Tag Archives: Natural variability

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Climates change faster in a warmer and wetter world

While more rain normally cools a summer environment, a warmer and wetter world could face quite unfamiliar problems.

LONDON, 16 March, 2018 – Climate change may still cause surprises, if simultaneously it means a warmer and wetter world. More heat and moisture together can unbalance ecosystems.

Scientists have been warning for decades of shifts towards ever greater risks of flooding in some places, more intense and sustained droughts and potentially lethal heatwaves in others.

But new research suggests an unexpected twist: temperate and subtropical zones could become both hotter and wetter during future summers.

And this could create a whole suite of unexpected problems: farmers and city dwellers who have adapted to a pattern of cool wet summers or hot dry summers could face a new range of fungal or pest infections in crops, or pathogens in crowded communities, as insects and microbes seize a new set of opportunities.

“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest”

Canadian scientists report in Nature Communications that they considered what they call “departures from natural variability” that may follow as a consequence of continual rises in global average temperature, driven by ever greater combustion of fossil fuels that emit ever higher ratios of greenhouse gases into the atmosphere.

They studied historical records back to 1901, and climate projections as far as the year 2100. And they see a problem: creatures – people, crops, pathogens and pests – that have adapted to particular regional ecosystems could be jolted out of their comfort zone.

“Some of the disruptions of climate change stem from basic physics and are easily anticipated. Increases in sea level, forest fires, heat waves, and droughts fall into that category.

“But there is a whole other category of unexpected disruptions that stem from upsetting the complex balance of ecosystems,” said Colin Mahony, a forester and doctoral student at the University of British Columbia, who led the research.

A global increase in outbreaks of fungal needle blight in pine plantations could be linked to wetter and warmer conditions. Mosquito-borne pathogens could flourish in hot cities with once rare puddles of standing water.

Literature overload

“The mountain pine beetle epidemic that devastated the pine forests of western North America ten years ago is an example of this. This study digs into global climate model output for clues about what kinds of ecological disruptions might be just over the horizon,” he said.

The research points to the south-eastern US, central Canada, northern Australia, southern Africa, central Asia and the African Sahel as regions that could unexpectedly become warmer and wetter in ways that could disrupt normal patterns.

“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest,” he said.

The research was triggered, he told Climate News Network, by the Network’s report of a 2015 paper that predicted harder rainfall in a warmer world.

“The scientific literature on climate change is so vast that sites like the Climate News Network are an important way to bridge the barriers between researchers in different disciplines like ecology and atmospheric sciences.” – Climate News Network

While more rain normally cools a summer environment, a warmer and wetter world could face quite unfamiliar problems.

LONDON, 16 March, 2018 – Climate change may still cause surprises, if simultaneously it means a warmer and wetter world. More heat and moisture together can unbalance ecosystems.

Scientists have been warning for decades of shifts towards ever greater risks of flooding in some places, more intense and sustained droughts and potentially lethal heatwaves in others.

But new research suggests an unexpected twist: temperate and subtropical zones could become both hotter and wetter during future summers.

And this could create a whole suite of unexpected problems: farmers and city dwellers who have adapted to a pattern of cool wet summers or hot dry summers could face a new range of fungal or pest infections in crops, or pathogens in crowded communities, as insects and microbes seize a new set of opportunities.

“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest”

Canadian scientists report in Nature Communications that they considered what they call “departures from natural variability” that may follow as a consequence of continual rises in global average temperature, driven by ever greater combustion of fossil fuels that emit ever higher ratios of greenhouse gases into the atmosphere.

They studied historical records back to 1901, and climate projections as far as the year 2100. And they see a problem: creatures – people, crops, pathogens and pests – that have adapted to particular regional ecosystems could be jolted out of their comfort zone.

“Some of the disruptions of climate change stem from basic physics and are easily anticipated. Increases in sea level, forest fires, heat waves, and droughts fall into that category.

“But there is a whole other category of unexpected disruptions that stem from upsetting the complex balance of ecosystems,” said Colin Mahony, a forester and doctoral student at the University of British Columbia, who led the research.

A global increase in outbreaks of fungal needle blight in pine plantations could be linked to wetter and warmer conditions. Mosquito-borne pathogens could flourish in hot cities with once rare puddles of standing water.

Literature overload

“The mountain pine beetle epidemic that devastated the pine forests of western North America ten years ago is an example of this. This study digs into global climate model output for clues about what kinds of ecological disruptions might be just over the horizon,” he said.

The research points to the south-eastern US, central Canada, northern Australia, southern Africa, central Asia and the African Sahel as regions that could unexpectedly become warmer and wetter in ways that could disrupt normal patterns.

“We found that where temperature and precipitation are increasing together, climates are changing faster than the temperature trend alone would suggest,” he said.

The research was triggered, he told Climate News Network, by the Network’s report of a 2015 paper that predicted harder rainfall in a warmer world.

“The scientific literature on climate change is so vast that sites like the Climate News Network are an important way to bridge the barriers between researchers in different disciplines like ecology and atmospheric sciences.” – Climate News Network

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By air, land and sea, global warming rises

Global warming took surface temperatures in 2017 to near-record levels, while the upper oceans reached their hottest known level.

LONDON, 19 January, 2018 – Global warming is real, and it’s happening now. Within hours of the announcement by scientists in the US that 2017 was at least the third warmest year recorded, if not the second, over the Earth’s land and oceans, there comes a further revelation: 2017 was also the warmest year on record for the global oceans.

Both disclosures are consistent with what scientists had expected from climate change, driven by global warming as a consequence of the profligate combustion of fossil fuels that dump ever greater levels of greenhouse gases in the atmosphere.

But they add to the scientists’ sense of urgency at the need for rapid and radical action to cut greenhouse emissions. Of the US announcement, Dr Dann Mitchell, of the University of Bristol, UK, said: “The most recent global temperature observations are in line with what we expected, both from our underlying theory, but also our model projections and understanding of the climate system.

“The atmosphere is warming, by almost 1°C globally to date, and we are getting ever closer to the Paris Agreement target of 1.5°C which we are so desperately trying to avoid.”

The news that the oceans are continuing to warm to hitherto unknown levels comes in an updated ocean analysis from the Institute of Atmospheric Physics/Chinese Academy of Science (IAP/CAS). Its study was published as an early online release in the journal Advances in Atmospheric Sciences.

“The biggest natural influence on the climate is being dwarfed by human activities – predominantly CO₂ emissions”

The authors say that in 2017 the oceans in the upper 2000-metre layer of water were warmer than the second warmest year, 2015, and above the 1981-2010 climatological reference period.

Thanks to their large heat capacity, the oceans absorb warming caused by human activities, and more than 90% of the Earth’s extra heat from global warming is absorbed by them.

The study says the global ocean heat content record robustly represents the signature of global warming, and is affected less by weather-related “noise” and climate variability such as El Niño and La Niña events.

The IAP says the last five years have been the five warmest years in the oceans, as the long-term warming trend driven by human activities continued unabated.

The rise in ocean heat in 2017 occurred in most regions of the world. Increases in ocean temperature cause the volume of seawater to expand, contributing to the global average sea level rise, which in 2017 amounted to 1.7 mm. Other consequences include a decline in ocean oxygen, the bleaching of coral reefs, and the melting of sea ice and ice shelves.

Discrepancy explained

The globally averaged temperature over land and ocean surfaces for 2017 was the third highest since record keeping began in 1880, according to NOAA scientists.

There is a slight difference in the figures for 2017’s temperature. NOAA says the globally averaged temperature for the year makes it the third hottest since record-keeping began in 1880, while NASA says in a separate analysis that 2017 was the second warmest on record, behind 2016.

This minor difference is explained by the different methods used by the two agencies to analyse global temperatures, they say, though they point out that over the long term their records agree closely.

Both agree that the five warmest years on record have all occurred since 2010. The UK Met Office and the World Meteorological Organisation (WMO) also listed 2017 among the top three warmest years on record.

One striking feature of the consensus on 2017’s place in the record books is less about what did happen, and more about what didn’t. Last year was the second or third hottest after 2016, and on a level with 2015, the data show.

