Tag Archives: global warming

Hotter Mediterranean will bring in desert

Should temperatures in the Mediterranean basin continue to rise, the dunes of the Sahara will march northwards and southern Spain will become a desert.

LONDON, 7 November, 2016 – If nations fail to limit global warming to 1.5°C this century, at least one region of the globe will experience change not seen in the last 10,000 years.

Temperatures in the Mediterranean basin are already 1.3°C higher than they were between 1880 and 1920. If they go on getting much hotter, there will be change on a scale not seen since the close of the last Ice Age, according to a new study.

Under the notorious business-as-usual scenario, in which humans go on burning fossil fuels at an ever-increasing rate, and releasing ever more carbon dioxide into the atmosphere, then the dunes of North Africa’s Sahara will march northwards and southern Spain will become a desert.

Deciduous trees will invade the mountain regions, and shrubland vegetation will replace the great deciduous forests in large areas of the Mediterranean, according to two scientists from the Universities of Aix-Marseille and Avignon in France.

Joël Guiot and Wolfgang Cramer report in the journal Science that they sifted the evidence from pollen cores and other telltale climatic indicators and modelled the pattern of ecosystem change through the Neolithic, the Bronze Age and recorded human history.

Role of the Mediterranean

The Mediterranean plays a powerful role in the human story: some of the world’s great staples – wheat and barley, olives and figs, lentils and pulses – were domesticated near its shores. Cattle, sheep and goats were tamed, and yoghurt and cheese first appeared there.

Mediterranean peoples learned to ferment wine and beer, forge tools with metals, create three of the world’s great religions, and lay the foundations for much of the world’s theatre and literature, art and science.

The Mediterranean Sea has been both a cockpit of conflict and the starting point for the creation of empires. But it is already changing as a response to global warming.

The present drought in the eastern Mediterranean has been pronounced the worst in 900 years. Warmer temperatures have brought invader fish from the Red Sea and driven the sardines out into the Atlantic.

The woodland and scrub along the coast have always been vulnerable to fire, but the fire season in the region has been extended so far by 29 days. There have been fears that, unchecked, heatwaves amplified by global warming could make some places uninhabitable.

And prehistory has its own lesson: there is evidence that at least one ancient civilisation may have been toppled by climate change.

Nations that met in Paris last December vowed to contain global warming to within 2°C overall, and if possible to 1.5°C. But that is a global atmospheric average temperature: in fact, some parts of the planet have already exceeded that.

Catastrophic drought

And vows are not to be confused with action. As nations prepare to meet again in Marrakech, in the Mediterranean nation of Morocco, the two scientists from the south of France have delivered another urgent warning. They foresee a period characterised by what they politely called “recurring precipitation deficits”: in other words, sustained and potentially catastrophic drought.

In this scenario climate change threatens the crops of the region, the creatures that live there, and the tourist industries that thrive on its climate and history. And, the two scientists warn, the changes they predict will be entirely a consequence of warming.

They have not taken into account population growth, economic expansion, or land use changes that degrade vegetation and soils. These additional effects, they warn, will enhance, rather than dampen, the shifts toward “a drier state than estimated by this analysis”. – Climate News Network

Should temperatures in the Mediterranean basin continue to rise, the dunes of the Sahara will march northwards and southern Spain will become a desert.

LONDON, 7 November, 2016 – If nations fail to limit global warming to 1.5°C this century, at least one region of the globe will experience change not seen in the last 10,000 years.

Temperatures in the Mediterranean basin are already 1.3°C higher than they were between 1880 and 1920. If they go on getting much hotter, there will be change on a scale not seen since the close of the last Ice Age, according to a new study.

Under the notorious business-as-usual scenario, in which humans go on burning fossil fuels at an ever-increasing rate, and releasing ever more carbon dioxide into the atmosphere, then the dunes of North Africa’s Sahara will march northwards and southern Spain will become a desert.

Deciduous trees will invade the mountain regions, and shrubland vegetation will replace the great deciduous forests in large areas of the Mediterranean, according to two scientists from the Universities of Aix-Marseille and Avignon in France.

Joël Guiot and Wolfgang Cramer report in the journal Science that they sifted the evidence from pollen cores and other telltale climatic indicators and modelled the pattern of ecosystem change through the Neolithic, the Bronze Age and recorded human history.

Role of the Mediterranean

The Mediterranean plays a powerful role in the human story: some of the world’s great staples – wheat and barley, olives and figs, lentils and pulses – were domesticated near its shores. Cattle, sheep and goats were tamed, and yoghurt and cheese first appeared there.

Mediterranean peoples learned to ferment wine and beer, forge tools with metals, create three of the world’s great religions, and lay the foundations for much of the world’s theatre and literature, art and science.

The Mediterranean Sea has been both a cockpit of conflict and the starting point for the creation of empires. But it is already changing as a response to global warming.

The present drought in the eastern Mediterranean has been pronounced the worst in 900 years. Warmer temperatures have brought invader fish from the Red Sea and driven the sardines out into the Atlantic.

The woodland and scrub along the coast have always been vulnerable to fire, but the fire season in the region has been extended so far by 29 days. There have been fears that, unchecked, heatwaves amplified by global warming could make some places uninhabitable.

