Combination punch could fell rainforests
BY THE end of the century, up to 82 per cent of today's tropical forests could be damaged by a combination of climate change and local destruction.
Gregory Asner of Stanford University in California, and colleagues, tried to calculate where the effects of climate change, logging and other causes of deforestation will impact upon forest ecosystems.
They ran 16 different climate models up until the year 2098 and used a vegetation model to work out which types of plants could survive in each area. The team assumed that deforestation and logging would continue at a rate similar to that between 2000 and 2005.
In some areas, the effects work separately. For example, in South America, climate change strikes hard in the north-east while deforestation hits the south-east. But in the central Amazon, both effects combine to devastate forests (Conservation Letters, DOI: 10.1111/j.1755-263X.2010.00133.x).
Asner says these patterns present both a challenge and an opportunity. "In regions with a lot of land-use change but low projected climate change, new protected areas could be established," he suggests.
"The basic method is very sound," says Yadvinder Malhi of the University of Oxford, though he is cautious about the numbers coming out of the model. He also worries that if people think a region is doomed by climate change, they might decide to go ahead and log it. "There's a danger of a perverse reaction," he warns.
Gregory Asner of Stanford University in California, and colleagues, tried to calculate where the effects of climate change, logging and other causes of deforestation will impact upon forest ecosystems.
They ran 16 different climate models up until the year 2098 and used a vegetation model to work out which types of plants could survive in each area. The team assumed that deforestation and logging would continue at a rate similar to that between 2000 and 2005.
In some areas, the effects work separately. For example, in South America, climate change strikes hard in the north-east while deforestation hits the south-east. But in the central Amazon, both effects combine to devastate forests (Conservation Letters, DOI: 10.1111/j.1755-263X.2010.00133.x).
Asner says these patterns present both a challenge and an opportunity. "In regions with a lot of land-use change but low projected climate change, new protected areas could be established," he suggests.
"The basic method is very sound," says Yadvinder Malhi of the University of Oxford, though he is cautious about the numbers coming out of the model. He also worries that if people think a region is doomed by climate change, they might decide to go ahead and log it. "There's a danger of a perverse reaction," he warns.
Is climate change burning Russia?
Russia has sweltered under an intense heatwave since mid-July, recording its highest ever temperatures. The heat has caused widespread drought, ruined crops and encouraged wildfires that have blanketed Moscow in smog and now threaten key nuclear sites. According to the head of Moscow's health department, the city's daily death rate has doubled – up to 700 from the usual average of 360 to 380.
What caused the heatwave?
The primary cause was a "blocking event" – a static atmospheric pattern that has trapped a high-pressure bubble over western Russia since mid-July, pulling in hot air from Africa.
Blocking events naturally occur from time to time. There is evidence that low solar activity increases their numbers , and the sun is currently in a period of minimum activityMovie Camera.
Jeff Knight of the UK Met Office says that the climatic pattern known as El Niño was also a factor. Around the new year, the eastern tropical Pacific heated up, sending a slow-moving wave of heat around the globe – conditions that are characteristic of El Niño. "It warms the global mean temperature with a delay of about six months," says Knight. This extra packet of heat will have increased the likelihood of heatwaves around the world.
Blocking events naturally occur from time to time. There is evidence that low solar activity increases their numbers , and the sun is currently in a period of minimum activityMovie Camera.
Jeff Knight of the UK Met Office says that the climatic pattern known as El Niño was also a factor. Around the new year, the eastern tropical Pacific heated up, sending a slow-moving wave of heat around the globe – conditions that are characteristic of El Niño. "It warms the global mean temperature with a delay of about six months," says Knight. This extra packet of heat will have increased the likelihood of heatwaves around the world.
Frozen jet stream links Pakistan floods, Russian fires
Raging wildfires in western Russia have reportedly doubled average daily death rates in Moscow. Diluvial rains over northern Pakistan are surging south – the UN reports that 6 million have been affected by the resulting floods.
It now seems that these two apparently disconnected events have a common cause. They are linked to the heatwave that killed more than 60 in Japan, and the end of the warm spell in western Europe. The unusual weather in the US and Canada last month also has a similar cause.
According to meteorologists monitoring the atmosphere above the northern hemisphere, unusual holding patterns in the jet stream are to blame. As a result, weather systems sat still. Temperatures rocketed and rainfall reached extremes.
Renowned for its influence on European and Asian weather, the jet stream flows between 7 and 12 kilometres above ground. In its basic form it is a current of fast-moving air that bobs north and south as it rushes around the globe from west to east. Its wave-like shape is caused by Rossby waves – powerful spinning wind currents that push the jet stream alternately north and south like a giant game of pinball.
