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UK seabirds sound climate warning

March 28, 2014 in Climate, Marine ecology, Ocean Warming, USA, Warming

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A Scottsh kittiwake: Numbers have plunged since 2000, with climate change thought to be reducing their main food source Image: By DickDaniels (http://carolinabirds.org)via Wikimedia Commons

A Scottsh kittiwake: Numbers have plunged since 2000, with climate change thought to be reducing their main food source
Image: By DickDaniels (http://carolinabirds.org)via Wikimedia Commons

By Alex Kirby

Once-familiar Scottish seabirds are among species whose numbers in the UK are falling sharply, scientists say – and the suspicion is that climate change is to blame.

LONDON, 28 March – Several familiar British birds are now showing drastic declines in numbers as the reality of climate change strikes home even at these temperate latitudes.

Scientists believe climate change is the driving force behind a crash in the numbers of kittiwakes, a seabird species which used to thrive in northern Scotland. The birds are doing so badly that there are fears some colonies could disappear entirely.

The Royal Society for the Protection of Birds (RSPB) is the UK’s largest nature conservation charity. In a report to mark the publication on 31 March by the Intergovernmental Panel on Climate Change (IPCC) of its latest findings, the RSPB says that on current trends kittiwakes face extinction from areas that were once core strongholds.

It says that since 2000 kittiwake numbers have declined by 87% on Orkney and Shetland, two island groups north of the Scottish mainland. The islands were once home to thriving cliff colonies of thousands of birds, but today, the RSPB says, many cliffs are virtually empty in the breeding season.

It says research shows that sea temperature changes are affecting the availability of the birds’ preferred prey, small fish called sandeels.

Leadership challenge

Paul Walton, head of habitats and species for RSPB Scotland, says: “Ten years ago Marwick Head on Orkney was a thriving seabird city – but now it looks like a ghost town. Evidence points to rising sea surface temperatures driving huge declines and species shifts in plankton populations. This is the food of sandeels, and the sandeels are food for the birds.”

Two other seabirds are declining sharply. Razorbills are down 57% from a total of 2,228 in 2000 to just 966 in 2013, and guillemots have fallen by 46% during the same period.

The RSPB wants the Scottish Government to designate key seabird feeding sites as marine protected areas. But it says a much bigger challenge is to persuade world leaders to heed the warnings in the IPCC report and do more to tackle climate change.

Other UK wildlife and habitats are also threatened by climate change. Machair is a rare, wildlife-rich coastal grassland, mostly found on Scottish islands,  and home to a traditional agricultural system that works in close harmony with nature. Working the machair is a big part of Gaelic culture, supporting corncrakes, ringed plovers, dunlins and great yellow bumblebees.

The machair is singled out in the IPCC report as one of the habitats most threatened by climate change. The IPCC says rising sea-levels, and the increased risk of storms and flooding, will mean the land becomes increasingly eroded.

Compounding the pressure

Another British bird of concern to the RSPB is the Dartford warbler, found on the heathlands of southern England and very sensitive to the cold. The species has been steadily moving northwards, apparently because of climate change. It is declining on the southern edge of its range in Spain, and in the UK conservationists are working hard to create new heathland habitat for the birds to move into.

Dotterels are birds which breed only on the highest mountain tops of Scotland. Their numbers have fallen from 630 breeding males in 1999 to 423 in 2011. Again, the RSPB believes, climate change is the culprit.

Martin Harper, the RSPB’s conservation director, says: “Kittiwakes, dotterels and Dartford warblers are three examples of wildlife being affected on our doorstep, but further afield the picture is stark for a whole range of species.

“Climate change will compound the many existing pressures on wildlife including habitat destruction, the introduction of non-native invasive species, over-exploitation and pollution.

“The overwhelming scientific consensus suggests that unless we take urgent action to reduce our greenhouse gas emissions, climate change will commit many species to extinction this century. The silent kittiwake colonies on Orkney should be a warning.” – Climate News Network

Rockies flora show climate impact

March 19, 2014 in Adaptation, Mountains, Phenology, USA, Vegetation changes

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Sky pilot, alpine buttercup and old-man-of-the-mountain in full bloom in the Rocky Mountains of Colorado Image: John Holm from Leadville, CO, uploaded by Hike395, via Wikimedia Commons

Sky pilot, alpine buttercup and old-man-of-the-mountain in full bloom in the Rocky Mountains of Colorado
Image: John Holm from Leadville, CO, uploaded by Hike395, via Wikimedia Commons

By Tim Radford

An intensive study of the flora of one meadow in the Rocky Mountains of Colorado over nearly 40 years reveals a widespread and consistent pattern of climate-induced change.

