Tag Archives: Africa

Less rain will fall during Mediterranean winters

Mediterranean winters could bring 40% less rain, hurting farmers in what’s called the cradle of agriculture – and not only farmers.

LONDON, 2 July, 2020 – A warmer world should also be a wetter one, but not for the cockpit of much of human history: Mediterranean winters will become increasingly parched. Winter rainfall – and winter is the rainy season – could see a 40% fall in precipitation.

Agriculture and human civilisation began in the Fertile Crescent that runs from eastern Turkey to Iraq: cattle, sheep and goats were domesticated there; the first figs, almonds, grapes and pulses were planted there; the progenitors of wheat were sown there.

Cities were built, irrigation schemes devised, empires rose and fell. Greece colonised the Mediterranean, Rome later controlled it and set the pattern of law and civic government for the next 2000 years in Northern Europe.

Islamic forces brought a different civilisation to the Balkans, North Africa and almost all of Spain. The grain fields of the Nile Valley underwrote the expansion of the Roman Empire.

“What’s really different about the Mediterranean is the geography. You have a big sea enclosed by continents, which doesn’t really occur anywhere else in the world”

But the pressure of history is likely to be affected by the high pressure of summers to come. In a world of rapid climate change, the already dry and sunny enclosed sea will become sunnier and drier, according to two scientists from the Massachusetts Institute of Technology.

They report in the American Meteorological Society’s Journal of Climate that the winter rains that are normally expected to fill the reservoirs and nourish the rich annual harvest from the orchards, vineyards and wheat fields can be expected to diminish significantly, as atmospheric pressures rise, to reduce rainfall by somewhere between 10% and 60%.

Ordinarily, a warmer world should be a wetter one. More water evaporates, and with each degree-rise in temperature the capacity of the air to hold water vapour increases by 7%, to fall inevitably as rain, somewhere.

But episodes of low pressure associated with rain clouds over the Mediterranean become less likely, according to climate simulations. The topography of the landscape and sea determines the probable pattern of the winds.

High pressure grows

“It just happened that the geography of where the Mediterranean is, and where the mountains are, impacts the pattern of air flow high in the atmosphere in a way that creates a high-pressure area over the Mediterranean,” said Alexandre Tuel, one of the authors.

“What’s really different about the Mediterranean compared to other regions is the geography. Basically, you have a big sea enclosed by continents, which doesn’t really occur anywhere else in the world.”

Another factor is the rate of warming: land warms faster than sea. The North African seaboard and the southern fringe of Europe will become 3 to 4°C hotter over the next hundred years. The sea will warm by only 2°C. The difference between land and sea will become smaller, to add to the pattern of high pressure circulation.

“Basically, the difference between the water and the land becomes smaller with time,” Tuel says.

Frequent warnings

Once again, the finding is no surprise: Europe has a long history of drought and flood, but drought tends to leave the more permanent mark. The eastern Mediterranean has already experienced its harshest drought for 900 years and this has been linked to the bitter conflict in Syria.

Researchers have repeatedly warned that the pattern of drought on the continent is likely to intensify, and at considerable economic and human cost.

What is different is that the latest research offers detailed predictions of the nature of change, and identifies the regions likeliest to be worst hit. These include Morocco in north-west Africa, and the eastern Mediterranean of Turkey and the Levant.

“These are areas where we already detect declines in precipitation,” said Elfatih Eltahir, the senior author. “We document from the observed record of precipitation that this eastern part has already experienced a significant decline of precipitation.” – Climate News Network

Mediterranean winters could bring 40% less rain, hurting farmers in what’s called the cradle of agriculture – and not only farmers.

LONDON, 2 July, 2020 – A warmer world should also be a wetter one, but not for the cockpit of much of human history: Mediterranean winters will become increasingly parched. Winter rainfall – and winter is the rainy season – could see a 40% fall in precipitation.

Agriculture and human civilisation began in the Fertile Crescent that runs from eastern Turkey to Iraq: cattle, sheep and goats were domesticated there; the first figs, almonds, grapes and pulses were planted there; the progenitors of wheat were sown there.

Cities were built, irrigation schemes devised, empires rose and fell. Greece colonised the Mediterranean, Rome later controlled it and set the pattern of law and civic government for the next 2000 years in Northern Europe.

Islamic forces brought a different civilisation to the Balkans, North Africa and almost all of Spain. The grain fields of the Nile Valley underwrote the expansion of the Roman Empire.

“What’s really different about the Mediterranean is the geography. You have a big sea enclosed by continents, which doesn’t really occur anywhere else in the world”

But the pressure of history is likely to be affected by the high pressure of summers to come. In a world of rapid climate change, the already dry and sunny enclosed sea will become sunnier and drier, according to two scientists from the Massachusetts Institute of Technology.

They report in the American Meteorological Society’s Journal of Climate that the winter rains that are normally expected to fill the reservoirs and nourish the rich annual harvest from the orchards, vineyards and wheat fields can be expected to diminish significantly, as atmospheric pressures rise, to reduce rainfall by somewhere between 10% and 60%.

Ordinarily, a warmer world should be a wetter one. More water evaporates, and with each degree-rise in temperature the capacity of the air to hold water vapour increases by 7%, to fall inevitably as rain, somewhere.

But episodes of low pressure associated with rain clouds over the Mediterranean become less likely, according to climate simulations. The topography of the landscape and sea determines the probable pattern of the winds.

High pressure grows

“It just happened that the geography of where the Mediterranean is, and where the mountains are, impacts the pattern of air flow high in the atmosphere in a way that creates a high-pressure area over the Mediterranean,” said Alexandre Tuel, one of the authors.

“What’s really different about the Mediterranean compared to other regions is the geography. Basically, you have a big sea enclosed by continents, which doesn’t really occur anywhere else in the world.”

Another factor is the rate of warming: land warms faster than sea. The North African seaboard and the southern fringe of Europe will become 3 to 4°C hotter over the next hundred years. The sea will warm by only 2°C. The difference between land and sea will become smaller, to add to the pattern of high pressure circulation.

“Basically, the difference between the water and the land becomes smaller with time,” Tuel says.

Frequent warnings

Once again, the finding is no surprise: Europe has a long history of drought and flood, but drought tends to leave the more permanent mark. The eastern Mediterranean has already experienced its harshest drought for 900 years and this has been linked to the bitter conflict in Syria.

Researchers have repeatedly warned that the pattern of drought on the continent is likely to intensify, and at considerable economic and human cost.

What is different is that the latest research offers detailed predictions of the nature of change, and identifies the regions likeliest to be worst hit. These include Morocco in north-west Africa, and the eastern Mediterranean of Turkey and the Levant.

“These are areas where we already detect declines in precipitation,” said Elfatih Eltahir, the senior author. “We document from the observed record of precipitation that this eastern part has already experienced a significant decline of precipitation.” – Climate News Network

3 bn people may face Saharan heat levels by 2070

For three billion people or more, heat levels could prove almost impossible for human civilisation – in half a century.

LONDON, 3 June, 2020 – If humans go on burning ever more fossil fuels to put ever higher concentrations of greenhouse gases into the atmosphere, then one third of the world’s population may face – within 50 years – heat levels that could be all but intolerable.

By 2070, 19% of the land area of the planet, home to 3.5 billion people, could be faced with a mean annual temperature of 29°C. That is, although there would be seasons in which temperatures fell well below this average, these would be followed by summers in which the thermometer went much higher.

Right now, only 0.8% of the land surface of the planet experiences such a mean annual temperature, and most of this space is located in the Saharan desert region of North Africa. But population growth – already highest in the poorest and hottest parts of the globe – and the projected increases in planetary average temperatures will expand this danger zone to almost one fifth of the planet’s land area, to embrace a third of the world’s people.

The conclusion – published in the Proceedings of the National Academy of Sciences – sounds like a dramatic advance on repeated warnings that planetary average temperatures could be 3°C above the long-term average for almost all of human history. But it may not be.

One important difference is that climate science forecasts tend to describe the entire planet. But almost three fourths of the planet is ocean, which is warming much more slowly than the land surfaces. Another is that climate forecasts predict average change for a sphere with a circumference of 40,000 kms. And the third factor is that such predictions do not specifically address where humans choose to live.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche”

Xu Chi of Nanjing University in China and his European co-authors started from the premise that humans – like all animal species – have a preferred climate niche. They looked back through 6000 years of the history of civilisation and concluded that most of humankind flourished within a climate space between annual averages of 11°C and 15°C. A much smaller number of people lived in places where the average temperature was between 20°C and 25°C.

And they found that – although civilisations rose and fell, whole peoples disappeared, wars, plagues and famines struck, and entire populations migrated to or invaded other homes – nearly all of humankind continued to prefer to live in land zones at between 11°C and 15°C.

“This strikingly constant climate niche likely represents fundamental constraints on what humans need to survive and thrive,” said Marten Scheffer of Wageningen University in the Netherlands.

But in the next 50 years, the average temperature experienced by an average human is expected to rise by 7.5°C. And because population growth is highest in the already hottest regions, these temperature rises will affect more and more people.

Warnings mount

By 2070 this total could reach 3.5bn people, across 19% of the planet’s land surface, many of them exposed to temperatures and climate conditions that right now would be considered difficult to survive.

