Tag Archives: Agriculture

Only intact forests can stave off climate change

The world’s forests are supposed to stave off climate change. Left alone, perhaps they could. But they’re not being left alone.

LONDON, 3 May, 2021 − In the last decade, the Amazon forests of Brazil released more carbon into the atmosphere than they absorbed, thanks largely to human activities that cleared or degraded the canopy. Those activities make it impossible for affected forests to stave off climate change.

And a survey of the cooler forests of North America has revealed that these, too, could be surrendering more carbon than they soak up from the atmosphere, thanks to human-triggered climate change and the ever greater hazard of wildfire.

The world’s forests are a key part of the great carbon conundrum: what happens to all the greenhouse gases emitted from power stations, vehicle exhausts and factory chimneys? The assumption is that approaching one third of all the carbon dioxide emissions are absorbed by the forests, and the conservation of the planet’s forests has become part of the proposed arsenal of global defence against catastrophic climate change.

Researchers have repeatedly confirmed that, undisturbed, the world’s great natural forests are important reservoirs of atmospheric carbon. They have also confirmed that, even without taking carbon sequestration into account, the forests represent precious natural capital: they are worth more to humankind undisturbed than they could ever be as sawn timber or ranchland.

“Forest degradation has become the largest process driving forest loss”

But the world’s forests are not being left alone: one study found that even many of those ecosystems set aside by national law for protection are being destroyed or damaged.

And the simple equation that an area of tree canopy represents so much carbon drawn down from the atmosphere turns out not to be so simple. A warming climate − and the planet as a whole is more than 1°C on average warmer than it was a century ago − can disturb the calculations.

As the thermometer notches up, trees grow faster and die younger;  they also grow shorter and the extra fertility conferred by an atmosphere richer in carbon could result in a richer spring growth that is not sustained over a longer summer season. As the temperature rises, so the character of the forests could change: some species may one day find it too hot to reproduce.

And then there is the direct effect of climate change driven by rising temperatures: with heat comes drought, and the greater risk of fire. Forests that had once been reservoirs of carbon could start to surrender it to accelerate climate change even more. The marvel that is the Amazon rainforest could, one researcher has warned, collapse altogether and change irrevocably in one human lifetime.

Degradation costs more

Both of the latest studies deliver evidence that, over time, this could already be on the cards. Scientists from the US, France, Denmark, the UK and China report in the journal Nature Climate Change that they worked through a vast collection of satellite data to calculate the levels of what they call “above ground carbon” − the mass of the element incorporated in timber and foliage − in the Brazilian Amazon between the years 2010 and 2019.

They worked out that in that decade, the growing forest gained 3.79 billion tonnes of carbon, but degradation or destruction of the forest resulted in a gross loss of 4.45 billion tonnes. And degradation − basically disturbance by humans in the shape of roads, or plantations, or mining or quarrying − was three times more costly in carbon terms than actual forest clearance.

“Forest degradation has become the largest process driving forest loss and should become a higher policy priority,” the authors say.

A second study in the same journal confirms a parallel finding over 2.82 million square kilometres of Alaska and western Canada. Researchers from the US looked at three decades of satellite data, from 1984 to 2014, to calculate that over those 30 years this area of boreal forest gained 434 billion tonnes of mass in the form of timber and foliage above ground. But forest fires also surrendered 789 billion tonnes of mass over those years.

Intact forests vital

The forests recovered − that is, new growth replaced the lost − but in that time only by 642 billion tonnes. Timber millers took 74 billion tonnes, and new growth added 32 billion tonnes in return. Above-ground mass is not the same thing as above-ground carbon, but it doesn’t change the big picture.

And the big picture is that any disturbance alters the value of forests to the atmospheric traffic in carbon. Within that is a warning to those scientists who have to calculate the global carbon budget: humans may have been over-estimating the capacities of the forests.

“It’s not enough for a forest to absorb and store carbon in its wood and soils. For that to be a real benefit, the forest has to remain intact,” said Jonathan Wang, of the University of California at Irvine, who led the study.

“The far north is home to vast, dense stores of carbon that are very sensitive to climate change, and it will take a lot of monitoring and effort to make sure these forests and their carbon stores remain intact.” − Climate News Network

The world’s forests are supposed to stave off climate change. Left alone, perhaps they could. But they’re not being left alone.

LONDON, 3 May, 2021 − In the last decade, the Amazon forests of Brazil released more carbon into the atmosphere than they absorbed, thanks largely to human activities that cleared or degraded the canopy. Those activities make it impossible for affected forests to stave off climate change.

And a survey of the cooler forests of North America has revealed that these, too, could be surrendering more carbon than they soak up from the atmosphere, thanks to human-triggered climate change and the ever greater hazard of wildfire.

The world’s forests are a key part of the great carbon conundrum: what happens to all the greenhouse gases emitted from power stations, vehicle exhausts and factory chimneys? The assumption is that approaching one third of all the carbon dioxide emissions are absorbed by the forests, and the conservation of the planet’s forests has become part of the proposed arsenal of global defence against catastrophic climate change.

Researchers have repeatedly confirmed that, undisturbed, the world’s great natural forests are important reservoirs of atmospheric carbon. They have also confirmed that, even without taking carbon sequestration into account, the forests represent precious natural capital: they are worth more to humankind undisturbed than they could ever be as sawn timber or ranchland.

“Forest degradation has become the largest process driving forest loss”

But the world’s forests are not being left alone: one study found that even many of those ecosystems set aside by national law for protection are being destroyed or damaged.

And the simple equation that an area of tree canopy represents so much carbon drawn down from the atmosphere turns out not to be so simple. A warming climate − and the planet as a whole is more than 1°C on average warmer than it was a century ago − can disturb the calculations.

As the thermometer notches up, trees grow faster and die younger;  they also grow shorter and the extra fertility conferred by an atmosphere richer in carbon could result in a richer spring growth that is not sustained over a longer summer season. As the temperature rises, so the character of the forests could change: some species may one day find it too hot to reproduce.

And then there is the direct effect of climate change driven by rising temperatures: with heat comes drought, and the greater risk of fire. Forests that had once been reservoirs of carbon could start to surrender it to accelerate climate change even more. The marvel that is the Amazon rainforest could, one researcher has warned, collapse altogether and change irrevocably in one human lifetime.

Degradation costs more

Both of the latest studies deliver evidence that, over time, this could already be on the cards. Scientists from the US, France, Denmark, the UK and China report in the journal Nature Climate Change that they worked through a vast collection of satellite data to calculate the levels of what they call “above ground carbon” − the mass of the element incorporated in timber and foliage − in the Brazilian Amazon between the years 2010 and 2019.

They worked out that in that decade, the growing forest gained 3.79 billion tonnes of carbon, but degradation or destruction of the forest resulted in a gross loss of 4.45 billion tonnes. And degradation − basically disturbance by humans in the shape of roads, or plantations, or mining or quarrying − was three times more costly in carbon terms than actual forest clearance.

“Forest degradation has become the largest process driving forest loss and should become a higher policy priority,” the authors say.

A second study in the same journal confirms a parallel finding over 2.82 million square kilometres of Alaska and western Canada. Researchers from the US looked at three decades of satellite data, from 1984 to 2014, to calculate that over those 30 years this area of boreal forest gained 434 billion tonnes of mass in the form of timber and foliage above ground. But forest fires also surrendered 789 billion tonnes of mass over those years.

Intact forests vital

The forests recovered − that is, new growth replaced the lost − but in that time only by 642 billion tonnes. Timber millers took 74 billion tonnes, and new growth added 32 billion tonnes in return. Above-ground mass is not the same thing as above-ground carbon, but it doesn’t change the big picture.

And the big picture is that any disturbance alters the value of forests to the atmospheric traffic in carbon. Within that is a warning to those scientists who have to calculate the global carbon budget: humans may have been over-estimating the capacities of the forests.

“It’s not enough for a forest to absorb and store carbon in its wood and soils. For that to be a real benefit, the forest has to remain intact,” said Jonathan Wang, of the University of California at Irvine, who led the study.

“The far north is home to vast, dense stores of carbon that are very sensitive to climate change, and it will take a lot of monitoring and effort to make sure these forests and their carbon stores remain intact.” − Climate News Network

Loss of Arctic sea ice can spoil French wine harvest

What happens in the Arctic may not stay there. Loss of Arctic sea ice can dump the polar blizzards elsewhere.