LONDON, 19 March – Two thirds of alpine flowers have changed their pattern of bloom in response to climate change. Half of them have begun to bloom weeks earlier than normal, one third are reaching their peak bloom well ahead of the traditional almanac date, and others are producing their last blooms later in the year.

The season of flowers – that feast for bees and butterflies, and a signal for insectivorous birds to make the most of their moment in the sun – is a month longer than it was four decades ago.

This conclusion comes with two qualifications. The first is that it is limited to one meadow in one location in Colorado’s Rocky Mountains in the US. But the other is that it is the product of a meticulous, painstaking 39-year-long study by one researcher. So it follows that since there is not much room for mistake or argument about the pattern in one well-studied location, then a similar pattern probably does apply in many upland temperate zone sites.

When David Inouye of the University of Maryland began his research, he was a graduate student who just wanted to know what sources of nectar were available for hummingbirds and bumble bees. So he started counting flowers about 3,000 metres above sea level in Crested Butte, Colorado, at the Rocky Mountain Biological Laboratory. And he carried on.

Big picture

He and colleagues report in the Proceedings of the National Academy of Sciences that they chose 60 common wildflower species – most of them perennial herbs – and they specifically excluded the rarer species because there was not enough data. So they made their judgement on the basis of two million flower counts, during the 39-year interval in which summer air temperatures increased by about 0.4°C per decade and in which the spring snow melt advanced by about 3.5 days per decade.

And they also specifically looked at the entire pattern of spring and summer bloom: the big picture of what biologists call phenology, the timing of biological events, in one place.

“Most studies rely on first dates like flowering or migration, because they use historical data sets that were not intended as scientific studies”, said Professor Inouye. “First flowering is easy to observe. You don’t have to take the time to count the flowers. So that’s often the only information available. It has taken a lot of effort to get the comprehensive insights needed for this analysis which helps us understand how ecological communities are going to change in the future.”

Biologists around the world have begun to use phenological shifts as indicators of climate, and as a basis for future conservation plans, and all of them have observed a pattern of change.

Consistent findings

European researchers confirmed that plants were either moving to higher latitudes, or blooming earlier in response to global warming, and that birds, butterflies and blossoms were actually heading to higher altitudes. Some have used historic observations by one of America’s literary giants as the basis for their research into climate change, and others have looked at the consequences of changes in the plant timetable for the grazers and predators that depend on specific plant communities.

But Inouye and colleagues now think that much of the phenological evidence so far has underestimated the numbers of species that have altered their flowering times, and probably overestimated the magnitude of change: what matters in the field or the meadow is the sum of all the changes, and not just the first dates of flowering.

Inouye and students divided the meadow into 30 plots, and counted flowers every other day for 39 years, for five months every year. So because of the initial basis of the research, continued for so many years, the scientists had sure data on changes for individual species, including the first flowering, the peak flowering and the last blooms, along with a measure of changes in abundance.

The date of first flowering has advanced by six days per decade, the spring peak is on average five days earlier per decade, and the last flower of autumn has been three days later every decade. – Climate News Network

Climate science ‘is beyond argument’

March 17, 2014 in Arctic, Business, Carbon, Climate deniers, Deep Ocean, Economy, Fish, Food security, Global Ocean Commission, Ice Loss, Marine ecology, Ocean acidification, Ocean Warming, Polar ice, Pollution, Science

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Not as sunny as it seems: The ocean is under attack on many fronts, with climate change foremost among them Image: kein via Wikimedia Commons

Not as sunny as it seems: The ocean is under attack on many fronts, with climate change foremost among them
Image: kein via Wikimedia Commons

By Alex Kirby

The Global Ocean Commission says climate change is one of the key threats to the health of the world’s marine life, which it says faces multiple pressures in a warming world.

HONG KONG, 17 March - South Africa’s former Finance Minister, Trevor Manuel, has derided those who deny the scientific argument that climate change is an urgent problem caused largely by human activity.