And prehistory has its own lesson: there is evidence that at least one ancient civilisation may have been toppled by climate change.

Nations that met in Paris last December vowed to contain global warming to within 2°C overall, and if possible to 1.5°C. But that is a global atmospheric average temperature: in fact, some parts of the planet have already exceeded that.

Catastrophic drought

And vows are not to be confused with action. As nations prepare to meet again in Marrakech, in the Mediterranean nation of Morocco, the two scientists from the south of France have delivered another urgent warning. They foresee a period characterised by what they politely called “recurring precipitation deficits”: in other words, sustained and potentially catastrophic drought.

In this scenario climate change threatens the crops of the region, the creatures that live there, and the tourist industries that thrive on its climate and history. And, the two scientists warn, the changes they predict will be entirely a consequence of warming.

They have not taken into account population growth, economic expansion, or land use changes that degrade vegetation and soils. These additional effects, they warn, will enhance, rather than dampen, the shifts toward “a drier state than estimated by this analysis”. – Climate News Network

Arctic warming gives US and Europe the chills

The effects of Arctic climate change on the jet stream could mean harsher winters for some of the most highly populated regions of the world.

LONDON, 2 November, 2016 Warming in the Arctic – one of the fastest-warming regions on the planet – could be heightening the chances of extreme winters in Europe and the US.

As the Arctic warms, the stratospheric jet stream that brings occasionally catastrophic ice storms and record snow falls to the eastern United States could also be on the move, according to new research in the journal Nature Climate Change.

The phenomenon is a natural one. Some years the track of the jet stream is wavy, and delivers severe cold weather to the mid-latitudes of the northern hemisphere. Some years the pattern alters, and Europe in particular experiences mild winters. The temperate zones have always experienced occasional extremes. But climate change could be tilting the balance.

Extreme spells

“We’ve always had years with wavy and not so wavy jet-stream winds, but in the last one or two decades the warming Arctic could well have been amplifying the effects of the wavy patterns.

“This may have contributed to some recent extreme cold winter spells along the eastern seaboard of the United States, in western Asia and at times over the UK,” says Edward Hanna, a geographer at the University of Sheffield, UK, and one of a team of British, European and US scientists behind the study.

“Improving our ability to predict how climate change
is affecting the jet stream will help improve
our long-term prediction of winter weather”

The study doesn’t claim to settle the question: notoriously, climate is what you expect but weather is what you get, and it may be impossible to prove that this or that unexpected event happened because the global average temperatures are now at least 1°C higher than they used to be, before the human combustion of fossil fuels began to increase the concentration of the greenhouse gas carbon dioxide in the atmosphere from 280 parts per million to 400 ppm.

But there are changes in the Arctic that are happening because of global warming, and meteorologists have been watching the knock-on effect on the stratospheric winds, especially the jet stream.

In the same issue of the journal one group identified a persistent shift and a weakening in the Arctic winter polar vortex, a meteorological monster that plays a role in temperate zone weather patterns.

Others identified a link between Arctic changes and the speed of the jet stream, and its effect on transatlantic airline timetables.

Yet others have linked Arctic warming to dangerous extremes of heat further south, and yet another group has linked polar climate change to both ice storms and heatwaves.

Arctic signals

The debate continues. The important thing is to monitor the melting sea ice, the rising sea-surface temperatures and the emerging pattern of severe winter weather. If meteorologists can learn to read the signals from the Arctic, then communities could plan more effectively for the consequences.

“Improving our ability to predict how climate change is affecting the jet stream will help improve our long-term prediction of winter weather in some of the most highly populated regions of the world,” Professor Hanna says. “This would be highly beneficial for communities, businesses and entire economies in the northern hemisphere.

“The public could better prepare for severe winter weather and have access to extra crucial information that could help make life-saving and cost-saving decisions.” Climate News Network

The effects of Arctic climate change on the jet stream could mean harsher winters for some of the most highly populated regions of the world.

LONDON, 2 November, 2016 Warming in the Arctic – one of the fastest-warming regions on the planet – could be heightening the chances of extreme winters in Europe and the US.

As the Arctic warms, the stratospheric jet stream that brings occasionally catastrophic ice storms and record snow falls to the eastern United States could also be on the move, according to new research in the journal Nature Climate Change.

The phenomenon is a natural one. Some years the track of the jet stream is wavy, and delivers severe cold weather to the mid-latitudes of the northern hemisphere. Some years the pattern alters, and Europe in particular experiences mild winters. The temperate zones have always experienced occasional extremes. But climate change could be tilting the balance.

Extreme spells

“We’ve always had years with wavy and not so wavy jet-stream winds, but in the last one or two decades the warming Arctic could well have been amplifying the effects of the wavy patterns.

“This may have contributed to some recent extreme cold winter spells along the eastern seaboard of the United States, in western Asia and at times over the UK,” says Edward Hanna, a geographer at the University of Sheffield, UK, and one of a team of British, European and US scientists behind the study.

