of this for years – will become cooler.

In the Antarctic, a lens of warm fresh water will form over the surface, allowing uprising warm ocean water to spread and cause what could be further Antarctic melting.

But how bad this could be is re-examined in a second, companion paper in Nature. Tamsin Edwards, now at King’s College London, Dr Golledge and others took a fresh look at an old scare: that the vast cliffs of ice – some of them 100 metres above sea level – around the Antarctic could become unstable and collapse, accelerating the retreat of the ice behind them.

They used geophysical techniques to analyse dramatic episodes of ice loss that must have happened 3 million years ago and 125,000 years ago, and they went back to the present patterns of melt. These losses, in their calculations, did not cause unstoppable ice loss in the past, and may not affect the future much either.

Instability less important

“We’ve shown that ice-cliff instability doesn’t appear to be an essential mechanism in reproducing past sea level changes and so this suggests ‘the jury’s still out’ when it comes to including it in future predictions,” said Dr Edwards.

“Even if we do include ice-cliff instability, our more thorough assessment shows the most likely contribution to sea level rise would be less than half a metre by 2100.”

At worst, there is a one in 20 chance that enough of Antarctica’s glacial burden will melt to raise sea levels by 39 cms. More likely, both studies conclude, under high levels of greenhouse gas concentrations, south polar ice will only melt to raise sea levels worldwide by about 15 cms. – Climate News Network

World is halfway through its hottest decade

Things are warming up: already the world is halfway through its hottest decade on record, if predictions prove correct.

LONDON, 13 February, 2019 – Here is a climate forecast that climate scientists, meteorologists, politicians, voters and even climate sceptics can check: the next five years will be warm, and will probably help to complete the hottest decade ever.

They will on a global average be at least 1°C higher than the average temperature of the planet 200 years ago, before the accelerating combustion of fossil fuels.

That is because the planet is already midway through what may well prove to be its warmest 10 years since records began on a planetary scale in 1850. There is even a possibility that within the next five years, the global temperature rise could tip 1.5°C above the long-term average for human history.

This is the ambitious limit to global warming that the world set itself at an historic meeting in Paris in 2015, for the year 2100.

And the forecasters can make such predictions with some confidence because tomorrow’s temperature chart is already inscribed in the air we breathe: the pattern of warming over the last century is consistent with the steady rise in greenhouse gas levels in the atmosphere, and these are still increasing because fossil fuel use is still going up.

“Predictions now suggest around a 10% chance of at least one year between 2019 and 2023 temporarily exceeding 1.5°C”

Adam Scaife, who heads long-range prediction research at the UK Met Office, said: “2015 was the first year that global annual average surface temperatures reached 1.0°C above pre-industrial levels and the following three years have all remained close to this level.

“The global average temperature between now and 2023 is predicted to remain high, potentially making the decade from 2014 the warmest in more than 150 years of records.”

Climate is what people can reasonably bank on; weather is what they get. The forecast is significant because it is evidence of swelling confidence in the understanding of global warming and climate change science.

Climate researchers began warning at least 40 years ago of the potentially calamitous consequences of climate change: they were, at the time, unwilling to link any single weather event – flood, drought, windstorm or heat wave – to long-term global warming as a consequence of the steady increase of carbon dioxide in the atmosphere, released from power stations, factory chimneys and vehicle exhausts.

Possible catastrophe predicted

Not any more: in 2013, one group of geographers in Hawaii even predicted the possible onset of catastrophic climate change in some regions of the globe as early as 2020.

And the Met Office prediction is accompanied by a danger that – for a short while at least – the global increase could reach or exceed the level that 195 nations in Paris agreed would be potentially disastrous for human civilisation.

“A run of temperatures of 1.0°C or above would increase the risk of a temporary excursion above the threshold of 1.5°C above pre-industrial levels,” said Doug Smith, a researcher at the Met Office. “Predictions now suggest around a 10% chance of at least one year between 2019 and 2023 temporarily exceeding 1.5°C.”

Global temperatures in 2018 were around 0.91°C above the long-term average. This would make 2018 the fourth warmest year ever, although oceanographers recently warned that the oceans – and 70% of the planet is covered by ocean – reached their warmest ever in 2018.

Almost imperceptible

The three warmest years on record are 2015, 2016 and 2017. Climate scientists – and health chiefs – have consistently warned that the average global increase is at almost imperceptible pace, and is a trend rather than a year-on-year rise. This made it possible for some to argue about the interpretation of the data, and to even claim that global warming had paused.

But within this slow increase in average temperatures, there has been a pattern of increasing extremes of rainfall and temperature with the threat of increasingly frequent and potentially lethal heat waves to come.