He told journalists here: “The science is now incontrovertible. There are a few people in the world who deny it, but they are mainly in lunatic asylums.”

Mr Manuel is one of three co-chairs of the Global Ocean Commission, a panel of global leaders who have just ended a meeting here to finalise the proposals they will present to the United Nations in June.

The meeting agreed that another key threat to the world’s oceans is overfishing and the subsidies which help to make it possible. It says this, and the other factors causing ocean degradation, threaten the food security of as many as 500 million people.

It is deeply worried about pollution. With plastic remains now so pervasive that they are found even in deep seafloor sediments, Mr Manuel said, it sometimes seemed that “you might as well not bother to buy seafood at all – just buy the plastic bag it comes in and eat that.”

Shells corroded

The Commission says climate change threatens the oceans in three main ways: by raising the temperature of the water; by reducing its oxygen content; and by increasing its acidity. Antarctic pteropods, small sea snails also known as sea butterflies, are already being found with severely corroded shells because of acidification, and larger creatures, including bigger shellfish and corals, are likely to be seriously affected.

Another of the co-chairs, José María Figueres, the former president of Costa Rica, told the Climate News Network the Commission was concerned at the prospect of exploitation of the high seas in the Arctic as the region’s sea ice continues to melt.

He said: “Beyond Arctic countries’ EEZs (exclusive economic zones stretching 200 nautical miles from the coast), the melting will leave us with a doughnut-shaped hole in the Arctic high seas, which are not under international control.

“Some nations are now looking to explore there for fish, minerals, valuable biodiversity and other resources. I believe we should not go down that route.

We should listen to the science and follow the precautionary principle, keeping this pristine area off-limits for exploitation until we understand the consequences.

Coalition builders

“We’re already pushing the high seas to the limit. We don’t need to push them over the edge by a lack of proper precaution in the Arctic.”

He said: “The jury is still out on whether we have 20 or 30 years ahead as a window of opportunity to act. But why wait? Listen to the science, which is overwhelming, and to the economics, which are sound.”

Describing the Commission as “not just a bunch of treehuggers, but a group that’s grounded itself in good sound economics”, Mr Figueres said the recommendations it planned to present to the UN on 24 June would represent about 20% of its work. The other 80% would involve building coalitions around each recommendation: there are expected to be no more than 10 in total.

The Commission’s third co-chair is the UK’s former Foreign Secretary, David Miliband. He told the Network: “Answers that sit on a shelf are a waste of time, and people who are positively inclined to protect the oceans are held back by institutional inertia.

“But the interplay between climate change and ocean damage is rising, and it very much needs to. The science of most of the last half-century shows us how we’ve been playing tricks with nature.” – Climate News Network

Climate change ‘raises extinction risk’

February 28, 2014 in Endangered Species, Extinction, USA, Warming, Wildlife

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A weather eye for possible risks: Climate change will make extinction likelier for many species Image: By Ren West via Wikimedia Commons

A weather eye for possible risks: Climate change will make extinction likelier for many species
Image: By Ren West via Wikimedia Commons

By Tim Radford

Climate change doesn’t pose a unique threat of extinction to a species, scientists say. It just makes the risk more likely to become a reality.

LONDON, 28 February – Environmental scientists believe they have a blueprint for extinction. They report in Nature Climate Change that they have identified those factors that might make a species more likely to slip away into eternal oblivion as the planet warms and climate conditions change.

It turns out that they knew them all along. There is, the researchers conclude, nothing specifically different about climate change as a threat: it could however make extinction much more likely.

Richard Pearson of University College London (and formerly of the American Museum of Natural History) and colleagues decided to take a small subset of species at risk, and look closely at the factors that determine species extinction.

They chose 36 amphibians and reptiles endemic to the United States. Reptiles and amphibians almost everywhere seem to be vulnerable for a mix of reasons: among them habitat destruction, environmental pollution and the introduction of new predators and new diseases. The more exquisite the ecological niche occupied by the species, the smaller its overall population and the more precarious its chances of survival.

The researchers examined all the information available on salamanders, turtles, tortoises, snakes and lizards and concluded that, overall, there was a 28% chance of extinction by 2100. But without climate change, this risk dwindled to 1%.