In just the last six or seven weeks, climate scientists have warned that rising temperatures present a direct threat to the natural ecosystems on which human civilisation depends; that the number of days that US farmworkers will find dangerously hot will almost double; that potentially lethal combinations of heat and humidity trailed as a future hazard may already have arrived, in limited locations for brief periods; that some will find more heat brings more extremes of rainfall, while other regions will become increasingly arid; and that South Asia, in particular, is at increasing hazard from ever more extreme temperatures and choking pollution, thanks to global climate change.

But the latest attempt to look at the big picture trumps all of these already bleak findings. As usual, other climate researchers will question their assumptions and challenge their conclusions, but the authors are fairly sure of their ground.

“We were frankly blown away by our initial results,” said Dr Xu. “As our findings were striking, we took an extra year to carefully check all assumptions and computations. We also decided to publish all data and computer codes for transparency and to facilitate follow-up work by others.

“The results are as important to China as they are to any other nation. Clearly we will need a global approach to safeguard our children against the potentially enormous social tensions the projected change could invoke.”

Range of pressures

This also raises issues already repeatedly raised by climate forecasters: the people most threatened by climate change are already among the world’s poorest. So there will be pressure to migrate. And there will be potential for conflict.

What will happen in the next 50 years under circumstances in which governments go on authorising fossil fuel consumption is difficult to predict with any certainty. Communities will to a certain extent adapt. Economic development could help contain some of the challenges. And governments could decide to act.

“The good news is that these impacts can be greatly reduced if humanity succeeds in curbing global warming,” said Tim Lenton, of Exeter University in the UK.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche.” – Climate News Network

For three billion people or more, heat levels could prove almost impossible for human civilisation – in half a century.

LONDON, 3 June, 2020 – If humans go on burning ever more fossil fuels to put ever higher concentrations of greenhouse gases into the atmosphere, then one third of the world’s population may face – within 50 years – heat levels that could be all but intolerable.

By 2070, 19% of the land area of the planet, home to 3.5 billion people, could be faced with a mean annual temperature of 29°C. That is, although there would be seasons in which temperatures fell well below this average, these would be followed by summers in which the thermometer went much higher.

Right now, only 0.8% of the land surface of the planet experiences such a mean annual temperature, and most of this space is located in the Saharan desert region of North Africa. But population growth – already highest in the poorest and hottest parts of the globe – and the projected increases in planetary average temperatures will expand this danger zone to almost one fifth of the planet’s land area, to embrace a third of the world’s people.

The conclusion – published in the Proceedings of the National Academy of Sciences – sounds like a dramatic advance on repeated warnings that planetary average temperatures could be 3°C above the long-term average for almost all of human history. But it may not be.

One important difference is that climate science forecasts tend to describe the entire planet. But almost three fourths of the planet is ocean, which is warming much more slowly than the land surfaces. Another is that climate forecasts predict average change for a sphere with a circumference of 40,000 kms. And the third factor is that such predictions do not specifically address where humans choose to live.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche”

Xu Chi of Nanjing University in China and his European co-authors started from the premise that humans – like all animal species – have a preferred climate niche. They looked back through 6000 years of the history of civilisation and concluded that most of humankind flourished within a climate space between annual averages of 11°C and 15°C. A much smaller number of people lived in places where the average temperature was between 20°C and 25°C.

And they found that – although civilisations rose and fell, whole peoples disappeared, wars, plagues and famines struck, and entire populations migrated to or invaded other homes – nearly all of humankind continued to prefer to live in land zones at between 11°C and 15°C.

“This strikingly constant climate niche likely represents fundamental constraints on what humans need to survive and thrive,” said Marten Scheffer of Wageningen University in the Netherlands.

But in the next 50 years, the average temperature experienced by an average human is expected to rise by 7.5°C. And because population growth is highest in the already hottest regions, these temperature rises will affect more and more people.

Warnings mount

By 2070 this total could reach 3.5bn people, across 19% of the planet’s land surface, many of them exposed to temperatures and climate conditions that right now would be considered difficult to survive.

In just the last six or seven weeks, climate scientists have warned that rising temperatures present a direct threat to the natural ecosystems on which human civilisation depends; that the number of days that US farmworkers will find dangerously hot will almost double; that potentially lethal combinations of heat and humidity trailed as a future hazard may already have arrived, in limited locations for brief periods; that some will find more heat brings more extremes of rainfall, while other regions will become increasingly arid; and that South Asia, in particular, is at increasing hazard from ever more extreme temperatures and choking pollution, thanks to global climate change.

But the latest attempt to look at the big picture trumps all of these already bleak findings. As usual, other climate researchers will question their assumptions and challenge their conclusions, but the authors are fairly sure of their ground.

“We were frankly blown away by our initial results,” said Dr Xu. “As our findings were striking, we took an extra year to carefully check all assumptions and computations. We also decided to publish all data and computer codes for transparency and to facilitate follow-up work by others.

“The results are as important to China as they are to any other nation. Clearly we will need a global approach to safeguard our children against the potentially enormous social tensions the projected change could invoke.”

Range of pressures

This also raises issues already repeatedly raised by climate forecasters: the people most threatened by climate change are already among the world’s poorest. So there will be pressure to migrate. And there will be potential for conflict.

What will happen in the next 50 years under circumstances in which governments go on authorising fossil fuel consumption is difficult to predict with any certainty. Communities will to a certain extent adapt. Economic development could help contain some of the challenges. And governments could decide to act.

“The good news is that these impacts can be greatly reduced if humanity succeeds in curbing global warming,” said Tim Lenton, of Exeter University in the UK.

“Our computations show that each degree of warming above present levels corresponds to roughly one billion people falling outside of the climate niche.” – Climate News Network

Tropical forests’ damage spreads catastrophically

Human inroads into tropical forests stretch far beyond oil plantations or the edge of cattle ranches and are a wider threat to conservation.

LONDON, 7 April, 2020 – Tropical forests are vital in the campaign to limit global heating. Here’s how to blunt them as a force – just put a clearing, or a plantation, a road or a ranch in the pristine wilderness. And then, as absorbers of atmospheric carbon, the trees up to 100 metres deep into the jungle will lose their edge.

Along that 100 metre width, the canopy height, leaf mass and phosphorus levels per square metre will begin to change. All three are measures of a tree’s capacity to grow vigorously and store carbon.

Researchers call this the edge effect. It matters. The world now has 1.2bn hectares of remaining tropical forest. This is an area far bigger than Canada.

But invasion of what, just one lifetime ago, were still unmapped wildernesses is now so aggressive that almost one fifth of the area of the world’s tropical forest is within 100 metres of a non-forest edge.

And about half of all the forest is within 500 metres of a ranch, road, settlement or plantation.

“The importance of this discovery trickles all the way down to how conservation managers work to mitigate biodiversity losses associated with agricultural expansion”

Scientists from the US report in the Proceedings of the National Academy of Sciences that they mapped change in the forests of Malaysian Borneo, looking closely at the sites where forest and commercial palm oil plantation co-exist.

They report that the levels of carbon stored “above ground” – that is, in the trunk and canopy – fell by an average of 22% along the forest edges, to a depth of 100 metres. The older this forest edge, the greater the fall in stored carbon.

There are already reports that degradation of the rainforest in the Amazon and Congo, amplified by the impact of climate change in the form of extreme heat and drought, is so advanced that within a decade or two these forests could cease to be “sinks” for atmospheric carbon, and instead start adding to the world’s burden of greenhouse gases that threaten to accelerate climate change, with potentially catastrophic consequences.

The world’s forests are vital in the global plans to contain or limit climate change driven by profligate combustion of fossil fuels that release carbon dioxide and other greenhouse gases.

Research has repeatedly confirmed that undisturbed forest is an efficient absorber and permanent store of atmospheric carbon and that almost any human transgression could damage the capacity of the rainforest to absorb carbon.

Road web spreads

And yet all the signs are ominous: humans will go on making inroads into natural wilderness, in the most literal sense: by 2050, there could be 25 million km new road lanes, most of them in the developing world, to carry timber trucks, livestock and minerals through the world’s forests.

There is an argument that “smart” roads can limit the damage to the environment and society caused by indiscriminate engineering: one group advocating this approach is the Centre for Tropical Environmental and Sustainability Science (TESS), based at James Cook University in Australia.

But the threat to the remaining forests is now so pronounced that many researchers simply point out, in the kind of understatement that comes naturally to scientists, that such changes have “far-reaching implications” for the conservation of forest biodiversity and carbon stocks.

They see their research as a potential guide to government and local authorities on the management of the remaining wild woodland.

“Not all forest-agriculture boundaries are created equal, and most remaining forests change for many years following the original land conversion that takes place nearby,” said Greg Asner of Arizona State University, one of the researchers.

“The importance of this discovery trickles all the way down to how conservation managers work to mitigate biodiversity losses associated with agricultural expansion.” – Climate News Network

Human inroads into tropical forests stretch far beyond oil plantations or the edge of cattle ranches and are a wider threat to conservation.

LONDON, 7 April, 2020 – Tropical forests are vital in the campaign to limit global heating. Here’s how to blunt them as a force – just put a clearing, or a plantation, a road or a ranch in the pristine wilderness. And then, as absorbers of atmospheric carbon, the trees up to 100 metres deep into the jungle will lose their edge.