And, researchers warned recently, the changes seem inexorable: by multiplying in number to more than 7bn in two centuries, by clearing forests and by burning fossil fuels, humans have managed to reverse a long-term climate trend and make the future uncomfortably hot.

A third UK researcher, Tim Osborn of the University of East Anglia’s Cllimatic Research Unit, spelled it out: “The warmth of 2018 is in line with the long-term warming trend driven by the world’s emissions of greenhouse gases.” – Climate News Network

Things are warming up: already the world is halfway through its hottest decade on record, if predictions prove correct.

LONDON, 13 February, 2019 – Here is a climate forecast that climate scientists, meteorologists, politicians, voters and even climate sceptics can check: the next five years will be warm, and will probably help to complete the hottest decade ever.

They will on a global average be at least 1°C higher than the average temperature of the planet 200 years ago, before the accelerating combustion of fossil fuels.

That is because the planet is already midway through what may well prove to be its warmest 10 years since records began on a planetary scale in 1850. There is even a possibility that within the next five years, the global temperature rise could tip 1.5°C above the long-term average for human history.

This is the ambitious limit to global warming that the world set itself at an historic meeting in Paris in 2015, for the year 2100.

And the forecasters can make such predictions with some confidence because tomorrow’s temperature chart is already inscribed in the air we breathe: the pattern of warming over the last century is consistent with the steady rise in greenhouse gas levels in the atmosphere, and these are still increasing because fossil fuel use is still going up.

“Predictions now suggest around a 10% chance of at least one year between 2019 and 2023 temporarily exceeding 1.5°C”

Adam Scaife, who heads long-range prediction research at the UK Met Office, said: “2015 was the first year that global annual average surface temperatures reached 1.0°C above pre-industrial levels and the following three years have all remained close to this level.

“The global average temperature between now and 2023 is predicted to remain high, potentially making the decade from 2014 the warmest in more than 150 years of records.”

Climate is what people can reasonably bank on; weather is what they get. The forecast is significant because it is evidence of swelling confidence in the understanding of global warming and climate change science.

Climate researchers began warning at least 40 years ago of the potentially calamitous consequences of climate change: they were, at the time, unwilling to link any single weather event – flood, drought, windstorm or heat wave – to long-term global warming as a consequence of the steady increase of carbon dioxide in the atmosphere, released from power stations, factory chimneys and vehicle exhausts.

Possible catastrophe predicted

Not any more: in 2013, one group of geographers in Hawaii even predicted the possible onset of catastrophic climate change in some regions of the globe as early as 2020.

And the Met Office prediction is accompanied by a danger that – for a short while at least – the global increase could reach or exceed the level that 195 nations in Paris agreed would be potentially disastrous for human civilisation.

“A run of temperatures of 1.0°C or above would increase the risk of a temporary excursion above the threshold of 1.5°C above pre-industrial levels,” said Doug Smith, a researcher at the Met Office. “Predictions now suggest around a 10% chance of at least one year between 2019 and 2023 temporarily exceeding 1.5°C.”

Global temperatures in 2018 were around 0.91°C above the long-term average. This would make 2018 the fourth warmest year ever, although oceanographers recently warned that the oceans – and 70% of the planet is covered by ocean – reached their warmest ever in 2018.

Almost imperceptible

The three warmest years on record are 2015, 2016 and 2017. Climate scientists – and health chiefs – have consistently warned that the average global increase is at almost imperceptible pace, and is a trend rather than a year-on-year rise. This made it possible for some to argue about the interpretation of the data, and to even claim that global warming had paused.

But within this slow increase in average temperatures, there has been a pattern of increasing extremes of rainfall and temperature with the threat of increasingly frequent and potentially lethal heat waves to come.

And, researchers warned recently, the changes seem inexorable: by multiplying in number to more than 7bn in two centuries, by clearing forests and by burning fossil fuels, humans have managed to reverse a long-term climate trend and make the future uncomfortably hot.

A third UK researcher, Tim Osborn of the University of East Anglia’s Cllimatic Research Unit, spelled it out: “The warmth of 2018 is in line with the long-term warming trend driven by the world’s emissions of greenhouse gases.” – Climate News Network

Coffee harvests face risk from rising heat

Global coffee harvests, which provide the drink of choice for millions and the livelihoods of many more, are in peril, not least from rising temperatures.

LONDON, 28 January, 2019 – Coffee drinkers, be warned. A combination of factors – including climate change – is threatening supplies of the beans on which the coffee harvests depend.

Latest analysis by a team of scientists at the Royal Botanic Gardens at Kew in London found that more than 60% of over 120 coffee species known across Africa, Asia and Australasia are threatened with extinction.