No boost

But those two years were affected by El Niño, the periodic natural phenomenon in the Pacific, which helps to boost temperatures worldwide. 2017 was not an El Niño year.

If it had been, the researchers say, it would probably have been the warmest year yet, outstripping the heat in 2015 and 2016.

The acting director of the UK Met Office, Professor Peter Stott, told BBC News: “It’s extraordinary that temperatures in 2017 have been so high when there’s no El Niño. In fact, we’ve been going into cooler La Niña conditions.

“It shows clearly that the biggest natural influence on the climate is being dwarfed by human activities – predominantly CO₂ emissions.”

The WMO secretary-general, Petteri Taalas, said the long-term temperature trend was far more important than the ranking of individual years: “That trend is an upward one. Seventeen of the 18 warmest years on record have all been during this century, and the degree of warming during the past three years has been exceptional.

“Arctic warmth has been especially pronounced, and this will have profound and long-lasting repercussions on sea levels, and on weather patterns in other parts of the world.” – Climate News Network

Global warming took surface temperatures in 2017 to near-record levels, while the upper oceans reached their hottest known level.

LONDON, 19 January, 2018 – Global warming is real, and it’s happening now. Within hours of the announcement by scientists in the US that 2017 was at least the third warmest year recorded, if not the second, over the Earth’s land and oceans, there comes a further revelation: 2017 was also the warmest year on record for the global oceans.

Both disclosures are consistent with what scientists had expected from climate change, driven by global warming as a consequence of the profligate combustion of fossil fuels that dump ever greater levels of greenhouse gases in the atmosphere.

But they add to the scientists’ sense of urgency at the need for rapid and radical action to cut greenhouse emissions. Of the US announcement, Dr Dann Mitchell, of the University of Bristol, UK, said: “The most recent global temperature observations are in line with what we expected, both from our underlying theory, but also our model projections and understanding of the climate system.

“The atmosphere is warming, by almost 1°C globally to date, and we are getting ever closer to the Paris Agreement target of 1.5°C which we are so desperately trying to avoid.”

The news that the oceans are continuing to warm to hitherto unknown levels comes in an updated ocean analysis from the Institute of Atmospheric Physics/Chinese Academy of Science (IAP/CAS). Its study was published as an early online release in the journal Advances in Atmospheric Sciences.

“The biggest natural influence on the climate is being dwarfed by human activities – predominantly CO₂ emissions”

The authors say that in 2017 the oceans in the upper 2000-metre layer of water were warmer than the second warmest year, 2015, and above the 1981-2010 climatological reference period.

Thanks to their large heat capacity, the oceans absorb warming caused by human activities, and more than 90% of the Earth’s extra heat from global warming is absorbed by them.

The study says the global ocean heat content record robustly represents the signature of global warming, and is affected less by weather-related “noise” and climate variability such as El Niño and La Niña events.

The IAP says the last five years have been the five warmest years in the oceans, as the long-term warming trend driven by human activities continued unabated.

The rise in ocean heat in 2017 occurred in most regions of the world. Increases in ocean temperature cause the volume of seawater to expand, contributing to the global average sea level rise, which in 2017 amounted to 1.7 mm. Other consequences include a decline in ocean oxygen, the bleaching of coral reefs, and the melting of sea ice and ice shelves.

Discrepancy explained

The globally averaged temperature over land and ocean surfaces for 2017 was the third highest since record keeping began in 1880, according to NOAA scientists.

There is a slight difference in the figures for 2017’s temperature. NOAA says the globally averaged temperature for the year makes it the third hottest since record-keeping began in 1880, while NASA says in a separate analysis that 2017 was the second warmest on record, behind 2016.

This minor difference is explained by the different methods used by the two agencies to analyse global temperatures, they say, though they point out that over the long term their records agree closely.

Both agree that the five warmest years on record have all occurred since 2010. The UK Met Office and the World Meteorological Organisation (WMO) also listed 2017 among the top three warmest years on record.

One striking feature of the consensus on 2017’s place in the record books is less about what did happen, and more about what didn’t. Last year was the second or third hottest after 2016, and on a level with 2015, the data show.

No boost

But those two years were affected by El Niño, the periodic natural phenomenon in the Pacific, which helps to boost temperatures worldwide. 2017 was not an El Niño year.

If it had been, the researchers say, it would probably have been the warmest year yet, outstripping the heat in 2015 and 2016.

The acting director of the UK Met Office, Professor Peter Stott, told BBC News: “It’s extraordinary that temperatures in 2017 have been so high when there’s no El Niño. In fact, we’ve been going into cooler La Niña conditions.

“It shows clearly that the biggest natural influence on the climate is being dwarfed by human activities – predominantly CO₂ emissions.”

The WMO secretary-general, Petteri Taalas, said the long-term temperature trend was far more important than the ranking of individual years: “That trend is an upward one. Seventeen of the 18 warmest years on record have all been during this century, and the degree of warming during the past three years has been exceptional.

“Arctic warmth has been especially pronounced, and this will have profound and long-lasting repercussions on sea levels, and on weather patterns in other parts of the world.” – Climate News Network

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Lizards help to explain climate impacts

Lizards can shed light on the development of ecological niches and how the changing climate may affect the natural world.

LONDON, 23 November, 2017 – US scientists think lizards could help them one step nearer to an old dream: a kind of “periodic table” for ecology.

Just as the great insight of the Russian chemist Dmitri Mendeleev now means that chemists can understand better the relationships between elements, and make predictions about their responses, a classification of ecological niches could help biologists better understand the impact of climate change on the millions of species that share the Earth.

Such a project may never be completed, but a new study in The American Naturalist demonstrates that it has begun.

An ecological niche is a tangle of environmental conditions and biological behaviours that mean an insect, an amphibian, a reptile, bird or mammal is specialised to make the best of its short life. For example, fig wasps need fig trees to survive, and if there are 900 species of fig tree on the planet, 900 species of fig wasp will evolve to fill those ecological niches.

The researchers worked out what constitutes a niche: they chose habitat, diet, life history, metabolism and defence, and then listed between seven and 15 variables for each of those properties. Then they compiled all the data they could find about 134 species of lizard on four continents from 24 of the planet’s 38 surviving lizard families. And then they started to impose order on their material.

“Summarising major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions”

They could do that because, even though Australian desert lizards are of entirely separate species from desert lizards in Africa, or America, they forage for food, stay lively or dormant at given times, reproduce and exploit their habitat in very similar ways. Evolutionary pressures mean that they have converged to fill similar ecological niches.

“Summarising major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions and the invasive potential of species,” said Eric Pianka, a zoologist at the University of Texas at Austin, who led the study. 

“It will inform us about how niches have evolved in the past and even how they will evolve in the future, all of which has direct bearing on impacts of climate change.”

Climate change presents biologists with a problem: humans depend on the natural world in myriad ways; plant, fungus and animal species recycle the world’s air and water, conserve rainfall, pollinate crops, generate fruits and seeds for nourishment and chemicals for pharmaceuticals, fabrics for clothes and shelter.

They dispose of excrement and other biological waste, and each species in this intricate economy survives because it occupies an ecological niche.

Global risk

But the ecosystems that support such helpful networks are everywhere at risk because of climate change.  They are at hazard on a global scale and at the level of single nations or marine environments.

But without an intellectual framework that identifies the features that ecosystems, and ecological niches within those ecosystems, might have in common, conservation biologists won’t know where best to start.

What they do know is that conservation is vital, and that the creatures of the world are stronger because they are so many and so varied: yet another study from Switzerland involving 2,200 species in 450 different landscapes has just confirmed once again that the richer the variety of life in it, the more productive the landscape, and the better it is able to withstand change.

Now the scientists from Texas, Oklahoma and Argentina have confirmed, with what they call “the lizard niche hypervolume”, the possibility of a living equivalent of the periodic table that permits predictions that could be confirmed by observation or experiment, not just for lizards but for other families.

Separate niches

Lizards, like birds, inhabit trees, lay eggs and devour insects: unlike birds, they rely on the environment to maintain their temperature, so what would be one day’s food for a small bird might keep a lizard alive for a month.

