Tag Archives: Natural variability

Prehistoric dogs learned new tricks as climate changed

Scientists have found evidence that profound changes in climate caused ancient predators to evolve into the ancestors of today’s dogs. LONDON, 24 August, 2015 – Man-made climate change is expected to have a “significant effect” on the wildlife of the planet. And, if fossil evidence is anything to go by, it could seriously alter the course of evolution. The hunting habits of the wolf – ancestor of man’s best friend, the dog – evolved over millions of years to cope with profound climate change, according to new research. Borja Figueirido, of the Department of Ecology and Geology at the University of Malaga in Spain, and colleagues report in Nature Communications that they examined the elbows and teeth of 32 native North American species of the dog family from between 39 million and 2 million years ago.

Ambush and pursuit

What they found was clear evidence that, in response to changing climate and foliage cover, dogs evolved from ambush predators that survived by surprising their prey, to pursuit predators that wore them down. The story begins with a warm, wooded North America in which a canine creature with flexible forelimbs, and not much bigger than a mongoose, used stealth to surprise and pounce cat-like on its dinner. Ultimately, it gave way to animals like wolves, which could chase a deer all day.

“It’s reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores”

In the course of those 37 million years, the climate cooled, the forests gave way to savannah and prairie, and the dog family began to evolve new strategies − including the short pursuit-and-pounce technique of the coyote or the fox, and the long-distance stamina hunting of the wolf. “It’s reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores,” says Christine Janis, professor of ecology and evolutionary biology at Brown University in the US, and a co-author of the report. “Although this seems logical, it hadn’t been demonstrated before.” The scientists backed up their conclusions by studying the teeth and forelimb structures of a wide range of hunting animals, including cheetah, hyena and wild dog in Africa, the tiger and snow leopard in Asia, and the jaguar, puma and wolverine in the Americas.

Conservation worries

Their formal conclusion is that when things changed for the herbivores that shaped the landscape, the predators also responded. Such research confirms the worries of wildlife conservationists that man-made climate change in response to rising levels of carbon dioxide in the atmosphere − as a consequence of the burning of fossil fuels − could seriously alter the evolutionary conditions and the ecosystems from which civilised humankind and its domestic animals emerged. The scientists say their studies demonstrate that “long periods of profound climatic change are critical for the emergence of ecological innovations, and could alter the direction of lineage evolution”. – Climate News Network

Scientists have found evidence that profound changes in climate caused ancient predators to evolve into the ancestors of today’s dogs. LONDON, 24 August, 2015 – Man-made climate change is expected to have a “significant effect” on the wildlife of the planet. And, if fossil evidence is anything to go by, it could seriously alter the course of evolution. The hunting habits of the wolf – ancestor of man’s best friend, the dog – evolved over millions of years to cope with profound climate change, according to new research. Borja Figueirido, of the Department of Ecology and Geology at the University of Malaga in Spain, and colleagues report in Nature Communications that they examined the elbows and teeth of 32 native North American species of the dog family from between 39 million and 2 million years ago.

Ambush and pursuit

What they found was clear evidence that, in response to changing climate and foliage cover, dogs evolved from ambush predators that survived by surprising their prey, to pursuit predators that wore them down. The story begins with a warm, wooded North America in which a canine creature with flexible forelimbs, and not much bigger than a mongoose, used stealth to surprise and pounce cat-like on its dinner. Ultimately, it gave way to animals like wolves, which could chase a deer all day.

“It’s reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores”

In the course of those 37 million years, the climate cooled, the forests gave way to savannah and prairie, and the dog family began to evolve new strategies − including the short pursuit-and-pounce technique of the coyote or the fox, and the long-distance stamina hunting of the wolf. “It’s reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores,” says Christine Janis, professor of ecology and evolutionary biology at Brown University in the US, and a co-author of the report. “Although this seems logical, it hadn’t been demonstrated before.” The scientists backed up their conclusions by studying the teeth and forelimb structures of a wide range of hunting animals, including cheetah, hyena and wild dog in Africa, the tiger and snow leopard in Asia, and the jaguar, puma and wolverine in the Americas.

Conservation worries

Their formal conclusion is that when things changed for the herbivores that shaped the landscape, the predators also responded. Such research confirms the worries of wildlife conservationists that man-made climate change in response to rising levels of carbon dioxide in the atmosphere − as a consequence of the burning of fossil fuels − could seriously alter the evolutionary conditions and the ecosystems from which civilised humankind and its domestic animals emerged. The scientists say their studies demonstrate that “long periods of profound climatic change are critical for the emergence of ecological innovations, and could alter the direction of lineage evolution”. – Climate News Network

Earth has warmed as usual, with no slowdown

US scientists re-examine the collection of data which seemed to show global warming slowing since 1998 and say temperatures have continued to rise steadily. LONDON, 7 June, 2015 − Forget about the so-called “hiatus” in global warming. The planet’s average temperatures are notching up as swiftly now as they did 20 or 30 years ago. A team of US researchers has looked again not just at the data for the last 60 years but at how it has been collected, and done the sums again. They conclude, in the journal Science,  that the “estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a ‘slowdown’ in the increase of global surface temperature rise.” But first, the story-so-far. Climate sceptics have repeatedly claimed that global warming has slowed or stopped. This was not the case: 13 of the hottest years ever recorded have all occurred in the last 14 years, and 2014 was the hottest of them all. But when climate scientists looked at a graph of the rise of temperatures in the last 60 years, they saw – or thought they saw – a distinct drop in the rate of increase in global average temperatures in the last 15 years. This apparent dip became the subject of a whole series of studies. Researchers had never expected the rise to follow a straight line – all sorts of natural climate cycles would naturally affect annual records – but the rate of increase was slower, and more sustained in its slowness, than anyone could explain, especially as there had been no drop in the greenhouse gas emissions that drive global warming.

Data anomalies

Some proposed that the expected extra heat in the atmosphere had been drawn down into the great oceans and others that an unnoticed increase in volcanic activity had helped screen the sunlight and cool the atmosphere unexpectedly. Yet another group looked not at average temperature patterns but the change in the frequency of heat waves and saw a different kind of rise. Yet another group wondered if the problem might be only apparent: more complete data from many more parts of the world might combine to tell a different story. Thomas Karl and colleagues at the National Oceanographic and Atmospheric Administration in the US made this their starting point. They looked again at how the data had been collected, and the gaps that might have appeared. Sea surface temperatures, for instance, were at different periods collected by bucket from a ship’s deck, by readings aboard surface drifting and moored buoys or by engine-intake thermometers in ships’ engine rooms, and there could be subtle differences not accounted for. There were very few readings from the Arctic, yet the Arctic is by far the fastest-warming region of the planet, and the pattern of land-based temperature readings, too, repaid re-examination. By the time the NOAA team had finished, the recalibrated figures told a different story. Between 1998 and 2012, the world warmed at the rate of 0.086°C per decade, more than twice the rate of 0.039°C per decade measured by the Intergovernmental Panel on Climate Change.