“Improving our ability to predict how climate change
is affecting the jet stream will help improve
our long-term prediction of winter weather”

The study doesn’t claim to settle the question: notoriously, climate is what you expect but weather is what you get, and it may be impossible to prove that this or that unexpected event happened because the global average temperatures are now at least 1°C higher than they used to be, before the human combustion of fossil fuels began to increase the concentration of the greenhouse gas carbon dioxide in the atmosphere from 280 parts per million to 400 ppm.

But there are changes in the Arctic that are happening because of global warming, and meteorologists have been watching the knock-on effect on the stratospheric winds, especially the jet stream.

In the same issue of the journal one group identified a persistent shift and a weakening in the Arctic winter polar vortex, a meteorological monster that plays a role in temperate zone weather patterns.

Others identified a link between Arctic changes and the speed of the jet stream, and its effect on transatlantic airline timetables.

Yet others have linked Arctic warming to dangerous extremes of heat further south, and yet another group has linked polar climate change to both ice storms and heatwaves.

Arctic signals

The debate continues. The important thing is to monitor the melting sea ice, the rising sea-surface temperatures and the emerging pattern of severe winter weather. If meteorologists can learn to read the signals from the Arctic, then communities could plan more effectively for the consequences.

“Improving our ability to predict how climate change is affecting the jet stream will help improve our long-term prediction of winter weather in some of the most highly populated regions of the world,” Professor Hanna says. “This would be highly beneficial for communities, businesses and entire economies in the northern hemisphere.

“The public could better prepare for severe winter weather and have access to extra crucial information that could help make life-saving and cost-saving decisions.” Climate News Network

Global ‘bright spots’ offer climate hope

Climate

Scientists show how humans can improve poor people’s lives by reversing practices that destroy the environment and fuel climate change.

LONDON, 15 October, 2016 − We are constantly bombarded with bad news about climate change and the state of the planet – to the point where problems can seem so great that we feel powerless to do anything about them.

But an international group of scientists is seeking to change that by collating examples from around the world of “bright spots” – practical, community-based initiatives that enhance people’s health and wellbeing, while at the same time protecting their environment and benefiting the climate.

Over the last two years, researchers have analysed 100 of more than 500 such case studies submitted to the newly established Good Anthropocene website. They range from an initiative in Indonesia, in which forest people are offered healthcare in exchange for conserving natural resources, to a not-for-profit company in the Netherlands manufacturing modular, easily repairable mobile phones.

Human impact

Scientists from McGill University in Canada, Stockholm University in Sweden and Stellenbosch University in South Africa have studied some of the common factors behind successful projects. Their research, in a new paper titled Bright Spots: Seeds of a good Anthropocene, is published in the Ecological Society of America journal Frontiers in Ecology and the Environment.

The term “Anthropocene” refers to the geological epoch that began when human activities first started to have a global impact on the Earth’s ecology.

The report notes that anthropogenic change is compromising the future of the biosphere − the area of the planet’s surface and atmosphere that supports all life − and threatening the planetary conditions necessary for human societies to flourish. However, it asserts that the future does not need to be bleak.

Among the initiatives highlighted are Health in Harmony, an award-winning project providing low-cost healthcare to marginalised communities in Indonesian Borneo in exchange for a commitment to protect natural resources and reduce deforestation.

I’m excited about this project because it offers environmental scientists a chance
to start looking at things positively”

Over the last five years, this has lead to a 68% reduction in illegal logging in Gunung Palung National Park, home to carbon-rich peat and one of the few remaining significant populations of orangutans. Over the same period, there has been a significant improvement in the general health of people living around the park.

Another success story is the Satoyama Project in Japan, which has helped revive traditional low-impact farming, where migration of wild animals can take place between ponds, rice paddies, grasslands and forests. City dwellers are collaborating with rural communities by staying on farms, carrying out voluntary manual work, offering financial support and helping to market eco-friendly products.

By contrast, Fairphone is a small Dutch non-profit company manufacturing mobile phones without using “conflict minerals” − materials mined in unstable parts of the world where human rights abuses are common.

The Fairphone is designed so that worn-out parts can be easily repaired or replaced, reducing the need for phones to be thrown away – and reducing demand for further mining of raw materials.

Big change

Lead author Dr Elena Bennett, associate professor at McGill University’s School of the Environment, thinks there is great potential for bright spots, or “seeds of good anthropocene”, to be replicated around the world.

“I’m excited about this project because it represents a big shift for environmental scientists to start looking at things positively,” she says.We tend to be very focused on problems, so to look at examples of the sustainable solutions that people are coming up with – and to move towards asking ‘What do the solutions have in common? – is a big change.”

Dr Bennett adds: “This is also a move away from the typical academic perspective of looking at things in a top-down way, where we the scientists determine the definitions.

“We have encouraged people who are involved in the projects to define what makes a project ‘good’ − partly because we didn’t want to be driven by our northern European or North American sensibilities. We wanted to see a variety of ideas about what people want from the future.”
Climate News Network

Scientists show how humans can improve poor people’s lives by reversing practices that destroy the environment and fuel climate change.

LONDON, 15 October, 2016 − We are constantly bombarded with bad news about climate change and the state of the planet – to the point where problems can seem so great that we feel powerless to do anything about them.

But an international group of scientists is seeking to change that by collating examples from around the world of “bright spots” – practical, community-based initiatives that enhance people’s health and wellbeing, while at the same time protecting their environment and benefiting the climate.