It follows that birds and lizards occupy separate ecological niches. Ecologists have a potential structure or scaffolding into which to place their specimen animal and its ideal habitat and consider it in relation to other ecological niches.

But, as the researchers point out, so far only 2.2% of known lizards are included in their analysis, and environments are dynamic things: they change with time. There is a lot more to be done in researching clades, groupings of organisms which share a common ancestor and all of its descendants.

“As more periodic tables are created,” they write, “comparative analyses among more distantly-related clades (fish-frogs-salamanders-lizards-snakes-birds-mammals) will become possible, ultimately leading to a wider understanding of niche evolution among vertebrates.” – Climate News Network

Lizards can shed light on the development of ecological niches and how the changing climate may affect the natural world.

LONDON, 23 November, 2017 – US scientists think lizards could help them one step nearer to an old dream: a kind of “periodic table” for ecology.

Just as the great insight of the Russian chemist Dmitri Mendeleev now means that chemists can understand better the relationships between elements, and make predictions about their responses, a classification of ecological niches could help biologists better understand the impact of climate change on the millions of species that share the Earth.

Such a project may never be completed, but a new study in The American Naturalist demonstrates that it has begun.

An ecological niche is a tangle of environmental conditions and biological behaviours that mean an insect, an amphibian, a reptile, bird or mammal is specialised to make the best of its short life. For example, fig wasps need fig trees to survive, and if there are 900 species of fig tree on the planet, 900 species of fig wasp will evolve to fill those ecological niches.

The researchers worked out what constitutes a niche: they chose habitat, diet, life history, metabolism and defence, and then listed between seven and 15 variables for each of those properties. Then they compiled all the data they could find about 134 species of lizard on four continents from 24 of the planet’s 38 surviving lizard families. And then they started to impose order on their material.

“Summarising major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions”

They could do that because, even though Australian desert lizards are of entirely separate species from desert lizards in Africa, or America, they forage for food, stay lively or dormant at given times, reproduce and exploit their habitat in very similar ways. Evolutionary pressures mean that they have converged to fill similar ecological niches.

“Summarising major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions and the invasive potential of species,” said Eric Pianka, a zoologist at the University of Texas at Austin, who led the study. 

“It will inform us about how niches have evolved in the past and even how they will evolve in the future, all of which has direct bearing on impacts of climate change.”

Climate change presents biologists with a problem: humans depend on the natural world in myriad ways; plant, fungus and animal species recycle the world’s air and water, conserve rainfall, pollinate crops, generate fruits and seeds for nourishment and chemicals for pharmaceuticals, fabrics for clothes and shelter.

They dispose of excrement and other biological waste, and each species in this intricate economy survives because it occupies an ecological niche.

Global risk

But the ecosystems that support such helpful networks are everywhere at risk because of climate change.  They are at hazard on a global scale and at the level of single nations or marine environments.

But without an intellectual framework that identifies the features that ecosystems, and ecological niches within those ecosystems, might have in common, conservation biologists won’t know where best to start.

What they do know is that conservation is vital, and that the creatures of the world are stronger because they are so many and so varied: yet another study from Switzerland involving 2,200 species in 450 different landscapes has just confirmed once again that the richer the variety of life in it, the more productive the landscape, and the better it is able to withstand change.

Now the scientists from Texas, Oklahoma and Argentina have confirmed, with what they call “the lizard niche hypervolume”, the possibility of a living equivalent of the periodic table that permits predictions that could be confirmed by observation or experiment, not just for lizards but for other families.

Separate niches

Lizards, like birds, inhabit trees, lay eggs and devour insects: unlike birds, they rely on the environment to maintain their temperature, so what would be one day’s food for a small bird might keep a lizard alive for a month.

It follows that birds and lizards occupy separate ecological niches. Ecologists have a potential structure or scaffolding into which to place their specimen animal and its ideal habitat and consider it in relation to other ecological niches.

But, as the researchers point out, so far only 2.2% of known lizards are included in their analysis, and environments are dynamic things: they change with time. There is a lot more to be done in researching clades, groupings of organisms which share a common ancestor and all of its descendants.

“As more periodic tables are created,” they write, “comparative analyses among more distantly-related clades (fish-frogs-salamanders-lizards-snakes-birds-mammals) will become possible, ultimately leading to a wider understanding of niche evolution among vertebrates.” – Climate News Network

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Climate change may increase California’s rain

In a warmer world California’s rain may be more ample than today. But so far most climate scientists foresee more drought.

LONDON, 8 July, 2017 – If humans go on burning fossil fuels, then California might, after all, remain the Golden State. It will get warmer. But, against all predictions, it might also get wetter.

A new study suggests that by the century’s end, Californians could see 12% more rain than they experienced in the last 20 years of the 20th century.

This is not the standard forecast. Almost all other climate models have warned that California – still recovering from a calamitous and sustained drought – could, like the whole of the US Southwest, become both hotter and drier and far more at risk of wildfire.

But that is not how two researchers see it. They report in the journal Nature Communications that although, under the notorious “business-as-usual” scenario, in which people go on filling cars with petrol and generating electricity by burning coal, the most southern tip of the state would indeed continue to parch, rain in northern California could increase by 14.1% and central California by 15.2%.

“The overall thought was California would become drier with continued climate change. We found the opposite, which is quite surprising”

The latest predictions are based – like all other previous analyses – on computer simulations of future climate, and, like all simulations, they depend on the data available to the modellers.

But overall, forecasts for California have repeatedly suggested that the state could be in for a run of very dry seasons, especially as falling winter precipitation would mean that the state could hardly rely on melting snow to deliver the irrigation for the orange groves, vineyards and market gardens.

But the latest researchers found that rain and snow in December, January and February – which has usually  been when the heavens opened for California – would actually increase: more than 39% in central California, 31.6% in the north, and 10.6% in the south, in comparison with averages from the years 1979 to 1999.

“Most previous research emphasised uncertainty with regards to future precipitation levels in California, but the overall thought was California would become drier with continued climate change,” said Robert Allen, of the University of California Riverside, one of the authors. “We found the opposite, which is quite surprising.”

Surprises

This is not the first contrary finding recently produced by climate modellers. Although, overall, climate scientists expect the already arid zones to become more arid, and the well-watered regions to get even more rain, climate change could deliver surprises.

One research team has just predicted the arrival of seasonal monsoons for the Sahel region of northern Africa, historically prone to drought. 

The Sahel forecasters and the Californian modellers linked their higher rainfall to shifts in ocean temperature. As the tropical eastern Pacific Ocean warms, there could be a shift in the jet stream to the southeast, which could bring more rain-producing cyclones over California.

“Essentially, this mechanism is similar to what we in California expect during an El Niño year,” Dr Allen said. “Ultimately, what I am arguing is El Niño-like years are going to become more the norm in California.” – Climate News Network 

In a warmer world California’s rain may be more ample than today. But so far most climate scientists foresee more drought.

LONDON, 8 July, 2017 – If humans go on burning fossil fuels, then California might, after all, remain the Golden State. It will get warmer. But, against all predictions, it might also get wetter.

A new study suggests that by the century’s end, Californians could see 12% more rain than they experienced in the last 20 years of the 20th century.

This is not the standard forecast. Almost all other climate models have warned that California – still recovering from a calamitous and sustained drought – could, like the whole of the US Southwest, become both hotter and drier and far more at risk of wildfire.

But that is not how two researchers see it. They report in the journal Nature Communications that although, under the notorious “business-as-usual” scenario, in which people go on filling cars with petrol and generating electricity by burning coal, the most southern tip of the state would indeed continue to parch, rain in northern California could increase by 14.1% and central California by 15.2%.

“The overall thought was California would become drier with continued climate change. We found the opposite, which is quite surprising”

The latest predictions are based – like all other previous analyses – on computer simulations of future climate, and, like all simulations, they depend on the data available to the modellers.

But overall, forecasts for California have repeatedly suggested that the state could be in for a run of very dry seasons, especially as falling winter precipitation would mean that the state could hardly rely on melting snow to deliver the irrigation for the orange groves, vineyards and market gardens.