“We need to look really carefully at data quality and issues of instrument change”

The new figure is much closer to the rate estimated for the decades 1950 to 1999, at 0.113°C per decade. And the new analysis lifts the rate of warming from 2000 to 2014 to 0.116°C per decade, which if anything is an acceleration, not a slowdown. British climate scientists have welcomed the finding: it is however the finding of just one group and, like all such research, will be accepted more readily if it can be separately replicated. “This study makes the important point that we need to look really carefully at data quality and issues of instrument change,” said Piers Forster, professor of climate change at the University of Leeds, UK. ”Yet there are several legitimate judgment calls made when combining datasets to make a global mean-time series. I still don’t think this study will be the last word on this complex subject.” But Peter Wadhams, a professor of ocean physics at the University of Cambridge, UK, called the study careful and persuasive, and said: “I think it shows clearly that the so-called ‘hiatus’ does not exist and that global warming has continued over the past few years at the same rate as in earlier years.” − Climate News Network

US scientists re-examine the collection of data which seemed to show global warming slowing since 1998 and say temperatures have continued to rise steadily. LONDON, 7 June, 2015 − Forget about the so-called “hiatus” in global warming. The planet’s average temperatures are notching up as swiftly now as they did 20 or 30 years ago. A team of US researchers has looked again not just at the data for the last 60 years but at how it has been collected, and done the sums again. They conclude, in the journal Science,  that the “estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a ‘slowdown’ in the increase of global surface temperature rise.” But first, the story-so-far. Climate sceptics have repeatedly claimed that global warming has slowed or stopped. This was not the case: 13 of the hottest years ever recorded have all occurred in the last 14 years, and 2014 was the hottest of them all. But when climate scientists looked at a graph of the rise of temperatures in the last 60 years, they saw – or thought they saw – a distinct drop in the rate of increase in global average temperatures in the last 15 years. This apparent dip became the subject of a whole series of studies. Researchers had never expected the rise to follow a straight line – all sorts of natural climate cycles would naturally affect annual records – but the rate of increase was slower, and more sustained in its slowness, than anyone could explain, especially as there had been no drop in the greenhouse gas emissions that drive global warming.

Data anomalies

Some proposed that the expected extra heat in the atmosphere had been drawn down into the great oceans and others that an unnoticed increase in volcanic activity had helped screen the sunlight and cool the atmosphere unexpectedly. Yet another group looked not at average temperature patterns but the change in the frequency of heat waves and saw a different kind of rise. Yet another group wondered if the problem might be only apparent: more complete data from many more parts of the world might combine to tell a different story. Thomas Karl and colleagues at the National Oceanographic and Atmospheric Administration in the US made this their starting point. They looked again at how the data had been collected, and the gaps that might have appeared. Sea surface temperatures, for instance, were at different periods collected by bucket from a ship’s deck, by readings aboard surface drifting and moored buoys or by engine-intake thermometers in ships’ engine rooms, and there could be subtle differences not accounted for. There were very few readings from the Arctic, yet the Arctic is by far the fastest-warming region of the planet, and the pattern of land-based temperature readings, too, repaid re-examination. By the time the NOAA team had finished, the recalibrated figures told a different story. Between 1998 and 2012, the world warmed at the rate of 0.086°C per decade, more than twice the rate of 0.039°C per decade measured by the Intergovernmental Panel on Climate Change.

“We need to look really carefully at data quality and issues of instrument change”

The new figure is much closer to the rate estimated for the decades 1950 to 1999, at 0.113°C per decade. And the new analysis lifts the rate of warming from 2000 to 2014 to 0.116°C per decade, which if anything is an acceleration, not a slowdown. British climate scientists have welcomed the finding: it is however the finding of just one group and, like all such research, will be accepted more readily if it can be separately replicated. “This study makes the important point that we need to look really carefully at data quality and issues of instrument change,” said Piers Forster, professor of climate change at the University of Leeds, UK. ”Yet there are several legitimate judgment calls made when combining datasets to make a global mean-time series. I still don’t think this study will be the last word on this complex subject.” But Peter Wadhams, a professor of ocean physics at the University of Cambridge, UK, called the study careful and persuasive, and said: “I think it shows clearly that the so-called ‘hiatus’ does not exist and that global warming has continued over the past few years at the same rate as in earlier years.” − Climate News Network

Science puzzles over recent rapid Antarctic thaw

Part of Antarctica has begun thawing unusually fast, leaving scientists unsure whether a natural cycle or human-caused climate change is responsible. LONDON, 31 May, 2015 − Antarctic glaciers once thought relatively stable are starting to melt. Evidence from a five-year satellite study of the frozen rivers on the southern Antarctic Peninsula now reveal that these are shedding ice at the rate of 60 cubic kilometres a year: altogether around 300 trillion litres of water has moved from the frozen continent to the oceans. Bert Wouters of the University of Bristol, UK, and colleagues report in the journal Science  that they used data from two very different research satellites to confirm their findings. The European Space Agency’s CryoSat-2 has been orbiting the polar world since April 2010, bouncing radar signals off the surface and measuring the return travel time. An examination of five years of results shows that the glacial surfaces are sinking, in some places by as much as four metres a year. There could be two reasons for that: either the snow is compacting or the ice is flowing faster.

“The glaciers added roughly 300 cubic km of water to the ocean. That’s the equivalent of the volume of nearly 350,000 Empire State Buildings”

But results from the US space agency Nasa’s GRACE mission – the acronym stands for Gravity Recovery and Climate Experiment – settle the matter. The mass of ice lost in the region is so large that it changes the local gravity field, and the changes in the sheer weight of 750 kilometres of glaciers in the region can be measured from space. “To date, the glaciers added roughly 300 cubic km of water to the ocean. That’s the equivalent of the volume of nearly 350,000 Empire State Buildings combined,” Dr Wouters said. “The fact that so many glaciers in such a large region suddenly started to lose ice came as a surprise to us. It shows a very fast response of the ice sheet: in just a few years the dynamic regime completely shifted.”

Melting maintained

That the southern continent is responding to climate change of some kind is not in doubt: another study has put the overall mass loss at 92 billion tons a year, and twin assaults of warmer air above, and warmer waters around the continent, continue the attrition. What is not yet certain is whether scientists are looking at the consequences of human-made global warming or at the see-saw conditions inherent in some kind of as-yet-unidentified natural cycle. But ice loss on that scale cannot be easily explained by changes in snowfall or air temperatures, so suspicion falls on the effect of warmer waters. The glaciers flow into seas that are surrounded by ice shelves. The ice shelves have lost one fifth of their thickness in recent decades, so they offer less resistance to the land-based ice, allowing the glaciers to accelerate. There is a second factor: some of the glaciers are grounded on continental bedrock that is depressed below sea level, which means that warmer ocean waters can penetrate further inland and melt the glaciers from below.

Cautious response

There are questions that have yet to be resolved. As usual in science, the interpretations are open to debate. “Although these latest CryoSat measurements of Antarctic thinning agree with findings from two studies reported last year, I think the new estimates of ice loss computed from them are far too high, because the glaciers in this sector just haven’t speeded up that much,” said Andy Shepherd, professor of earth observation at the University of Leeds in the UK and principal scientific advisor to the CryoSat mission. “It could be that a bigger chunk of the thinning is down to snowfall fluctuations than the authors have accounted for, and so I would be cautious about the new numbers until more information is to hand.” Dr Wouters agrees that more research is necessary. “It appears that some time around 2009, the ice shelf thinning and the subsurface melting of the glaciers passed a critical threshold which triggered the sudden ice loss. However, compared to other regions in Antarctica, the Southern Peninsula is rather understudied, exactly because it did not show any changes in the past, ironically,” he said. “To pinpoint the cause of the changes, more data need to be collected. A detailed knowledge of the geometry of the local ice shelves, the ocean floor topography, ice sheet thickness and glacier flow speeds are crucial to tell how much longer the thinning will continue.” − Climate News Network

Part of Antarctica has begun thawing unusually fast, leaving scientists unsure whether a natural cycle or human-caused climate change is responsible. LONDON, 31 May, 2015 − Antarctic glaciers once thought relatively stable are starting to melt. Evidence from a five-year satellite study of the frozen rivers on the southern Antarctic Peninsula now reveal that these are shedding ice at the rate of 60 cubic kilometres a year: altogether around 300 trillion litres of water has moved from the frozen continent to the oceans. Bert Wouters of the University of Bristol, UK, and colleagues report in the journal Science  that they used data from two very different research satellites to confirm their findings. The European Space Agency’s CryoSat-2 has been orbiting the polar world since April 2010, bouncing radar signals off the surface and measuring the return travel time. An examination of five years of results shows that the glacial surfaces are sinking, in some places by as much as four metres a year. There could be two reasons for that: either the snow is compacting or the ice is flowing faster.