Over the last two years, researchers have analysed 100 of more than 500 such case studies submitted to the newly established Good Anthropocene website. They range from an initiative in Indonesia, in which forest people are offered healthcare in exchange for conserving natural resources, to a not-for-profit company in the Netherlands manufacturing modular, easily repairable mobile phones.

Human impact

Scientists from McGill University in Canada, Stockholm University in Sweden and Stellenbosch University in South Africa have studied some of the common factors behind successful projects. Their research, in a new paper titled Bright Spots: Seeds of a good Anthropocene, is published in the Ecological Society of America journal Frontiers in Ecology and the Environment.

The term “Anthropocene” refers to the geological epoch that began when human activities first started to have a global impact on the Earth’s ecology.

The report notes that anthropogenic change is compromising the future of the biosphere − the area of the planet’s surface and atmosphere that supports all life − and threatening the planetary conditions necessary for human societies to flourish. However, it asserts that the future does not need to be bleak.

Among the initiatives highlighted are Health in Harmony, an award-winning project providing low-cost healthcare to marginalised communities in Indonesian Borneo in exchange for a commitment to protect natural resources and reduce deforestation.

I’m excited about this project because it offers environmental scientists a chance
to start looking at things positively”

Over the last five years, this has lead to a 68% reduction in illegal logging in Gunung Palung National Park, home to carbon-rich peat and one of the few remaining significant populations of orangutans. Over the same period, there has been a significant improvement in the general health of people living around the park.

Another success story is the Satoyama Project in Japan, which has helped revive traditional low-impact farming, where migration of wild animals can take place between ponds, rice paddies, grasslands and forests. City dwellers are collaborating with rural communities by staying on farms, carrying out voluntary manual work, offering financial support and helping to market eco-friendly products.

By contrast, Fairphone is a small Dutch non-profit company manufacturing mobile phones without using “conflict minerals” − materials mined in unstable parts of the world where human rights abuses are common.

The Fairphone is designed so that worn-out parts can be easily repaired or replaced, reducing the need for phones to be thrown away – and reducing demand for further mining of raw materials.

Big change

Lead author Dr Elena Bennett, associate professor at McGill University’s School of the Environment, thinks there is great potential for bright spots, or “seeds of good anthropocene”, to be replicated around the world.

“I’m excited about this project because it represents a big shift for environmental scientists to start looking at things positively,” she says.We tend to be very focused on problems, so to look at examples of the sustainable solutions that people are coming up with – and to move towards asking ‘What do the solutions have in common? – is a big change.”

Dr Bennett adds: “This is also a move away from the typical academic perspective of looking at things in a top-down way, where we the scientists determine the definitions.

“We have encouraged people who are involved in the projects to define what makes a project ‘good’ − partly because we didn’t want to be driven by our northern European or North American sensibilities. We wanted to see a variety of ideas about what people want from the future.”
Climate News Network

Tropics' climate sensitivity increases

FOR IMMEDIATE RELEASE
The sensitivity to climate change of tropical ecosystems appears to be increasing and their ability to store carbon declining, a development which has surprised scientists.

LONDON, 30 January – Tropical ecosystems may be responding to global warming more energetically than anyone had expected. Scientists from China, Germany, France, the UK and the US report in Nature that the tropical carbon cycle – the uptake and release of carbon dioxide from and back into the atmosphere – has become twice as sensitive to temperature change in the last 50 years.

A one degree rise in average tropical temperature leads to a release of around two billion more tonnes of carbon per year from tropical forests and savannahs, compared with the 1960s and 1970s.

This is unexpected. Climate scientists had foreseen the ability of land-based ecosystems to store carbon declining through the coming century as average global temperatures rise, but not on this scale.

To arrive at their conclusions, the researchers looked not at the crude rise in carbon dioxide levels in the atmosphere, but the year-to-year variations of traces of the gas recorded both at the top of the Mauna Loa volcano in Hawaii and at the South Pole, and then matched these with mean annual temperature variations over the same timescale.

Together, the findings seem to show that tropical ecosystems are becoming more sensitive to climate change. This could be another example of what engineers call positive feedback – warmer summers make forests drier and release more carbon dioxide to make summers warmer, and so on.

More information needed

There is evidence that the tropical regions have experienced more drought over the last five decades. More to the point, the team’s conclusion really suggests that if existing climate models provide uncertain projections of the future, it is because the information available is still incomplete.

It does however also indicate that variations in carbon dioxide levels would provide a monitor of the way tropical forests and grasslands are responding to climate.

“This enhancement is very unlikely to have resulted from chance, and may provide a new perspective on a possible shift in the terrestrial carbon cycle over the past five decades”, said Xuhui Wang of Peking University in Beijing, who led the study.

And Pierre Friedlingstein of the University of Exeter in the UK, one of the research team, said: “Current land carbon cycle systems do not show this increase over the last fifty years, because these models underestimate emerging drought effects on tropical ecosystems.” – Climate News Network

FOR IMMEDIATE RELEASE
The sensitivity to climate change of tropical ecosystems appears to be increasing and their ability to store carbon declining, a development which has surprised scientists.