But the latest researchers found that rain and snow in December, January and February – which has usually  been when the heavens opened for California – would actually increase: more than 39% in central California, 31.6% in the north, and 10.6% in the south, in comparison with averages from the years 1979 to 1999.

“Most previous research emphasised uncertainty with regards to future precipitation levels in California, but the overall thought was California would become drier with continued climate change,” said Robert Allen, of the University of California Riverside, one of the authors. “We found the opposite, which is quite surprising.”

Surprises

This is not the first contrary finding recently produced by climate modellers. Although, overall, climate scientists expect the already arid zones to become more arid, and the well-watered regions to get even more rain, climate change could deliver surprises.

One research team has just predicted the arrival of seasonal monsoons for the Sahel region of northern Africa, historically prone to drought. 

The Sahel forecasters and the Californian modellers linked their higher rainfall to shifts in ocean temperature. As the tropical eastern Pacific Ocean warms, there could be a shift in the jet stream to the southeast, which could bring more rain-producing cyclones over California.

“Essentially, this mechanism is similar to what we in California expect during an El Niño year,” Dr Allen said. “Ultimately, what I am arguing is El Niño-like years are going to become more the norm in California.” – Climate News Network 

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Polar sea ice reaches record low

Arctic sea ice polar
Arctic sea ice polar

NASA scientists say that in the last six months the world has lost an area of polar sea ice that is bigger than Mexico.

LONDON, 30 March, 2017 Arctic sea ice in March reached a new record low: the area of frozen ocean at the height of winter on 7 March reached a new maximum low for the third year running, according to NASA scientists. Only a few days earlier, on 3 March, Antarctic sea ice reached its own new record summer low since satellite observations began in 1979.

And on 13 February the total area of frozen ocean in the two hemispheres was at its lowest: 16.21 million square kilometres, which is about 2m sq km less than the average global minimum for 1981 to 2010.

In effect, the NASA scientists report, the world had lost a chunk of sea ice of an area bigger than Mexico.

Extraordinary conditions

It has been quite extraordinary for several months in the Arctic,” says Julienne Stroeve, professor of polar observation at University College London. “Pretty much all through October, November, December, January, February and now March, we have been tracking record low conditions. I don’t think there has ever been a time in the Arctic when we have seen so many months of just record consecutive low conditions.”

The most dramatic losses of sea ice have over the decades been observed in summer – where the decline has been measured at 14% per decade. Winter shrinkage has been at a much lower rate: about 3% per decade. But the ice has been thinning as well as dwindling in area, and temperatures earlier in the winter were unusually high: 20°C above the average for the time of the year.

Nobody can be sure what will happen once the spring thaw has begun, but polar scientists are expecting the worst. “We are pretty much poised to have really low summer ice conditions,” Professor Stroeve says.

We have been at record low levels. There is a lot
of year-to-year variability, and it was only
a couple of years ago we saw a maximum”

The frozen ocean around the Antarctic continent, too, has scientists worried. Sea ice fell to 2.11m sq km on 3 March. This is below the previous lowest minimum on record, exactly 20 years ago.

The two poles are very different. The Arctic is an ocean surrounded by land, while the Antarctic is a vast continent ringed by ocean, therefore the dynamics of ice formation and loss are not the same. And in recent years, the extent of sea ice in Antarctica had been growing. But this March, at the close of the Antarctic summer, there was a dramatic change.

It is tempting to say that the record low we are seeing is global warming finally catching up with Antarctica,” says Walt Meier of NASA’s Goddard Space Flight Centre in Maryland.

However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend.”

Both polar regions are affected by natural variation. But the suspicion is that the long-term trend in global warming driven by human combustion of fossil fuels that dump vast quantities of greenhouse gases into the atmosphere must be playing a part. One research group recently proposed that human action might be responsible for at least half and perhaps 70% of Arctic warming.

Polar variability

Southern polar sea ice reached its peak at the end of August, and November, December, January and February all saw rapid declines.

We have been at record low levels,” says Emily Shuckburgh, deputy head of polar oceans at the British Antarctic Survey. “There is a lot of year-to-year variability, and it was only a couple of years ago we saw a maximum.

This is just one year where there is a lot of variability, and really understanding what the implications are is the research challenge.” Climate News Network

NASA scientists say that in the last six months the world has lost an area of polar sea ice that is bigger than Mexico.

LONDON, 30 March, 2017 Arctic sea ice in March reached a new record low: the area of frozen ocean at the height of winter on 7 March reached a new maximum low for the third year running, according to NASA scientists. Only a few days earlier, on 3 March, Antarctic sea ice reached its own new record summer low since satellite observations began in 1979.

And on 13 February the total area of frozen ocean in the two hemispheres was at its lowest: 16.21 million square kilometres, which is about 2m sq km less than the average global minimum for 1981 to 2010.

In effect, the NASA scientists report, the world had lost a chunk of sea ice of an area bigger than Mexico.

Extraordinary conditions

It has been quite extraordinary for several months in the Arctic,” says Julienne Stroeve, professor of polar observation at University College London. “Pretty much all through October, November, December, January, February and now March, we have been tracking record low conditions. I don’t think there has ever been a time in the Arctic when we have seen so many months of just record consecutive low conditions.”

The most dramatic losses of sea ice have over the decades been observed in summer – where the decline has been measured at 14% per decade. Winter shrinkage has been at a much lower rate: about 3% per decade. But the ice has been thinning as well as dwindling in area, and temperatures earlier in the winter were unusually high: 20°C above the average for the time of the year.

Nobody can be sure what will happen once the spring thaw has begun, but polar scientists are expecting the worst. “We are pretty much poised to have really low summer ice conditions,” Professor Stroeve says.

We have been at record low levels. There is a lot
of year-to-year variability, and it was only
a couple of years ago we saw a maximum”

The frozen ocean around the Antarctic continent, too, has scientists worried. Sea ice fell to 2.11m sq km on 3 March. This is below the previous lowest minimum on record, exactly 20 years ago.

The two poles are very different. The Arctic is an ocean surrounded by land, while the Antarctic is a vast continent ringed by ocean, therefore the dynamics of ice formation and loss are not the same. And in recent years, the extent of sea ice in Antarctica had been growing. But this March, at the close of the Antarctic summer, there was a dramatic change.

It is tempting to say that the record low we are seeing is global warming finally catching up with Antarctica,” says Walt Meier of NASA’s Goddard Space Flight Centre in Maryland.

However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend.”

Both polar regions are affected by natural variation. But the suspicion is that the long-term trend in global warming driven by human combustion of fossil fuels that dump vast quantities of greenhouse gases into the atmosphere must be playing a part. One research group recently proposed that human action might be responsible for at least half and perhaps 70% of Arctic warming.

Polar variability

Southern polar sea ice reached its peak at the end of August, and November, December, January and February all saw rapid declines.

We have been at record low levels,” says Emily Shuckburgh, deputy head of polar oceans at the British Antarctic Survey. “There is a lot of year-to-year variability, and it was only a couple of years ago we saw a maximum.

This is just one year where there is a lot of variability, and really understanding what the implications are is the research challenge.” Climate News Network

*

Warming’s mixed effects on migratory animals

Global warming brent geese
Global warming brent geese

New studies on beluga whales and Brent geese reveal that they respond to global warming in conflicting ways, making species survival hard to predict.

LONDON, 13 January, 2017 Beluga whales are responding to climate change in a rapidly warming Arctic – but only some of them. And migratory geese ought to be flourishing with milder conditions at nesting grounds in the far north – but the mother geese are at greater risk.

Both studies leave biologists guessing a bit at the response of their animal subjects to climate change. But the evidence shows that even the animals themselves may have to take a guess.

Warming Arctic

US scientists report in Global Change Biology that one population of beluga whales is taking advantage of the longer summers in the far north, while another is keeping to a calendar that pre-dates climate change.

Beluga whales, those ghostly white hunters of the northern seas, tend to winter in the Bering Sea between two continents, and then swim north as the ice melts and the Arctic seas open up.

The two populations of whales are genetically distinct – they have different ancestries – and travel as family groups, the young learning from their mothers.