“The glaciers added roughly 300 cubic km of water to the ocean. That’s the equivalent of the volume of nearly 350,000 Empire State Buildings”

But results from the US space agency Nasa’s GRACE mission – the acronym stands for Gravity Recovery and Climate Experiment – settle the matter. The mass of ice lost in the region is so large that it changes the local gravity field, and the changes in the sheer weight of 750 kilometres of glaciers in the region can be measured from space. “To date, the glaciers added roughly 300 cubic km of water to the ocean. That’s the equivalent of the volume of nearly 350,000 Empire State Buildings combined,” Dr Wouters said. “The fact that so many glaciers in such a large region suddenly started to lose ice came as a surprise to us. It shows a very fast response of the ice sheet: in just a few years the dynamic regime completely shifted.”

Melting maintained

That the southern continent is responding to climate change of some kind is not in doubt: another study has put the overall mass loss at 92 billion tons a year, and twin assaults of warmer air above, and warmer waters around the continent, continue the attrition. What is not yet certain is whether scientists are looking at the consequences of human-made global warming or at the see-saw conditions inherent in some kind of as-yet-unidentified natural cycle. But ice loss on that scale cannot be easily explained by changes in snowfall or air temperatures, so suspicion falls on the effect of warmer waters. The glaciers flow into seas that are surrounded by ice shelves. The ice shelves have lost one fifth of their thickness in recent decades, so they offer less resistance to the land-based ice, allowing the glaciers to accelerate. There is a second factor: some of the glaciers are grounded on continental bedrock that is depressed below sea level, which means that warmer ocean waters can penetrate further inland and melt the glaciers from below.

Cautious response

There are questions that have yet to be resolved. As usual in science, the interpretations are open to debate. “Although these latest CryoSat measurements of Antarctic thinning agree with findings from two studies reported last year, I think the new estimates of ice loss computed from them are far too high, because the glaciers in this sector just haven’t speeded up that much,” said Andy Shepherd, professor of earth observation at the University of Leeds in the UK and principal scientific advisor to the CryoSat mission. “It could be that a bigger chunk of the thinning is down to snowfall fluctuations than the authors have accounted for, and so I would be cautious about the new numbers until more information is to hand.” Dr Wouters agrees that more research is necessary. “It appears that some time around 2009, the ice shelf thinning and the subsurface melting of the glaciers passed a critical threshold which triggered the sudden ice loss. However, compared to other regions in Antarctica, the Southern Peninsula is rather understudied, exactly because it did not show any changes in the past, ironically,” he said. “To pinpoint the cause of the changes, more data need to be collected. A detailed knowledge of the geometry of the local ice shelves, the ocean floor topography, ice sheet thickness and glacier flow speeds are crucial to tell how much longer the thinning will continue.” − Climate News Network

US farmers given early warning about hungry crop pest

Biologists say a destructive insect is likely to cause even more damage than usual as rising temperatures prompt leaves to sprout earlier. LONDON, 24 May, 2015 − It is small, bright green and an unwelcome visitor. But global warming means that this particular agricultural menace arrives earlier than ever − and consumes more than ever. New research has confirmed that the potato leafhopper now turns up to devour US crops on average 10 days earlier than it did 60 years ago. Despite its informal name, Empoasca fabae is known to have developed an appetite not just for potatoes, but for anything from rhubarb to red maple trees. It survives over the winter in the southernmost states, then moves north as the temperatures begin to rise and crops begin to sprout. It has been observed to reproduce itself on around 200 plant species, and it also has a taste for apples, celery, beans, grapes, hops and the important perennial forage crop alfalfa, sometimes also known as lucerne.

Severe infestation

Three biologists from two US universities report in PLOS One, the Public Library of Science journal, that leafhopper infestation is more severe in the warmest years, and that the damage caused by the tiny insect is likely to increase as average temperatures continue to rise. It arrives in the growing season and pierces the plant leaf tissue to get at the sap. Its saliva carries a toxin that can cause the leaf to dry, curl and rot, and the consequent damage is called “hopperburn”.

“You don’t realise they’re even there until you see the damage to the plants . . . By then it’s too late”

“Earlier arrival dates make it particularly important for farmers to get out early in the season and scout for leafhoppers,” says William Lamp, associate professor of entomology at the University of Maryland, and one of the three authors of the study. “They’re tiny, flighty and very hard to see. You don’t realise they’re even there until you see the damage to the plants, which can take up to a week to manifest. By then it’s too late.” The researchers combed the records between 1951 and 2012 to track the dates in which the pest was recorded in each of 19 affected US states, and matched this with weather records over the same timespan. Such a finding was  possible only because scientists had access to systematic data. Dilip Venugopal, an ecologist, and colleague of Lamp at the University of Maryland, says: “The historical records on agricultural pests are a gold mine, made possible by decades of hard work by agricultural research and extension personnel who collect this data. There has been a decline in data collection activity over the past decade, and we would love to see an effort to ramp this up again.” Global average temperatures have risen by 0.74°C since 1951, and the last decade has been the warmest since climate records began.

Changed behaviour

The leafhopper is only one of many long-distance migratory pests likely to change behaviour in response to climate change. Other researchers have already observed crop pests’ steady movement towards higher latitudes in recent decades. “Climate change is not just costly because temperatures and oceans rise, but because it makes it harder to feed ourselves,” says report co-author Mitchell Baker, assistant professor of biology at Queens College, City University of New York. “Increased pest pressure in agriculture is one of the complex effects of continued warming. Predicting arrival time and severity is critical to managing this pest and others like it.” – Climate News Network

Biologists say a destructive insect is likely to cause even more damage than usual as rising temperatures prompt leaves to sprout earlier. LONDON, 24 May, 2015 − It is small, bright green and an unwelcome visitor. But global warming means that this particular agricultural menace arrives earlier than ever − and consumes more than ever. New research has confirmed that the potato leafhopper now turns up to devour US crops on average 10 days earlier than it did 60 years ago. Despite its informal name, Empoasca fabae is known to have developed an appetite not just for potatoes, but for anything from rhubarb to red maple trees. It survives over the winter in the southernmost states, then moves north as the temperatures begin to rise and crops begin to sprout. It has been observed to reproduce itself on around 200 plant species, and it also has a taste for apples, celery, beans, grapes, hops and the important perennial forage crop alfalfa, sometimes also known as lucerne.

Severe infestation

Three biologists from two US universities report in PLOS One, the Public Library of Science journal, that leafhopper infestation is more severe in the warmest years, and that the damage caused by the tiny insect is likely to increase as average temperatures continue to rise. It arrives in the growing season and pierces the plant leaf tissue to get at the sap. Its saliva carries a toxin that can cause the leaf to dry, curl and rot, and the consequent damage is called “hopperburn”.

“You don’t realise they’re even there until you see the damage to the plants . . . By then it’s too late”

“Earlier arrival dates make it particularly important for farmers to get out early in the season and scout for leafhoppers,” says William Lamp, associate professor of entomology at the University of Maryland, and one of the three authors of the study. “They’re tiny, flighty and very hard to see. You don’t realise they’re even there until you see the damage to the plants, which can take up to a week to manifest. By then it’s too late.” The researchers combed the records between 1951 and 2012 to track the dates in which the pest was recorded in each of 19 affected US states, and matched this with weather records over the same timespan. Such a finding was  possible only because scientists had access to systematic data. Dilip Venugopal, an ecologist, and colleague of Lamp at the University of Maryland, says: “The historical records on agricultural pests are a gold mine, made possible by decades of hard work by agricultural research and extension personnel who collect this data. There has been a decline in data collection activity over the past decade, and we would love to see an effort to ramp this up again.” Global average temperatures have risen by 0.74°C since 1951, and the last decade has been the warmest since climate records began.