LONDON, 19 April, 2021 − Once again, scientists have linked a weather-related catastrophe directly to human-induced climate change. Extreme frost and springtime snowfalls in Western Europe can be pinned to the dramatic loss of Arctic sea ice.

So, paradoxically, global heating may have had the unexpected effect of wiping out around one third of the French wine harvest for this coming year, after temperatures so low that growers were forced to light bonfires in their vineyards to save the first buds from the chill.

“Climate change doesn’t always manifest in the most obvious ways,” said Alun Hubbard, of the Arctic University of Norway. “It’s easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should be beware of making broad, sweeping statements about the impacts of climate change.”

Professor Hubbard and colleagues report in the journal Nature Geoscience that they measured telltale isotope signatures in water vapour from Finland in February 2018 during an episode of freezing snow in Europe, in an anticyclone dubbed “the Beast from the East” by meteorologists and the media.

“The abrupt changes being witnessed across the Arctic now really are affecting the entire planet”

They found that the Barents Sea north of Scandinavia was anomalously warm. And 60% of the sea’s surface was free of ice, and the same sea lost 140 billion tonnes of water to evaporation during this too-warm February. This enormous atmospheric burden of water vapour provided, they calculate, 88% of the snow that was to fall over northern Europe that month.

Then they looked at the pattern over the years from 1979 to 2020, to find that, for every square metre of ice that vanished in the month of March − itself part of a pattern of Arctic temperature rise − evaporation across the Barents Sea increased by 70 kg, and this could be matched with increases in Europe’s maximum snowfall.

“Our analysis directly links Arctic sea ice loss with increased evaporation and extreme snow fall,” they write, and warn that by 2080 an ice-free Barents Sea “will be a major source of winter moisture for continental Europe.”

The Beast from the East brought much of Europe to a halt, at an economic cost of an estimated $1bn (£0.72bn) a day. It is still rare for researchers to directly link any particular weather event with climate change driven by profligate use of fossil fuels − that is because climate is what forecasters can reasonably expect, but weather is what actually happens − but some scientists have begun to do so with increasing confidence. And this time, they can explain why.

Natural complexity

The ice cover over the Barents Sea has fallen by 54% since 1979, at the rate of 11,200 sq kms a year, and snow mass across Eurasia has increased. The latest study confirms the link: the isotope signature of Barents water was repeated in the European snows that arrived with the Beast from the East.

“What we’re finding is that sea ice is effectively a lid on the ocean. And with its long term reduction across the Arctic, we’re seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extremely heavy snowfalls,” said Hannah Bailey of the University of Oulu in Finland, who led the research.

“It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn’t stay in the Arctic.”

And Professor Hubbard said: “This study illustrates that the abrupt changes being witnessed across the Arctic now really are affecting the entire planet.” − Climate News Network

What happens in the Arctic may not stay there. Loss of Arctic sea ice can dump the polar blizzards elsewhere.

LONDON, 19 April, 2021 − Once again, scientists have linked a weather-related catastrophe directly to human-induced climate change. Extreme frost and springtime snowfalls in Western Europe can be pinned to the dramatic loss of Arctic sea ice.

So, paradoxically, global heating may have had the unexpected effect of wiping out around one third of the French wine harvest for this coming year, after temperatures so low that growers were forced to light bonfires in their vineyards to save the first buds from the chill.

“Climate change doesn’t always manifest in the most obvious ways,” said Alun Hubbard, of the Arctic University of Norway. “It’s easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should be beware of making broad, sweeping statements about the impacts of climate change.”

Professor Hubbard and colleagues report in the journal Nature Geoscience that they measured telltale isotope signatures in water vapour from Finland in February 2018 during an episode of freezing snow in Europe, in an anticyclone dubbed “the Beast from the East” by meteorologists and the media.

“The abrupt changes being witnessed across the Arctic now really are affecting the entire planet”

They found that the Barents Sea north of Scandinavia was anomalously warm. And 60% of the sea’s surface was free of ice, and the same sea lost 140 billion tonnes of water to evaporation during this too-warm February. This enormous atmospheric burden of water vapour provided, they calculate, 88% of the snow that was to fall over northern Europe that month.

Then they looked at the pattern over the years from 1979 to 2020, to find that, for every square metre of ice that vanished in the month of March − itself part of a pattern of Arctic temperature rise − evaporation across the Barents Sea increased by 70 kg, and this could be matched with increases in Europe’s maximum snowfall.

“Our analysis directly links Arctic sea ice loss with increased evaporation and extreme snow fall,” they write, and warn that by 2080 an ice-free Barents Sea “will be a major source of winter moisture for continental Europe.”

The Beast from the East brought much of Europe to a halt, at an economic cost of an estimated $1bn (£0.72bn) a day. It is still rare for researchers to directly link any particular weather event with climate change driven by profligate use of fossil fuels − that is because climate is what forecasters can reasonably expect, but weather is what actually happens − but some scientists have begun to do so with increasing confidence. And this time, they can explain why.

Natural complexity

The ice cover over the Barents Sea has fallen by 54% since 1979, at the rate of 11,200 sq kms a year, and snow mass across Eurasia has increased. The latest study confirms the link: the isotope signature of Barents water was repeated in the European snows that arrived with the Beast from the East.

“What we’re finding is that sea ice is effectively a lid on the ocean. And with its long term reduction across the Arctic, we’re seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extremely heavy snowfalls,” said Hannah Bailey of the University of Oulu in Finland, who led the research.

“It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn’t stay in the Arctic.”

And Professor Hubbard said: “This study illustrates that the abrupt changes being witnessed across the Arctic now really are affecting the entire planet.” − Climate News Network

Monsoon changes threaten Asia and warn the world

For generations India’s farmers have relied on its arrival, but monsoon changes suggest a hotter and less predictable world.

LONDON, 16 April, 2021 − As the world warms, monsoon changes are set to cause havoc across a huge and densely populated swathe of the planet. The great South Asian summer monsoon will become both stronger and less reliable.

German scientists predict a pattern of extremely wet years in the future, but the arrival of these will be chaotic. Even a late monsoon can be devastating for those whose lives and livelihoods depend on the rainy season. A failure can be catastrophic.

And yet too much rain can also have calamitous consequences: it can flood ripening grain fields, wash away topsoils and even − by reducing the storage of carbon in the soil − help accelerate further warming of the planet.

Around one billion people depend on the monsoon for their well-being, for trade and manufacture, and for food systems and agriculture. And the years ahead could become more chaotic, as a consequence of global heating driven by profligate use of fossil fuels and the destruction of natural ecosystems worldwide.

“For every degree Celsius of warming, monsoon rainfalls will likely increase by about 5%,” said Anja Katzenberger of the Potsdam Institute for Climate Impact Research.

“A more chaotic monsoon season poses a threat to the region and should be a wake-up call to drastically cut greenhouse gas emissions worldwide”

“We were also able to confirm previous studies, but find that global warming is increasing monsoon rainfall in India even more than previously thought. It is dominating monsoon dynamics in the 21st century.”

She and colleagues report in the journal Earth System Dynamics that they analysed 32 advanced climate simulations to look for a pattern of change in the region’s weather.

About four-fifths of all the region’s rainfall happens in the summer: crop yields − especially rice − are highly sensitive to the monsoon’s coming. Agriculture makes up at least one-fifth of the Indian gross domestic product or GDP, so rainfall is vital to the economic and social well-being of hundreds of millions of people.

During the second half of the 20th century, the trend seemed to be towards a gradual drying of the rains. In the first decades of this century, the pattern seems reversed: monsoons are getting stronger. Quite how tiny annual rises in global average temperatures affect the winds that bring the summer rains has still to be ascertained, but ocean warming driven by human changes to greenhouse gas levels in the atmosphere is almost certainly involved.

Rice at risk

And this is not good news for the farmers who, for generations, have placed their bets on the regular arrival of the rains. There is even evidence that in the deep past, a succession of monsoon failures may have toppled an early civilisation.