Those that feed on fish and molluscs in the Beaufort Sea north of Alaska and Canada tend to leave the summer feeding grounds in autumn with the first risk of freezing. Those that hunt in the Chukchi Sea to the north and east of Alaska are delaying their response to take advantage of the longer spells of open water.

Summer sea ice has been in retreat for the last 30 years, and last autumn was an astonishing 20°C above average.

So biologists are confronted with a big question: is one population guarding against being caught by a sudden build-up of Arctic ice, while the other is consciously taking a risk but benefiting from a longer spell in richer feeding grounds?

The biggest take-home message is that belugas can respond relatively quickly to their changing environment, yet we can’t expect a uniform response across all beluga populations,” says Donna Hauser, of the University of Washington’s polar science centre in the US, who led the research.

If were trying to understand how these species are going to respond to climate change, we should expect to see variability in the response across populations and across time. That may complicate our predictions for the future.”

The polar puzzle is nothing new for biologists: creatures that migrate to the Arctic have always experienced a mix of good and bad summers.

Research like this is important because
we have to understand how animal populations
will respond to the changing climate if we want
to make decisions about protecting biodiversity”

Some Arctic predators, such as the polar bear, which depends on sea ice for a living, are imperilled by the early thaw and the late freeze. Other predators and herbivores can shift to new territories, or gain from changing climate one year and lose the next.

But as ecosystems shift dramatically in response to global warming, the tally of winners and losers becomes harder to predict.

The light-bellied Brent geese that breed each summer in northeast Canada could become a textbook example, according to a new study in the Journal of Animal Ecology.

Climate change means that nesting mothers breed more successfully in longer, warmer summers. But the latest study suggests that the same high productivity is accompanied by a higher death rate among mothers. That could be because the birds nest on the ground, stay longer in better conditions and become more vulnerable to predators.

In a bad breeding season, mothers abandon nests or do not breed – but they do survive to try again another year.

Climate change

We tend to think of climate change as being all one way, but here we’ve got a population being affected in conflicting ways,” says Ian Cleasby, of the Centre for Ecology and Conservation at the University of Exeter in the UK.

This population is sensitive to changes in adult survival, so the increased breeding may not be enough to offset the loss of more adult females.

Research like this is important because we have to understand how animal populations will respond to the changing climate if we want to make decisions about protecting biodiversity.” Climate News Network

New studies on beluga whales and Brent geese reveal that they respond to global warming in conflicting ways, making species survival hard to predict.

LONDON, 13 January, 2017 Beluga whales are responding to climate change in a rapidly warming Arctic – but only some of them. And migratory geese ought to be flourishing with milder conditions at nesting grounds in the far north – but the mother geese are at greater risk.

Both studies leave biologists guessing a bit at the response of their animal subjects to climate change. But the evidence shows that even the animals themselves may have to take a guess.

Warming Arctic

US scientists report in Global Change Biology that one population of beluga whales is taking advantage of the longer summers in the far north, while another is keeping to a calendar that pre-dates climate change.

Beluga whales, those ghostly white hunters of the northern seas, tend to winter in the Bering Sea between two continents, and then swim north as the ice melts and the Arctic seas open up.

The two populations of whales are genetically distinct – they have different ancestries – and travel as family groups, the young learning from their mothers.

Those that feed on fish and molluscs in the Beaufort Sea north of Alaska and Canada tend to leave the summer feeding grounds in autumn with the first risk of freezing. Those that hunt in the Chukchi Sea to the north and east of Alaska are delaying their response to take advantage of the longer spells of open water.

Summer sea ice has been in retreat for the last 30 years, and last autumn was an astonishing 20°C above average.

So biologists are confronted with a big question: is one population guarding against being caught by a sudden build-up of Arctic ice, while the other is consciously taking a risk but benefiting from a longer spell in richer feeding grounds?

The biggest take-home message is that belugas can respond relatively quickly to their changing environment, yet we can’t expect a uniform response across all beluga populations,” says Donna Hauser, of the University of Washington’s polar science centre in the US, who led the research.

If were trying to understand how these species are going to respond to climate change, we should expect to see variability in the response across populations and across time. That may complicate our predictions for the future.”

The polar puzzle is nothing new for biologists: creatures that migrate to the Arctic have always experienced a mix of good and bad summers.

Research like this is important because
we have to understand how animal populations
will respond to the changing climate if we want
to make decisions about protecting biodiversity”

Some Arctic predators, such as the polar bear, which depends on sea ice for a living, are imperilled by the early thaw and the late freeze. Other predators and herbivores can shift to new territories, or gain from changing climate one year and lose the next.

But as ecosystems shift dramatically in response to global warming, the tally of winners and losers becomes harder to predict.

The light-bellied Brent geese that breed each summer in northeast Canada could become a textbook example, according to a new study in the Journal of Animal Ecology.

Climate change means that nesting mothers breed more successfully in longer, warmer summers. But the latest study suggests that the same high productivity is accompanied by a higher death rate among mothers. That could be because the birds nest on the ground, stay longer in better conditions and become more vulnerable to predators.

In a bad breeding season, mothers abandon nests or do not breed – but they do survive to try again another year.

Climate change

We tend to think of climate change as being all one way, but here we’ve got a population being affected in conflicting ways,” says Ian Cleasby, of the Centre for Ecology and Conservation at the University of Exeter in the UK.

This population is sensitive to changes in adult survival, so the increased breeding may not be enough to offset the loss of more adult females.

Research like this is important because we have to understand how animal populations will respond to the changing climate if we want to make decisions about protecting biodiversity.” Climate News Network

*

Africa’s dust is a priceless export

dust storm
dust storm

Scientists show how different the world would be without a sprinkling of the wind-borne African dust that fertilises oceans and forests.

LONDON, 3 December, 2016 − Climate scientists have identified Africa’s single biggest export – the wind-borne dust that fertilises the Amazon forests, nourishes life in the Atlantic ocean and softens the noonday blaze of the sun. And they have calculated its vital role in climate change over the last 23,000 years.

In the words of US oceanographers and Earth scientists, “North Africa exports teragrams of wind-blown mineral aerosol over the tropical North Atlantic each year, with significant climate and biogeochemical impacts.”

A teragram is a million tonnes, and the quantities airlifted into the sky from the Sahara and the Sahel each year by the trade winds and blown abroad would be enough to fill 10 million heavy trucks.

About 11,000 years ago, the continent’s total exports of fine dust began to fall dramatically, the researchers report in Science Advances journal.

Fine particles

The lower levels of fine particles in the sky may have allowed more sunlight to hit the ocean waters, may have warmed surface temperatures by 0.15°C, and may have helped whip up monsoons over North Africa to make the conditions far more temperate than they are today.

“In the tropical ocean, fractions of a degree can cause big differences in precipitation patterns and winds,” says one of the report’s authors, David McGee, assistant professor of paleoclimate and geochronology at the Massachusetts Institute of Technology.

“It does seem like dust variations may have large enough effects that it’s important to know how big those impacts are on past and future climates.”

Researchers have already established the importance of windblown dust, both as a source of mineral nutrient for marine life and for the rainforests of Brazil. Scientists have even identified dust kicked into the air by heavy rain.

“We need to figure out how big those dust impacts are, to understand both past and future climates”

But the latest study focused on the changing pattern of dust delivery from the peak of the last Ice Age to the present, the role it may have played in bygone climate change, and its importance in the human story.

North Africa was once a more temperate and hospitable place. Dr McGee says: “There was also extensive human settlement throughout the Sahara, with lifestyles that would never be possible today.

“Researchers at archaeological sites have found fish hooks and spears in the middle of the Sahara, in places that would be completely uninhabitable today. So there was clearly much more water and precipitation over the Sahara.”

Some of this may be explained by subtle cyclic shifts in the planetary axis, exposing the northern hemisphere to more sunlight, more evaporation and more rainfall over land.

Dust sediments

But climate models suggest that this might not be enough, so the researchers examined dust sediments deposited in the Bahamas over the last 23,000 years to identify the role of dust.

Towards the end of the last Ice Age, 16,000 years ago, African dust exports were twice what they are today. But between 11,000 and 5,000 years ago, Africa exported only about half the dust it airlifts now.