Changed behaviour

The leafhopper is only one of many long-distance migratory pests likely to change behaviour in response to climate change. Other researchers have already observed crop pests’ steady movement towards higher latitudes in recent decades. “Climate change is not just costly because temperatures and oceans rise, but because it makes it harder to feed ourselves,” says report co-author Mitchell Baker, assistant professor of biology at Queens College, City University of New York. “Increased pest pressure in agriculture is one of the complex effects of continued warming. Predicting arrival time and severity is critical to managing this pest and others like it.” – Climate News Network

Two oceans may explain global warming pause

Temperatures may be rising more slowly than expected because of two natural oceanic cycles − the latest refutation of the global warming “pause”. LONDON, 1 March, 2015 − US scientists have suggested yet another explanation for the so-called pause in global warming. They think it might all be down to the juxtaposition of two independent natural climate cycles – each with periods of half a century or more – one of which is blowing cold, and the other not very hot. Between them, the phenomena known to meteorologists as the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation could account for the seeming slowdown in predicted temperature rises. Any pause or hiatus in global warming is only apparent: in fact, 14 of the warmest years on record have happened in the last 15 years and 2014 was scored separately, by the World Meteorological Organisation, the US National Oceanic and Atmospheric Administration, and the US space agency Nasa,  as the warmest on record. But overall, the palpable increases in average temperatures per decade recorded in the last 30 years of the 20th century have not been maintained, and climate scientists and meteorologists have been trying to work out why. The latest proposal is from Byron Steinman, a geologist at the University of Minnesota Duluth, and Michael Mann and Sonya Miller of Pennsylvania State University.

Multiple theories

Professor Mann is the scientist who, much to the fury of people who deny climate change, first formulated the famous “hockey-stick graph” which highlights the magnitude of change that threatens to overtake global climate as greenhouse gas levels rise because of human activity. They report in Science that the northern hemisphere is warming more slowly, not because of the Atlantic oscillation, which has been relatively flat, but because of a second, different but still natural downward trend in the Pacific cycle. This is not the only explanation on the table. In the past two years Climate News Network has reported that climate scientists certainly expected a slowdown, but just not right now; or that planetary measurements might be incomplete or misleading; or that even though average levels were down, this masked a series of hotter extremes. The oceans have certainly been under suspicion. One group has already identified the cooling Pacific as a damper on global warming. Another has suggested that in fact the “missing heat” is collecting in the Atlantic depths. Yet another has questioned the role of the trade winds, while still another has pointed to an upswing in volcanic activity that could have delivered a fine smear of sunblock aerosols to the atmosphere.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural… climate variability on timescales of decades”

Any or all of these could have some role in the big picture. The climate would vary anyway, and the question in every case is: how much would any or all natural variation affect the overall path of change because of increasing carbon dioxide levels in the atmosphere? The latest study is based on sophisticated climate models that match the predicted impact of the great ocean-atmosphere cycles with the pattern of climate shifts recorded in the past. “We know that it is important to distinguish between human-caused and natural climate variability so we can assess the impact of human-caused climate change, including drought and weather extremes,” Professor Mann said. “The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural, internal climate variability on timescales of decades.” – Climate News Network

Temperatures may be rising more slowly than expected because of two natural oceanic cycles − the latest refutation of the global warming “pause”. LONDON, 1 March, 2015 − US scientists have suggested yet another explanation for the so-called pause in global warming. They think it might all be down to the juxtaposition of two independent natural climate cycles – each with periods of half a century or more – one of which is blowing cold, and the other not very hot. Between them, the phenomena known to meteorologists as the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation could account for the seeming slowdown in predicted temperature rises. Any pause or hiatus in global warming is only apparent: in fact, 14 of the warmest years on record have happened in the last 15 years and 2014 was scored separately, by the World Meteorological Organisation, the US National Oceanic and Atmospheric Administration, and the US space agency Nasa,  as the warmest on record. But overall, the palpable increases in average temperatures per decade recorded in the last 30 years of the 20th century have not been maintained, and climate scientists and meteorologists have been trying to work out why. The latest proposal is from Byron Steinman, a geologist at the University of Minnesota Duluth, and Michael Mann and Sonya Miller of Pennsylvania State University.

Multiple theories

Professor Mann is the scientist who, much to the fury of people who deny climate change, first formulated the famous “hockey-stick graph” which highlights the magnitude of change that threatens to overtake global climate as greenhouse gas levels rise because of human activity. They report in Science that the northern hemisphere is warming more slowly, not because of the Atlantic oscillation, which has been relatively flat, but because of a second, different but still natural downward trend in the Pacific cycle. This is not the only explanation on the table. In the past two years Climate News Network has reported that climate scientists certainly expected a slowdown, but just not right now; or that planetary measurements might be incomplete or misleading; or that even though average levels were down, this masked a series of hotter extremes. The oceans have certainly been under suspicion. One group has already identified the cooling Pacific as a damper on global warming. Another has suggested that in fact the “missing heat” is collecting in the Atlantic depths. Yet another has questioned the role of the trade winds, while still another has pointed to an upswing in volcanic activity that could have delivered a fine smear of sunblock aerosols to the atmosphere.

“The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural… climate variability on timescales of decades”

Any or all of these could have some role in the big picture. The climate would vary anyway, and the question in every case is: how much would any or all natural variation affect the overall path of change because of increasing carbon dioxide levels in the atmosphere? The latest study is based on sophisticated climate models that match the predicted impact of the great ocean-atmosphere cycles with the pattern of climate shifts recorded in the past. “We know that it is important to distinguish between human-caused and natural climate variability so we can assess the impact of human-caused climate change, including drought and weather extremes,” Professor Mann said. “The North Atlantic and North Pacific Oceans appear to be drivers of substantial natural, internal climate variability on timescales of decades.” – Climate News Network

Climate change opens new doors to deadly diseases

Scientists warn that humans will face epidemics of diseases never encountered before as global warming drives animals and parasites into new habitats. LONDON, 23 February, 2015 − Disease emergencies such as the eruption of Ebola in West Africa or the spread of West Nile virus in North America may be a consequence of climate change − and could become more frequent as the world warms, according to scientists. That is because the change in climate conditions means that the insects that transmit diseases, and the animal hosts that serve as a natural reservoir of infection, can spread to new territories. Malaria, which kills 600,000 people a year, has moved to higher latitudes and higher altitudes, claiming new victims. But, the scientists argue, the issue is wider than that. Ease of travel, the international traffic of large volumes of crops and animal products, and increasing human disruption of ecosystems are all factors in the spread of what they call emerging infectious diseases (EID).

Agents of disease

And there could be yet another factor: humans haven’t completely appreciated just how opportunistic parasites and other agents of disease can be. Zoologists Daniel Brooks, of the University of Nebraska-Lincoln, and Eric Hoberg, of the US National Parasite Collection, argue in the Philosophical Transactions of the Royal Society that changes in climate will mean changes in habitat. And changes in habitat will mean that animals are exposed to new pathogens – anything that causes a disease – and parasites. It follows that humans will increasingly be exposed to epidemics of new diseases never encountered before on such a scale. But it will not, Professor Brooks says, be like the plot of the 1971 science fiction movie, The Andromeda Strain, about a single deadly global infection. “There are going to be a lot of localised outbreaks putting pressure on medical and veterinary health systems,” he says. “It will be the death of a thousand cuts.” Infectious microbes evolved to survive in a natural host, occasionally spreading to a new host. The assumption has been that because evolution is a gradual process, new host infections would be rare. But microbes have turned out to be much more resourceful.