“Surprisingly, we found that the most important factors – such as having a small range or low population size – are already used in conservation assessments,” said Dr Pearson. “The new results indicate that current systems may be able to better identify species vulnerability to climate change than previously thought.”

Carry on conserving

And his co-author Resit Akçakaya of Stony Brook University in the US said: “The bad news is that climate change will cause many extinctions unless species-specific conservation actions are taken; but the good news is that the methods conservation organisations have been using to identify which species need the most urgent help also work when climate change is the main threat.”

So to preserve biodiversity conservationists have to do what many are doing already: focus on species that occupy a small or dwindling space, or are few in number.

Other predictions of future extinction under climate change have usually been based on the rate at which habitat with the right climate will shift or contract, and researchers have been more concerned with how easily species can adapt or migrate and why some species do better than others at shifting to new ground.

In the latest research, the scientists selected a class of animals but did not try to make individual predictions for each species: what they were looking for were general principles.

“Our analysis will hopefully be able to help create better guidelines that account for the effects of climate change in assessing extinction risk,” said Dr Pearson. – Climate News Network

Half of plants may move in warmer world

February 16, 2014 in Adaptation, Agriculture, Arctic, China, forest fires, Vegetation changes, Warming, Wildlife

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Vegetation changes on a warmer planet may mean that giant pandas go hungry Image: Jeff Kubina via Wikimedia Commons

Vegetation changes on a warmer planet may mean that giant pandas go hungry
Image: Jeff Kubina via Wikimedia Commons

By Tim Radford

An international team of scientists says that by the end of the century one probable consequence of climate change will be a change in patterns of vegetation over much of the planet’s land surface.

LONDON, 16 February – By 2100, vegetation patterns will be shifting in almost half the land area of the planet, according to new research in the journal Global and Planetary Change.

Song Feng of the University of Arkansas in the US and colleagues in Nebraska, China and South Korea have taken a long cool look at what the projected patterns of warming are likely to do to the planet’s mosaic of climate types. And they predict dramatic changes.

Climate type is a century-old idea useful for making sense of geographical zones: regions are grouped according to the type of vegetation they support. Since a global map of native vegetation types can also deliver useful information about altitude, rainfall, soil type, prevailing weather and latitude, geographers regard the Köppen-Geiger classification – and an updated version known as Köppen-Trewartha – as a helpful way of describing the world.

Feng and his colleagues decided to see what projected changes in temperature would do to climate types. He wasn’t the first to do so; scientists from the US National Oceanic and Atmospheric Administration reported in 2013 in Nature Climate Change on the probable speed of change in such zones.

But science advances by challenge and replication, and the Arkansas team began looking for themselves at the details of simulated change under the notorious “business as usual scenario”  – the one in which global fossil fuel use continues to increase and higher levels of carbon dioxide and other greenhouse gases concentrate in the atmosphere.

The Intergovernmental Panel on Climate Change has made a series of predictions of rising global average temperatures, but plants, of course, don’t care about global average temperatures: they are however distinctly vulnerable to local extremes of frost and heat.

The Feng scenario projected an increase of between 3°C and 10°C; the team analysed observations made between 1900 and 2010, and then ran computer simulations from 1900 to 2100.

Drastic changes ahead

In the last three decades of the 21st century, for instance, northern winter temperatures are likely to rise by between 3° and 12°C; Arctic coastal temperatures are likely to rise by 8°C; warming in mid-latitudes is likely to be between 5°C and 7°C, the tropics and the southern hemisphere around 5°C.

The Arctic will shrink. Sub-polar vegetation is expected to advance by 5° of latitude and the temperate zones will push northwards too. Arid and semi-arid climate zones are expected to expand by somewhere between 3.3 and 6.6 million square kilometers in the last three decades of this century.

What this does to native vegetation types is hard to predict in detail but some projections have been made. In the Qinling mountain region of China, for instance, somewhere between 80% and 100% of the bamboo forests on which the giant pandas depend could disappear, because the rising temperature would be “no longer feasible for bamboo growth.”

In the south-western US higher temperatures and drier conditions could lead to more forest fires, and pest outbreaks could lead to changes in forest structure and composition.