“Crops need water especially in the initial growing period, but too much rainfall during other growing states can harm plants − including rice, on which the majority of India’s population is depending for sustenance,” said Julia Pongratz from the Ludwig-Maximilian University in Munich, another of the authors.

“This makes the Indian economy and food system highly sensitive to volatile monsoon patterns.”

And Anders Levermann, also from the Potsdam Institute, said: “We see more and more that climate change is about unpredictable weather extremes and their serious consequences, because what is really on the line is the socio-economic well-being of the Indian subcontinent.

“A more chaotic monsoon season poses a threat to the agriculture and economy in the region and should be a wake-up call for policymakers to drastically cut greenhouse gas emissions worldwide.” − Climate News Network

For generations India’s farmers have relied on its arrival, but monsoon changes suggest a hotter and less predictable world.

LONDON, 16 April, 2021 − As the world warms, monsoon changes are set to cause havoc across a huge and densely populated swathe of the planet. The great South Asian summer monsoon will become both stronger and less reliable.

German scientists predict a pattern of extremely wet years in the future, but the arrival of these will be chaotic. Even a late monsoon can be devastating for those whose lives and livelihoods depend on the rainy season. A failure can be catastrophic.

And yet too much rain can also have calamitous consequences: it can flood ripening grain fields, wash away topsoils and even − by reducing the storage of carbon in the soil − help accelerate further warming of the planet.

Around one billion people depend on the monsoon for their well-being, for trade and manufacture, and for food systems and agriculture. And the years ahead could become more chaotic, as a consequence of global heating driven by profligate use of fossil fuels and the destruction of natural ecosystems worldwide.

“For every degree Celsius of warming, monsoon rainfalls will likely increase by about 5%,” said Anja Katzenberger of the Potsdam Institute for Climate Impact Research.

“A more chaotic monsoon season poses a threat to the region and should be a wake-up call to drastically cut greenhouse gas emissions worldwide”

“We were also able to confirm previous studies, but find that global warming is increasing monsoon rainfall in India even more than previously thought. It is dominating monsoon dynamics in the 21st century.”

She and colleagues report in the journal Earth System Dynamics that they analysed 32 advanced climate simulations to look for a pattern of change in the region’s weather.

About four-fifths of all the region’s rainfall happens in the summer: crop yields − especially rice − are highly sensitive to the monsoon’s coming. Agriculture makes up at least one-fifth of the Indian gross domestic product or GDP, so rainfall is vital to the economic and social well-being of hundreds of millions of people.

During the second half of the 20th century, the trend seemed to be towards a gradual drying of the rains. In the first decades of this century, the pattern seems reversed: monsoons are getting stronger. Quite how tiny annual rises in global average temperatures affect the winds that bring the summer rains has still to be ascertained, but ocean warming driven by human changes to greenhouse gas levels in the atmosphere is almost certainly involved.

Rice at risk

And this is not good news for the farmers who, for generations, have placed their bets on the regular arrival of the rains. There is even evidence that in the deep past, a succession of monsoon failures may have toppled an early civilisation.

“Crops need water especially in the initial growing period, but too much rainfall during other growing states can harm plants − including rice, on which the majority of India’s population is depending for sustenance,” said Julia Pongratz from the Ludwig-Maximilian University in Munich, another of the authors.

“This makes the Indian economy and food system highly sensitive to volatile monsoon patterns.”

And Anders Levermann, also from the Potsdam Institute, said: “We see more and more that climate change is about unpredictable weather extremes and their serious consequences, because what is really on the line is the socio-economic well-being of the Indian subcontinent.

“A more chaotic monsoon season poses a threat to the agriculture and economy in the region and should be a wake-up call for policymakers to drastically cut greenhouse gas emissions worldwide.” − Climate News Network

Global farming feels the impacts of global heating

Global heating has already set back farming around the world, and wiped out seven years of steady advance.

LONDON, 12 April, 2021 − Climate change has begun to harm the world’s farmers. Compared with a notional world in which global heating is not being driven ever higher by fossil fuel use, a new study finds that the riches to be gleaned from the soil have fallen by 21%.

This, the researchers say, is as if the steady advance in agricultural productivity worldwide − in crop breeding, in farming technologies and in fertiliser use − has been eroded everywhere by more extreme temperatures, more prolonged droughts and more intense rainfall.

“We find that climate change has basically wiped out about seven years of improvements in agricultural productivity over the past 60 years,” said Ariel Ortiz-Bobea, an economist at Cornell University in the US.

“It is equivalent to pressing the pause button on productivity growth back in 2013, and experiencing no improvements since then. Anthropogenic climate change is already slowing us down.”

He and colleagues from Maryland and California report in the journal Nature Climate Change that they developed new ways of looking at farm costs and yields that could account for climate- and weather-related factors. The findings are potentially alarming.

Productivity drops

In the last century, the planet has warmed by at least 1°C above the long term average for most of human history, and is heading for 3°C or more by the end of this century.

By 2050, the total global population could have risen to 10bn: more than two billion extra mouths to be fed. But during the last 60 years, growth in agricultural productivity in the US has been slowed by somewhere between 5 and 15%. In Africa, in Latin America and the Caribbean, growth has slowed by between 26 and 34%.

A study of this kind − comparing the present world with one that might have been − is always open to challenge, and farmers have always had to gamble on good weather and cope with bad harvests.

But over the last seven years, researchers have repeatedly confirmed that a hotter world promises to be a hungrier one. Studies have found that yields of wheat, maize and rice are all vulnerable to climate change.

They have warned that higher temperatures and more atmospheric greenhouse gases could actually affect the nutritional values of legumes, fruit and vegetables, and that changes in weather patterns − in droughts, rainfall and heat waves − will hit harvests.

“Most people perceive climate change as a distant problem. But this is something that is already having an effect”

And since the higher temperatures that global heating brings  inevitably threaten more intense, more prolonged and more extensive heat extremes and droughts, the chances of calamitous harvest failure in more than one continent at the same time will be much greater: global famine could follow.

So the latest study simply provides another way of confirming anxieties already expressed. This time there is a new perspective: the attrition of climate change began decades ago. In the constant race to keep up with demand and compensate for possible loss, the farmers may be falling behind. Technological progress has yet to deliver climate resilience.

“It is not what we can do, but where we are headed,” said Robert Chambers, of the University of Maryland, a co-author. “This gives us an idea of trends to help see what to do in the future with new changes in the climate that are beyond what we’ve previously seen.

“We are projected to have almost 10 billion people to feed by 2050, so making sure our productivity is stable but growing faster than ever before is a serious concern.”

And Dr Otiz-Bobea said: “Most people perceive climate change as a distant problem. But this is something that is already having an effect. We have to address climate change now so that we can avoid further damage for future generations.” − Climate News Network

Global heating has already set back farming around the world, and wiped out seven years of steady advance.

LONDON, 12 April, 2021 − Climate change has begun to harm the world’s farmers. Compared with a notional world in which global heating is not being driven ever higher by fossil fuel use, a new study finds that the riches to be gleaned from the soil have fallen by 21%.

This, the researchers say, is as if the steady advance in agricultural productivity worldwide − in crop breeding, in farming technologies and in fertiliser use − has been eroded everywhere by more extreme temperatures, more prolonged droughts and more intense rainfall.

“We find that climate change has basically wiped out about seven years of improvements in agricultural productivity over the past 60 years,” said Ariel Ortiz-Bobea, an economist at Cornell University in the US.

“It is equivalent to pressing the pause button on productivity growth back in 2013, and experiencing no improvements since then. Anthropogenic climate change is already slowing us down.”

He and colleagues from Maryland and California report in the journal Nature Climate Change that they developed new ways of looking at farm costs and yields that could account for climate- and weather-related factors. The findings are potentially alarming.

Productivity drops

In the last century, the planet has warmed by at least 1°C above the long term average for most of human history, and is heading for 3°C or more by the end of this century.

By 2050, the total global population could have risen to 10bn: more than two billion extra mouths to be fed. But during the last 60 years, growth in agricultural productivity in the US has been slowed by somewhere between 5 and 15%. In Africa, in Latin America and the Caribbean, growth has slowed by between 26 and 34%.

A study of this kind − comparing the present world with one that might have been − is always open to challenge, and farmers have always had to gamble on good weather and cope with bad harvests.