“There are going to be a lot of localised outbreaks . . . It will be the death of a thousand cuts”

When humans hunted capuchin and spider monkeys out of existence in Costa Rica, their parasites switched promptly to the local howler monkeys. In the Canadian Arctic, as temperature patterns changed, lungworms have moved northward and switched hosts from caribou to musk oxen. The implication is that pathogens are more versatile and opportunistic than anyone had predicted. In which case, humans are likely to see more emerging infectious diseases as conditions change. The two scientists propose a “fundamental conceptual shift” in thinking about disease. “Even though a parasite might have a very specialised relationship with one particular host in one particular place, there are other hosts that may be as susceptible,” Professor Brooks says. Resistance could evolve too, but this would then mean that the pathogen became a chronic disease problem, rather than an acute one.

Unexpected circumstances

So public health chiefs and veterinary scientists will be called upon to co-operate in increasingly unexpected circumstances, especially as climate change begins to alter the ground rules. “Palaeontological studies suggest that species with large geographical ranges and with high ability to disperse are most successful at surviving large-scale environmental perturbation and mass extinctions,” the two authors conclude. “Thus, the species most successful at surviving global climate changes will be the primary sources of emerging infectious diseases (EID), so host extinction will not limit the risk of EID. “The planet is thus an evolutionary and ecological minefield of EID through which millions of people, their crops and their livestock wander daily.” – Climate News Network

Scientists warn that humans will face epidemics of diseases never encountered before as global warming drives animals and parasites into new habitats. LONDON, 23 February, 2015 − Disease emergencies such as the eruption of Ebola in West Africa or the spread of West Nile virus in North America may be a consequence of climate change − and could become more frequent as the world warms, according to scientists. That is because the change in climate conditions means that the insects that transmit diseases, and the animal hosts that serve as a natural reservoir of infection, can spread to new territories. Malaria, which kills 600,000 people a year, has moved to higher latitudes and higher altitudes, claiming new victims. But, the scientists argue, the issue is wider than that. Ease of travel, the international traffic of large volumes of crops and animal products, and increasing human disruption of ecosystems are all factors in the spread of what they call emerging infectious diseases (EID).

Agents of disease

And there could be yet another factor: humans haven’t completely appreciated just how opportunistic parasites and other agents of disease can be. Zoologists Daniel Brooks, of the University of Nebraska-Lincoln, and Eric Hoberg, of the US National Parasite Collection, argue in the Philosophical Transactions of the Royal Society that changes in climate will mean changes in habitat. And changes in habitat will mean that animals are exposed to new pathogens – anything that causes a disease – and parasites. It follows that humans will increasingly be exposed to epidemics of new diseases never encountered before on such a scale. But it will not, Professor Brooks says, be like the plot of the 1971 science fiction movie, The Andromeda Strain, about a single deadly global infection. “There are going to be a lot of localised outbreaks putting pressure on medical and veterinary health systems,” he says. “It will be the death of a thousand cuts.” Infectious microbes evolved to survive in a natural host, occasionally spreading to a new host. The assumption has been that because evolution is a gradual process, new host infections would be rare. But microbes have turned out to be much more resourceful.

“There are going to be a lot of localised outbreaks . . . It will be the death of a thousand cuts”

When humans hunted capuchin and spider monkeys out of existence in Costa Rica, their parasites switched promptly to the local howler monkeys. In the Canadian Arctic, as temperature patterns changed, lungworms have moved northward and switched hosts from caribou to musk oxen. The implication is that pathogens are more versatile and opportunistic than anyone had predicted. In which case, humans are likely to see more emerging infectious diseases as conditions change. The two scientists propose a “fundamental conceptual shift” in thinking about disease. “Even though a parasite might have a very specialised relationship with one particular host in one particular place, there are other hosts that may be as susceptible,” Professor Brooks says. Resistance could evolve too, but this would then mean that the pathogen became a chronic disease problem, rather than an acute one.

Unexpected circumstances

So public health chiefs and veterinary scientists will be called upon to co-operate in increasingly unexpected circumstances, especially as climate change begins to alter the ground rules. “Palaeontological studies suggest that species with large geographical ranges and with high ability to disperse are most successful at surviving large-scale environmental perturbation and mass extinctions,” the two authors conclude. “Thus, the species most successful at surviving global climate changes will be the primary sources of emerging infectious diseases (EID), so host extinction will not limit the risk of EID. “The planet is thus an evolutionary and ecological minefield of EID through which millions of people, their crops and their livestock wander daily.” – Climate News Network

Scientists track natural responses to climate change

Researchers in the US have identified a wide range of impacts – human and natural – that global warming has on fish, forests, birds and wildflowers. LONDON, 31 December, 2014 − Lumberjacks are selecting different trees, US fishermen are sailing further north to catch black sea bass, desert birds are nesting later in California and Arizona, and one kind of wildflower is changing shape in the Rocky Mountains − and all in response to climate change, according to new research. None of these responses is simple, or necessarily ominous, and global warming is not the only factor at work. But all are nevertheless examples of adaptation to − so far – very modest changes in temperature. Adena Rissman and Chad Rittenhouse, of the University of Wisconsin-Madison, report in the Journal of Environmental Management that they looked at weather records and logging data and found that, since 1948, the winter interval during which ground is firmly frozen has declined by an average of two to three weeks. Hard winters are the logger’s friend as the ground can support heavy machinery, whereas muddy soils can make tracks impassable. So, over the decades, foresters have harvested more and more red pine and jack pine − species that flourish in sandy, well-drained soil more accessible to trucks, tractors and chainsaws.

Significant decline

“We wanted to know how weather affects our ability to support sustainable working forests,” says Dr Rissman, assistant professor of human dimensions of ecosystem management. “We found a significant decline in the duration of frozen ground over the past 65 years and, at the same time, a significant shift in the species being harvested.” Such changes in selection tend to affect ecosystems – on land or at sea. Scientists at the Northeast Fisheries Science Centre in the US report in the ICES Journal of Marine Science that they looked at trawl survey data collected between 1972 and 2008 to analyse variations in abundance of black sea bass, scup, and summer and winter flounder. All had shown “significant poleward shifts” in at least one season.

“We demonstrated how a combination of fishing and climate can influence the distribution of marine fish”

The bass and scup were responding to changes in temperature. The summer flounder were more likely to be responding to a decrease in fishing pressure − that is, the species could recolonise former habitat. There was no change in the distribution in the southern New England/Mid Atlantic Bight stock of winter flounder. “Using these data, we demonstrated how a combination of fishing and climate can influence the distribution of marine fish,” said lead author Richard Bell, research associate at the US National Oceanic and Atmospheric Administration fisheries service laboratory at Narrangansett.“It is not one or the other.” Meanwhile, in the arid American southwest’s Sonora Desert, all 13 desert bird species have tended to delay nesting by two weeks or more, as a response to severe drought.

Delays in nesting

This makes survival a problem for the birds as their young are more vulnerable to nest predators and parasites. Some species forego breeding entirely during an extreme drought. Even without global warming, droughts are an enduring fact of life in the region. But ecologists point out that climate models predict a greater frequency of droughts, which could lead to even more delays in nesting. “These responses are predicted to become more frequent and extreme, due to climate change, causing us to question how desert birds will persist in the long term,” Chris McCreedy, a desert ecologist at Point Blue Conservation Science, reports in The Auk, the American Ornithologists’ Union journal.