For many people, coffee is their favourite tipple. In the UK alone, more than 80 million cups of coffee are drunk every day. The experts at Kew say a total of 100 million people around the world depend on coffee for their livelihoods.

Climate change, together with fungal diseases and the impact of land clearances and deforestation, are all having negative impacts on coffee plants.

Coffee plants are fragile and often acutely sensitive to temperature changes, particularly those belonging to the Arabica species (Coffea arabica), the source of the world’s most popular coffee variety.

“Climate change will have a damaging impact on commercial coffee production worldwide”

The Coffee Research Institute says Arabica plants need year-round temperatures of between 15°C and 24°C in order to maintain high production levels and good quality.

Wild coffee plants play an essential role in building up more robust plants for cultivation; cross-bred with plantation plants, they provide the genetic resources to help withstand pests and diseases. They also encourage resilience to changes in climate and improve the flavour and quality of the coffee beans.

The Kew scientists, together with colleagues in Ethiopia,
the biggest producer of Arabica coffee in Africa, used climate change models and temperature projections to gauge the future health and survival rates of wild Arabica plants.

The results of the analysis, the first ever comprehensive survey linking climate change with Arabica coffee production, will have coffee drinkers crying into their cups.

Wide extinction threat

Dr Justin Moat, who headed up the Kew study, says more than 60% of wild Arabica plants are threatened with extinction.

“The worst case scenario, as drawn from our analyses, is that wild Arabica could be extinct by 2080.

“This should alert decision makers to the fragility of the species.”

The highlands of Ethiopia and of South Sudan are the natural home of Arabica coffee. Researchers found that deforestation over the past 70 years plus more recent changes in climate could result in wild Arabica becoming extinct in South Sudan within the next two years.

“The climate sensitivity of Arabica is confirmed, supporting the widely reported assumption that climate change will have a damaging impact on commercial coffee production worldwide”, says Dr Moat.

Pay growers more

In coffee-growing areas around the world, including Ethiopia and Brazil, temperatures have been rising while amounts of rainfall have been decreasing.

The Kew study says that while bumper coffee harvests over the last two years have led to generally low prices, this pattern is unlikely to continue as crop yields decline and demand grows.

The study says coffee growers, mostly smallholders, should be paid more for their produce in order not only to improve living standards but to encourage more sustainable and innovative cultivation methods. The Yayu Project in Ethiopia is seen as a model for this form of development.

There should also be more research into wild coffee species and investment in building up collections and seed banks. – Climate News Network

Global coffee harvests, which provide the drink of choice for millions and the livelihoods of many more, are in peril, not least from rising temperatures.

LONDON, 28 January, 2019 – Coffee drinkers, be warned. A combination of factors – including climate change – is threatening supplies of the beans on which the coffee harvests depend.

Latest analysis by a team of scientists at the Royal Botanic Gardens at Kew in London found that more than 60% of over 120 coffee species known across Africa, Asia and Australasia are threatened with extinction.

For many people, coffee is their favourite tipple. In the UK alone, more than 80 million cups of coffee are drunk every day. The experts at Kew say a total of 100 million people around the world depend on coffee for their livelihoods.

Climate change, together with fungal diseases and the impact of land clearances and deforestation, are all having negative impacts on coffee plants.

Coffee plants are fragile and often acutely sensitive to temperature changes, particularly those belonging to the Arabica species (Coffea arabica), the source of the world’s most popular coffee variety.

“Climate change will have a damaging impact on commercial coffee production worldwide”

The Coffee Research Institute says Arabica plants need year-round temperatures of between 15°C and 24°C in order to maintain high production levels and good quality.

Wild coffee plants play an essential role in building up more robust plants for cultivation; cross-bred with plantation plants, they provide the genetic resources to help withstand pests and diseases. They also encourage resilience to changes in climate and improve the flavour and quality of the coffee beans.

The Kew scientists, together with colleagues in Ethiopia,
the biggest producer of Arabica coffee in Africa, used climate change models and temperature projections to gauge the future health and survival rates of wild Arabica plants.

The results of the analysis, the first ever comprehensive survey linking climate change with Arabica coffee production, will have coffee drinkers crying into their cups.

Wide extinction threat

Dr Justin Moat, who headed up the Kew study, says more than 60% of wild Arabica plants are threatened with extinction.

“The worst case scenario, as drawn from our analyses, is that wild Arabica could be extinct by 2080.

“This should alert decision makers to the fragility of the species.”

The highlands of Ethiopia and of South Sudan are the natural home of Arabica coffee. Researchers found that deforestation over the past 70 years plus more recent changes in climate could result in wild Arabica becoming extinct in South Sudan within the next two years.