In recent weeks, meteorologists have noticed a change in the jet stream's normal pattern. Its waves normally shift east, dragging weather systems along with it. But in mid-July they ground to a halt, says Mike Blackburn of the University of Reading, UK (see diagram). There was a similar pattern over the US in late June.
Stationary patterns in the jet stream are called "blocking events". They are the consequence of strong Rossby waves, which push westward against the flow of the jet stream. They are normally overpowered by the jet stream's eastward flow, but they can match it if they get strong enough. When this happens, the jet stream's meanders hold steady, says Blackburn, creating the perfect conditions for extreme weather.
A static jet stream freezes in place the weather systems that sit inside the peaks and troughs of its meanders. Warm air to the south of the jet stream gets sucked north into the "peaks". The "troughs" on the other hand, draw in cold, low-pressure air from the north. Normally, these systems are constantly on the move – but not during a blocking event.
And so it was that Pakistan fell victim to torrents of rain. The blocking event coincided with the summer monsoon, bringing down additional rain on the mountains to the north of the country. It was the final straw for the Indus's congested river bed (see "Thirst for Indus water upped flood risk").
Similarly, as the static jet stream snaked north over Russia, it pulled in a constant stream of hot air from Africa. The resulting heatwave is responsible for extensive drought and nearly 800 wildfires at the latest count. The same effect is probably responsible for the heatwave in Japan, which killed over 60 people in late July. At the same time, the blocking event put an end to unusually warm weather in western Europe.
Blocking events are not the preserve of Europe and Asia. Back in June, a similar pattern developed over the US, allowing a high-pressure system to sit over the eastern seaboard and push up the mercury. Meanwhile, the Midwest was bombarded by air from the north, with chilly effects. Instead of moving on in a matter of days, "the pattern persisted for more than a week", says Deke Arndt of the US National Climatic Data Center in North Carolina.
So what is the root cause of all of this? Meteorologists are unsure. Climate change models predict that rising greenhouse gas concentrations in the atmosphere will drive up the number of extreme heat events. Whether this is because greenhouse gas concentrations are linked to blocking events or because of some other mechanism entirely is impossible to say. Gerald Meehl of the National Center for Atmospheric Research in Boulder, Colorado – who has done much of this modelling himself – points out that the resolution in climate models is too low to reproduce atmospheric patterns like blocking events. So they cannot say anything about whether or not their frequency will change.
There is some tentative evidence that the sun may be involved. Earlier this year astrophysicist Mike Lockwood of the University of Reading, UK, showed that winter blocking events were more likely to happen over Europe when solar activity is low – triggering freezing winters (New Scientist, 17 April, p 6).
Now he says he has evidence from 350 years of historical records to show that low solar activity is also associated with summer blocking events (Environmental Research Letters, in press). "There's enough evidence to suspect that the jet stream behaviour is being modulated by the sun," he says.
Blackburn says that blocking events have been unusually common over the last three years, for instance, causing severe floods in the UK and heatwaves in eastern Europe in 2007. Solar activity has been low throughout.
It now seems that these two apparently disconnected events have a common cause. They are linked to the heatwave that killed more than 60 in Japan, and the end of the warm spell in western Europe. The unusual weather in the US and Canada last month also has a similar cause.
According to meteorologists monitoring the atmosphere above the northern hemisphere, unusual holding patterns in the jet stream are to blame. As a result, weather systems sat still. Temperatures rocketed and rainfall reached extremes.
Renowned for its influence on European and Asian weather, the jet stream flows between 7 and 12 kilometres above ground. In its basic form it is a current of fast-moving air that bobs north and south as it rushes around the globe from west to east. Its wave-like shape is caused by Rossby waves – powerful spinning wind currents that push the jet stream alternately north and south like a giant game of pinball.
In recent weeks, meteorologists have noticed a change in the jet stream's normal pattern. Its waves normally shift east, dragging weather systems along with it. But in mid-July they ground to a halt, says Mike Blackburn of the University of Reading, UK (see diagram). There was a similar pattern over the US in late June.
Stationary patterns in the jet stream are called "blocking events". They are the consequence of strong Rossby waves, which push westward against the flow of the jet stream. They are normally overpowered by the jet stream's eastward flow, but they can match it if they get strong enough. When this happens, the jet stream's meanders hold steady, says Blackburn, creating the perfect conditions for extreme weather.
A static jet stream freezes in place the weather systems that sit inside the peaks and troughs of its meanders. Warm air to the south of the jet stream gets sucked north into the "peaks". The "troughs" on the other hand, draw in cold, low-pressure air from the north. Normally, these systems are constantly on the move – but not during a blocking event.