The hardy Rocky Mountain mustard plant Image: USDA via Wikimedia Commons

The hardy Rocky Mountain mustard plant
Image: USDA via Wikimedia Commonse

At least one species has responded to climate change by altering not just its life cycle but its shape. Students at Dartmouth College in New Hampshire and the University of South Carolina report in Global Change Biology that the Rocky Mountain mustard plant (Boechera stricta) offers an example of what biologists call “phenotypic plasticity”. This means that it doesn’t evolve to meet climate change − it just looks different under different conditions. It changes according to whether the conditions are hot and dry, or cold and wet. In experiments that simulated future climate change, it also flowered seven days earlier. This little ready-for-anything brassica plant seemed able to respond differently according to whether or not there was snow around it. Or, as the researchers put it: “Extensive plasticity could buffer against immediate fitness declines due to changing climates.” – Climate News Network

Researchers in the US have identified a wide range of impacts – human and natural – that global warming has on fish, forests, birds and wildflowers. LONDON, 31 December, 2014 − Lumberjacks are selecting different trees, US fishermen are sailing further north to catch black sea bass, desert birds are nesting later in California and Arizona, and one kind of wildflower is changing shape in the Rocky Mountains − and all in response to climate change, according to new research. None of these responses is simple, or necessarily ominous, and global warming is not the only factor at work. But all are nevertheless examples of adaptation to − so far – very modest changes in temperature. Adena Rissman and Chad Rittenhouse, of the University of Wisconsin-Madison, report in the Journal of Environmental Management that they looked at weather records and logging data and found that, since 1948, the winter interval during which ground is firmly frozen has declined by an average of two to three weeks. Hard winters are the logger’s friend as the ground can support heavy machinery, whereas muddy soils can make tracks impassable. So, over the decades, foresters have harvested more and more red pine and jack pine − species that flourish in sandy, well-drained soil more accessible to trucks, tractors and chainsaws.

Significant decline

“We wanted to know how weather affects our ability to support sustainable working forests,” says Dr Rissman, assistant professor of human dimensions of ecosystem management. “We found a significant decline in the duration of frozen ground over the past 65 years and, at the same time, a significant shift in the species being harvested.” Such changes in selection tend to affect ecosystems – on land or at sea. Scientists at the Northeast Fisheries Science Centre in the US report in the ICES Journal of Marine Science that they looked at trawl survey data collected between 1972 and 2008 to analyse variations in abundance of black sea bass, scup, and summer and winter flounder. All had shown “significant poleward shifts” in at least one season.

“We demonstrated how a combination of fishing and climate can influence the distribution of marine fish”

The bass and scup were responding to changes in temperature. The summer flounder were more likely to be responding to a decrease in fishing pressure − that is, the species could recolonise former habitat. There was no change in the distribution in the southern New England/Mid Atlantic Bight stock of winter flounder. “Using these data, we demonstrated how a combination of fishing and climate can influence the distribution of marine fish,” said lead author Richard Bell, research associate at the US National Oceanic and Atmospheric Administration fisheries service laboratory at Narrangansett.“It is not one or the other.” Meanwhile, in the arid American southwest’s Sonora Desert, all 13 desert bird species have tended to delay nesting by two weeks or more, as a response to severe drought.

Delays in nesting

This makes survival a problem for the birds as their young are more vulnerable to nest predators and parasites. Some species forego breeding entirely during an extreme drought. Even without global warming, droughts are an enduring fact of life in the region. But ecologists point out that climate models predict a greater frequency of droughts, which could lead to even more delays in nesting. “These responses are predicted to become more frequent and extreme, due to climate change, causing us to question how desert birds will persist in the long term,” Chris McCreedy, a desert ecologist at Point Blue Conservation Science, reports in The Auk, the American Ornithologists’ Union journal.

The hardy Rocky Mountain mustard plant Image: USDA via Wikimedia Commons

The hardy Rocky Mountain mustard plant
Image: USDA via Wikimedia Commonse

At least one species has responded to climate change by altering not just its life cycle but its shape. Students at Dartmouth College in New Hampshire and the University of South Carolina report in Global Change Biology that the Rocky Mountain mustard plant (Boechera stricta) offers an example of what biologists call “phenotypic plasticity”. This means that it doesn’t evolve to meet climate change − it just looks different under different conditions. It changes according to whether the conditions are hot and dry, or cold and wet. In experiments that simulated future climate change, it also flowered seven days earlier. This little ready-for-anything brassica plant seemed able to respond differently according to whether or not there was snow around it. Or, as the researchers put it: “Extensive plasticity could buffer against immediate fitness declines due to changing climates.” – Climate News Network

Insects get light relief from warming

FOR IMMEDIATE RELEASE Research reveals that lighter-coloured insects are thriving as European summers get warmer – but milder winters in the southern hemisphere are restricting the growth of some shrubs and trees LONDON, 31 May − Europe’s butterflies are fading in the sunlight as the summers warm − while some species of shrubs and trees in the southern hemisphere are growing less as winters become milder. Lead author Dirk Zeuss, of Philipps-University Marburg in Germany, and fellow researchers report in Nature Communications that as the climate of Europe begins to warm, the lighter shades of butterfly and dragonfly species begin to outcompete the darker-coloured insects. The researchers, who looked at 366 species of butterfly and 107 kinds of dragonfly, observed a clear pattern of change between 1988 and 2006. In warmer, sunnier southern Europe, the light-coloured varieties are doing well, and the darker kinds have migrated northwards. The southern migrant hawker dragonfly (Aeshna affinis), the scarlet darter (Crocothemis erythraea) have moved to Germany, and in 2010 the dainty damselfly (Coenagrion scitulum) was seen in England for the first time in 50 years.

Direct link

“For two of the major groups of insects, we have now demonstrated a direct link between climate and insect colour,” said co-author Carsten Rahbek, of Imperial College London and the University of Copenhagen. “We now know that lighter-coloured butterflies and dragonflies are doing better in a warmer world. And we have also demonstrated that the effects of climate change are not something of the future, but that nature and its ecosystems are changing as we speak.” This research is part of a pan-European effort to understand what climate change is going to do to the animals and plants that evolved in regions where the climate once most suited them. Research in Switzerland, for instance, has shown butterflies heading for higher ground. In Britain, some species have responded to temperature rises and moved northwards. Measures of what happens don’t always explain why things happen. A famous evolutionary study linked the changes in colour of the peppered moth to the rise and fall of soot and dust in the atmosphere since the beginning of the Industrial Revolution. But this latest study has nothing to do with air quality, and everything to do with energy supply and temperature regulation in insects.

Overheating

Dark-coloured insects can absorb more sunlight than pale varieties, and increase their body temperature, so they can cope with cooler climates. In hotter climates, other and lighter-coloured species protect themselves against overheating by reflecting more sunlight. As the temperatures inch up with the decades, the darker coloured creatures must move to cooler places or perish. There are other factors that influence distribution: water supplies and the plants on which insects depend are also changing with average temperatures. But the simple concentration on shade and depth of colour in species clears up a little of the confusion. The ability to absorb and reflect sunlight makes a big difference.

“Now we have an idea of what could be a strong cause of the changes [in the insect fauna]”

“Until now, we could only watch the massive changes in the insect fauna during the last 20 years,” Zeuss said. “Now we have an idea of what could be a strong cause of the changes.” Paradoxically, warmer winters can have a limiting effect of on some plant species. Melanie Harsch, of the University of Washington in Seattle, US, and colleagues report in PLOS One, the Public Library of Science journal that on Campbell Island, 600 kilometres south of New Zealand, warm spells in winter are actually limiting the growth of trees and shrubs. Researchers have been taking temperature measurements there for more than 70 years, so scientists know that, since then, the climate has on average warmed by 0.6°C. But two long-lived species of evergreen haven’t grown much in average height, and nor have the trees moved up hill − something ecologists might expect with a rise in average warming.