As the plants change, the animal species that evolved with the vegetation types could be increasingly at risk. Altogether, up to 46.3% of the planet’s land area could shift to warmer or drier climate types

“Climates are associated with certain types of vegetation. If the surface continues to get warmer, certain native species may no longer grow well in their climate, especially in higher latitudes. They will give their territory to other species. That is the most likely scenario”, said Feng. – Climate News Network

Cat litter killer in the whales of the North

February 14, 2014 in Adaptation, Arctic, Atlantic, Disease, Ice Loss, Indigenous peoples, Marine ecology, Ocean Warming, Polar ice, Wildlife

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Blissful domesticity: But even domestic cats can spread Toxoplasma gondii

Blissful domesticity: But even domestic cats can spread Toxoplasma gondii

By Tim Radford

One consequence of a warming climate is new patterns of disease, and researchers have identified two parasites formerly unknown in the Arctic in marine mammals.

CHICAGO, 14 February – The great Arctic thaw – up to 50% of sea ice by area and 75% by volume in the summer season – could be offering new opportunities for one of the planet’s most successful parasites. Toxoplasma gondii, an infection spread by almost all cat species, has been identified for the first time in the western Arctic Beluga whale.

Toxoplasma is found almost everywhere that cats settle: domestic pets, ocelots, cougar, wild cats all carry and spread oocysts of the parasite (structures it uses to transfer to new hosts) in their faeces, to be spread further with discarded cat litter.

The parasite is notoriously hard to kill. Scientists store their samples in sulphuric acid, and the creature can survive unharmed in bleach. It is, however, routinely killed by freezing conditions, or boiling water.

The suspicion is that with the steady, sustained warming of the Arctic over the past 30 years, chiefly because of a buildup of carbon dioxide in the atmosphere, the retreat of the ice has begun to allow new traffic in parasite infections.

Another parasitic killer, a new strain called Sarcocystis pinnipedi, normally found only in the highest, iciest latitudes, has been linked with mass deaths too: 406 grey seals died in 2012 in the north Atlantic. It has also been observed to kill Steller’s sea lions, Hawaiian monk seals, walruses, grizzly bears and polar bears as far south as British Columbia.

In the case of Toxoplasma, warming polar summers could have created conditions in which the parasite could find new warm-blooded hosts further north. In the case of the second parasite, the loss of ice has meant a greater mixing of species, and allowed Sarcocystis to find new hosts in warmer waters.

Cause of blindness

“Ice is a major barrier for pathogens”, Michael Grigg, of the US National Institutes of Health told the American Association for the Advancement of Science annual meeting here. “What we are seeing with the big thaw is the liberation of pathogens gaining access to vulnerable new hosts and wreaking havoc.”

Toxoplasma can also infect people: it is the leading cause of infectious blindness in humans, and can be dangerous to unborn children and to people with compromised immunity.

It has been found in human communities in northern Quebec, perhaps spread by the consumption of dried seal meat. The discovery of Toxoplasma in Beluga whales has begun to worry health officials. Belugas are part of the traditional diet of the Inuit hunters of the far North.

Seals, walruses and polar bears are all what scientists like to call “ice obligate animals”: the ice sheet provides them with their preferred habitat. With the loss of the ice, new species are colonizing the Arctic, and those creatures that cannot now use the ice sheet have been forced to invade new habitats.

“Marine mammals can act as ecosystem sentinels because they respond to climate change through shifts in distribution, timing of their movements and feeding locations”, said Sue Moore of the US National Oceanic and Atmospheric Administration. “These long-lived mammals also reflect changes to the ecosystem in their shifts in diet, body condition and physical health.” – Climate News Network

Equatorial fish feel the heat

February 12, 2014 in Adaptation, Fish, Food security, Indonesia, Marine ecology, Ocean Warming, Warming, Wildlife

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Weaving through the coral: Small fish like these are important sources of food for larger reef species Image: D. Dixson

Weaving through the coral: Small fish like these are important sources of food for larger reef species
Image: D. Dixson

By Alex Kirby

Many species of fish living near the Equator are sensitive to variations in heat and will not thrive in the warmer oceans of the future, scientists in Australia have found.

LONDON, 12 February – Lying in a hot bath may be a pleasant experience, because you can always get out when you’ve had enough. For some of the fish that swim in equatorial seas, though, that is not an option: climate change threatens to make the water not just uncomfortable, but unendurable.