Along that 100 metre width, the canopy height, leaf mass and phosphorus levels per square metre will begin to change. All three are measures of a tree’s capacity to grow vigorously and store carbon.

Researchers call this the edge effect. It matters. The world now has 1.2bn hectares of remaining tropical forest. This is an area far bigger than Canada.

But invasion of what, just one lifetime ago, were still unmapped wildernesses is now so aggressive that almost one fifth of the area of the world’s tropical forest is within 100 metres of a non-forest edge.

And about half of all the forest is within 500 metres of a ranch, road, settlement or plantation.

“The importance of this discovery trickles all the way down to how conservation managers work to mitigate biodiversity losses associated with agricultural expansion”

Scientists from the US report in the Proceedings of the National Academy of Sciences that they mapped change in the forests of Malaysian Borneo, looking closely at the sites where forest and commercial palm oil plantation co-exist.

They report that the levels of carbon stored “above ground” – that is, in the trunk and canopy – fell by an average of 22% along the forest edges, to a depth of 100 metres. The older this forest edge, the greater the fall in stored carbon.

There are already reports that degradation of the rainforest in the Amazon and Congo, amplified by the impact of climate change in the form of extreme heat and drought, is so advanced that within a decade or two these forests could cease to be “sinks” for atmospheric carbon, and instead start adding to the world’s burden of greenhouse gases that threaten to accelerate climate change, with potentially catastrophic consequences.

The world’s forests are vital in the global plans to contain or limit climate change driven by profligate combustion of fossil fuels that release carbon dioxide and other greenhouse gases.

Research has repeatedly confirmed that undisturbed forest is an efficient absorber and permanent store of atmospheric carbon and that almost any human transgression could damage the capacity of the rainforest to absorb carbon.

Road web spreads

And yet all the signs are ominous: humans will go on making inroads into natural wilderness, in the most literal sense: by 2050, there could be 25 million km new road lanes, most of them in the developing world, to carry timber trucks, livestock and minerals through the world’s forests.

There is an argument that “smart” roads can limit the damage to the environment and society caused by indiscriminate engineering: one group advocating this approach is the Centre for Tropical Environmental and Sustainability Science (TESS), based at James Cook University in Australia.

But the threat to the remaining forests is now so pronounced that many researchers simply point out, in the kind of understatement that comes naturally to scientists, that such changes have “far-reaching implications” for the conservation of forest biodiversity and carbon stocks.

They see their research as a potential guide to government and local authorities on the management of the remaining wild woodland.

“Not all forest-agriculture boundaries are created equal, and most remaining forests change for many years following the original land conversion that takes place nearby,” said Greg Asner of Arizona State University, one of the researchers.

“The importance of this discovery trickles all the way down to how conservation managers work to mitigate biodiversity losses associated with agricultural expansion.” – Climate News Network

Tropical forests may be heating Earth by 2035

Climate change so far has meant more vigorous forest growth as greenhouse gases rise. The tropical forests may soon change that.

LONDON, 6 March, 2020 – Within about fifteen years, the great tropical forests of Amazonia and Africa could stop absorbing atmospheric carbon, and slowly start to release more carbon than growing trees can fix.

A team of scientists from 100 research institutions has looked at the evidence from pristine tracts of tropical forest to find that – overall – the foliage soaked up the most carbon, most efficiently, more than two decades ago.

Since then, the measured efficiency of the forests as a “sink” in which carbon is sequestered from the atmosphere has been dwindling. By the last decade, the ability of a tropical forest to absorb carbon had dropped by a third.

All plant growth is a balancing act based on sunshine and atmospheric carbon and rainfall. Plants absorb carbon dioxide as they grow, and surrender it as they die.

In a dense, undisturbed wilderness, fallen leaves and even fallen trees are slightly less likely to decompose completely: the atmospheric carbon in leaf and wood form has a better chance of being preserved in flooded forests as peat, or being buried before it can completely decompose.

The forest becomes a bank vault, repository or sink of the extra carbon that humans are now spilling into the atmosphere from car exhausts, factory chimneys and power station furnaces.

Theory and practice

And in theory, as more and more carbon dioxide gets into the atmosphere, plants respond to the more generous fertilisation by growing more vigorously, and absorbing more carbon.

But as more carbon gets into the atmosphere, the temperature rises and weather patterns begin to become more extreme. Summers get hotter, rainfall more capricious. Then trees become vulnerable to drought, forest fire and invasive diseases, and die more often, and decompose more completely.

Wannes Hubau, once of the University of Leeds in the UK and now at the Royal Museum for Central Africa in Belgium, and more than 100 colleagues from around the world, report in the journal Nature that they assembled 30 years of measurement from more than 300,000 trees in 244 undisturbed plots of forest in 11 countries in Africa, and from 321 plots of forest in Amazonia, and did the sums.

In the 1990s, intact tropical forests removed around 46 billion tonnes of carbon dioxide from the atmosphere. By the 2010s, the uptake had fallen to around 25 billion tonnes. This means that 21 billion tons of greenhouse gas that might otherwise have been turned into timber and root had been added to the atmosphere.

This is pretty much what the UK, France, Germany and Canada together spilled into the atmosphere from fossil fuel combustion over a 10-year period.

“We’ve found one of the most worrying impacts of climate change has already begun. This is decades ahead of even the most pessimistic climate models”

“Extra carbon boosts tree growth, but every year this effect is being increasingly countered by the negative impacts of higher temperatures and droughts which slow growth and can kill trees,” said Dr Hubau.

“Our modeling shows a long-term decline in the African sink and that the Amazon sink will continue to rapidly weaken, which we predict will become a carbon source in the mid-2030s.”

Tropical forests are an integral factor in the planetary carbon budget – a crude accounting system that climate scientists rely upon to model the choice of futures that face humankind as the world heats up.

Around half of Earth’s carbon is stored in terrestrial vegetation and the tropical forests account for about a third of the planet’s primary productivity. So how forests respond to a warmer world is vital.

Because the Amazon region is being hit by higher temperatures, and more frequent and prolonged droughts than forests in tropical Africa, Amazonia is weakening at a faster rate.

But decline has also begun in Africa. In the 1990s, the undisturbed tropical forests alone inhaled 17% of human-made carbon dioxide emissions. In the decade just ended, this proportion fell to 6%.

Catastrophic prospect

In roughly the same period, the area of intact forest fell by 19%, and global carbon dioxide emissions rose by 46%. Even so, the tropical forests store 250 billion tonnes of carbon in their trees alone: 90 years of fossil fuel emissions at the present rate. So their sustained loss would be catastrophic.

“Intact tropical forests remain a vital carbon sink but this research reveals that unless policies are put in place to stabilise the Earth’s climate, it is only a matter of time until they are no longer able to sequester carbon,” said Simon Lewis, a geographer at the University of Leeds, and one of the authors.

“One big concern for the future of humanity is when carbon-cycle feedbacks really kick in, with nature switching from slowing climate change to accelerating it.

“After years of work deep in the Congo and Amazon rainforests, we’ve found one of the most worrying impacts of climate change has already begun.

“This is decades ahead of even the most pessimistic climate models. There is no time to lose in tackling climate change.” – Climate News Network

Climate change so far has meant more vigorous forest growth as greenhouse gases rise. The tropical forests may soon change that.

LONDON, 6 March, 2020 – Within about fifteen years, the great tropical forests of Amazonia and Africa could stop absorbing atmospheric carbon, and slowly start to release more carbon than growing trees can fix.

A team of scientists from 100 research institutions has looked at the evidence from pristine tracts of tropical forest to find that – overall – the foliage soaked up the most carbon, most efficiently, more than two decades ago.

Since then, the measured efficiency of the forests as a “sink” in which carbon is sequestered from the atmosphere has been dwindling. By the last decade, the ability of a tropical forest to absorb carbon had dropped by a third.

All plant growth is a balancing act based on sunshine and atmospheric carbon and rainfall. Plants absorb carbon dioxide as they grow, and surrender it as they die.

In a dense, undisturbed wilderness, fallen leaves and even fallen trees are slightly less likely to decompose completely: the atmospheric carbon in leaf and wood form has a better chance of being preserved in flooded forests as peat, or being buried before it can completely decompose.

The forest becomes a bank vault, repository or sink of the extra carbon that humans are now spilling into the atmosphere from car exhausts, factory chimneys and power station furnaces.

Theory and practice

And in theory, as more and more carbon dioxide gets into the atmosphere, plants respond to the more generous fertilisation by growing more vigorously, and absorbing more carbon.

But as more carbon gets into the atmosphere, the temperature rises and weather patterns begin to become more extreme. Summers get hotter, rainfall more capricious. Then trees become vulnerable to drought, forest fire and invasive diseases, and die more often, and decompose more completely.

Wannes Hubau, once of the University of Leeds in the UK and now at the Royal Museum for Central Africa in Belgium, and more than 100 colleagues from around the world, report in the journal Nature that they assembled 30 years of measurement from more than 300,000 trees in 244 undisturbed plots of forest in 11 countries in Africa, and from 321 plots of forest in Amazonia, and did the sums.

In the 1990s, intact tropical forests removed around 46 billion tonnes of carbon dioxide from the atmosphere. By the 2010s, the uptake had fallen to around 25 billion tonnes. This means that 21 billion tons of greenhouse gas that might otherwise have been turned into timber and root had been added to the atmosphere.