The implication is that wind-blown dust is an important factor in climate science, and even small changes in sea surface temperatures – of the sort that could be attributed to dusty skies – can have big effects on Atlantic winds and African rainfall.

“We’re not saying, the expansion of monsoon rains into the Sahara was caused solely by dust impacts,” Dr McGee says. “We’re saying we need to figure out how big those dust impacts are, to understand both past and future climates.” – Climate News Network

Scientists show how different the world would be without a sprinkling of the wind-borne African dust that fertilises oceans and forests.

LONDON, 3 December, 2016 − Climate scientists have identified Africa’s single biggest export – the wind-borne dust that fertilises the Amazon forests, nourishes life in the Atlantic ocean and softens the noonday blaze of the sun. And they have calculated its vital role in climate change over the last 23,000 years.

In the words of US oceanographers and Earth scientists, “North Africa exports teragrams of wind-blown mineral aerosol over the tropical North Atlantic each year, with significant climate and biogeochemical impacts.”

A teragram is a million tonnes, and the quantities airlifted into the sky from the Sahara and the Sahel each year by the trade winds and blown abroad would be enough to fill 10 million heavy trucks.

About 11,000 years ago, the continent’s total exports of fine dust began to fall dramatically, the researchers report in Science Advances journal.

Fine particles

The lower levels of fine particles in the sky may have allowed more sunlight to hit the ocean waters, may have warmed surface temperatures by 0.15°C, and may have helped whip up monsoons over North Africa to make the conditions far more temperate than they are today.

“In the tropical ocean, fractions of a degree can cause big differences in precipitation patterns and winds,” says one of the report’s authors, David McGee, assistant professor of paleoclimate and geochronology at the Massachusetts Institute of Technology.

“It does seem like dust variations may have large enough effects that it’s important to know how big those impacts are on past and future climates.”

Researchers have already established the importance of windblown dust, both as a source of mineral nutrient for marine life and for the rainforests of Brazil. Scientists have even identified dust kicked into the air by heavy rain.

“We need to figure out how big those dust impacts are, to understand both past and future climates”

But the latest study focused on the changing pattern of dust delivery from the peak of the last Ice Age to the present, the role it may have played in bygone climate change, and its importance in the human story.

North Africa was once a more temperate and hospitable place. Dr McGee says: “There was also extensive human settlement throughout the Sahara, with lifestyles that would never be possible today.

“Researchers at archaeological sites have found fish hooks and spears in the middle of the Sahara, in places that would be completely uninhabitable today. So there was clearly much more water and precipitation over the Sahara.”

Some of this may be explained by subtle cyclic shifts in the planetary axis, exposing the northern hemisphere to more sunlight, more evaporation and more rainfall over land.

Dust sediments

But climate models suggest that this might not be enough, so the researchers examined dust sediments deposited in the Bahamas over the last 23,000 years to identify the role of dust.

Towards the end of the last Ice Age, 16,000 years ago, African dust exports were twice what they are today. But between 11,000 and 5,000 years ago, Africa exported only about half the dust it airlifts now.

The implication is that wind-blown dust is an important factor in climate science, and even small changes in sea surface temperatures – of the sort that could be attributed to dusty skies – can have big effects on Atlantic winds and African rainfall.

“We’re not saying, the expansion of monsoon rains into the Sahara was caused solely by dust impacts,” Dr McGee says. “We’re saying we need to figure out how big those dust impacts are, to understand both past and future climates.” – Climate News Network

*

Speed of Arctic changes defies scientists

The Arctic climate is changing so quickly that science can barely keep track of what is happening and predict the global consequences, the UN says.

LONDON, 29 September, 2016 In an unusually stark warning a leading international scientific body says the Arctic climate is changing so fast that researchers are struggling to keep up. The changes happening there, it says, are affecting the weather worldwide.

The World Meteorological Organisation (WMO) says: Dramatic and unprecedented warming in the Arctic is driving sea level rise, affecting weather patterns around the world and may trigger even more changes in the climate system.

The rate of change is challenging the current scientific capacity to monitor and predict what is becoming a journey into uncharted territory. 

The WMO is the United Nations’ main agency responsible for weather, climate and water.    

Its president, David Grimes, said: The Arctic is a principal, global driver of the climate system and is undergoing an unprecedented rate of change with consequences far beyond its boundaries.

Arctic collaboration

The changes in the Arctic are serving as a global indicator – like a canary in the coal mine – and are happening at a much faster rate than we would have expected.

He was speaking before addressing the first White House Science Ministerial meeting in Washington DC, held to develop international collaboration on Arctic science.

Climate change is causing global average temperatures to rise: 2014, 2015 and the first eight months of 2016 have all been record-breakers. The Arctic is warming at least twice as fast as the global average, in places even faster: the Canadian town of Inuvik has warmed by almost 4°C since 1948, about four times more than the global figure.

The increasing loss of Arctic sea ice is threatening polar bears across their range; melting sea ice is affecting the Arctic climate in a feedback loop; and scientists expect melting permafrost will release more carbon dioxide and methane

The WMO secretary-general, Petteri Taalas, said the Arctic changes had also been a factor in unusual winter weather patterns in North America and Europe. He said the thawing of the permafrost could release vast quantities of greenhouse gases into the atmosphere.

These are part of the vicious circles of climate change which are the subject of intense scientific research, he said.

The Arctic is a principal, global driver of the climate system and is undergoing an unprecedented rate of change with consequences far beyond its boundaries

Despite its certainty that the Arctic is in trouble, the WMO says it is hard to establish the implications of what is happening there. The Arctic makes up about 4% of the Earth’s surface, but the WMO says it is one of the most data-sparse regions in the world because of its remoteness and previous inaccessibility.

Lack of data and forecasts in the Arctic does impact on the quality of weather forecasts in other parts of the world. 

That’s a worry which is echoed at the other end of the planet. A study led by Dr Julie Jones, from the department of geography at the University of Sheffield, UK, says limited data on Antarctica’s climate is making it difficult for researchers to disentangle changes caused by human activity from natural climate fluctuations.

It was only when regular satellite observations began in 1979 that measurement of surface climate over the Antarctic and the Southern Ocean became possible, says the study, published in the journal Nature Climate Change

To gain a longer view, Dr Jones and her colleagues used a compilation of records from natural archives such as ice cores from the Antarctic ice sheet, which show how the region’s climate has changed over the last 200 years.

Separating signals

They confirmed that human-induced changes have caused the belt of prevailing westerly winds over the Southern Ocean to shift towards Antarctica.

But they conclude that for other changes, including regional warming and sea ice changes, the observations since 1979 are not yet long enough for the signal of human activity to be clearly separated from the strong natural variability.

The shift in the westerly winds has moved rainfall away from southern Australia. This year is set to be the country’s hottest on record.

Dr Jones said: “The Antarctic climate is like a giant jigsaw puzzle with most of the pieces still missing.

“There are some parts of the picture which are clear, particularly the way that climate change is causing westerly winds to shift southwards, but there are still huge gaps that we need to fill in order to fully understand how much human activity is changing weather in the region.” – Climate News Network

The Arctic climate is changing so quickly that science can barely keep track of what is happening and predict the global consequences, the UN says.

LONDON, 29 September, 2016 In an unusually stark warning a leading international scientific body says the Arctic climate is changing so fast that researchers are struggling to keep up. The changes happening there, it says, are affecting the weather worldwide.

The World Meteorological Organisation (WMO) says: Dramatic and unprecedented warming in the Arctic is driving sea level rise, affecting weather patterns around the world and may trigger even more changes in the climate system.

The rate of change is challenging the current scientific capacity to monitor and predict what is becoming a journey into uncharted territory. 

The WMO is the United Nations’ main agency responsible for weather, climate and water.    

Its president, David Grimes, said: The Arctic is a principal, global driver of the climate system and is undergoing an unprecedented rate of change with consequences far beyond its boundaries.

Arctic collaboration

The changes in the Arctic are serving as a global indicator – like a canary in the coal mine – and are happening at a much faster rate than we would have expected.

He was speaking before addressing the first White House Science Ministerial meeting in Washington DC, held to develop international collaboration on Arctic science.