An international team of researchers based in Australia reports in Global Change Biology that the rapid pace of climate change is threatening the future of some of the fish which live near the Equator.

Over a 14-day period the team tested four species of damsel fish and two of cardinal fish. They say: “Our results indicate that low-latitude reef fish populations are living close to their thermal optima and may be more sensitive to ocean warming than higher-latitude populations.”

“Our studies found that one species of fish could not even survive in water just 3°C warmer than it lives in now”, says the lead author of the study, Dr Jodie Rummer from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University in Queensland.

Dr Rummer and her colleagues studied six common species living on coral reefs near the Equator. She says many species in this region experience only a very narrow range of temperatures throughout their lives, and so are probably adapted to perform best at those temperatures.

The world’s oceans are projected to warm by 2-3°C by the end of this century. “Such an increase in warming leads to a loss of performance”, Dr Rummer said. “Already, we found four species of fish are living at or above the temperatures at which they function best.”

Breeding compromised

The team measured the rates at which fish use oxygen across different temperatures – at rest and during maximal performance. The results showed that in warmer water fish lose their ability to perform properly. In the wild this would limit activities crucial to survival, such as evading predators, finding food, and finding the energy to breed.

With many of the Earth’s equatorial wild populations now living close to their thermal limits, there will be serious consequences if some – like the fish the researchers studied – cannot adapt to the speed at which the oceans are warming.

The response of many species to increasing warmth is to migrate to somewhere that suits them better, which could help to drain the equatorial oceans of fish which play a key role there. Dr Rummer suggests there will be declines in fish populations as species move away from the Equator to find refuge in areas with more agreeable temperatures.

“This will have a substantial impact on the human societies that depend on these fish,” she says. Many developing countries are in the equatorial zone, and fish are central to the livelihoods and survival of millions of people, including many in Indonesia and south-east Asia.

With rapid climate change, the scientists say, understanding the link between an organism and its environment is crucial to developing management strategies to conserve biodiversity and to allow the sustainable use of marine fisheries. This is especially urgent for ensuring food security for people. – Climate News Network

Woodman, spare that tree!

January 26, 2014 in Carbon Dioxide, Forests, Vegetation changes

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By Tim Radford

It may seem unlikely, but an international team of researchers has found that most large trees keep absorbing atmospheric carbon dioxide even in old age.

LONDON, 26 January – Giant trees could play a giant role in fixing carbon dioxide from the atmosphere. This counter-intuitive discovery – surely, young faster-growing trees would be more efficient at soaking up carbon?  – emerges from a study of more than 403 species by a consortium of 38 scientists in 16 countries who report in Nature.

Nathan Stephenson of the US Geological Survey and his 37 colleagues between them studied data collected from more than 650,000 individual trees on six continents over a span of 80 years to show that the world’s oldest trees actually grow more quickly, and also accumulate carbon more rapidly than younger, smaller trees.

Some trees are known to reach vast heights and masses. But acknowledged giants such as the Australian mountain ash Eucalyptus regnans and the coastal redwood Sequoia sempervirens are not just lonely examples of spectacular weight gain.

The researchers observed continuing gains in 97% of the trees surveyed. “Rapid growth in giant trees is the global norm and can exceed 600 kg per year in the largest individuals”, they reported.

“In human terms it is as if our growth just keeps accelerating after adolescence, instead of slowing down”, Stephenson said. “By that measure, humans would weight half a ton by middle age and well over a ton by retirement.”

Continued utility

The research matters for three reasons. The first is that it is a tribute to the power of patient data collection over decades: much of it by amateur naturalists and natural history and conservation groups.

The second is that it adds significantly to the chances of making more complete sense of the great carbon conundrum – where, when carbon disappears from the atmosphere, does it go, and how long does it stay there?

A large western white pine in California: Trees as large and old as this will still absorn CO2 from the atmosphere Image: Dcrjsr via Wikimedia Commons

A large western white pine in California: Trees as large and old as this will still absorn CO2 from the atmosphere
Image: Dcrjsr via Wikimedia Commons

And the third is that it helps resolve the open question of whether established forests can continue to serve as reservoirs of atmospheric carbon. In August, researchers published a study in Nature Climate Change that suggested that Europe’s forests, for instance, might have reached saturation point.