This is pretty much what the UK, France, Germany and Canada together spilled into the atmosphere from fossil fuel combustion over a 10-year period.

“We’ve found one of the most worrying impacts of climate change has already begun. This is decades ahead of even the most pessimistic climate models”

“Extra carbon boosts tree growth, but every year this effect is being increasingly countered by the negative impacts of higher temperatures and droughts which slow growth and can kill trees,” said Dr Hubau.

“Our modeling shows a long-term decline in the African sink and that the Amazon sink will continue to rapidly weaken, which we predict will become a carbon source in the mid-2030s.”

Tropical forests are an integral factor in the planetary carbon budget – a crude accounting system that climate scientists rely upon to model the choice of futures that face humankind as the world heats up.

Around half of Earth’s carbon is stored in terrestrial vegetation and the tropical forests account for about a third of the planet’s primary productivity. So how forests respond to a warmer world is vital.

Because the Amazon region is being hit by higher temperatures, and more frequent and prolonged droughts than forests in tropical Africa, Amazonia is weakening at a faster rate.

But decline has also begun in Africa. In the 1990s, the undisturbed tropical forests alone inhaled 17% of human-made carbon dioxide emissions. In the decade just ended, this proportion fell to 6%.

Catastrophic prospect

In roughly the same period, the area of intact forest fell by 19%, and global carbon dioxide emissions rose by 46%. Even so, the tropical forests store 250 billion tonnes of carbon in their trees alone: 90 years of fossil fuel emissions at the present rate. So their sustained loss would be catastrophic.

“Intact tropical forests remain a vital carbon sink but this research reveals that unless policies are put in place to stabilise the Earth’s climate, it is only a matter of time until they are no longer able to sequester carbon,” said Simon Lewis, a geographer at the University of Leeds, and one of the authors.

“One big concern for the future of humanity is when carbon-cycle feedbacks really kick in, with nature switching from slowing climate change to accelerating it.

“After years of work deep in the Congo and Amazon rainforests, we’ve found one of the most worrying impacts of climate change has already begun.

“This is decades ahead of even the most pessimistic climate models. There is no time to lose in tackling climate change.” – Climate News Network

Egyptian theatre aids climate change fight

To help to alert people to the hotter future ahead, an Egyptian theatre troupe is taking the climate message to villages to enlist farmers.

LONDON, 4 September, 2019 − Ever been to an Egyptian theatre? Go to one if you get the chance. You might have an enlightening time.

How to get the message about a warming world and the challenges ahead across to people in a straightforward, simple way is a problem as old as climate change itself:

In a project funded by the World Food Programme, a group of local actors is touring villages in Egypt, putting on performances on the theme of climate change. The aim is to persuade farmers to pool their efforts in order to adapt to the changing weather patterns already evident in many areas.

Egypt is considered a country acutely vulnerable to changes in climate. The Nile Delta, densely populated and the centre of Egypt’s vast agricultural sector, is already threatened by sea level rise, its lands eaten away by salt intrusion from the Mediterranean.

Several settlements along Egypt’s north coast, including Alexandria, the country’s second most populated city, are regularly inundated by seawater.

“The plays seek to encourage villagers to form co-operatives in order to maximise the output of wheat and other crops and use less wasteful methods of irrigation”

Rising temperatures mean more water is being evaporated from the Nile, Egypt’s water lifeline. Extensive dam building upstream further threatens Nile water flows.

The theatre project, though, is playing to packed houses. The crowds are flocking in to see what is a mix of entertainment and information on ways that farming methods can be adapted to changes in climate. Light-hearted banter is part of the show.

Bloomberg news agency reports that the plays seek to encourage villagers to form co-operatives in order to maximise the output of wheat and other crops and use less wasteful methods of irrigation, so as to conserve precious water resources.

One recent play, according to Bloomberg, featured a farmer unwilling to co-operate with his neighbours to fight climate change and refusing to help pay for a new irrigation canal. In the end, though, the farmer realises the folly of his actions.

Almost 30% of jobs in Egypt are in agriculture, and farmers regularly have to battle the impact of increases in temperature and more sporadic rainfall patterns.

Sun power replaces diesel

A heatwave in 2010 resulted in serious losses for Egypt’s wheat crop, a staple in the diet of the country’s population of nearly 100 million people. Earlier this year temperatures reached near-record levels, particularly in the south of the country. Last year sudden rain deluges caused flooding in several cities.

Bloomberg reports that the theatre shows have had an impact; in many areas solar-powered irrigation pumps have replaced diesel pumps.

Forecasts of sudden changes in weather are broadcast from mosques and via mobile phones. As a result of more co-operation between farmers and increased efficiency in the use of water resources, wheat output has improved, especially in the south of the country.

Recent reports have indicated that the Middle East and North Africa region (MENA) will have to endure ever-higher temperatures in the years ahead. Researchers say parts of the region can expect increased social unrest. Others have warned that extreme heat and humidity may make some areas uninhabitable, with outside activities having to be severely restricted.

Last month came a warning that the rising heat could threaten the lives of many thousands of Muslims performing the annual Hajj pilgrimage to Egypt’s neighbour Saudi Arabia. − Climate News Network

To help to alert people to the hotter future ahead, an Egyptian theatre troupe is taking the climate message to villages to enlist farmers.

LONDON, 4 September, 2019 − Ever been to an Egyptian theatre? Go to one if you get the chance. You might have an enlightening time.

How to get the message about a warming world and the challenges ahead across to people in a straightforward, simple way is a problem as old as climate change itself:

In a project funded by the World Food Programme, a group of local actors is touring villages in Egypt, putting on performances on the theme of climate change. The aim is to persuade farmers to pool their efforts in order to adapt to the changing weather patterns already evident in many areas.

Egypt is considered a country acutely vulnerable to changes in climate. The Nile Delta, densely populated and the centre of Egypt’s vast agricultural sector, is already threatened by sea level rise, its lands eaten away by salt intrusion from the Mediterranean.

Several settlements along Egypt’s north coast, including Alexandria, the country’s second most populated city, are regularly inundated by seawater.

“The plays seek to encourage villagers to form co-operatives in order to maximise the output of wheat and other crops and use less wasteful methods of irrigation”

Rising temperatures mean more water is being evaporated from the Nile, Egypt’s water lifeline. Extensive dam building upstream further threatens Nile water flows.

The theatre project, though, is playing to packed houses. The crowds are flocking in to see what is a mix of entertainment and information on ways that farming methods can be adapted to changes in climate. Light-hearted banter is part of the show.

Bloomberg news agency reports that the plays seek to encourage villagers to form co-operatives in order to maximise the output of wheat and other crops and use less wasteful methods of irrigation, so as to conserve precious water resources.

One recent play, according to Bloomberg, featured a farmer unwilling to co-operate with his neighbours to fight climate change and refusing to help pay for a new irrigation canal. In the end, though, the farmer realises the folly of his actions.

Almost 30% of jobs in Egypt are in agriculture, and farmers regularly have to battle the impact of increases in temperature and more sporadic rainfall patterns.

Sun power replaces diesel

A heatwave in 2010 resulted in serious losses for Egypt’s wheat crop, a staple in the diet of the country’s population of nearly 100 million people. Earlier this year temperatures reached near-record levels, particularly in the south of the country. Last year sudden rain deluges caused flooding in several cities.

Bloomberg reports that the theatre shows have had an impact; in many areas solar-powered irrigation pumps have replaced diesel pumps.

Forecasts of sudden changes in weather are broadcast from mosques and via mobile phones. As a result of more co-operation between farmers and increased efficiency in the use of water resources, wheat output has improved, especially in the south of the country.

Recent reports have indicated that the Middle East and North Africa region (MENA) will have to endure ever-higher temperatures in the years ahead. Researchers say parts of the region can expect increased social unrest. Others have warned that extreme heat and humidity may make some areas uninhabitable, with outside activities having to be severely restricted.

Last month came a warning that the rising heat could threaten the lives of many thousands of Muslims performing the annual Hajj pilgrimage to Egypt’s neighbour Saudi Arabia. − Climate News Network

Elephants’ diets help forests to thrive

Elephants may throw their weight around, but they pay their dues to the environment: they help the great forests store ever more carbon.

LONDON, 30 July, 2019 – Like humans, all social animals exploit, disturb and alter their natural environment. Biologists have just identified at least one species, elephants, that – in the course of bulldozing their way through the undergrowth and destroying young trees – actually make the forest more efficient at storing carbon and thus containing global heating.

The African forest elephant Loxodonta cyclotis browses upon and uproots young trees with stems smaller than 30cms and deposits the digested foliage as fertiliser, rich in seeds for the next generation of saplings.

Researchers from Italy, France, Brazil and the US report in the journal Nature Geoscience that this simple act – performed by perhaps one elephant in one square kilometre of forest – actually adds to the biomass locked in the remaining timber at the rate of by between 26 and 60 tonnes per hectare.

And if these ancient mega-herbivores were not crashing through the forest, consuming young trees, the forest would be home to 7% less biomass in the form of dense timber.

Forest elephants, the same scientists say, are rapidly declining in numbers. The researchers had been studying the species for years, and devised a mathematical model of their impact on the environment that supported them.