And so it was that Pakistan fell victim to torrents of rain. The blocking event coincided with the summer monsoon, bringing down additional rain on the mountains to the north of the country. It was the final straw for the Indus's congested river bed (see "Thirst for Indus water upped flood risk").
Similarly, as the static jet stream snaked north over Russia, it pulled in a constant stream of hot air from Africa. The resulting heatwave is responsible for extensive drought and nearly 800 wildfires at the latest count. The same effect is probably responsible for the heatwave in Japan, which killed over 60 people in late July. At the same time, the blocking event put an end to unusually warm weather in western Europe.
Blocking events are not the preserve of Europe and Asia. Back in June, a similar pattern developed over the US, allowing a high-pressure system to sit over the eastern seaboard and push up the mercury. Meanwhile, the Midwest was bombarded by air from the north, with chilly effects. Instead of moving on in a matter of days, "the pattern persisted for more than a week", says Deke Arndt of the US National Climatic Data Center in North Carolina.
So what is the root cause of all of this? Meteorologists are unsure. Climate change models predict that rising greenhouse gas concentrations in the atmosphere will drive up the number of extreme heat events. Whether this is because greenhouse gas concentrations are linked to blocking events or because of some other mechanism entirely is impossible to say. Gerald Meehl of the National Center for Atmospheric Research in Boulder, Colorado – who has done much of this modelling himself – points out that the resolution in climate models is too low to reproduce atmospheric patterns like blocking events. So they cannot say anything about whether or not their frequency will change.
There is some tentative evidence that the sun may be involved. Earlier this year astrophysicist Mike Lockwood of the University of Reading, UK, showed that winter blocking events were more likely to happen over Europe when solar activity is low – triggering freezing winters (New Scientist, 17 April, p 6).
Now he says he has evidence from 350 years of historical records to show that low solar activity is also associated with summer blocking events (Environmental Research Letters, in press). "There's enough evidence to suspect that the jet stream behaviour is being modulated by the sun," he says.
Blackburn says that blocking events have been unusually common over the last three years, for instance, causing severe floods in the UK and heatwaves in eastern Europe in 2007. Solar activity has been low throughout.
Green machine: Don't burn plant waste, bury it
When it comes to using plant waste to mitigate climate change, most people think of turning it into ethanol or biodiesel for use as a fuel. But a new study suggests we may have more to gain by converting plant material into biochar, a type of charcoal, and burying it in farmers' fields.
Biochar is produced by heating plant waste in an oxygen-free environment, a process known as pyrolysis. This also yields syngas – a mix of carbon monoxide and hydrogen – plus a small amount of oil. Both can be burned as fuels.
Typically, up to 60 per cent of the plant's carbon ends up as biochar. When buried, this can lock the carbon away for thousands of years if necessary. The pyrolysis itself releases no carbon dioxide into the air.
Biochar is produced by heating plant waste in an oxygen-free environment, a process known as pyrolysis. This also yields syngas – a mix of carbon monoxide and hydrogen – plus a small amount of oil. Both can be burned as fuels.
Typically, up to 60 per cent of the plant's carbon ends up as biochar. When buried, this can lock the carbon away for thousands of years if necessary. The pyrolysis itself releases no carbon dioxide into the air.
Burning issue
The new study was the work of James Amonette at the Pacific Northwest National Laboratory in Richland, Washington, and colleagues. It centres on a computer model they developed to compare the carbon emissions that would be saved by converting the world's available supplies of plant waste into either biofuel or biochar.
The model showed that converting all the world's available plant waste into biofuels would cut carbon emissions by 10 per cent from today's levels. Turning it into biochar could cut emissions by up to 12 per cent – or 1.8 gigatonnes of the 15.4 gigatonnes emitted each year (Nature Communications, DOI: 10.1038/ncomms1053).
The model showed that converting all the world's available plant waste into biofuels would cut carbon emissions by 10 per cent from today's levels. Turning it into biochar could cut emissions by up to 12 per cent – or 1.8 gigatonnes of the 15.4 gigatonnes emitted each year (Nature Communications, DOI: 10.1038/ncomms1053).
Grey wolves regain protected status
Grey wolves in the northern Rocky mountains have had their protected species status restored.
Efforts over 15 years to protect the species in the US have helped boost the wolves' numbers. This has been so successful that last year the US Fish and Wildlife Service removed Endangered Species Act (ESA) protection for wolves in Idaho and Montana, though not in Wyoming.
But last week, district judge Donald Malloy overturned that decision. He ruled that the law did not allow one part of the population to be hunted and another part protected.
"This decision is a significant victory for wolves, for the integrity of the ESA, and for all Americans who care deeply about conservation," says Rodger Schlickeisen, president of Defenders of Wildlife, which was a plaintiff in the case.