But over the last seven years, researchers have repeatedly confirmed that a hotter world promises to be a hungrier one. Studies have found that yields of wheat, maize and rice are all vulnerable to climate change.

They have warned that higher temperatures and more atmospheric greenhouse gases could actually affect the nutritional values of legumes, fruit and vegetables, and that changes in weather patterns − in droughts, rainfall and heat waves − will hit harvests.

“Most people perceive climate change as a distant problem. But this is something that is already having an effect”

And since the higher temperatures that global heating brings  inevitably threaten more intense, more prolonged and more extensive heat extremes and droughts, the chances of calamitous harvest failure in more than one continent at the same time will be much greater: global famine could follow.

So the latest study simply provides another way of confirming anxieties already expressed. This time there is a new perspective: the attrition of climate change began decades ago. In the constant race to keep up with demand and compensate for possible loss, the farmers may be falling behind. Technological progress has yet to deliver climate resilience.

“It is not what we can do, but where we are headed,” said Robert Chambers, of the University of Maryland, a co-author. “This gives us an idea of trends to help see what to do in the future with new changes in the climate that are beyond what we’ve previously seen.

“We are projected to have almost 10 billion people to feed by 2050, so making sure our productivity is stable but growing faster than ever before is a serious concern.”

And Dr Otiz-Bobea said: “Most people perceive climate change as a distant problem. But this is something that is already having an effect. We have to address climate change now so that we can avoid further damage for future generations.” − Climate News Network

Rich world’s demands fell poorer world’s forests

The tropical forests maintain global climate and nurture the riches of nature. The rich world’s demands are destroying them.

LONDON, 9 April, 2021 − The world’s great ecosystems − moderators of climate, nurseries for evolution − are still being destroyed in the service of global trade, to meet the rich world’s demands. Once again, researchers have confirmed that the wealthy nations are in effect ploughing savanna and felling tropical forests at a distance.

In the first 15 years of this century, the growing demand from the well-heeled for chocolate, rubber, cotton, soy, beef and exotic timber has meant that poorer nations have actually increased their levels of deforestation.

In effect, every human in the G7 nations − Canada, France, Germany, Italy, Japan, the UK and the US − is responsible for the loss of at least four trees a year, mostly in the developing world.

And in a separate study in another journal, another team of scientists has examined satellite data to confirm that between 1985 and 2018, humans cleared or altered 268 million hectares of natural ecosystem on the continent of South America. This is 2.68 million sq kilometres: an area almost the size of Argentina.

Two scientists in Japan report in Nature Ecology and Evolution that they matched levels of deforestation against trade with the world’s biggest economies, to find a clear correlation. They could even distinguish demand in one rich country and its impact on the forests of a poorer nation.

“Richer countries are encouraging deforestation through demand for commodities”

“While cocoa consumption in Germany poses the highest risk to the forests in Côte d’Ivoire and Ghana, deforestation in coastal Tanzania is dominated by Japanese consumers for some agricultural commodities, such as cotton and sesame seed,” they write.

“China shares the most significant responsibility for deforestation in Indochina − particularly in northern Laos for timber and rubber.”

Ironically, many of the richer nations have expanded the areas of forest on their own soil. More than 90% of the deforestation caused by five of the G7 nations was beyond their own borders. In effect, the rich were exporting the destruction of the natural world, and the cost to the planet was disproportionate. The loss of three trees in the Amazon might be more damaging than the loss of 14 trees in Norway, the scientists argue.

“Most forests are in poorer countries who are overwhelmed with economic incentives to cut them down. Our findings show that richer countries are encouraging deforestation through demand for commodities,” said Keiichiro Kanemoto of the Research Institute for Humanity and Nature in Kyoto.

“Policies that aim to preserve forests need to also alleviate poverty. With the coronavirus pandemic, unemployment poses more challenges to forest conservation in developing countries. We want our data to assist in the policy making.”

South American losses

And in the journal Science Advances, a team from the University of Maryland reports on a closer look at the impact of demand for pulpwood, sugar cane, beef, corn and other commodities on one continent: South America, home to some of the world’s most important ecosystems.

They found that human impact on the continent’s land surface just between the years 1985 and 2018 had expanded by 60%. In those years the natural tree cover had dwindled by 16%, and the scale of pasture increased by 23%, cropland by 160% and plantation by 288%.

The sum of all the altered land reached 268 million hectares, or 2.68m sq kms. Argentina, which coincidentally covers 2.73m sq kms, saw an increase of only 23% in human conversion of land use. Brazil tipped the scales with an expansion of 65% in those years.

And, say the researchers, of all this altered land cover on the continent, around 55 million hectares had been degraded − that is, it was no longer functioning as an ecosystem − while being employed for no commercial return. This is the equivalent of more than half a million square kilometres: an area slightly bigger than France.

“No region on Earth is likely to have experienced the scale of land conversion for the sake of agricultural commodity production that South America has,” the authors write. − Climate News Network

The tropical forests maintain global climate and nurture the riches of nature. The rich world’s demands are destroying them.

LONDON, 9 April, 2021 − The world’s great ecosystems − moderators of climate, nurseries for evolution − are still being destroyed in the service of global trade, to meet the rich world’s demands. Once again, researchers have confirmed that the wealthy nations are in effect ploughing savanna and felling tropical forests at a distance.

In the first 15 years of this century, the growing demand from the well-heeled for chocolate, rubber, cotton, soy, beef and exotic timber has meant that poorer nations have actually increased their levels of deforestation.

In effect, every human in the G7 nations − Canada, France, Germany, Italy, Japan, the UK and the US − is responsible for the loss of at least four trees a year, mostly in the developing world.

And in a separate study in another journal, another team of scientists has examined satellite data to confirm that between 1985 and 2018, humans cleared or altered 268 million hectares of natural ecosystem on the continent of South America. This is 2.68 million sq kilometres: an area almost the size of Argentina.

Two scientists in Japan report in Nature Ecology and Evolution that they matched levels of deforestation against trade with the world’s biggest economies, to find a clear correlation. They could even distinguish demand in one rich country and its impact on the forests of a poorer nation.

“Richer countries are encouraging deforestation through demand for commodities”

“While cocoa consumption in Germany poses the highest risk to the forests in Côte d’Ivoire and Ghana, deforestation in coastal Tanzania is dominated by Japanese consumers for some agricultural commodities, such as cotton and sesame seed,” they write.

“China shares the most significant responsibility for deforestation in Indochina − particularly in northern Laos for timber and rubber.”

Ironically, many of the richer nations have expanded the areas of forest on their own soil. More than 90% of the deforestation caused by five of the G7 nations was beyond their own borders. In effect, the rich were exporting the destruction of the natural world, and the cost to the planet was disproportionate. The loss of three trees in the Amazon might be more damaging than the loss of 14 trees in Norway, the scientists argue.

“Most forests are in poorer countries who are overwhelmed with economic incentives to cut them down. Our findings show that richer countries are encouraging deforestation through demand for commodities,” said Keiichiro Kanemoto of the Research Institute for Humanity and Nature in Kyoto.

“Policies that aim to preserve forests need to also alleviate poverty. With the coronavirus pandemic, unemployment poses more challenges to forest conservation in developing countries. We want our data to assist in the policy making.”

South American losses

And in the journal Science Advances, a team from the University of Maryland reports on a closer look at the impact of demand for pulpwood, sugar cane, beef, corn and other commodities on one continent: South America, home to some of the world’s most important ecosystems.

They found that human impact on the continent’s land surface just between the years 1985 and 2018 had expanded by 60%. In those years the natural tree cover had dwindled by 16%, and the scale of pasture increased by 23%, cropland by 160% and plantation by 288%.

The sum of all the altered land reached 268 million hectares, or 2.68m sq kms. Argentina, which coincidentally covers 2.73m sq kms, saw an increase of only 23% in human conversion of land use. Brazil tipped the scales with an expansion of 65% in those years.

And, say the researchers, of all this altered land cover on the continent, around 55 million hectares had been degraded − that is, it was no longer functioning as an ecosystem − while being employed for no commercial return. This is the equivalent of more than half a million square kilometres: an area slightly bigger than France.