“Humanity is doing its best to rid the planet of elephants as quickly as it can. Forest elephants are facing extinction. All of their positive effect on carbon and their roles as forest gardeners and engineers will be lost”

Humans convert forest to farmland and increase the levels of carbon dioxide and other greenhouse gases that fuel global heating and the climate emergency. Forest elephants, on the other hand, simply alter the composition of the forest and make their environment a little cooler.

They do so by clearing away the fast-growing species to make more space for trees slower to climb towards the sunlight but with timber of higher density.

“Lo and behold, as we look at numbers of elephants in a forest and we look at the composition of forest over time, we find that the proportion of trees with high-density wood is higher in forests with elephants,” said Stephen Blake of St Louis University in the US, one of the authors.

“The simulation found that the slow-growing plant species survive better when elephants are present. These species aren’t eaten by elephants and, over time, the forest becomes dominated by these slow-growing species. Wood (lignin) has a carbon backbone, meaning it has a large number of carbon molecules in it.

“Slow-growing high wood-density species contain more carbon molecules per unit volume than fast-growing low wood-density species. As the elephants ‘thin’ the forest, they increase the number of slow-growing trees and the forest is capable of storing more carbon.”

Support for Gaia

The finding is consistent with the Gaia theory of earth system science: that life unconsciously but collectively tends to work in ways that keep the planet’s atmosphere stable and the planetary temperatures within comfortable boundaries.

So far humans are the most conspicuous exception to this rule. Biologists have wondered about the contribution of the mega-herbivores: in this one case, it seems that forest elephants are good for the forest and good for climate control.

The finding is also consistent with an argument put by conservationists, biologists and climate scientists: the healthiest and most efficient forests at absorbing atmospheric carbon are those that are home to the richest levels of biodiversity – that is, forests that remain natural wilderness.

Biologists and conservationists talk a lot about “ecosystem services” and “natural capital”: that is, the contribution of the natural world,  directly or indirectly, to human wealth. The researchers put a cash value on the carbon contribution of the African forest elephants: they perform a carbon storage service of $43 bn.

“The sad reality is that humanity is doing its best to rid the planet of elephants as quickly as it can,” said Dr Blake. “Forest elephants are rapidly declining and facing extinction. From a climate perspective, all of their positive effect on carbon and their myriad other ecological roles as forest gardeners and engineers will be lost.” – Climate News Network

Elephants may throw their weight around, but they pay their dues to the environment: they help the great forests store ever more carbon.

LONDON, 30 July, 2019 – Like humans, all social animals exploit, disturb and alter their natural environment. Biologists have just identified at least one species, elephants, that – in the course of bulldozing their way through the undergrowth and destroying young trees – actually make the forest more efficient at storing carbon and thus containing global heating.

The African forest elephant Loxodonta cyclotis browses upon and uproots young trees with stems smaller than 30cms and deposits the digested foliage as fertiliser, rich in seeds for the next generation of saplings.

Researchers from Italy, France, Brazil and the US report in the journal Nature Geoscience that this simple act – performed by perhaps one elephant in one square kilometre of forest – actually adds to the biomass locked in the remaining timber at the rate of by between 26 and 60 tonnes per hectare.

And if these ancient mega-herbivores were not crashing through the forest, consuming young trees, the forest would be home to 7% less biomass in the form of dense timber.

Forest elephants, the same scientists say, are rapidly declining in numbers. The researchers had been studying the species for years, and devised a mathematical model of their impact on the environment that supported them.

“Humanity is doing its best to rid the planet of elephants as quickly as it can. Forest elephants are facing extinction. All of their positive effect on carbon and their roles as forest gardeners and engineers will be lost”

Humans convert forest to farmland and increase the levels of carbon dioxide and other greenhouse gases that fuel global heating and the climate emergency. Forest elephants, on the other hand, simply alter the composition of the forest and make their environment a little cooler.

They do so by clearing away the fast-growing species to make more space for trees slower to climb towards the sunlight but with timber of higher density.

“Lo and behold, as we look at numbers of elephants in a forest and we look at the composition of forest over time, we find that the proportion of trees with high-density wood is higher in forests with elephants,” said Stephen Blake of St Louis University in the US, one of the authors.

“The simulation found that the slow-growing plant species survive better when elephants are present. These species aren’t eaten by elephants and, over time, the forest becomes dominated by these slow-growing species. Wood (lignin) has a carbon backbone, meaning it has a large number of carbon molecules in it.

“Slow-growing high wood-density species contain more carbon molecules per unit volume than fast-growing low wood-density species. As the elephants ‘thin’ the forest, they increase the number of slow-growing trees and the forest is capable of storing more carbon.”

Support for Gaia

The finding is consistent with the Gaia theory of earth system science: that life unconsciously but collectively tends to work in ways that keep the planet’s atmosphere stable and the planetary temperatures within comfortable boundaries.

So far humans are the most conspicuous exception to this rule. Biologists have wondered about the contribution of the mega-herbivores: in this one case, it seems that forest elephants are good for the forest and good for climate control.

The finding is also consistent with an argument put by conservationists, biologists and climate scientists: the healthiest and most efficient forests at absorbing atmospheric carbon are those that are home to the richest levels of biodiversity – that is, forests that remain natural wilderness.

Biologists and conservationists talk a lot about “ecosystem services” and “natural capital”: that is, the contribution of the natural world,  directly or indirectly, to human wealth. The researchers put a cash value on the carbon contribution of the African forest elephants: they perform a carbon storage service of $43 bn.

“The sad reality is that humanity is doing its best to rid the planet of elephants as quickly as it can,” said Dr Blake. “Forest elephants are rapidly declining and facing extinction. From a climate perspective, all of their positive effect on carbon and their myriad other ecological roles as forest gardeners and engineers will be lost.” – Climate News Network

Planting more trees could cut carbon by 25%

Scientists now know where to start restoring the forests to soak up carbon and cool the planet, by planting more trees on unused land.

LONDON, 5 July, 2019 − Swiss scientists have identified an area roughly the size of the United States that could be newly shaded by planting more trees. If the world’s nations then protected these 9 million square kilometres  of canopy over unused land, the new global forest could in theory soak up enough carbon to reduce atmospheric greenhouse gas by an estimated 25%.

That is, the extent of new tree canopy would be enough to take the main driver of global heating back to conditions on Earth a century ago.

And a second study, released in the same week, identifies 100 million hectares of degraded or destroyed tropical forest in 15 countries where restoration could start right now – and 87% of these hectares are in biodiversity hotspots that hold high concentrations of species found nowhere else.

The global study of the space available for tree canopy is published in the journal Science. Researchers looked for land not used for agriculture or developed for human settlement. They excluded wetlands and grasslands already fulfilling important ecological functions.

Huge canopy increase

They left existing forests out of their calculations. And they identified enough degraded, wasted, or simply unused land to provide another 0.9 billion hectares – that is, 9 million square kilometres – of tree canopy.

Such new or restored forest could store 205 billion tonnes of carbon. This is about two-thirds of the 300 billion tonnes of extra carbon humans have pumped into the atmosphere since the start of the Industrial Revolution 200 years ago.

“We all knew that restoring forests could play a part in tackling climate change, but we didn’t really know how big the impact would be. Our study shows clearly that forest restoration is the best climate change solution available today,” said Tom Crowther of the Swiss Federal Institute of Technology, now known as ETH Zurich.

“But we must act quickly, as new forests will take decades to mature and achieve their full potential as a source of natural carbon storage.”

“Restoring forests is a must-do – and it’s doable”

Forecasts for the future start with the data available now: the Swiss team worked from a dataset of observations of 80,000 forests, and used mapping software to predict possible tree cover worldwide under current conditions.

The big unknown is: what will global heating and climate change do for future forest growth? If nations go on burning fossil fuels at the present rates, then parts of the world could begin to experience harsher conditions and by 2050 the area available for tree cover could have dwindled by 223 million hectares, much of this in the tropics.

Forests are an integral part of the answer to the climate crisis. But forests worldwide, and particularly in the tropics, are also vulnerable to extremes of heat and drought and windstorm that are likely to come with ever higher average temperatures.

Where and when and how nations act to restore forests involves political decisions that must be based on evidence. So researchers have for years been trying to establish the extent of the global tree inventory, and its variety.

Unrecorded forest

They have confirmed the importance and value of urban forests. They have identified huge areas of woodland  hitherto not mapped or recorded. They have tried to make an estimate of the number of trees on the planet and the rate at which they are being felled, grazed, burned, or even extinguished.

They have identified threats to tropical forests, monitored the increasing damage to or degradation of what are  supposed to be protected areas, much of them forested, and they have measured changes in forests as the temperatures rise.

Right now, the world has 5.5 billion hectares of forest or woodland with at least 10% and up to 100% of tree cover: altogether this adds up to 2.8bn hectares of canopy. It also has a challenge to get on with: the Bonn Challenge to extend national forest areas by 350 million hectares by 2030 has been accepted by 48 countries so far.

The Swiss researchers calculated that there were up to 1.8 billion hectares of land of “low human activity” that could be reforested. If half of this was shaded by foliage, that would yield another 900 million hectares of canopy to soak up and store atmospheric carbon, and more than half of this potential tree space was in just six countries: Russia, the US, Canada, Australia, Brazil and China.

Best restoration options

But a second study, led by Brazilian scientists and published in the journal Science Advances, used high-resolution satellite studies to find that the most compelling opportunities for forest restoration exist in the lowland tropical rainforests of Central and South America, Africa and Southeast Asia.