LONDON, 30 January – Tropical ecosystems may be responding to global warming more energetically than anyone had expected. Scientists from China, Germany, France, the UK and the US report in Nature that the tropical carbon cycle – the uptake and release of carbon dioxide from and back into the atmosphere – has become twice as sensitive to temperature change in the last 50 years.

A one degree rise in average tropical temperature leads to a release of around two billion more tonnes of carbon per year from tropical forests and savannahs, compared with the 1960s and 1970s.

This is unexpected. Climate scientists had foreseen the ability of land-based ecosystems to store carbon declining through the coming century as average global temperatures rise, but not on this scale.

To arrive at their conclusions, the researchers looked not at the crude rise in carbon dioxide levels in the atmosphere, but the year-to-year variations of traces of the gas recorded both at the top of the Mauna Loa volcano in Hawaii and at the South Pole, and then matched these with mean annual temperature variations over the same timescale.

Together, the findings seem to show that tropical ecosystems are becoming more sensitive to climate change. This could be another example of what engineers call positive feedback – warmer summers make forests drier and release more carbon dioxide to make summers warmer, and so on.

More information needed

There is evidence that the tropical regions have experienced more drought over the last five decades. More to the point, the team’s conclusion really suggests that if existing climate models provide uncertain projections of the future, it is because the information available is still incomplete.

It does however also indicate that variations in carbon dioxide levels would provide a monitor of the way tropical forests and grasslands are responding to climate.

“This enhancement is very unlikely to have resulted from chance, and may provide a new perspective on a possible shift in the terrestrial carbon cycle over the past five decades”, said Xuhui Wang of Peking University in Beijing, who led the study.

And Pierre Friedlingstein of the University of Exeter in the UK, one of the research team, said: “Current land carbon cycle systems do not show this increase over the last fifty years, because these models underestimate emerging drought effects on tropical ecosystems.” – Climate News Network

Tropics’ climate sensitivity increases

FOR IMMEDIATE RELEASE The sensitivity to climate change of tropical ecosystems appears to be increasing and their ability to store carbon declining, a development which has surprised scientists. LONDON, 30 January – Tropical ecosystems may be responding to global warming more energetically than anyone had expected. Scientists from China, Germany, France, the UK and the US report in Nature that the tropical carbon cycle – the uptake and release of carbon dioxide from and back into the atmosphere – has become twice as sensitive to temperature change in the last 50 years. A one degree rise in average tropical temperature leads to a release of around two billion more tonnes of carbon per year from tropical forests and savannahs, compared with the 1960s and 1970s. This is unexpected. Climate scientists had foreseen the ability of land-based ecosystems to store carbon declining through the coming century as average global temperatures rise, but not on this scale. To arrive at their conclusions, the researchers looked not at the crude rise in carbon dioxide levels in the atmosphere, but the year-to-year variations of traces of the gas recorded both at the top of the Mauna Loa volcano in Hawaii and at the South Pole, and then matched these with mean annual temperature variations over the same timescale. Together, the findings seem to show that tropical ecosystems are becoming more sensitive to climate change. This could be another example of what engineers call positive feedback – warmer summers make forests drier and release more carbon dioxide to make summers warmer, and so on.

More information needed

There is evidence that the tropical regions have experienced more drought over the last five decades. More to the point, the team’s conclusion really suggests that if existing climate models provide uncertain projections of the future, it is because the information available is still incomplete. It does however also indicate that variations in carbon dioxide levels would provide a monitor of the way tropical forests and grasslands are responding to climate. “This enhancement is very unlikely to have resulted from chance, and may provide a new perspective on a possible shift in the terrestrial carbon cycle over the past five decades”, said Xuhui Wang of Peking University in Beijing, who led the study. And Pierre Friedlingstein of the University of Exeter in the UK, one of the research team, said: “Current land carbon cycle systems do not show this increase over the last fifty years, because these models underestimate emerging drought effects on tropical ecosystems.” – Climate News Network

FOR IMMEDIATE RELEASE The sensitivity to climate change of tropical ecosystems appears to be increasing and their ability to store carbon declining, a development which has surprised scientists. LONDON, 30 January – Tropical ecosystems may be responding to global warming more energetically than anyone had expected. Scientists from China, Germany, France, the UK and the US report in Nature that the tropical carbon cycle – the uptake and release of carbon dioxide from and back into the atmosphere – has become twice as sensitive to temperature change in the last 50 years. A one degree rise in average tropical temperature leads to a release of around two billion more tonnes of carbon per year from tropical forests and savannahs, compared with the 1960s and 1970s. This is unexpected. Climate scientists had foreseen the ability of land-based ecosystems to store carbon declining through the coming century as average global temperatures rise, but not on this scale. To arrive at their conclusions, the researchers looked not at the crude rise in carbon dioxide levels in the atmosphere, but the year-to-year variations of traces of the gas recorded both at the top of the Mauna Loa volcano in Hawaii and at the South Pole, and then matched these with mean annual temperature variations over the same timescale. Together, the findings seem to show that tropical ecosystems are becoming more sensitive to climate change. This could be another example of what engineers call positive feedback – warmer summers make forests drier and release more carbon dioxide to make summers warmer, and so on.