Warm summers

Overall, the climate is cool – winters are never very cold, nor summers very warm − and there isn’t much snow, and the US scientists examined growth records to work out what was happening. The plants won’t grow below 5°C, and winter temperatures hover below that figure. The problem is that the winters are getting warmer – at least for long enough for the trees to wake up from semi-dormancy and start growing again. “When winter temperatures fluctuate between being cold and warm enough for growth, plants deplete their resources trying to photosynthesise, and end the winter with fewer reserves than they initially had,” said Dr Harsch. “In the summer, they have to play catch up.” The other problem of a warmer winter was that seedlings got established, and competed to affect the growth of the older plants. Quite possibly, a new order will be established, in which the island is warm enough for plants can grow all year round. “It’s this transition part that the plants are not adapted for,” Harsch explained. − Climate News Network

FOR IMMEDIATE RELEASE Research reveals that lighter-coloured insects are thriving as European summers get warmer – but milder winters in the southern hemisphere are restricting the growth of some shrubs and trees LONDON, 31 May − Europe’s butterflies are fading in the sunlight as the summers warm − while some species of shrubs and trees in the southern hemisphere are growing less as winters become milder. Lead author Dirk Zeuss, of Philipps-University Marburg in Germany, and fellow researchers report in Nature Communications that as the climate of Europe begins to warm, the lighter shades of butterfly and dragonfly species begin to outcompete the darker-coloured insects. The researchers, who looked at 366 species of butterfly and 107 kinds of dragonfly, observed a clear pattern of change between 1988 and 2006. In warmer, sunnier southern Europe, the light-coloured varieties are doing well, and the darker kinds have migrated northwards. The southern migrant hawker dragonfly (Aeshna affinis), the scarlet darter (Crocothemis erythraea) have moved to Germany, and in 2010 the dainty damselfly (Coenagrion scitulum) was seen in England for the first time in 50 years.

Direct link

“For two of the major groups of insects, we have now demonstrated a direct link between climate and insect colour,” said co-author Carsten Rahbek, of Imperial College London and the University of Copenhagen. “We now know that lighter-coloured butterflies and dragonflies are doing better in a warmer world. And we have also demonstrated that the effects of climate change are not something of the future, but that nature and its ecosystems are changing as we speak.” This research is part of a pan-European effort to understand what climate change is going to do to the animals and plants that evolved in regions where the climate once most suited them. Research in Switzerland, for instance, has shown butterflies heading for higher ground. In Britain, some species have responded to temperature rises and moved northwards. Measures of what happens don’t always explain why things happen. A famous evolutionary study linked the changes in colour of the peppered moth to the rise and fall of soot and dust in the atmosphere since the beginning of the Industrial Revolution. But this latest study has nothing to do with air quality, and everything to do with energy supply and temperature regulation in insects.

Overheating

Dark-coloured insects can absorb more sunlight than pale varieties, and increase their body temperature, so they can cope with cooler climates. In hotter climates, other and lighter-coloured species protect themselves against overheating by reflecting more sunlight. As the temperatures inch up with the decades, the darker coloured creatures must move to cooler places or perish. There are other factors that influence distribution: water supplies and the plants on which insects depend are also changing with average temperatures. But the simple concentration on shade and depth of colour in species clears up a little of the confusion. The ability to absorb and reflect sunlight makes a big difference.

“Now we have an idea of what could be a strong cause of the changes [in the insect fauna]”

“Until now, we could only watch the massive changes in the insect fauna during the last 20 years,” Zeuss said. “Now we have an idea of what could be a strong cause of the changes.” Paradoxically, warmer winters can have a limiting effect of on some plant species. Melanie Harsch, of the University of Washington in Seattle, US, and colleagues report in PLOS One, the Public Library of Science journal that on Campbell Island, 600 kilometres south of New Zealand, warm spells in winter are actually limiting the growth of trees and shrubs. Researchers have been taking temperature measurements there for more than 70 years, so scientists know that, since then, the climate has on average warmed by 0.6°C. But two long-lived species of evergreen haven’t grown much in average height, and nor have the trees moved up hill − something ecologists might expect with a rise in average warming.

Warm summers

Overall, the climate is cool – winters are never very cold, nor summers very warm − and there isn’t much snow, and the US scientists examined growth records to work out what was happening. The plants won’t grow below 5°C, and winter temperatures hover below that figure. The problem is that the winters are getting warmer – at least for long enough for the trees to wake up from semi-dormancy and start growing again. “When winter temperatures fluctuate between being cold and warm enough for growth, plants deplete their resources trying to photosynthesise, and end the winter with fewer reserves than they initially had,” said Dr Harsch. “In the summer, they have to play catch up.” The other problem of a warmer winter was that seedlings got established, and competed to affect the growth of the older plants. Quite possibly, a new order will be established, in which the island is warm enough for plants can grow all year round. “It’s this transition part that the plants are not adapted for,” Harsch explained. − Climate News Network

Global warmth trend hides local variants

FOR IMMEDIATE RELEASE There are some surprises hidden in the record of rising global average temperatures, researchers say – but the picture seems in keeping with increasing levels of greenhouse gas emissions. LONDON, 7 May – US scientists have studied the obvious and found some surprises. The average rise in global temperatures because of rising levels of greenhouse gases is just that, an average – but it masks some unexpected variations. Zhaohua Wu and colleagues at Florida State University report in Nature Climate Change that they looked at 100 years of data about land surface temperatures in every continent except Antarctica. And they found that when global warming began to announce itself, it did so in different regions at different times, and some places even got cooler. The overall result was global warming, but new statistical analysis revealed a changing mosaic of temperature differences. “Global warming was not as understood as we thought,” said Wu. The first clear pattern of warming emerged around the Arctic Circle and the sub-tropical regions in both hemispheres. The largest accumulated warming so far has been in the mid-latitude regions of the northern hemisphere.

Cooling Andes

The match of old data and new techniques enabled the researchers to make a series of world maps, offering “snapshots” of local average temperature increases at 10-year intervals from 1950 to 2009. These reveal a pattern of warming that began in Labrador, Greenland, Scandinavia and eastern Siberia, with blotches of unexpected cooling in the western Sahara, inland Brazil and the Chilean Andes. Over the following six decades, Asia, Europe and North America warmed conspicuously, and the southern hemisphere unevenly: by 2009 the only region that seemed to have actually grown cooler and stayed that way was in the Andes.

Consistent

In one sense, the research confirms what meteorologists and climate scientists and geographers have known all along: that the world is a complicated place. Atmospheric circulation patterns in the two hemispheres are different, and atmospheric mixing is slow; oceans and atmosphere and land interact in ways that produce local temperature variations that have nothing in particular to do with anthropogenic global warming. But the study could also help other researchers begin to tease out more precisely the differences between local and regional natural cycles of warming and cooling and the overall impact of greenhouse gas emissions, and help economists, politicians and planners prepare a little better for climate change. And, the scientists warn, the trend they observe “seems to be consistent with the slowly increasing carbon dioxide in the atmosphere.” – Climate News Network

FOR IMMEDIATE RELEASE There are some surprises hidden in the record of rising global average temperatures, researchers say – but the picture seems in keeping with increasing levels of greenhouse gas emissions. LONDON, 7 May – US scientists have studied the obvious and found some surprises. The average rise in global temperatures because of rising levels of greenhouse gases is just that, an average – but it masks some unexpected variations. Zhaohua Wu and colleagues at Florida State University report in Nature Climate Change that they looked at 100 years of data about land surface temperatures in every continent except Antarctica. And they found that when global warming began to announce itself, it did so in different regions at different times, and some places even got cooler. The overall result was global warming, but new statistical analysis revealed a changing mosaic of temperature differences. “Global warming was not as understood as we thought,” said Wu. The first clear pattern of warming emerged around the Arctic Circle and the sub-tropical regions in both hemispheres. The largest accumulated warming so far has been in the mid-latitude regions of the northern hemisphere.