“No region on Earth is likely to have experienced the scale of land conversion for the sake of agricultural commodity production that South America has,” the authors write. − Climate News Network

Plants will be hit as a warming world turns drier

If a warming world becomes a drier one, how will the green things respond? Not well, according to a new prediction.

LONDON, 26 March, 2021 − The air of planet Earth has been gradually drying this century. If this goes on, that could be bad news for humankind. In a warming world crop harvests will dwindle, even in well-watered farmlands, and trees could shrink in height.

The prospect of stunted forests and shortages of food in a world hit by global heating, climate change and rapid population growth is ominous. But if US and Canadian scientists are right, it may be a simple consequence of plant response to a rarely-discussed worldwide phenomenon known as vapour pressure deficit, which has been rising for the past 20 years as the world has warmed.

The argument isn’t a simple one. Higher global temperatures mean more evaporation. Higher atmospheric temperatures also mean that the capacity of the atmosphere to hold moisture also rises − the rule of thumb is 7% more vapour per degree Celsius rise. So a warmer world should be a wetter world.

But climate science also predicts that although those regions already rainy will get rainier, the drylands and arid zones will get even dryer as the thermometer soars.

“As we race to increase production to feed a bigger population, this is a new hurdle. Atmospheric drying could limit yields, even in regions where irrigation or soil moisture is not limiting”

Now there is another factor in the calculations: vapour pressure deficit, or the overall drying of the atmosphere, and how plants react to the problem of dwindling atmospheric moisture.

New research in the journal Global Change Biology analyses 50 years of research and 112 plant species, and 59 physiological traits in those plants. The evidence suggests that atmospheric drying reduces plant yield, as the plants adjust to new conditions.

“When there is a high vapour pressure deficit, our atmosphere pulls water from other sources: animals, plants, etc. An increase in vapour pressure deficit places greater demand on the crop to use more water. In turn, this puts more pressure on farmers to ensure this demand for water is met − either via precipitation or irrigation − so that yields do not decrease,” said Walid Sadok, of the University of Minnesota.

“We believe a climate change-driven increase in atmospheric drying will reduce plant productivity and crop yields both in Minnesota and globally.”

The paradox is that plants can adjust to a changing world but in this case by becoming more drought-resistant. Which, in the case of wheat, maize and even birch trees, means growing less.

Less productive plants

Findings such as this are tentative, and will in any case be tested by time. But they also illustrate just how much there is yet to learn about the consequence of climate change in a complex, responsive world.

Other research teams have repeatedly observed that even in the drier regions, plants have so far responded to rising greenhouse gas emissions by an increase in global greenness. But there is nothing simple about the greenhouse effect. And there has been repeated evidence too that forest conservation and more tree plantations may not provide all the answers to the challenge of growth in an ever-warmer world.

The reasoning within the new study is that plant stomata, those tiny holes in foliage through which plants breathe and release water, adjust according to new conditions. The plants become more conservative. They grow shorter, smaller and more resistant to drought, even if there is no drought. And in parallel, they become less able to fix atmospheric carbon dioxide to provide new tissue. So, overall, plant productivity is reduced.

“As we race to increase production to feed a bigger population, this is a new hurdle that will need to be cleared,” said Dr Sadok. “Atmospheric drying could limit yields, even in regions where irrigation or soil moisture is not limiting, such as Minnesota.” − Climate News Network

If a warming world becomes a drier one, how will the green things respond? Not well, according to a new prediction.

LONDON, 26 March, 2021 − The air of planet Earth has been gradually drying this century. If this goes on, that could be bad news for humankind. In a warming world crop harvests will dwindle, even in well-watered farmlands, and trees could shrink in height.

The prospect of stunted forests and shortages of food in a world hit by global heating, climate change and rapid population growth is ominous. But if US and Canadian scientists are right, it may be a simple consequence of plant response to a rarely-discussed worldwide phenomenon known as vapour pressure deficit, which has been rising for the past 20 years as the world has warmed.

The argument isn’t a simple one. Higher global temperatures mean more evaporation. Higher atmospheric temperatures also mean that the capacity of the atmosphere to hold moisture also rises − the rule of thumb is 7% more vapour per degree Celsius rise. So a warmer world should be a wetter world.

But climate science also predicts that although those regions already rainy will get rainier, the drylands and arid zones will get even dryer as the thermometer soars.

“As we race to increase production to feed a bigger population, this is a new hurdle. Atmospheric drying could limit yields, even in regions where irrigation or soil moisture is not limiting”

Now there is another factor in the calculations: vapour pressure deficit, or the overall drying of the atmosphere, and how plants react to the problem of dwindling atmospheric moisture.

New research in the journal Global Change Biology analyses 50 years of research and 112 plant species, and 59 physiological traits in those plants. The evidence suggests that atmospheric drying reduces plant yield, as the plants adjust to new conditions.

“When there is a high vapour pressure deficit, our atmosphere pulls water from other sources: animals, plants, etc. An increase in vapour pressure deficit places greater demand on the crop to use more water. In turn, this puts more pressure on farmers to ensure this demand for water is met − either via precipitation or irrigation − so that yields do not decrease,” said Walid Sadok, of the University of Minnesota.

“We believe a climate change-driven increase in atmospheric drying will reduce plant productivity and crop yields both in Minnesota and globally.”

The paradox is that plants can adjust to a changing world but in this case by becoming more drought-resistant. Which, in the case of wheat, maize and even birch trees, means growing less.

Less productive plants

Findings such as this are tentative, and will in any case be tested by time. But they also illustrate just how much there is yet to learn about the consequence of climate change in a complex, responsive world.

Other research teams have repeatedly observed that even in the drier regions, plants have so far responded to rising greenhouse gas emissions by an increase in global greenness. But there is nothing simple about the greenhouse effect. And there has been repeated evidence too that forest conservation and more tree plantations may not provide all the answers to the challenge of growth in an ever-warmer world.

The reasoning within the new study is that plant stomata, those tiny holes in foliage through which plants breathe and release water, adjust according to new conditions. The plants become more conservative. They grow shorter, smaller and more resistant to drought, even if there is no drought. And in parallel, they become less able to fix atmospheric carbon dioxide to provide new tissue. So, overall, plant productivity is reduced.

“As we race to increase production to feed a bigger population, this is a new hurdle that will need to be cleared,” said Dr Sadok. “Atmospheric drying could limit yields, even in regions where irrigation or soil moisture is not limiting, such as Minnesota.” − Climate News Network

Nature left alone offers more than if we exploit it

Save nature, save money. It’s a simple argument. Wilderness cleared and ploughed offers us less than nature left alone.

LONDON, 19 March, 2021 − British scientists have once again made the commercial case for conserving wilderness. They have demonstrated that in its pristine state − mangrove swamps, wetlands, savannahs, forests and so on − nature left alone is of more value to humankind than as exploited real estate.

This argument has been made already, and more than once. But this time the researchers can provide the detail for their argument: they report in the journal Nature Sustainability that they had devised an accounting methodology to test such arguments, and then applied this in 24 selected sites around the planet.

Some of the value would be in intangibles such as providing a shelter for the wild things and wild plants; some of it would be measurable. For instance, if the damage inherent in carbon spilled into the atmosphere through habitat destruction or fossil fuel combustion presents an overall cost to society of $31 a tonne − and this is a conservative estimate − then almost three quarters of the sample sites have greater value simply as natural habitats.

And that includes 100% of all forests. If that greenhouse gas carbon was valued at a paltry $5 a tonne, almost two thirds of the sites would still be, over a 50-year period, a better investment left untouched.

“At current levels of habitat conversion, conserving and restoring sites typically benefits human prosperity”

But what climate scientists now call “natural capital” − the invisible services  provided by nature in crop pollination, water filtration and planetary air conditioning − is of measurable commercial value even without the vital role of carbon sink. Of the 24 sites, 42% would still be worth more in their natural form than converted to cropland.

“Stemming biodiversity loss is a vital goal in itself, but nature also fundamentally underpins human wellbeing,” said Richard Bradbury, of the University of Cambridge. “We need nature-related financial disclosure, and incentives for nature-focused land management, whether through taxes and regulation or subsidies for ecosystem services.”

And his Cambridge co-author Andrew Balmford said: “Current rates of habitat conversion are driving a species extinction crisis unlike anything in human history. Even if you are only interested in dollars and cents, we can see that conserving and restoring nature is now very often the best bet for human prosperity.”