However, Carolyn Sime, statewide wolf coordinator at Montana Fish, Wildlife and Parks, says the decision will be costly for farmers. "A minimum of 100 cattle and in some years up to 200 sheep are confirmed killed by wolves each year in Montana. That represents a significant financial burden if you're a livestock owner," Sime says. "The ability to manage a wolf population under fair chase hunting is now lost."
Efforts over 15 years to protect the species in the US have helped boost the wolves' numbers. This has been so successful that last year the US Fish and Wildlife Service removed Endangered Species Act (ESA) protection for wolves in Idaho and Montana, though not in Wyoming.
But last week, district judge Donald Malloy overturned that decision. He ruled that the law did not allow one part of the population to be hunted and another part protected.
"This decision is a significant victory for wolves, for the integrity of the ESA, and for all Americans who care deeply about conservation," says Rodger Schlickeisen, president of Defenders of Wildlife, which was a plaintiff in the case.
However, Carolyn Sime, statewide wolf coordinator at Montana Fish, Wildlife and Parks, says the decision will be costly for farmers. "A minimum of 100 cattle and in some years up to 200 sheep are confirmed killed by wolves each year in Montana. That represents a significant financial burden if you're a livestock owner," Sime says. "The ability to manage a wolf population under fair chase hunting is now lost."
Wiped out
There are more than 1700 grey wolves in the northern Rockies – an area that includes all of Idaho, Montana and Wyoming, plus portions of Washington, Oregon and Utah. Once abundant throughout North America, by the 1930s grey wolves had been exterminated in Montana, Idaho, Wyoming and south-western Canada. They were listed as endangered in 1974 under the ESA and reintroduced to the northern Rockies in the mid-1990s.
"The service's decision to delist the wolf in Idaho and Montana reflected the strong commitments from the states of Idaho and Montana to manage grey wolves in a sustainable manner," says Tom Strickland of the US Fish and Wildlife Service. "Today's ruling makes it clear this wolf population cannot be delisted until the state of Wyoming has instituted an adequate management programme, similar to those of Idaho and Montana."
"The million-dollar question is how to manage the wolves with these new legal hurdles," says Sime. She says the parks service is looking at a range of options, including appealing the decision.
"The service's decision to delist the wolf in Idaho and Montana reflected the strong commitments from the states of Idaho and Montana to manage grey wolves in a sustainable manner," says Tom Strickland of the US Fish and Wildlife Service. "Today's ruling makes it clear this wolf population cannot be delisted until the state of Wyoming has instituted an adequate management programme, similar to those of Idaho and Montana."
"The million-dollar question is how to manage the wolves with these new legal hurdles," says Sime. She says the parks service is looking at a range of options, including appealing the decision.
Slit pupils help snakes ambush their prey
Vertical pupils weren't just made for night vision. It turns out they may also help snakes stalk prey without being seen.
Richard Shine and Francois Brischoux at the University of Sydney, Australia, scoured the literature and found that vertical pupils on most animals become round in low light. This went against the common theory that vertical pupils evolved to give animal's night vision.
So they compared the pupil shape of 127 Australian snake species with Shine's data on their hunting behaviour and the time of day that they are most active.
This revealed that snakes that ambush their prey and hunt at night tend to have vertical pupils, while round pupils were more characteristic of diurnal snakes that actively seek out and pursue their prey.
Overall, however, pupils were more strongly associated with hunting behaviour than nocturnal activity.
By studying the evolutionary relationship between the various species, the team found that vertical and circular pupils evolved several times in different groups of snakes, and that hunting behaviour was the strongest driver for pupil shape. Ted Maddess a biologist at the Australian National University in Canberra, who was not involved in the study, says the findings provide "good evidence" for this.
Richard Shine and Francois Brischoux at the University of Sydney, Australia, scoured the literature and found that vertical pupils on most animals become round in low light. This went against the common theory that vertical pupils evolved to give animal's night vision.
So they compared the pupil shape of 127 Australian snake species with Shine's data on their hunting behaviour and the time of day that they are most active.
This revealed that snakes that ambush their prey and hunt at night tend to have vertical pupils, while round pupils were more characteristic of diurnal snakes that actively seek out and pursue their prey.
Overall, however, pupils were more strongly associated with hunting behaviour than nocturnal activity.
By studying the evolutionary relationship between the various species, the team found that vertical and circular pupils evolved several times in different groups of snakes, and that hunting behaviour was the strongest driver for pupil shape. Ted Maddess a biologist at the Australian National University in Canberra, who was not involved in the study, says the findings provide "good evidence" for this.