Cooling Andes

The match of old data and new techniques enabled the researchers to make a series of world maps, offering “snapshots” of local average temperature increases at 10-year intervals from 1950 to 2009. These reveal a pattern of warming that began in Labrador, Greenland, Scandinavia and eastern Siberia, with blotches of unexpected cooling in the western Sahara, inland Brazil and the Chilean Andes. Over the following six decades, Asia, Europe and North America warmed conspicuously, and the southern hemisphere unevenly: by 2009 the only region that seemed to have actually grown cooler and stayed that way was in the Andes.

Consistent

In one sense, the research confirms what meteorologists and climate scientists and geographers have known all along: that the world is a complicated place. Atmospheric circulation patterns in the two hemispheres are different, and atmospheric mixing is slow; oceans and atmosphere and land interact in ways that produce local temperature variations that have nothing in particular to do with anthropogenic global warming. But the study could also help other researchers begin to tease out more precisely the differences between local and regional natural cycles of warming and cooling and the overall impact of greenhouse gas emissions, and help economists, politicians and planners prepare a little better for climate change. And, the scientists warn, the trend they observe “seems to be consistent with the slowly increasing carbon dioxide in the atmosphere.” – Climate News Network

Lapland's mystery moths puzzle science

FOR IMMEDIATE RELEASE
LONDON, 22 April – Finnish and US scientists have an unsolved puzzle: good news when they expected bad news. They have invested 32 years studying the forest moths of Finnish Lapland to measure the effect of climate change – and there doesn’t seem on the face of it to have been a change. Yet between 1978 and 2009, average annual temperatures in the region rose by 2°C and precipitation was higher.

“You see it getting warmer, you see it getting wetter and you see that the moth populations are either staying the same or going up,” said Mark Hunter of the University of Michigan. “So you might think ‘Great. The moths like this warmer, wetter climate.’ But that is not what is happening.”

The study looked at population records for 80 species of moth, and found that 90% of them were stable or increasing through the three decades. But warmer temperatures and wetter seasons are more likely to reduce the rate of population growth: species tend to do best under the conditions to which they have adapted over thousands of years.

“So the only possibility is that something else other than climate change – some other factor that we did not measure – is buffering the moths from substantial population reductions and masking the negative effects of climate change,” Professor Hunter said.

He and his colleagues report in Global Change Biology that they used nocturnal light traps to catch 388,779 moths from 456 species at the Värriö Strict Nature Reserve inside the Arctic Circle, 100 kilometres from a road and about 6 km from the Russian frontier. They selected the data for the 80 most common species for statistical analysis.

Winners and losers

At such high latitudes, any change in climate means a change in vegetation and an altered ecosystem, which should affect insect numbers. So the logic suggests that some unknown forces are at work, to protect the moth numbers just when they should be going down.

Ecologists don’t like unexplained outcomes. Because insects are the most numerous animals on earth, because they are pests, pollinators, food sources and disease bearers, and because their numbers ought to be indicators of both annual and long-term climate change, ecologists like to know what happens to them, and when, and why.

Researchers in Europe and the US have repeatedly tested animal population responses to climate change to identify winners and losers and understand what makes one species a loser, another a winner.

A 20-year study by Ben Hatchwell and colleagues at the University of Sheffield in the UK has found that warm dry spring weather makes all the difference to long-tailed tits: these short-lived passerines stand a much better chance of rearing chicks and then surviving to the next year, and the next chance to breed. A cold wet autumn normally increases mortality, but a preceding warm dry spring can offset this effect, they report in the journal Oikos.

Wide implications

So the British ornithologists have an explanation for one bird’s good performance. The Finnish entomologists would like to know what helps keep the larvae alive and the moths aflutter in the warming, changing Arctic Circle. The question is important not just for one group of high-latitude moths: scientists could be misreading the effects of climate change across a whole suite of species because these effects might be masked by other, unidentified factors.

And it becomes increasingly important with a prediction, from the Bjerknes Centre for Climate Research in Norway, that northern Europe could warm by 3°C in the winter by mid-century, with increasing rainfall.

Stefan Sobolowski and Robert Vaulard of the Pierre-Simon Laplace Institute in France report in Environmental Research Letters that even if global average warming is kept to 2°C there will be “substantial and robust changes” across Europe. Against such a backdrop, it becomes important to know why one group of animals is doing better than expected – for the moment.

“The big unknown is how long this buffering will last,” said Professor Hunter. “Will it keep going indefinitely, or will the negative effects of climate change eventually just override these buffers, causing the moth populations to collapse?” – Climate News Network

FOR IMMEDIATE RELEASE
LONDON, 22 April – Finnish and US scientists have an unsolved puzzle: good news when they expected bad news. They have invested 32 years studying the forest moths of Finnish Lapland to measure the effect of climate change – and there doesn’t seem on the face of it to have been a change. Yet between 1978 and 2009, average annual temperatures in the region rose by 2°C and precipitation was higher.

“You see it getting warmer, you see it getting wetter and you see that the moth populations are either staying the same or going up,” said Mark Hunter of the University of Michigan. “So you might think ‘Great. The moths like this warmer, wetter climate.’ But that is not what is happening.”

The study looked at population records for 80 species of moth, and found that 90% of them were stable or increasing through the three decades. But warmer temperatures and wetter seasons are more likely to reduce the rate of population growth: species tend to do best under the conditions to which they have adapted over thousands of years.

“So the only possibility is that something else other than climate change – some other factor that we did not measure – is buffering the moths from substantial population reductions and masking the negative effects of climate change,” Professor Hunter said.

He and his colleagues report in Global Change Biology that they used nocturnal light traps to catch 388,779 moths from 456 species at the Värriö Strict Nature Reserve inside the Arctic Circle, 100 kilometres from a road and about 6 km from the Russian frontier. They selected the data for the 80 most common species for statistical analysis.

Winners and losers

At such high latitudes, any change in climate means a change in vegetation and an altered ecosystem, which should affect insect numbers. So the logic suggests that some unknown forces are at work, to protect the moth numbers just when they should be going down.

Ecologists don’t like unexplained outcomes. Because insects are the most numerous animals on earth, because they are pests, pollinators, food sources and disease bearers, and because their numbers ought to be indicators of both annual and long-term climate change, ecologists like to know what happens to them, and when, and why.

Researchers in Europe and the US have repeatedly tested animal population responses to climate change to identify winners and losers and understand what makes one species a loser, another a winner.

A 20-year study by Ben Hatchwell and colleagues at the University of Sheffield in the UK has found that warm dry spring weather makes all the difference to long-tailed tits: these short-lived passerines stand a much better chance of rearing chicks and then surviving to the next year, and the next chance to breed. A cold wet autumn normally increases mortality, but a preceding warm dry spring can offset this effect, they report in the journal Oikos.

Wide implications

So the British ornithologists have an explanation for one bird’s good performance. The Finnish entomologists would like to know what helps keep the larvae alive and the moths aflutter in the warming, changing Arctic Circle. The question is important not just for one group of high-latitude moths: scientists could be misreading the effects of climate change across a whole suite of species because these effects might be masked by other, unidentified factors.

And it becomes increasingly important with a prediction, from the Bjerknes Centre for Climate Research in Norway, that northern Europe could warm by 3°C in the winter by mid-century, with increasing rainfall.

Stefan Sobolowski and Robert Vaulard of the Pierre-Simon Laplace Institute in France report in Environmental Research Letters that even if global average warming is kept to 2°C there will be “substantial and robust changes” across Europe. Against such a backdrop, it becomes important to know why one group of animals is doing better than expected – for the moment.

“The big unknown is how long this buffering will last,” said Professor Hunter. “Will it keep going indefinitely, or will the negative effects of climate change eventually just override these buffers, causing the moth populations to collapse?” – Climate News Network