In fact the researchers made their conclusions based on 62 sites, but concentrated on 24 simply because in these cases they had the most reliable information about the potential commercial value of their sample against which to measure the value of restoring it, or protecting it, or both.

Valuable saltmarsh

If Nepal’s Shivapuri-Nagarjun National Park was turned from forest to farmland, investors would gain immediate capital from the value of the timber, and a longer-term income from crops. But the loss of carbon storage would be 60%, and the damage to water quality would be 88%, and Nepal would be $11m worse off.

Even a saltmarsh near Preston in the United Kingdom proved to be worth $2000 a hectare in terms of its value in mitigating carbon emissions: no income from crops or forage grazing could match that.

That left 38 sites for which the economic data was less certain: even in these cases, the “goods and services” delivered by the site in its natural state was, for two thirds of them, of more value to humankind as a whole than calculated exploitation by a few.

“Our findings indicate that, at current levels of habitat conversion, conserving and restoring sites typically benefits human prosperity,” the authors say. − Climate News Network

Save nature, save money. It’s a simple argument. Wilderness cleared and ploughed offers us less than nature left alone.

LONDON, 19 March, 2021 − British scientists have once again made the commercial case for conserving wilderness. They have demonstrated that in its pristine state − mangrove swamps, wetlands, savannahs, forests and so on − nature left alone is of more value to humankind than as exploited real estate.

This argument has been made already, and more than once. But this time the researchers can provide the detail for their argument: they report in the journal Nature Sustainability that they had devised an accounting methodology to test such arguments, and then applied this in 24 selected sites around the planet.

Some of the value would be in intangibles such as providing a shelter for the wild things and wild plants; some of it would be measurable. For instance, if the damage inherent in carbon spilled into the atmosphere through habitat destruction or fossil fuel combustion presents an overall cost to society of $31 a tonne − and this is a conservative estimate − then almost three quarters of the sample sites have greater value simply as natural habitats.

And that includes 100% of all forests. If that greenhouse gas carbon was valued at a paltry $5 a tonne, almost two thirds of the sites would still be, over a 50-year period, a better investment left untouched.

“At current levels of habitat conversion, conserving and restoring sites typically benefits human prosperity”

But what climate scientists now call “natural capital” − the invisible services  provided by nature in crop pollination, water filtration and planetary air conditioning − is of measurable commercial value even without the vital role of carbon sink. Of the 24 sites, 42% would still be worth more in their natural form than converted to cropland.

“Stemming biodiversity loss is a vital goal in itself, but nature also fundamentally underpins human wellbeing,” said Richard Bradbury, of the University of Cambridge. “We need nature-related financial disclosure, and incentives for nature-focused land management, whether through taxes and regulation or subsidies for ecosystem services.”

And his Cambridge co-author Andrew Balmford said: “Current rates of habitat conversion are driving a species extinction crisis unlike anything in human history. Even if you are only interested in dollars and cents, we can see that conserving and restoring nature is now very often the best bet for human prosperity.”

In fact the researchers made their conclusions based on 62 sites, but concentrated on 24 simply because in these cases they had the most reliable information about the potential commercial value of their sample against which to measure the value of restoring it, or protecting it, or both.

Valuable saltmarsh

If Nepal’s Shivapuri-Nagarjun National Park was turned from forest to farmland, investors would gain immediate capital from the value of the timber, and a longer-term income from crops. But the loss of carbon storage would be 60%, and the damage to water quality would be 88%, and Nepal would be $11m worse off.

Even a saltmarsh near Preston in the United Kingdom proved to be worth $2000 a hectare in terms of its value in mitigating carbon emissions: no income from crops or forage grazing could match that.

That left 38 sites for which the economic data was less certain: even in these cases, the “goods and services” delivered by the site in its natural state was, for two thirds of them, of more value to humankind as a whole than calculated exploitation by a few.

“Our findings indicate that, at current levels of habitat conversion, conserving and restoring sites typically benefits human prosperity,” the authors say. − Climate News Network

Longer summers will probably prove bummers

By the century’s end, longer summers could last for almost half the year − probably a bit too much for many of us.

LONDON, 18 March, 2021 − Summer’s lease, mourned William Shakespeare more than 400 years ago in one of his most quoted sonnets, “has all too short a date.” Not for much longer. Thanks to global heating, by the close of the century the longer summers arriving by then may have been extended to almost six months.

The lengthening of the northern hemisphere summer has already begun, according to a new study in the journal Geophysical Research Letters. The four seasons are normally defined as calendar events, pinned to the progress of a tilted planet in its annual orbit of the sun.

But Chinese scientists took a simpler approach. They defined summer’s commencement as the onset of temperatures in the hottest 25% of the year, winter by the coming of the coldest 25%.

And then they looked at the temperature data to work out what had already happened, and what is likely to happen as global average temperatures rise, in response to ever-higher greenhouse gas emissions linked to fossil fuel combustion and forest destruction.

They found that in 1952, summer could be counted as 78 days long; by 2011, this had stretched to 95 days in the northern hemisphere. Winter contracted from 76 to 73 days in duration. Spring had dwindled from 124 days to 115; autumn from 87 to 82 days.

Health risk

And if this trend continues, and humans go on burning fossil fuels under the notorious “business as usual” scenario, then by 2100 spring and autumn will go on diminishing, and winter will be over in just two months. Summer will however have been extended to nearly half the year.

“The changing seasonal clock,” the scientists write, “signifies disturbed agriculture seasons and rhythm of species activities, more frequent heat waves, storms and wildfires, amounting to increased risks to humanity.”

The findings will present no immediate surprise to farmers, nor to phenologists, those scientists who have spent a lifetime observing changes in the timing of the natural order: the first buds, the first leaves and flowers, the arrival of insects and migrating birds, all of them affected by the increasingly early arrival of spring.

The abbreviation of winter may not however make the natural world more fecund or productive: many crops and a very large number of deciduous trees rely for health and strength on a reliable period of winter chill, and a shorter winter is inevitably going to be a warmer one.

Conversely a long hot summer is unlikely to be particularly welcome: these will arrive with more intense, more enduring and more extensive heat waves, to pose a threat to both harvests and to human health for perhaps a billion or more people.

“The changing seasonal clock signifies disturbed agriculture seasons,  more frequent heat waves, storms and wildfires, amounting to increased risks to humanity”

The researchers warn that longer, hotter summers will affect the capacity to produce energy while at the same time accelerating demand for electricity to power air-conditioning systems.

Longer summers mean more stress for plants and for forests, more and larger wildfires and health hazards for outdoor workers.

Higher temperatures have been linked to high crime rates in some parts of the US and − the researchers warn − earlier and colder spring seasons can mean more “false springs” followed by severe frosts of the kind that, in 2012 in Michigan, cost fruit growers more than $500,000 in crop
losses.

In yet a further caution they say that virus-bearing mosquitos will have a wider range and longer breeding seasons, to produce sudden outbreaks of disease in regions once considered safe. Those sensitive to plant pollen will find the season of sneezes has suddenly got a lot longer.

“As global warming intensifies, the four seasons of a year no longer have equal months, and their onsets are irregular,” the authors write. This change of seasonal lengths, they add. can trigger a chain of reactions, and “policy-making for agricultural management, health care, and disaster prevention requires adjustment.” − Climate News Network

By the century’s end, longer summers could last for almost half the year − probably a bit too much for many of us.

LONDON, 18 March, 2021 − Summer’s lease, mourned William Shakespeare more than 400 years ago in one of his most quoted sonnets, “has all too short a date.” Not for much longer. Thanks to global heating, by the close of the century the longer summers arriving by then may have been extended to almost six months.

The lengthening of the northern hemisphere summer has already begun, according to a new study in the journal Geophysical Research Letters. The four seasons are normally defined as calendar events, pinned to the progress of a tilted planet in its annual orbit of the sun.

But Chinese scientists took a simpler approach. They defined summer’s commencement as the onset of temperatures in the hottest 25% of the year, winter by the coming of the coldest 25%.

And then they looked at the temperature data to work out what had already happened, and what is likely to happen as global average temperatures rise, in response to ever-higher greenhouse gas emissions linked to fossil fuel combustion and forest destruction.