Almost three-fourths of the restoration hotspots were in countries that had already made commitments under the Bonn Challenge. The five nations with the largest areas in need of restoration are Brazil, Indonesia, India, Madagascar and Colombia. Madagascar is also one of six African nations – the others are Rwanda, Uganda, Burundi, Togo and South Sudan – that, on average, offer the best immediate opportunities for forest restoration.

“Restoring tropical forests is fundamental to the planet’s health, now and for generations to come,” said Pedro Brancalion, of the University of Sao Paulo in Brazil, who led the study.

“For the first time, our study helps governments, investors and others seeking to restore global tropical moist forests to determine precise locations where restoring forests is most viable, enduring and beneficial. Restoring forests is a must-do – and it’s doable.” − Climate News Network

Scientists now know where to start restoring the forests to soak up carbon and cool the planet, by planting more trees on unused land.

LONDON, 5 July, 2019 − Swiss scientists have identified an area roughly the size of the United States that could be newly shaded by planting more trees. If the world’s nations then protected these 9 million square kilometres  of canopy over unused land, the new global forest could in theory soak up enough carbon to reduce atmospheric greenhouse gas by an estimated 25%.

That is, the extent of new tree canopy would be enough to take the main driver of global heating back to conditions on Earth a century ago.

And a second study, released in the same week, identifies 100 million hectares of degraded or destroyed tropical forest in 15 countries where restoration could start right now – and 87% of these hectares are in biodiversity hotspots that hold high concentrations of species found nowhere else.

The global study of the space available for tree canopy is published in the journal Science. Researchers looked for land not used for agriculture or developed for human settlement. They excluded wetlands and grasslands already fulfilling important ecological functions.

Huge canopy increase

They left existing forests out of their calculations. And they identified enough degraded, wasted, or simply unused land to provide another 0.9 billion hectares – that is, 9 million square kilometres – of tree canopy.

Such new or restored forest could store 205 billion tonnes of carbon. This is about two-thirds of the 300 billion tonnes of extra carbon humans have pumped into the atmosphere since the start of the Industrial Revolution 200 years ago.

“We all knew that restoring forests could play a part in tackling climate change, but we didn’t really know how big the impact would be. Our study shows clearly that forest restoration is the best climate change solution available today,” said Tom Crowther of the Swiss Federal Institute of Technology, now known as ETH Zurich.

“But we must act quickly, as new forests will take decades to mature and achieve their full potential as a source of natural carbon storage.”

“Restoring forests is a must-do – and it’s doable”

Forecasts for the future start with the data available now: the Swiss team worked from a dataset of observations of 80,000 forests, and used mapping software to predict possible tree cover worldwide under current conditions.

The big unknown is: what will global heating and climate change do for future forest growth? If nations go on burning fossil fuels at the present rates, then parts of the world could begin to experience harsher conditions and by 2050 the area available for tree cover could have dwindled by 223 million hectares, much of this in the tropics.

Forests are an integral part of the answer to the climate crisis. But forests worldwide, and particularly in the tropics, are also vulnerable to extremes of heat and drought and windstorm that are likely to come with ever higher average temperatures.

Where and when and how nations act to restore forests involves political decisions that must be based on evidence. So researchers have for years been trying to establish the extent of the global tree inventory, and its variety.

Unrecorded forest

They have confirmed the importance and value of urban forests. They have identified huge areas of woodland  hitherto not mapped or recorded. They have tried to make an estimate of the number of trees on the planet and the rate at which they are being felled, grazed, burned, or even extinguished.

They have identified threats to tropical forests, monitored the increasing damage to or degradation of what are  supposed to be protected areas, much of them forested, and they have measured changes in forests as the temperatures rise.

Right now, the world has 5.5 billion hectares of forest or woodland with at least 10% and up to 100% of tree cover: altogether this adds up to 2.8bn hectares of canopy. It also has a challenge to get on with: the Bonn Challenge to extend national forest areas by 350 million hectares by 2030 has been accepted by 48 countries so far.

The Swiss researchers calculated that there were up to 1.8 billion hectares of land of “low human activity” that could be reforested. If half of this was shaded by foliage, that would yield another 900 million hectares of canopy to soak up and store atmospheric carbon, and more than half of this potential tree space was in just six countries: Russia, the US, Canada, Australia, Brazil and China.

Best restoration options

But a second study, led by Brazilian scientists and published in the journal Science Advances, used high-resolution satellite studies to find that the most compelling opportunities for forest restoration exist in the lowland tropical rainforests of Central and South America, Africa and Southeast Asia.

Almost three-fourths of the restoration hotspots were in countries that had already made commitments under the Bonn Challenge. The five nations with the largest areas in need of restoration are Brazil, Indonesia, India, Madagascar and Colombia. Madagascar is also one of six African nations – the others are Rwanda, Uganda, Burundi, Togo and South Sudan – that, on average, offer the best immediate opportunities for forest restoration.

“Restoring tropical forests is fundamental to the planet’s health, now and for generations to come,” said Pedro Brancalion, of the University of Sao Paulo in Brazil, who led the study.

“For the first time, our study helps governments, investors and others seeking to restore global tropical moist forests to determine precise locations where restoring forests is most viable, enduring and beneficial. Restoring forests is a must-do – and it’s doable.” − Climate News Network

African city heat is set to grow intolerably

Up to a third of urban dwellers could soon face extreme African city heat and humidity. Risks could at worst multiply 50-fold.

LONDON, 11 June, 2019 – An entire continent faces lethal conditions for many of its people: by 2090, one person in three can expect African city heat in the great conurbations severe enough to expose them to potentially deadly temperatures.

That is: the number of days in which the apparent temperature – a notional balance of thermometer-measured heat and maximum humidity – could reach or surpass 40.6°C will increase dramatically, and the days when individuals could be at risk could in some scenarios multiply 50-fold.

The scientists selected this “apparent” temperature of 40.6°C because it is significantly beyond the natural temperature of the human body, which must then be kept cool by perspiration. This is possible in arid climates.

But as humidity goes up – and with each 1°C rise in temperature, the capacity of the air to hold moisture rises by 7% – cooling by perspiration becomes less efficient.

So at this notionally-defined apparent temperature, people who cannot retreat to air-conditioned or cooler, shadier places could die. Heat kills: researchers recently counted 27 ways in which extreme temperatures could claim lives.

“If we follow the Paris Agreement, we’ll halve the number of people at risk in 2090, which is encouraging”

And more, and more intense and prolonged heat waves are on the way, and with them episodes of potentially extreme humidity. By 2100, according to some studies, certain regions of the planet could become dangerous habitat.

European scientists report in the journal Earth’s Future that they considered the hazard for just one, rapidly-growing continent: Africa. They selected 173 cities of more than 300,000 people in 43 nations across a range of climates, from Algiers on the Mediterranean to the burgeoning monsoon cities of the equatorial west coast, such as Lagos and Kinshasa, the drier east African states, and the relatively mild townships of Southern Africa.

They then considered how much cities might grow, by migration or birth-rate increases, and how they might develop. Then they factored in a range of climate scenarios and looked at possible forecasts for the years 2030, 2060 and 2090.

They found that because of population growth, the numbers of days on which people could be at risk – measured in person-days (one person working for one full day) – would in any case increase.

Sharper rise

“In the best case, 20 billion person-days will be affected by 2030, compared with 4.2bn in 2010 – a jump, in other words, of 376%” said Guillaume Rohat, of the University of Geneva, who led the study. “This figure climbs to 45bn in 2060 (up 971%) and reaches 86bn in 2090 (up 1947%).

And that is the best-case scenario. When the researchers factored in the steepest population increases, the most rapid growth of the cities and the worst disturbances in climate, the figures rose more sharply. By 2030, 26 billion, a fivefold increase, could be at risk, 95bn in 2060 and 217 bn in 2090. This is an increase of 4967%, or nearly 50-fold.

The researchers assumed that not everybody in their 173 cities would be exposed to dangerous levels of heat. Were that to happen, the number of person-days could hit 647 billion. But the researchers made a conservative estimate of one in three people who would be exposed to a minimum temperature of 40.6°C.

Research of this kind makes assumptions about how the climate is going to change, and separately about how nations are going to develop, how populations are going to grow and change, and how governments are going to respond to the climate emergency, and the authors recognise the problems.

Conservative conclusions

The sample is biased towards the larger cities. Their calculations don’t include predictions for capital investment. But the researchers say their conclusions are if anything conservative. They do not, for instance, factor in the notorious urban heat island effect that tends to make cities 3°C or more hotter than the surrounding countryside, and therefore even more dangerous.

The good news to emerge from the study is that concerted action, by governments and civic authorities, can reduce the risk. Were nations to stick to an agreement made by 195 of them in Paris in 2015, and keep global temperature rise to “well below” 2°C, the final exposure hazard would be reduced by 48%.

“This proves that if we follow the Paris Agreement, we’ll halve the number of people at risk in 2090, which is encouraging,” said Rohat.

“We can see the importance of the UN Sustainable Development Goals: access to education, a drop in the number of children per woman, developments in the standard of living and so on.” – Climate News Network

Up to a third of urban dwellers could soon face extreme African city heat and humidity. Risks could at worst multiply 50-fold.