“The climate sensitivity of Arabica is confirmed, supporting the widely reported assumption that climate change will have a damaging impact on commercial coffee production worldwide”, says Dr Moat.

Pay growers more

In coffee-growing areas around the world, including Ethiopia and Brazil, temperatures have been rising while amounts of rainfall have been decreasing.

The Kew study says that while bumper coffee harvests over the last two years have led to generally low prices, this pattern is unlikely to continue as crop yields decline and demand grows.

The study says coffee growers, mostly smallholders, should be paid more for their produce in order not only to improve living standards but to encourage more sustainable and innovative cultivation methods. The Yayu Project in Ethiopia is seen as a model for this form of development.

There should also be more research into wild coffee species and investment in building up collections and seed banks. – Climate News Network

Global water supply shrinks in rainier world

The global water supply is dwindling, even though rainfall is heavier. Once again, climate change is to blame.

LONDON, 20 December, 2018 – Even in a world with more intense rain, communities could begin to run short of water. New research has confirmed that, in a warming world, extremes of drought have begun to diminish the world’s groundwater – and ever more intense rainstorms will do little to make up the loss in the global water supply.

And a second, separate study delivers support for this seeming paradox: worldwide, there is evidence that rainfall patterns are, increasingly, being disturbed. The number of record-dry months has increased overall. And so has the number of record-breaking rainy months.

Both studies match predictions in a world of climate change driven by ever-higher ratios of greenhouse gases in the atmosphere, from ever-increasing combustion of fossil fuels. But, unlike many climate studies, neither of these is based on computer simulation of predicted change.

Each is instead based on the meticulous analysis of huge quantities of on-the-ground data. Together they provide substance to a 40-year-old prediction of climate change research: that in a warming world, those regions already wet will get ever more rain, while the drylands will tend to become increasingly more arid.

As global temperatures creep up – and they have already risen by 1°C in the past century, and could be set to reach 3°C by 2100 – so does the capacity of the atmosphere to absorb more moisture. It follows that more rain must fall. But at the same time more groundwater evaporates, and the risk of damaging drought increases.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out”

Australian scientists report in the journal Water Resources Research that they studied readings from 43,000 rainfall stations and 5,300 river monitoring sites in 160 countries. And they confirm that even in a world of more intense rain, drought could become the new normal in those regions already at risk.

“This is something that has been missed. We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too,” said Ashish Sharma, an environmental engineer at the University of New South Wales.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out. We believe the cause is the drying of soils in our catchments. Where once these were moist before a storm event – allowing excess rainfall to run off into rivers – they are now drier and soak up more rain, so less water makes it as flow.”

The study matches predictions. Just in the last few months, climate scientists have warned that catastrophic climate change could be on the way, and that the double hazard of heat waves and sustained drought could devastate harvests in more than one climatic zone in the same season; and that those landlocked rainfall catchment areas that are already dry are becoming increasingly more parched.

But over the same few months, researchers have established repeatedly that tomorrow’s storms will be worse and that more devastating flash floods can be expected even in one of the world’s driest continents, Australia itself.

Less water available

Of all rainfall, only 36% gets into aquifers, streams and lakes. The remaining two thirds seeps into the soils, grasslands and woodlands. But more soil evaporation means less water is available from river supplies for cities and farms.

US researchers have already confirmed that if soils are moist before a storm, 62% of rainfall leads to floods that fill catchments. If soils are dry, only 13% of the rain leads to flooding.

“It’s a double whammy. Less water is ending up where we can’t store it for later use. At the same time, more rain is overwhelming drainage infrastructure in towns and cities, leading to more urban flooding,” said Professor Sharma.

“Small floods are very important for water supply, because they refill dams and form the basis of our water supply. But they’re happening less often, because the soils are sucking up extra rain. Even when a major storm dumps a lot of rain, the soils are so dry they absorb more water than before, and less reaches the rivers and reservoirs”, he said. “We need to adapt to this emerging reality.”

In the second close look at change so far, researchers based in Germany report in the journal Geophysical Research Letters  that they analysed data from 50,000 weather stations worldwide to measure rainfall on a monthly basis.

Climate drives aridity

The US has seen a more than 25% increase of record wet months in the eastern and central regions between 1980 and 2013. Argentina has seen a 32% increase. In central and northern Europe the increase is between 19% and 37%; in Asian Russia, it has been about 20%.

But in Africa south of the Sahara the incidence of very dry months has increased by 50%. “This implies that approximately one out of three record dry months in this region would not have occurred without long-term climate change,” said Dim Coumou, of the Potsdam Institute for Climate Impact Research.

“Generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records. This largely fits the patterns that scientists expect from human-caused climate change.”

His colleague and lead author Jascha Lehmann said: “Normally, record weather events occur by chance and we know how many would happen in a climate without warning. It’s like throwing a dice: on average one out of six times you get a six.

“But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often, with severe impacts for society and the environment.

“It is worrying that we see significant increases of such extremes with just one degree of global warming.” – Climate News Network

The global water supply is dwindling, even though rainfall is heavier. Once again, climate change is to blame.

LONDON, 20 December, 2018 – Even in a world with more intense rain, communities could begin to run short of water. New research has confirmed that, in a warming world, extremes of drought have begun to diminish the world’s groundwater – and ever more intense rainstorms will do little to make up the loss in the global water supply.

And a second, separate study delivers support for this seeming paradox: worldwide, there is evidence that rainfall patterns are, increasingly, being disturbed. The number of record-dry months has increased overall. And so has the number of record-breaking rainy months.

Both studies match predictions in a world of climate change driven by ever-higher ratios of greenhouse gases in the atmosphere, from ever-increasing combustion of fossil fuels. But, unlike many climate studies, neither of these is based on computer simulation of predicted change.

Each is instead based on the meticulous analysis of huge quantities of on-the-ground data. Together they provide substance to a 40-year-old prediction of climate change research: that in a warming world, those regions already wet will get ever more rain, while the drylands will tend to become increasingly more arid.

As global temperatures creep up – and they have already risen by 1°C in the past century, and could be set to reach 3°C by 2100 – so does the capacity of the atmosphere to absorb more moisture. It follows that more rain must fall. But at the same time more groundwater evaporates, and the risk of damaging drought increases.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out”

Australian scientists report in the journal Water Resources Research that they studied readings from 43,000 rainfall stations and 5,300 river monitoring sites in 160 countries. And they confirm that even in a world of more intense rain, drought could become the new normal in those regions already at risk.

“This is something that has been missed. We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too,” said Ashish Sharma, an environmental engineer at the University of New South Wales.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out. We believe the cause is the drying of soils in our catchments. Where once these were moist before a storm event – allowing excess rainfall to run off into rivers – they are now drier and soak up more rain, so less water makes it as flow.”

The study matches predictions. Just in the last few months, climate scientists have warned that catastrophic climate change could be on the way, and that the double hazard of heat waves and sustained drought could devastate harvests in more than one climatic zone in the same season; and that those landlocked rainfall catchment areas that are already dry are becoming increasingly more parched.

But over the same few months, researchers have established repeatedly that tomorrow’s storms will be worse and that more devastating flash floods can be expected even in one of the world’s driest continents, Australia itself.

Less water available

Of all rainfall, only 36% gets into aquifers, streams and lakes. The remaining two thirds seeps into the soils, grasslands and woodlands. But more soil evaporation means less water is available from river supplies for cities and farms.

US researchers have already confirmed that if soils are moist before a storm, 62% of rainfall leads to floods that fill catchments. If soils are dry, only 13% of the rain leads to flooding.

“It’s a double whammy. Less water is ending up where we can’t store it for later use. At the same time, more rain is overwhelming drainage infrastructure in towns and cities, leading to more urban flooding,” said Professor Sharma.

“Small floods are very important for water supply, because they refill dams and form the basis of our water supply. But they’re happening less often, because the soils are sucking up extra rain. Even when a major storm dumps a lot of rain, the soils are so dry they absorb more water than before, and less reaches the rivers and reservoirs”, he said. “We need to adapt to this emerging reality.”

In the second close look at change so far, researchers based in Germany report in the journal Geophysical Research Letters  that they analysed data from 50,000 weather stations worldwide to measure rainfall on a monthly basis.

Climate drives aridity

The US has seen a more than 25% increase of record wet months in the eastern and central regions between 1980 and 2013. Argentina has seen a 32% increase. In central and northern Europe the increase is between 19% and 37%; in Asian Russia, it has been about 20%.

But in Africa south of the Sahara the incidence of very dry months has increased by 50%. “This implies that approximately one out of three record dry months in this region would not have occurred without long-term climate change,” said Dim Coumou, of the Potsdam Institute for Climate Impact Research.

“Generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records. This largely fits the patterns that scientists expect from human-caused climate change.”

His colleague and lead author Jascha Lehmann said: “Normally, record weather events occur by chance and we know how many would happen in a climate without warning. It’s like throwing a dice: on average one out of six times you get a six.

“But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often, with severe impacts for society and the environment.

“It is worrying that we see significant increases of such extremes with just one degree of global warming.” – Climate News Network