More information needed

There is evidence that the tropical regions have experienced more drought over the last five decades. More to the point, the team’s conclusion really suggests that if existing climate models provide uncertain projections of the future, it is because the information available is still incomplete. It does however also indicate that variations in carbon dioxide levels would provide a monitor of the way tropical forests and grasslands are responding to climate. “This enhancement is very unlikely to have resulted from chance, and may provide a new perspective on a possible shift in the terrestrial carbon cycle over the past five decades”, said Xuhui Wang of Peking University in Beijing, who led the study. And Pierre Friedlingstein of the University of Exeter in the UK, one of the research team, said: “Current land carbon cycle systems do not show this increase over the last fifty years, because these models underestimate emerging drought effects on tropical ecosystems.” – Climate News Network

Stockholm heat toll 'doubled in 30 years'

FOR IMMEDIATE RELEASE
Swedish researchers think the changing climate was responsible for doubling the number of heat-related deaths in the capital, Stockholm, in the 30 years from 1980.

LONDON, 23 October – It’s a small sample – just one city, during one 30-year interval – but it could have significance everywhere: deaths from extreme heat doubled in Stockholm, Sweden, between 1980 and 2009 and the agent behind this grim reckoning looks very much like global warming.

Daniel Oudin Åström of Umeå University, Sweden, and colleagues, report in Nature Climate Change that they looked at recent mortality in Stockholm, and then compared the records of deaths with those from 1900-1929.  The period 1980-2009 was marked by northern hemisphere summers with unprecedented extremes of heat – in 2003, 2007, 2010 and 2012 – and in 2010, temperatures in Europe exceeded all 20th and 21st century records.

Stockholm is a city more adapted to cold than heat, more associated with long bleak winters than stifling summers. Sweden is a society with a long history of good record-keeping, but Stockholm in particular is also a city of demographic change and immigration. So the population at risk from extremes of heat in this century cannot be matched very easily with that of a century ago, but Åström and his fellow researchers decided it was worth a try.

They calculated the weeks in which people would have been most at risk – from cold in winter as well as heat in summer – and considered the age groups most likely to suffer and collapse from heat exhaustion and heat stroke or from hypothermia and other winter hazards. They counted 220 extremes of cold at the beginning of the 20th century, and 251 such extremes in the last 30 years. Then they compared the pattern of mortality over the two timespans, and concluded that the extra 31 cold spells accounted for 75 premature deaths.

Then they looked at the high end of the thermometer, and saw a much more dramatic change. In the early 20th century, there were 220 very hot spells. In the most recent period, there were 381 extremes of heat. On this basis, an additional 288 people who died in Stockholm from the effects of heat did so with a 95% probability that climate change was implicated.

Determining the cause

Comparisons like these are very difficult to make. Human life expectancy has increased, and so has overall health care, sanitation and education.  Cities have expanded dramatically in the last 100 years. Motor traffic, street lighting, central heating and air conditioning have all helped make air temperatures in cities so much higher than in the surrounding countryside, where comparative meteorological measurements are normally made.

The Swedish scientists took such changes into account: without such adjustments, their extra death toll would have been 447.  They concluded that heat-related deaths in the last 30 years were twice those to be expected in the period before global warming.

Despite overall warming, and higher than average winter temperatures overall, the frequency of extremes of cold had increased during the same period, with a smaller excess of deaths. And the researchers confirm that they found no evidence that humans had physiologically adapted to a warmer world in the years since global temperatures began to rise.

Scientists make such calculations and then publish them, inviting other researchers to pour cold water on them. In fact, the cold water is coming anyway, according to Andrea Toreti of Justus Liebig University Giessen in Germany and colleagues.

They report in Geophysical Research Letters that as the atmosphere warms, so the air will be able to hold more water vapour, with all the more to fall on rainy days. The researchers took eight high resolution global general circulation models and tried to calculate rainfall extremes for the remainder of the century.

To do that, they took reliable data from the past, and projected the pattern of extremes to 2099. They also divided their projections into three time periods: from 1966 to 2005; from 2020 to 2059; and from 2060 to 2099.

The not very surprising conclusion is that with increasing temperatures, and with more moisture in the air, there will be more rain. But the scientists were looking for extreme events, and conclude that as the century wears on, extreme torrential downpours of the kind that once happened only every 50 years will start to happen every 20 years or so.

In the high latitude northern hemisphere (and that includes Stockholm) the strongest change will be in autumn and spring, where the daily extreme precipitation is expected to increase by 45% and 39% respectively. – Climate News Network

FOR IMMEDIATE RELEASE
Swedish researchers think the changing climate was responsible for doubling the number of heat-related deaths in the capital, Stockholm, in the 30 years from 1980.

LONDON, 23 October – It’s a small sample – just one city, during one 30-year interval – but it could have significance everywhere: deaths from extreme heat doubled in Stockholm, Sweden, between 1980 and 2009 and the agent behind this grim reckoning looks very much like global warming.

Daniel Oudin Åström of Umeå University, Sweden, and colleagues, report in Nature Climate Change that they looked at recent mortality in Stockholm, and then compared the records of deaths with those from 1900-1929.  The period 1980-2009 was marked by northern hemisphere summers with unprecedented extremes of heat – in 2003, 2007, 2010 and 2012 – and in 2010, temperatures in Europe exceeded all 20th and 21st century records.