LONDON, 11 June, 2019 – An entire continent faces lethal conditions for many of its people: by 2090, one person in three can expect African city heat in the great conurbations severe enough to expose them to potentially deadly temperatures.

That is: the number of days in which the apparent temperature – a notional balance of thermometer-measured heat and maximum humidity – could reach or surpass 40.6°C will increase dramatically, and the days when individuals could be at risk could in some scenarios multiply 50-fold.

The scientists selected this “apparent” temperature of 40.6°C because it is significantly beyond the natural temperature of the human body, which must then be kept cool by perspiration. This is possible in arid climates.

But as humidity goes up – and with each 1°C rise in temperature, the capacity of the air to hold moisture rises by 7% – cooling by perspiration becomes less efficient.

So at this notionally-defined apparent temperature, people who cannot retreat to air-conditioned or cooler, shadier places could die. Heat kills: researchers recently counted 27 ways in which extreme temperatures could claim lives.

“If we follow the Paris Agreement, we’ll halve the number of people at risk in 2090, which is encouraging”

And more, and more intense and prolonged heat waves are on the way, and with them episodes of potentially extreme humidity. By 2100, according to some studies, certain regions of the planet could become dangerous habitat.

European scientists report in the journal Earth’s Future that they considered the hazard for just one, rapidly-growing continent: Africa. They selected 173 cities of more than 300,000 people in 43 nations across a range of climates, from Algiers on the Mediterranean to the burgeoning monsoon cities of the equatorial west coast, such as Lagos and Kinshasa, the drier east African states, and the relatively mild townships of Southern Africa.

They then considered how much cities might grow, by migration or birth-rate increases, and how they might develop. Then they factored in a range of climate scenarios and looked at possible forecasts for the years 2030, 2060 and 2090.

They found that because of population growth, the numbers of days on which people could be at risk – measured in person-days (one person working for one full day) – would in any case increase.

Sharper rise

“In the best case, 20 billion person-days will be affected by 2030, compared with 4.2bn in 2010 – a jump, in other words, of 376%” said Guillaume Rohat, of the University of Geneva, who led the study. “This figure climbs to 45bn in 2060 (up 971%) and reaches 86bn in 2090 (up 1947%).

And that is the best-case scenario. When the researchers factored in the steepest population increases, the most rapid growth of the cities and the worst disturbances in climate, the figures rose more sharply. By 2030, 26 billion, a fivefold increase, could be at risk, 95bn in 2060 and 217 bn in 2090. This is an increase of 4967%, or nearly 50-fold.

The researchers assumed that not everybody in their 173 cities would be exposed to dangerous levels of heat. Were that to happen, the number of person-days could hit 647 billion. But the researchers made a conservative estimate of one in three people who would be exposed to a minimum temperature of 40.6°C.

Research of this kind makes assumptions about how the climate is going to change, and separately about how nations are going to develop, how populations are going to grow and change, and how governments are going to respond to the climate emergency, and the authors recognise the problems.

Conservative conclusions

The sample is biased towards the larger cities. Their calculations don’t include predictions for capital investment. But the researchers say their conclusions are if anything conservative. They do not, for instance, factor in the notorious urban heat island effect that tends to make cities 3°C or more hotter than the surrounding countryside, and therefore even more dangerous.

The good news to emerge from the study is that concerted action, by governments and civic authorities, can reduce the risk. Were nations to stick to an agreement made by 195 of them in Paris in 2015, and keep global temperature rise to “well below” 2°C, the final exposure hazard would be reduced by 48%.

“This proves that if we follow the Paris Agreement, we’ll halve the number of people at risk in 2090, which is encouraging,” said Rohat.

“We can see the importance of the UN Sustainable Development Goals: access to education, a drop in the number of children per woman, developments in the standard of living and so on.” – Climate News Network

Changing rainfall poses dilemma on dams

A changing climate usually means changing rainfall patterns. And that means a headache for dam builders.

LONDON, 23 May, 2019 − For the builders of hydro-electric schemes – usually multi-billion dollar projects involving vast amounts of complex engineering work – changing rainfall is a serious problem.

With climate change either on the horizon or already happening in many regions of the world, rainfall patterns, on which hydro schemes ultimately depend, are becoming ever more unpredictable.

Christian Rynning-Tonnesen is CEO of Statkraft AS, Norway’s biggest power producer and a major player in the international hydro power business.

In an interview with the Bloomberg news agency, Rynning-Tonnesen says his company has had to double its spending over the last 10 years to reinforce dams in order to cope with heavier rains. He says climate change is hard to ignore when you’re in the hydro-electric business.

“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”

“The general trend all over the world is areas that are dry become more dry and areas that are wet become more wet.”

Norway has seen a 5% rise in rainfall over recent years, says Rynning-Tonnesen.

Others say planning processes behind dam building have to be revised in the face of climate change.

Emilio Moran, a visiting professor at the University of Campinas in São Paulo state in Brazil, says that in one of the world’s biggest hydro-electric building programmes, a total of 147 dams have been planned in the Amazon Basin, with 65 of them in Brazil.

Output fears

In a study published in the Proceedings of the National Academy of Sciences journal, Moran and his co-authors say many of the dams in Brazil − either completed or still in the planning stages − are likely to produce far less power than anticipated, owing to climate variability.

The Amazon Basin is predicted to receive less rainfall and to be hit with higher temperatures in future.

“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”, says Moran.

“To reduce its vulnerability with regard to energy in the context of global climate change, Brazil must diversify its energy mix. It’s still too dependent on hydro-electricity. It needs to invest more in other renewable sources, such as solar, biomass and wind.”

Rainfall drops

Deforestation is expected to create further water shortage problems for hydro plants in the Amazon region. About half the area’s rainfall is due to recycling within the forest.

“Deforestation will, therefore, lead to less precipitation in the region aside from the expected decline due to global climate change”, say the study’s authors.

They say that if the building of large dams in developing countries is to continue, full consideration has to be given to their social impact, the overall cost to the environment and to climate change.

International tensions

In many cases, this doesn’t seem to be happening. Turkey is spending billions on ambitious dam building projects on the Euphrates and Tigris rivers in the south-east of the country. Climate change is predicted to alter the amounts of water available to drive the operation of these dams.

The rivers flow onwards into Syria and Iraq: already water flows downstream are severely reduced at certain times of the year, creating regional tensions and putting in jeopardy the livelihoods of millions dependent on the rivers for drinking water and for agricultural production.

One of the world’s biggest dam projects is in East Africa − the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, which flows into the Nile itself. Ethiopia wants to sell electricity generated by the dam to neighbouring countries.

Critics of the GERD project say climate change, including reduced rainfall in the Blue Nile’s catchment area, could seriously affect the dam’s generating capability. − Climate News Network

A changing climate usually means changing rainfall patterns. And that means a headache for dam builders.

LONDON, 23 May, 2019 − For the builders of hydro-electric schemes – usually multi-billion dollar projects involving vast amounts of complex engineering work – changing rainfall is a serious problem.

With climate change either on the horizon or already happening in many regions of the world, rainfall patterns, on which hydro schemes ultimately depend, are becoming ever more unpredictable.

Christian Rynning-Tonnesen is CEO of Statkraft AS, Norway’s biggest power producer and a major player in the international hydro power business.

In an interview with the Bloomberg news agency, Rynning-Tonnesen says his company has had to double its spending over the last 10 years to reinforce dams in order to cope with heavier rains. He says climate change is hard to ignore when you’re in the hydro-electric business.

“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”

“The general trend all over the world is areas that are dry become more dry and areas that are wet become more wet.”

Norway has seen a 5% rise in rainfall over recent years, says Rynning-Tonnesen.

Others say planning processes behind dam building have to be revised in the face of climate change.

Emilio Moran, a visiting professor at the University of Campinas in São Paulo state in Brazil, says that in one of the world’s biggest hydro-electric building programmes, a total of 147 dams have been planned in the Amazon Basin, with 65 of them in Brazil.

Output fears

In a study published in the Proceedings of the National Academy of Sciences journal, Moran and his co-authors say many of the dams in Brazil − either completed or still in the planning stages − are likely to produce far less power than anticipated, owing to climate variability.

The Amazon Basin is predicted to receive less rainfall and to be hit with higher temperatures in future.

“Depending on water as the main source of power in future when we’ll have less of this natural resource looks like an unreliable strategy”, says Moran.

“To reduce its vulnerability with regard to energy in the context of global climate change, Brazil must diversify its energy mix. It’s still too dependent on hydro-electricity. It needs to invest more in other renewable sources, such as solar, biomass and wind.”

Rainfall drops

Deforestation is expected to create further water shortage problems for hydro plants in the Amazon region. About half the area’s rainfall is due to recycling within the forest.

“Deforestation will, therefore, lead to less precipitation in the region aside from the expected decline due to global climate change”, say the study’s authors.

They say that if the building of large dams in developing countries is to continue, full consideration has to be given to their social impact, the overall cost to the environment and to climate change.

International tensions

In many cases, this doesn’t seem to be happening. Turkey is spending billions on ambitious dam building projects on the Euphrates and Tigris rivers in the south-east of the country. Climate change is predicted to alter the amounts of water available to drive the operation of these dams.

The rivers flow onwards into Syria and Iraq: already water flows downstream are severely reduced at certain times of the year, creating regional tensions and putting in jeopardy the livelihoods of millions dependent on the rivers for drinking water and for agricultural production.