They found that in 1952, summer could be counted as 78 days long; by 2011, this had stretched to 95 days in the northern hemisphere. Winter contracted from 76 to 73 days in duration. Spring had dwindled from 124 days to 115; autumn from 87 to 82 days.

Health risk

And if this trend continues, and humans go on burning fossil fuels under the notorious “business as usual” scenario, then by 2100 spring and autumn will go on diminishing, and winter will be over in just two months. Summer will however have been extended to nearly half the year.

“The changing seasonal clock,” the scientists write, “signifies disturbed agriculture seasons and rhythm of species activities, more frequent heat waves, storms and wildfires, amounting to increased risks to humanity.”

The findings will present no immediate surprise to farmers, nor to phenologists, those scientists who have spent a lifetime observing changes in the timing of the natural order: the first buds, the first leaves and flowers, the arrival of insects and migrating birds, all of them affected by the increasingly early arrival of spring.

The abbreviation of winter may not however make the natural world more fecund or productive: many crops and a very large number of deciduous trees rely for health and strength on a reliable period of winter chill, and a shorter winter is inevitably going to be a warmer one.

Conversely a long hot summer is unlikely to be particularly welcome: these will arrive with more intense, more enduring and more extensive heat waves, to pose a threat to both harvests and to human health for perhaps a billion or more people.

“The changing seasonal clock signifies disturbed agriculture seasons,  more frequent heat waves, storms and wildfires, amounting to increased risks to humanity”

The researchers warn that longer, hotter summers will affect the capacity to produce energy while at the same time accelerating demand for electricity to power air-conditioning systems.

Longer summers mean more stress for plants and for forests, more and larger wildfires and health hazards for outdoor workers.

Higher temperatures have been linked to high crime rates in some parts of the US and − the researchers warn − earlier and colder spring seasons can mean more “false springs” followed by severe frosts of the kind that, in 2012 in Michigan, cost fruit growers more than $500,000 in crop
losses.

In yet a further caution they say that virus-bearing mosquitos will have a wider range and longer breeding seasons, to produce sudden outbreaks of disease in regions once considered safe. Those sensitive to plant pollen will find the season of sneezes has suddenly got a lot longer.

“As global warming intensifies, the four seasons of a year no longer have equal months, and their onsets are irregular,” the authors write. This change of seasonal lengths, they add. can trigger a chain of reactions, and “policy-making for agricultural management, health care, and disaster prevention requires adjustment.” − Climate News Network

Europe has grown drier over the last two millennia

Global heating may be to blame for the fact that Europe has grown drier over the last 2,000 years to a new high in 2015.

LONDON, 17 March, 2021 − Europe has grown drier, an outcome shown by the continent’s last five summers, which have been marked by drought that has no parallel in the last two millennia.

Researchers studied two kinds of evidence delivered by 27,000 measurements taken from 21 living oak trees and 126 samples from ancient beams and rafters, to piece together a precise picture of the climate of Germany, Switzerland and the Czech Republic over the last 2,110 years.

They report, after 2015, that drought conditions intensified suddenly, in ways that were beyond anything over that entire 2000-year tract of time. And, they add, “this hydroclimatic anomaly is probably caused by anthropogenic warming.”

Europe is also getting hotter. In 2003, 2015 and 2018 it was hit by severe summer heat waves and spells of drought that damaged plantations, crops and vines; the damage from drought was intensified by more virulent attacks from pathogens, insect outbreaks and tree death.

“Extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole”

In the baking summer of 2003, an estimated 70,000 people died because of extremes of heat. And, the researchers say, “a further increase in the frequency and severity of heat waves under projected global warming implies a multitude of harmful direct and indirect impacts on human health.”

In other words, things are bad now and are likely to get worse, according to a report by 17 British, European and Canadian researchers in the journal Nature Geoscience.

Dendrochronologists can and do routinely build up a picture of bygone temperatures by measuring the growth rings in trees: enough old living trees, and reliable knowledge about the felling of oaks for chateaux, cathedrals, sailing ships, fortresses and stockades can help pinpoint seasonal change on an annual basis.

But trees are also living chronicles of changes in carbon and oxygen isotope ratios − tiny atomic variations in the plant’s biochemistry − which provide evidence of rainfall and therefore a more precise picture of any growing season.

Wandering jet stream

The trees delivered mute evidence of very wet summers in 200, 720 and 1100 AD, and very dry summers in the years 40, 590, 950 and 1510 of the Common Era. But overall the big picture emerged: for the years 75 BC to 2018, Europe has slowly been getting drier.

Even so, the evidence from 2015 to 2018 shows that drought conditions in the area from which the trees were taken far exceeds anything in the previous centuries. The mostly likely explanation is the impact of ever-rising temperatures, driven by ever-higher greenhouse gas emissions from the ever-more profligate combustion of fossil fuels.

These temperatures are now considered high enough to affect the course of the stratospheric jet stream in ways that alter the long-term pattern of temperature and rainfall that defines a region’s climate.

“Climate change does not mean it will get drier everywhere,” said Ulf Büntgen, who holds research posts in the University of Cambridge, UK and the Czech Republic and Switzerland. “Some places may get wetter or colder, but extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole.” − Climate News Network

Global heating may be to blame for the fact that Europe has grown drier over the last 2,000 years to a new high in 2015.

LONDON, 17 March, 2021 − Europe has grown drier, an outcome shown by the continent’s last five summers, which have been marked by drought that has no parallel in the last two millennia.

Researchers studied two kinds of evidence delivered by 27,000 measurements taken from 21 living oak trees and 126 samples from ancient beams and rafters, to piece together a precise picture of the climate of Germany, Switzerland and the Czech Republic over the last 2,110 years.

They report, after 2015, that drought conditions intensified suddenly, in ways that were beyond anything over that entire 2000-year tract of time. And, they add, “this hydroclimatic anomaly is probably caused by anthropogenic warming.”

Europe is also getting hotter. In 2003, 2015 and 2018 it was hit by severe summer heat waves and spells of drought that damaged plantations, crops and vines; the damage from drought was intensified by more virulent attacks from pathogens, insect outbreaks and tree death.

“Extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole”

In the baking summer of 2003, an estimated 70,000 people died because of extremes of heat. And, the researchers say, “a further increase in the frequency and severity of heat waves under projected global warming implies a multitude of harmful direct and indirect impacts on human health.”

In other words, things are bad now and are likely to get worse, according to a report by 17 British, European and Canadian researchers in the journal Nature Geoscience.

Dendrochronologists can and do routinely build up a picture of bygone temperatures by measuring the growth rings in trees: enough old living trees, and reliable knowledge about the felling of oaks for chateaux, cathedrals, sailing ships, fortresses and stockades can help pinpoint seasonal change on an annual basis.

But trees are also living chronicles of changes in carbon and oxygen isotope ratios − tiny atomic variations in the plant’s biochemistry − which provide evidence of rainfall and therefore a more precise picture of any growing season.

Wandering jet stream

The trees delivered mute evidence of very wet summers in 200, 720 and 1100 AD, and very dry summers in the years 40, 590, 950 and 1510 of the Common Era. But overall the big picture emerged: for the years 75 BC to 2018, Europe has slowly been getting drier.

Even so, the evidence from 2015 to 2018 shows that drought conditions in the area from which the trees were taken far exceeds anything in the previous centuries. The mostly likely explanation is the impact of ever-rising temperatures, driven by ever-higher greenhouse gas emissions from the ever-more profligate combustion of fossil fuels.

These temperatures are now considered high enough to affect the course of the stratospheric jet stream in ways that alter the long-term pattern of temperature and rainfall that defines a region’s climate.

“Climate change does not mean it will get drier everywhere,” said Ulf Büntgen, who holds research posts in the University of Cambridge, UK and the Czech Republic and Switzerland. “Some places may get wetter or colder, but extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole.” − Climate News Network

Extreme drought and fire risk may double by 2060

Climate change may soon double the impact of extreme drought and fire. And it’s a two-way traffic.

LONDON, 25 January, 2021 − As climate change threatens a doubling of the impact of extreme drought and fire within a generation, researchers are uncovering the influence of human activity on both these growing risks.