Stockholm is a city more adapted to cold than heat, more associated with long bleak winters than stifling summers. Sweden is a society with a long history of good record-keeping, but Stockholm in particular is also a city of demographic change and immigration. So the population at risk from extremes of heat in this century cannot be matched very easily with that of a century ago, but Åström and his fellow researchers decided it was worth a try.

They calculated the weeks in which people would have been most at risk – from cold in winter as well as heat in summer – and considered the age groups most likely to suffer and collapse from heat exhaustion and heat stroke or from hypothermia and other winter hazards. They counted 220 extremes of cold at the beginning of the 20th century, and 251 such extremes in the last 30 years. Then they compared the pattern of mortality over the two timespans, and concluded that the extra 31 cold spells accounted for 75 premature deaths.

Then they looked at the high end of the thermometer, and saw a much more dramatic change. In the early 20th century, there were 220 very hot spells. In the most recent period, there were 381 extremes of heat. On this basis, an additional 288 people who died in Stockholm from the effects of heat did so with a 95% probability that climate change was implicated.

Determining the cause

Comparisons like these are very difficult to make. Human life expectancy has increased, and so has overall health care, sanitation and education.  Cities have expanded dramatically in the last 100 years. Motor traffic, street lighting, central heating and air conditioning have all helped make air temperatures in cities so much higher than in the surrounding countryside, where comparative meteorological measurements are normally made.

The Swedish scientists took such changes into account: without such adjustments, their extra death toll would have been 447.  They concluded that heat-related deaths in the last 30 years were twice those to be expected in the period before global warming.

Despite overall warming, and higher than average winter temperatures overall, the frequency of extremes of cold had increased during the same period, with a smaller excess of deaths. And the researchers confirm that they found no evidence that humans had physiologically adapted to a warmer world in the years since global temperatures began to rise.

Scientists make such calculations and then publish them, inviting other researchers to pour cold water on them. In fact, the cold water is coming anyway, according to Andrea Toreti of Justus Liebig University Giessen in Germany and colleagues.

They report in Geophysical Research Letters that as the atmosphere warms, so the air will be able to hold more water vapour, with all the more to fall on rainy days. The researchers took eight high resolution global general circulation models and tried to calculate rainfall extremes for the remainder of the century.

To do that, they took reliable data from the past, and projected the pattern of extremes to 2099. They also divided their projections into three time periods: from 1966 to 2005; from 2020 to 2059; and from 2060 to 2099.

The not very surprising conclusion is that with increasing temperatures, and with more moisture in the air, there will be more rain. But the scientists were looking for extreme events, and conclude that as the century wears on, extreme torrential downpours of the kind that once happened only every 50 years will start to happen every 20 years or so.

In the high latitude northern hemisphere (and that includes Stockholm) the strongest change will be in autumn and spring, where the daily extreme precipitation is expected to increase by 45% and 39% respectively. – Climate News Network

Stockholm heat toll ‘doubled in 30 years’

FOR IMMEDIATE RELEASE Swedish researchers think the changing climate was responsible for doubling the number of heat-related deaths in the capital, Stockholm, in the 30 years from 1980. LONDON, 23 October – It’s a small sample – just one city, during one 30-year interval – but it could have significance everywhere: deaths from extreme heat doubled in Stockholm, Sweden, between 1980 and 2009 and the agent behind this grim reckoning looks very much like global warming. Daniel Oudin Åström of Umeå University, Sweden, and colleagues, report in Nature Climate Change that they looked at recent mortality in Stockholm, and then compared the records of deaths with those from 1900-1929.  The period 1980-2009 was marked by northern hemisphere summers with unprecedented extremes of heat – in 2003, 2007, 2010 and 2012 – and in 2010, temperatures in Europe exceeded all 20th and 21st century records. Stockholm is a city more adapted to cold than heat, more associated with long bleak winters than stifling summers. Sweden is a society with a long history of good record-keeping, but Stockholm in particular is also a city of demographic change and immigration. So the population at risk from extremes of heat in this century cannot be matched very easily with that of a century ago, but Åström and his fellow researchers decided it was worth a try. They calculated the weeks in which people would have been most at risk – from cold in winter as well as heat in summer – and considered the age groups most likely to suffer and collapse from heat exhaustion and heat stroke or from hypothermia and other winter hazards. They counted 220 extremes of cold at the beginning of the 20th century, and 251 such extremes in the last 30 years. Then they compared the pattern of mortality over the two timespans, and concluded that the extra 31 cold spells accounted for 75 premature deaths. Then they looked at the high end of the thermometer, and saw a much more dramatic change. In the early 20th century, there were 220 very hot spells. In the most recent period, there were 381 extremes of heat. On this basis, an additional 288 people who died in Stockholm from the effects of heat did so with a 95% probability that climate change was implicated.