Climate change is causing global average temperatures to rise: 2014, 2015 and the first eight months of 2016 have all been record-breakers. The Arctic is warming at least twice as fast as the global average, in places even faster: the Canadian town of Inuvik has warmed by almost 4°C since 1948, about four times more than the global figure.

The increasing loss of Arctic sea ice is threatening polar bears across their range; melting sea ice is affecting the Arctic climate in a feedback loop; and scientists expect melting permafrost will release more carbon dioxide and methane

The WMO secretary-general, Petteri Taalas, said the Arctic changes had also been a factor in unusual winter weather patterns in North America and Europe. He said the thawing of the permafrost could release vast quantities of greenhouse gases into the atmosphere.

These are part of the vicious circles of climate change which are the subject of intense scientific research, he said.

The Arctic is a principal, global driver of the climate system and is undergoing an unprecedented rate of change with consequences far beyond its boundaries

Despite its certainty that the Arctic is in trouble, the WMO says it is hard to establish the implications of what is happening there. The Arctic makes up about 4% of the Earth’s surface, but the WMO says it is one of the most data-sparse regions in the world because of its remoteness and previous inaccessibility.

Lack of data and forecasts in the Arctic does impact on the quality of weather forecasts in other parts of the world. 

That’s a worry which is echoed at the other end of the planet. A study led by Dr Julie Jones, from the department of geography at the University of Sheffield, UK, says limited data on Antarctica’s climate is making it difficult for researchers to disentangle changes caused by human activity from natural climate fluctuations.

It was only when regular satellite observations began in 1979 that measurement of surface climate over the Antarctic and the Southern Ocean became possible, says the study, published in the journal Nature Climate Change

To gain a longer view, Dr Jones and her colleagues used a compilation of records from natural archives such as ice cores from the Antarctic ice sheet, which show how the region’s climate has changed over the last 200 years.

Separating signals

They confirmed that human-induced changes have caused the belt of prevailing westerly winds over the Southern Ocean to shift towards Antarctica.

But they conclude that for other changes, including regional warming and sea ice changes, the observations since 1979 are not yet long enough for the signal of human activity to be clearly separated from the strong natural variability.

The shift in the westerly winds has moved rainfall away from southern Australia. This year is set to be the country’s hottest on record.

Dr Jones said: “The Antarctic climate is like a giant jigsaw puzzle with most of the pieces still missing.

“There are some parts of the picture which are clear, particularly the way that climate change is causing westerly winds to shift southwards, but there are still huge gaps that we need to fill in order to fully understand how much human activity is changing weather in the region.” – Climate News Network

*

Antarctic peninsula cools – for now

After warming for nearly 50 years the Antarctic peninsula has begun cooling, though probably not for long, UK scientists say.

LONDON, 21 July, 2016  Life is full of surprises, not least the climate. The Antarctic Peninsula, part of which reported spectacularly high temperatures as recently as last year, is now in a cooling phase.

Scientists from the British Antarctic Survey (BAS), based in Cambridge, UK, www.bas.ac.uk say the warming which occurred on the peninsula from the early 1950s to the late 1990s has paused.

But they say they know at least some of the reasons for the change, and that if greenhouse gas concentrations continue to rise at their current rate, temperatures will increase across the peninsula by several degrees Celsius by the end of this century.

It is the slowing rate of ozone loss and the climate’s natural variability, the researchers say, that were “significant in bringing about the change” to a temporary cooling phase. But temperatures remain higher than measured during the middle of the last century, and glaciers are still retreating. 

“The Antarctic peninsula is one of the most challenging places on Earth on which to identify the causes of decade-to-decade temperature changes“ 

Writing in the journal Nature, researchers from BAS describe how the stabilisation of the ozone hole and changing wind patterns have driven a regional cooling phase that is temporarily masking the warming influence of greenhouse gases.

In the last month, atmospheric levels of carbon dioxide above Antarctica rose past the 400 parts per million (ppm) milestone, contrasting with the pre-industrial level of 280 ppm recorded in Antarctic ice cores.

Average temperatures on the peninsula rose by about 0.5⁰C each decade from the early 1950s until the late 1990s, when the researchers found they began falling at the same rate..  

The lead author, Professor John Turner of BAS, says: “The Antarctic peninsula is one of the most challenging places on Earth on which to identify the causes of decade-to-decade temperature changes.

“The Antarctic peninsula climate system shows large natural variations, which can overwhelm the signals of human-induced global warming . . . Even in a generally warming world, over the next couple of decades, temperatures in this region may go up or down, but our models predict that in the longer term greenhouse gases will lead to an increase in temperatures by the end of the 21st century.”

Warming century

During the last century the temperature rise of up to 0.5⁰C each decade on the peninsula helped to trigger the collapse of ice shelves and caused many glaciers to retreat.  

While sea ice extent around the peninsula fell towards the end of the last century it has been increasing in recent years, particularly in the north-east of the region. The cold easterly winds observed this century have had a greater impact on the region because the sea ice has prevented ocean heat from entering the atmosphere.    

The researchers also looked at a 2,000-year climate reconstruction using the chemical signals in ice cores. This suggested that peninsula warming over the whole twentieth century was unusual, but not unprecedented in the context of two millennia.  

Climate model simulations predict that if greenhouse gas concentrations continue to increase at currently projected rates their warming effect will predominate over natural variability and the cooling effect associated with recovering ozone levels, producing several degrees of warming across the region by the end of this century.

Not surprising

The researchers’ study needs to be seen in context. The area they examined is about 1% of the entire Antarctic continent and is an area roughly the size of England.

Eric J. Steig, of the University of Washington, US, wrote: “Even before Turner and colleagues’ analysis, there was little evidence that the rapid warming in Antarctica falls outside the range of natural variability. . . In short, Turner and co-workers’ findings should not be surprising.”

But the work by the BAS team, if not an outright surprise, is still a valuable reminder that natural limits can vary widely, and that well-intentioned adjustments to the climate in one area (limiting ozone loss, for example, or efforts to reduce air pollution) can have unpredictable consequences elsewhere.

It is a reminder as well that, so far as science can see, the inexorable trend of present fossil fuel use is towards more warming and greater disruption. – Climate News Network

After warming for nearly 50 years the Antarctic peninsula has begun cooling, though probably not for long, UK scientists say.

LONDON, 21 July, 2016  Life is full of surprises, not least the climate. The Antarctic Peninsula, part of which reported spectacularly high temperatures as recently as last year, is now in a cooling phase.

Scientists from the British Antarctic Survey (BAS), based in Cambridge, UK, www.bas.ac.uk say the warming which occurred on the peninsula from the early 1950s to the late 1990s has paused.

But they say they know at least some of the reasons for the change, and that if greenhouse gas concentrations continue to rise at their current rate, temperatures will increase across the peninsula by several degrees Celsius by the end of this century.

It is the slowing rate of ozone loss and the climate’s natural variability, the researchers say, that were “significant in bringing about the change” to a temporary cooling phase. But temperatures remain higher than measured during the middle of the last century, and glaciers are still retreating. 

“The Antarctic peninsula is one of the most challenging places on Earth on which to identify the causes of decade-to-decade temperature changes“ 

Writing in the journal Nature, researchers from BAS describe how the stabilisation of the ozone hole and changing wind patterns have driven a regional cooling phase that is temporarily masking the warming influence of greenhouse gases.

In the last month, atmospheric levels of carbon dioxide above Antarctica rose past the 400 parts per million (ppm) milestone, contrasting with the pre-industrial level of 280 ppm recorded in Antarctic ice cores.

Average temperatures on the peninsula rose by about 0.5⁰C each decade from the early 1950s until the late 1990s, when the researchers found they began falling at the same rate..  

The lead author, Professor John Turner of BAS, says: “The Antarctic peninsula is one of the most challenging places on Earth on which to identify the causes of decade-to-decade temperature changes.

“The Antarctic peninsula climate system shows large natural variations, which can overwhelm the signals of human-induced global warming . . . Even in a generally warming world, over the next couple of decades, temperatures in this region may go up or down, but our models predict that in the longer term greenhouse gases will lead to an increase in temperatures by the end of the 21st century.”