One study has found that human numbers exposed to the hazard of extreme drought are likely to double in the decades to come, as global heating bakes away the groundwater and limits annual snowfall.

Another team of researchers says the risks of extreme wildfire could also rise twofold in the next 40 years in the Mediterranean, southern Africa, eastern North America and the Amazon. In those places already severely scorched by frequent fire − western North America, equatorial Africa, south-east Asia and Australia − hazards could rise by 50%.

And a third, separate study warns that global temperature rise will shift the patterns of rainfall around the tropics − with the consequent risks to tropical crop harvests and to equatorial ecosystems such as rainforest and savannah.

All three studies are reminders of the intricacies of the planetary climate system and the impact of human action in the last hundred years.

“Areas of the southern hemisphere, where water scarcity is already a problem, will be disproportionately affected. We predict this will affect food security and escalate human migration and conflict.”

An international research team reports in the journal Nature Climate Change that it looked at the simple problem of global terrestrial water storage: all the moisture in the canopies of forest trees, in the mountain snows and ice, in the lakes, rivers, wetlands, and in the soil itself.

This wealth of stored water is a big player in the patterns of global flooding and drought in the monsoon climates and the arid lands alike. But, the researchers say, there has so far been no study of the potential impact of global climate change on global terrestrial water storage overall.

So researchers from the US, China, Japan and Europe began modelling tomorrow’s world. And they found that, while 3% of the planet’s people were vulnerable to extreme drought in the timespan from 1976 to 2005, later in the century this proportion could increase to 7% or even 8%.

“More and more people will suffer from extreme droughts if a medium-to-high level of global warming continues and water management is maintained in its present state,” warned Yadu Pokhrel, an engineer at Michigan State University, who led the research.

“Areas of the southern hemisphere, where water scarcity is already a problem, will be disproportionately affected. We predict this increase in water scarcity will affect food security and escalate human migration and conflict.”

Fire chances increased

Australia is a southern hemisphere country that knows about water scarcity: its wildfires in 2019 broke all records and sent a vast cloud of smoke to an altitude of 35 kms.

And, on the evidence of a new study in the journal Nature Communications, it won’t be the last such extreme event. Californian scientists, struck by the scale and intensity of Californian wildfires in 2017 and 2018, report that they took a closer look at the way greenhouse gas emissions and human land use change have played into the risks of extreme fire weather.

The simple act of setting forests afire to clear land for farm use has amplified the risk of extreme blazes in the Amazon and North America by 30% in the last century. Fires create aerosols that could, by absorbing sunlight, help cool the terrain beneath them − in some zones. But they could also affect rainfall levels and raise the chances of fire. The nature of such impacts varies from place to place.

“South-east Asia relies on the monsoon, but aerosols cause so much cooling on land that they can actually suppress a monsoon,” said Danielle Touma of the University of California at Santa Barbara. “It’s not just whether you have aerosols or not, it’s the way the regional climate interacts with aerosols.”

Aerosols − with other forces − cannot just suppress a monsoon, they can shift rain patterns permanently. The tropics, too, have begun to feel the heat of the moment.

Drought stress rises

The footprint of extreme drought and fire is massive. Californian researchers report in Nature Climate Change that, across two thirds of the globe, the tropical rainbelt is likely to shift north over eastern Africa and the Indian Ocean to cause more drought stress in south-eastern Africa and Madagascar and intensified flooding in south Asia.

In the western hemisphere, however, as the Gulf Stream current and the North Atlantic deep water formation weaken, the rain belt could move south to bring greater drought stress to Central America.

And once again, climate change driven by global heating is at work with other human influences to alter what had for most of human history been a stable pattern of climate.

“In Asia, projected reductions in aerosol emissions, glacier melting in the Himalayas and loss of snow cover in northern areas brought on by climate change will cause the atmosphere to heat up faster than in other regions,” said James Randerson of the University of California, Irvine, one of the authors.

“We know the rainbelt shifts towards this heating, and that its northward movement in the eastern hemisphere is consistent with these expected impacts of climate change.” − Climate News Network

Climate change may soon double the impact of extreme drought and fire. And it’s a two-way traffic.

LONDON, 25 January, 2021 − As climate change threatens a doubling of the impact of extreme drought and fire within a generation, researchers are uncovering the influence of human activity on both these growing risks.

One study has found that human numbers exposed to the hazard of extreme drought are likely to double in the decades to come, as global heating bakes away the groundwater and limits annual snowfall.

Another team of researchers says the risks of extreme wildfire could also rise twofold in the next 40 years in the Mediterranean, southern Africa, eastern North America and the Amazon. In those places already severely scorched by frequent fire − western North America, equatorial Africa, south-east Asia and Australia − hazards could rise by 50%.

And a third, separate study warns that global temperature rise will shift the patterns of rainfall around the tropics − with the consequent risks to tropical crop harvests and to equatorial ecosystems such as rainforest and savannah.

All three studies are reminders of the intricacies of the planetary climate system and the impact of human action in the last hundred years.

“Areas of the southern hemisphere, where water scarcity is already a problem, will be disproportionately affected. We predict this will affect food security and escalate human migration and conflict.”

An international research team reports in the journal Nature Climate Change that it looked at the simple problem of global terrestrial water storage: all the moisture in the canopies of forest trees, in the mountain snows and ice, in the lakes, rivers, wetlands, and in the soil itself.

This wealth of stored water is a big player in the patterns of global flooding and drought in the monsoon climates and the arid lands alike. But, the researchers say, there has so far been no study of the potential impact of global climate change on global terrestrial water storage overall.

So researchers from the US, China, Japan and Europe began modelling tomorrow’s world. And they found that, while 3% of the planet’s people were vulnerable to extreme drought in the timespan from 1976 to 2005, later in the century this proportion could increase to 7% or even 8%.

“More and more people will suffer from extreme droughts if a medium-to-high level of global warming continues and water management is maintained in its present state,” warned Yadu Pokhrel, an engineer at Michigan State University, who led the research.

“Areas of the southern hemisphere, where water scarcity is already a problem, will be disproportionately affected. We predict this increase in water scarcity will affect food security and escalate human migration and conflict.”

Fire chances increased

Australia is a southern hemisphere country that knows about water scarcity: its wildfires in 2019 broke all records and sent a vast cloud of smoke to an altitude of 35 kms.

And, on the evidence of a new study in the journal Nature Communications, it won’t be the last such extreme event. Californian scientists, struck by the scale and intensity of Californian wildfires in 2017 and 2018, report that they took a closer look at the way greenhouse gas emissions and human land use change have played into the risks of extreme fire weather.

The simple act of setting forests afire to clear land for farm use has amplified the risk of extreme blazes in the Amazon and North America by 30% in the last century. Fires create aerosols that could, by absorbing sunlight, help cool the terrain beneath them − in some zones. But they could also affect rainfall levels and raise the chances of fire. The nature of such impacts varies from place to place.

“South-east Asia relies on the monsoon, but aerosols cause so much cooling on land that they can actually suppress a monsoon,” said Danielle Touma of the University of California at Santa Barbara. “It’s not just whether you have aerosols or not, it’s the way the regional climate interacts with aerosols.”

Aerosols − with other forces − cannot just suppress a monsoon, they can shift rain patterns permanently. The tropics, too, have begun to feel the heat of the moment.

Drought stress rises

The footprint of extreme drought and fire is massive. Californian researchers report in Nature Climate Change that, across two thirds of the globe, the tropical rainbelt is likely to shift north over eastern Africa and the Indian Ocean to cause more drought stress in south-eastern Africa and Madagascar and intensified flooding in south Asia.

In the western hemisphere, however, as the Gulf Stream current and the North Atlantic deep water formation weaken, the rain belt could move south to bring greater drought stress to Central America.

And once again, climate change driven by global heating is at work with other human influences to alter what had for most of human history been a stable pattern of climate.

“In Asia, projected reductions in aerosol emissions, glacier melting in the Himalayas and loss of snow cover in northern areas brought on by climate change will cause the atmosphere to heat up faster than in other regions,” said James Randerson of the University of California, Irvine, one of the authors.

“We know the rainbelt shifts towards this heating, and that its northward movement in the eastern hemisphere is consistent with these expected impacts of climate change.” − Climate News Network