Determining the cause

Comparisons like these are very difficult to make. Human life expectancy has increased, and so has overall health care, sanitation and education.  Cities have expanded dramatically in the last 100 years. Motor traffic, street lighting, central heating and air conditioning have all helped make air temperatures in cities so much higher than in the surrounding countryside, where comparative meteorological measurements are normally made. The Swedish scientists took such changes into account: without such adjustments, their extra death toll would have been 447.  They concluded that heat-related deaths in the last 30 years were twice those to be expected in the period before global warming. Despite overall warming, and higher than average winter temperatures overall, the frequency of extremes of cold had increased during the same period, with a smaller excess of deaths. And the researchers confirm that they found no evidence that humans had physiologically adapted to a warmer world in the years since global temperatures began to rise. Scientists make such calculations and then publish them, inviting other researchers to pour cold water on them. In fact, the cold water is coming anyway, according to Andrea Toreti of Justus Liebig University Giessen in Germany and colleagues. They report in Geophysical Research Letters that as the atmosphere warms, so the air will be able to hold more water vapour, with all the more to fall on rainy days. The researchers took eight high resolution global general circulation models and tried to calculate rainfall extremes for the remainder of the century. To do that, they took reliable data from the past, and projected the pattern of extremes to 2099. They also divided their projections into three time periods: from 1966 to 2005; from 2020 to 2059; and from 2060 to 2099. The not very surprising conclusion is that with increasing temperatures, and with more moisture in the air, there will be more rain. But the scientists were looking for extreme events, and conclude that as the century wears on, extreme torrential downpours of the kind that once happened only every 50 years will start to happen every 20 years or so. In the high latitude northern hemisphere (and that includes Stockholm) the strongest change will be in autumn and spring, where the daily extreme precipitation is expected to increase by 45% and 39% respectively. – Climate News Network

FOR IMMEDIATE RELEASE Swedish researchers think the changing climate was responsible for doubling the number of heat-related deaths in the capital, Stockholm, in the 30 years from 1980. LONDON, 23 October – It’s a small sample – just one city, during one 30-year interval – but it could have significance everywhere: deaths from extreme heat doubled in Stockholm, Sweden, between 1980 and 2009 and the agent behind this grim reckoning looks very much like global warming. Daniel Oudin Åström of Umeå University, Sweden, and colleagues, report in Nature Climate Change that they looked at recent mortality in Stockholm, and then compared the records of deaths with those from 1900-1929.  The period 1980-2009 was marked by northern hemisphere summers with unprecedented extremes of heat – in 2003, 2007, 2010 and 2012 – and in 2010, temperatures in Europe exceeded all 20th and 21st century records. Stockholm is a city more adapted to cold than heat, more associated with long bleak winters than stifling summers. Sweden is a society with a long history of good record-keeping, but Stockholm in particular is also a city of demographic change and immigration. So the population at risk from extremes of heat in this century cannot be matched very easily with that of a century ago, but Åström and his fellow researchers decided it was worth a try. They calculated the weeks in which people would have been most at risk – from cold in winter as well as heat in summer – and considered the age groups most likely to suffer and collapse from heat exhaustion and heat stroke or from hypothermia and other winter hazards. They counted 220 extremes of cold at the beginning of the 20th century, and 251 such extremes in the last 30 years. Then they compared the pattern of mortality over the two timespans, and concluded that the extra 31 cold spells accounted for 75 premature deaths. Then they looked at the high end of the thermometer, and saw a much more dramatic change. In the early 20th century, there were 220 very hot spells. In the most recent period, there were 381 extremes of heat. On this basis, an additional 288 people who died in Stockholm from the effects of heat did so with a 95% probability that climate change was implicated.

Determining the cause

Comparisons like these are very difficult to make. Human life expectancy has increased, and so has overall health care, sanitation and education.  Cities have expanded dramatically in the last 100 years. Motor traffic, street lighting, central heating and air conditioning have all helped make air temperatures in cities so much higher than in the surrounding countryside, where comparative meteorological measurements are normally made. The Swedish scientists took such changes into account: without such adjustments, their extra death toll would have been 447.  They concluded that heat-related deaths in the last 30 years were twice those to be expected in the period before global warming. Despite overall warming, and higher than average winter temperatures overall, the frequency of extremes of cold had increased during the same period, with a smaller excess of deaths. And the researchers confirm that they found no evidence that humans had physiologically adapted to a warmer world in the years since global temperatures began to rise. Scientists make such calculations and then publish them, inviting other researchers to pour cold water on them. In fact, the cold water is coming anyway, according to Andrea Toreti of Justus Liebig University Giessen in Germany and colleagues. They report in Geophysical Research Letters that as the atmosphere warms, so the air will be able to hold more water vapour, with all the more to fall on rainy days. The researchers took eight high resolution global general circulation models and tried to calculate rainfall extremes for the remainder of the century. To do that, they took reliable data from the past, and projected the pattern of extremes to 2099. They also divided their projections into three time periods: from 1966 to 2005; from 2020 to 2059; and from 2060 to 2099. The not very surprising conclusion is that with increasing temperatures, and with more moisture in the air, there will be more rain. But the scientists were looking for extreme events, and conclude that as the century wears on, extreme torrential downpours of the kind that once happened only every 50 years will start to happen every 20 years or so. In the high latitude northern hemisphere (and that includes Stockholm) the strongest change will be in autumn and spring, where the daily extreme precipitation is expected to increase by 45% and 39% respectively. – Climate News Network