Warming century

During the last century the temperature rise of up to 0.5⁰C each decade on the peninsula helped to trigger the collapse of ice shelves and caused many glaciers to retreat.  

While sea ice extent around the peninsula fell towards the end of the last century it has been increasing in recent years, particularly in the north-east of the region. The cold easterly winds observed this century have had a greater impact on the region because the sea ice has prevented ocean heat from entering the atmosphere.    

The researchers also looked at a 2,000-year climate reconstruction using the chemical signals in ice cores. This suggested that peninsula warming over the whole twentieth century was unusual, but not unprecedented in the context of two millennia.  

Climate model simulations predict that if greenhouse gas concentrations continue to increase at currently projected rates their warming effect will predominate over natural variability and the cooling effect associated with recovering ozone levels, producing several degrees of warming across the region by the end of this century.

Not surprising

The researchers’ study needs to be seen in context. The area they examined is about 1% of the entire Antarctic continent and is an area roughly the size of England.

Eric J. Steig, of the University of Washington, US, wrote: “Even before Turner and colleagues’ analysis, there was little evidence that the rapid warming in Antarctica falls outside the range of natural variability. . . In short, Turner and co-workers’ findings should not be surprising.”

But the work by the BAS team, if not an outright surprise, is still a valuable reminder that natural limits can vary widely, and that well-intentioned adjustments to the climate in one area (limiting ozone loss, for example, or efforts to reduce air pollution) can have unpredictable consequences elsewhere.

It is a reminder as well that, so far as science can see, the inexorable trend of present fossil fuel use is towards more warming and greater disruption. – Climate News Network

*

Europe’s floods come as no surprise

Scientists have warned that the extra moisture in warmer air will mean more intense rainfall, but floods still leave governments unprepared.

LONDON, 5 June, 2016 – At least 18 people have lost their lives in central Europe as severe floods engulf the continent from France to Ukraine. In Paris the River Seine reached 6.1 metres (20 feet) above normal, and tens of thousands of people have fled their homes.

If the downpours and swollen rivers came as a surprise, they shouldn’t have done. Not only are there historical precedents for disastrous floods. There have been graphic recent warnings too, spelling out the growing likelihood that the warming climate will make bouts of flooding and other extreme weather more frequent. 

Last March a study reported in the journal Nature said climate change was already driving an increase in extremes of rainfall and snowfall across most of the globe, even in arid regions. The study said the trend would continue as the world warmed.

The role of global warming in unusually large rainfall events in countries from the United Kingdom to China has been hotly debated. But this latest study showed that climate change is driving an overall increase in rainfall extremes.

Its lead author, Markus Donat, a climate scientist at the University of New South Wales in Australia, said: “In both wet and dry regions, we see these significant and robust increases in heavy precipitation.”

“It is probably a good idea to invest in infrastructure that helps in dealing with heavier precipitation”

Warm air holds more moisture, and global warming is already increasing the odds of extreme rainfall. “The paper is convincing and provides some useful insights,” said Sonia Seneviratne, a climate scientist at the Swiss Federal Institute of Technology. “What is particularly new in this article is the demonstration of such a signal for observed changes in dry regions.”

The results obtained by Donat and his team suggest that both annual precipitation and extreme precipitation increased by 1–2% per decade in dry regions, with wet areas showing similar increases in the extent of extreme precipitation and smaller increases for annual totals.

Their results are in line with a 2015 study by researchers at the Potsdam Institute for Climate Impact Research (PIK) in Germany, which found that global warming has increased the number of record-breaking rainfall events.

Both studies strengthen predictions by models that more extreme weather is in prospect. Donat said their findings were an alert to governments. In a comment which could have been directed at several European countries, he said: “It is probably a good idea to invest in infrastructure that helps in dealing with heavier precipitation, in particular if you are not yet used to those events.”

Breaking records 

The PIK researchers found that heavy rainfall events setting ever new records had been “increasing strikingly” in the past thirty years. Before 1980 natural variability was enough to explain rainfall fluctuations, they said, but they had detected a clear upward trend in the past few decades towards more unprecedented daily rainfall events.

The researchers said this worldwide increase was consistent with rising global temperatures caused by greenhouse gas emissions from burning fossil fuels. The year 2010 had seen extreme rainfall cause devastating flooding in Pakistan, killing hundreds of people and prompting an outbreak of cholera. There had also been rainstorms in Texas, causing dozens of flash floods.

No fewer than than three supposedly “once-in-a-century” floods occurred in Germany in the space of a couple of years, starting in 1997. “In all of these places, the amount of rain pouring down in one day broke local records – and while each of these individual events has been caused by a number of different factors, we find a clear overall upward trend for these unprecedented hazards”, said the PIK study’s lead author, Jascha Lehmann.

The team found that from 1980 to 2010 there were 12% more of these extreme events than would be expected in what they called “a stationary climate”, one without global warming. In the last year they studied, that increase rose to 26%. – Climate News Network

Scientists have warned that the extra moisture in warmer air will mean more intense rainfall, but floods still leave governments unprepared.

LONDON, 5 June, 2016 – At least 18 people have lost their lives in central Europe as severe floods engulf the continent from France to Ukraine. In Paris the River Seine reached 6.1 metres (20 feet) above normal, and tens of thousands of people have fled their homes.

If the downpours and swollen rivers came as a surprise, they shouldn’t have done. Not only are there historical precedents for disastrous floods. There have been graphic recent warnings too, spelling out the growing likelihood that the warming climate will make bouts of flooding and other extreme weather more frequent. 

Last March a study reported in the journal Nature said climate change was already driving an increase in extremes of rainfall and snowfall across most of the globe, even in arid regions. The study said the trend would continue as the world warmed.

The role of global warming in unusually large rainfall events in countries from the United Kingdom to China has been hotly debated. But this latest study showed that climate change is driving an overall increase in rainfall extremes.

Its lead author, Markus Donat, a climate scientist at the University of New South Wales in Australia, said: “In both wet and dry regions, we see these significant and robust increases in heavy precipitation.”

“It is probably a good idea to invest in infrastructure that helps in dealing with heavier precipitation”

Warm air holds more moisture, and global warming is already increasing the odds of extreme rainfall. “The paper is convincing and provides some useful insights,” said Sonia Seneviratne, a climate scientist at the Swiss Federal Institute of Technology. “What is particularly new in this article is the demonstration of such a signal for observed changes in dry regions.”

The results obtained by Donat and his team suggest that both annual precipitation and extreme precipitation increased by 1–2% per decade in dry regions, with wet areas showing similar increases in the extent of extreme precipitation and smaller increases for annual totals.

Their results are in line with a 2015 study by researchers at the Potsdam Institute for Climate Impact Research (PIK) in Germany, which found that global warming has increased the number of record-breaking rainfall events.

Both studies strengthen predictions by models that more extreme weather is in prospect. Donat said their findings were an alert to governments. In a comment which could have been directed at several European countries, he said: “It is probably a good idea to invest in infrastructure that helps in dealing with heavier precipitation, in particular if you are not yet used to those events.”

Breaking records 

The PIK researchers found that heavy rainfall events setting ever new records had been “increasing strikingly” in the past thirty years. Before 1980 natural variability was enough to explain rainfall fluctuations, they said, but they had detected a clear upward trend in the past few decades towards more unprecedented daily rainfall events.

The researchers said this worldwide increase was consistent with rising global temperatures caused by greenhouse gas emissions from burning fossil fuels. The year 2010 had seen extreme rainfall cause devastating flooding in Pakistan, killing hundreds of people and prompting an outbreak of cholera. There had also been rainstorms in Texas, causing dozens of flash floods.

No fewer than than three supposedly “once-in-a-century” floods occurred in Germany in the space of a couple of years, starting in 1997. “In all of these places, the amount of rain pouring down in one day broke local records – and while each of these individual events has been caused by a number of different factors, we find a clear overall upward trend for these unprecedented hazards”, said the PIK study’s lead author, Jascha Lehmann.

The team found that from 1980 to 2010 there were 12% more of these extreme events than would be expected in what they called “a stationary climate”, one without global warming. In the last year they studied, that increase rose to 26%. – Climate News Network