One of the world’s biggest dam projects is in East Africa − the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, which flows into the Nile itself. Ethiopia wants to sell electricity generated by the dam to neighbouring countries.

Critics of the GERD project say climate change, including reduced rainfall in the Blue Nile’s catchment area, could seriously affect the dam’s generating capability. − Climate News Network

Desert dust cools vulnerable Red Sea corals

Desert dust whipped up by strong winds and volcanic aerosols alter the climate as the world warms.

LONDON, 20 May, 2019 − Located between two of the hottest and driest places on earth, the Red Sea is being protected by the desert dust that the winds whip up in the lands that surround it.

The dust so effectively blocks out the sun that the Red Sea is kept cool, saving its coral reefs from dangerous overheating and providing nutrients that keep its waters healthy.

The sea lies between North Africa and the Arabian Peninsula, the world’s largest region for generating dust, which strong summer winds pump down a narrowing mountain-fringed passage that forces it into the air over the widest southern portion of the sea.

The research, carried out by the King Abdullah University of Science and Technology (KAUST, the first mixed-gender university in Saudi Arabia), is part of a wider programme to discover the effect of dust in the atmosphere in changing the weather and climate.

Cooling influence

Volcanic eruptions can have a significant effect by ejecting aerosol particles into the upper atmosphere where they block out some of the sun’s rays, radiating heat back into space, a process known as radiative forcing. Dust blown from deserts also has a strong regional effect.

Sergey Osipov, postdoctoral fellow and co-author with his supervisor Georgiy Stenchikov of the Red Sea study, said: “We show that summer conditions over the Red Sea produce the world’s largest aerosol radiative forcing, and yet the impact of dust on the Red Sea was never studied − it was simply unknown.”

A surprising finding relates to biological productivity. “Dust deposition adds nutrients,” he said. “However, we find that dust radiative forcing slows down the Red Sea circulation and reduces the main nutrient supply to the Red Sea through the Bab-el Mandeb strait. The net effect on overall bioproductivity remains to be established.”

Volcanoes’ impact

Large volcanic eruptions, such as the 1991 eruption of Mount Pinatubo in the Philippines, inject vast amounts of sulphur dioxide into the upper atmosphere, where it is converted into tiny sulphate aerosol droplets.

These sulphate aerosols spread around the globe, exerting a strong radiative forcing effect, and reducing global temperature for nearly two years by 0.6°C before the dust finally settled back to earth.

The university is using its supercomputer to look at the effects of dust on the whole of the region, which is extremely arid and hurls large quantities of dust into the atmosphere, potentially changing weather patterns. It is important for future climate projections to predict droughts and famines that might cause mass migrations of the region’s peoples.

Another KAUST climate modelling study reveals potential changes in the West African monsoon caused by global warming and the dust it creates.

African monsoon

Home to more than 300 million people, West Africa has an agriculture-based economy: its food security is affected by the monsoon, making it important to understand present and future variability.

A KAUST doctoral student, Jerry Raj, simulated the monsoon under present and future climates. The results show that West Africa will become generally hotter as a result of climate change – with higher areas of the Sahel and Western Sahara projected to have increased temperatures of 4°C or more by the century’s end.

The simulations also indicate precipitation increases over the equatorial Atlantic and the Guinean coast, yet the southern Sahel appears drier. At the same time, Western Sahara experiences a moderate increase of rain.

Finally, and crucially for farmers sowing crops, the onset of the monsoon occurs earlier over the eastern part of the region, but is delayed over the western part.

“Strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood”

“Climate projection is the first and the most important step toward adaptation policies aimed at avoiding damaging environmental and socio-economic consequences,” Raj said.

Another doctoral student, Evgeniya Predybaylo, is looking further afield at the impact of large volcanic eruptions on a major natural climate variation, the El Niño‐Southern Oscillation.

This periodic warm water flush in the Pacific drives extreme weather events like hurricane and tornado activity as well as coral bleaching. It also causes floods and droughts and disrupts fish populations.

Forecasting El Niño events would help people prepare for possible collapses of fish stocks and agricultural crises, says Predybaylo. However, El Niño is notoriously difficult to predict, but volcanic eruptions may play a role.

El Niño link?

“Interestingly, strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood,” says Predybaylo.

She says the response to volcanoes partly depends on the eruption’s seasonal timing: summer eruptions induce stronger El Niños than winter or spring eruptions.
Ocean conditions prevailing at the time of the eruption also play a role.

“Radiative forcing following large eruptions generally results in surface cooling,” explains Predybaylo. “However, the tropical Pacific often shows a warming response. We show that this is due to uneven equatorial ocean cooling and changes in trade winds.”

“A Pinatubo-size eruption may partially determine the phase, magnitude and duration of El Niño, but it is crucial to account for the eruption season and ocean conditions just before the eruption,” she says. − Climate News Network

Desert dust whipped up by strong winds and volcanic aerosols alter the climate as the world warms.

LONDON, 20 May, 2019 − Located between two of the hottest and driest places on earth, the Red Sea is being protected by the desert dust that the winds whip up in the lands that surround it.

The dust so effectively blocks out the sun that the Red Sea is kept cool, saving its coral reefs from dangerous overheating and providing nutrients that keep its waters healthy.

The sea lies between North Africa and the Arabian Peninsula, the world’s largest region for generating dust, which strong summer winds pump down a narrowing mountain-fringed passage that forces it into the air over the widest southern portion of the sea.

The research, carried out by the King Abdullah University of Science and Technology (KAUST, the first mixed-gender university in Saudi Arabia), is part of a wider programme to discover the effect of dust in the atmosphere in changing the weather and climate.

Cooling influence

Volcanic eruptions can have a significant effect by ejecting aerosol particles into the upper atmosphere where they block out some of the sun’s rays, radiating heat back into space, a process known as radiative forcing. Dust blown from deserts also has a strong regional effect.

Sergey Osipov, postdoctoral fellow and co-author with his supervisor Georgiy Stenchikov of the Red Sea study, said: “We show that summer conditions over the Red Sea produce the world’s largest aerosol radiative forcing, and yet the impact of dust on the Red Sea was never studied − it was simply unknown.”

A surprising finding relates to biological productivity. “Dust deposition adds nutrients,” he said. “However, we find that dust radiative forcing slows down the Red Sea circulation and reduces the main nutrient supply to the Red Sea through the Bab-el Mandeb strait. The net effect on overall bioproductivity remains to be established.”

Volcanoes’ impact

Large volcanic eruptions, such as the 1991 eruption of Mount Pinatubo in the Philippines, inject vast amounts of sulphur dioxide into the upper atmosphere, where it is converted into tiny sulphate aerosol droplets.

These sulphate aerosols spread around the globe, exerting a strong radiative forcing effect, and reducing global temperature for nearly two years by 0.6°C before the dust finally settled back to earth.

The university is using its supercomputer to look at the effects of dust on the whole of the region, which is extremely arid and hurls large quantities of dust into the atmosphere, potentially changing weather patterns. It is important for future climate projections to predict droughts and famines that might cause mass migrations of the region’s peoples.

Another KAUST climate modelling study reveals potential changes in the West African monsoon caused by global warming and the dust it creates.

African monsoon

Home to more than 300 million people, West Africa has an agriculture-based economy: its food security is affected by the monsoon, making it important to understand present and future variability.

A KAUST doctoral student, Jerry Raj, simulated the monsoon under present and future climates. The results show that West Africa will become generally hotter as a result of climate change – with higher areas of the Sahel and Western Sahara projected to have increased temperatures of 4°C or more by the century’s end.

The simulations also indicate precipitation increases over the equatorial Atlantic and the Guinean coast, yet the southern Sahel appears drier. At the same time, Western Sahara experiences a moderate increase of rain.

Finally, and crucially for farmers sowing crops, the onset of the monsoon occurs earlier over the eastern part of the region, but is delayed over the western part.

“Strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood”

“Climate projection is the first and the most important step toward adaptation policies aimed at avoiding damaging environmental and socio-economic consequences,” Raj said.

Another doctoral student, Evgeniya Predybaylo, is looking further afield at the impact of large volcanic eruptions on a major natural climate variation, the El Niño‐Southern Oscillation.

This periodic warm water flush in the Pacific drives extreme weather events like hurricane and tornado activity as well as coral bleaching. It also causes floods and droughts and disrupts fish populations.

Forecasting El Niño events would help people prepare for possible collapses of fish stocks and agricultural crises, says Predybaylo. However, El Niño is notoriously difficult to predict, but volcanic eruptions may play a role.

El Niño link?

“Interestingly, strong equatorial volcanic eruptions often coincide with an El Niño warm phase, but the relationship is complex and poorly understood,” says Predybaylo.

She says the response to volcanoes partly depends on the eruption’s seasonal timing: summer eruptions induce stronger El Niños than winter or spring eruptions.
Ocean conditions prevailing at the time of the eruption also play a role.

“Radiative forcing following large eruptions generally results in surface cooling,” explains Predybaylo. “However, the tropical Pacific often shows a warming response. We show that this is due to uneven equatorial ocean cooling and changes in trade winds.”

“A Pinatubo-size eruption may partially determine the phase, magnitude and duration of El Niño, but it is crucial to account for the eruption season and ocean conditions just before the eruption,” she says. − Climate News Network