Previous studies have tended to measure forest growth at the level of the leaf, and the level of the forest as a whole. Stephenson and his colleagues considered the tree as the agency that mattered most, and observed a different outcome.

They calculated that a single large, old tree could add as much carbon to the forest in one year as was contained in an entire middle-sized tree. Even though individual leaf level productivity declined with age, the tree’s total leaf area increased to outpace this decline.

More questions

So even though each leaf might be less efficient at absorbing carbon, the tree kept on growing because it was bigger and therefore had more leaves with which to soak up nourishment from the atmosphere.

It’s a question of scale: in the language of mathematics, total tree leaf mass increases as the square of trunk diameter. So a tree that makes a tenfold increase in diameter will make a 100-fold increase in leaf mass, and at least a 50-fold increase in total leaf area.

To put it another way, in old western US forests, individuals more than a metre across comprised 6% of the tree population, but contributed 33% of the annual forest growth in terms of mass.

But, as usual, such research raises more questions that must be settled. The authors themselves warn that what is true for individual trees might not hold for stands of trees in a block of woodland. As trees age, some will die, leaving fewer individuals occupying an area of forest, and therefore possibly less carbon overall.

“Our results are relevant to understanding and predicting forest feedbacks to the terrestrial carbon cycle and global climate system”, the authors write. – Climate News Network

Be small, stay cool, forget the climate

January 25, 2014 in Adaptation, Temperature Increase, USA, Wildlife

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Moose are one of the large species likely to feel more stress in a warming world than smaller creatures Image: Hagerty Ryan, US Fish & Wildlife Service, via Wikimedia Commons

Moose are one of the large species likely to feel more stress in a warming world than smaller creatures
Image: Hagerty Ryan, US Fish & Wildlife Service, via Wikimedia Commons

By Tim Radford

Climate change is not affecting all species equally, US researchers say. The smaller the species, the less stress they are likely to feel than their bigger cousins.

LONDON, 25 January – When it comes to climate change, small could be beautiful. Christy McCain of the University of Colorado Boulder looked at more than 1,000 scientific studies of mammalian behaviour and responses to climate change in North America and came to one big conclusion: bigger animals are more likely to experience stress than the smaller ones. A tiny shrew in the American forests was 27 times less likely to respond to climate change than a moose not far away.

She settled on 140 scientific papers that contained population responses from 73 North American mammal species, and examined a number of observations that could be called a response. Was there some sort of local extinction? Did the creature’s range contract, did it shift, did the species numbers increase? Did seasonal behaviour betray any change? Was there any variation in body size? Or in genetic diversity?

She and her colleague Sarah King report in Global Change Biology that only about half of the mammals responded as expected to climate change; 7% did the opposite of what might be expected and the remaining 41% betrayed no response. Those characteristics that indicated a response to climate change were large body size and restricted times in the day when a mammal might be active.

Tailored conservation

Almost all the large mammals responded negatively to the gradual warming and seasonal shifts of recent decades. Mammals active only in the daylight, or only at night, were twice as likely to respond as mammals that had a more flexible approach to time-keeping.

Mammals in the high latitudes, or at high elevation ranges – polar bears in the first case, American pikas and shadow chipmunks in the second – were also more likely to be in some way affected than those further south or further downhill. Small mammals however seemed to be able to exploit a wider range of micro-climates – shady patches, burrows and so on – to shelter from the effects of climate change.

“Overall the study suggests our large charismatic fauna – animals like foxes, elk, reindeer and bighorn sheep – may be more at risk from climate change”, said Dr McCain. “If we can determine which mammals are responding to climate change and the ones that are at risk of disappearing, then we can tailor conservation efforts toward those individual species.” – Climate News Network

Few would welcome geo-engineering

January 17, 2014 in Adaptation, Australia, Geoengineering, Human response, New Zealand, Technology

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Simplest is often best: Biochar, made from vegetable matter, arouses fewer objections Image: K.salo.85 via Wikimedia Commons

Simplest is often best: Biochar, made from vegetable matter, arouses fewer objections
Image: K.salo.85 via Wikimedia Commons

By Tim Radford

Trying to avert dangerously high global temperatures by modifying the climate – geo-engineering – may or may not be possible. It certainly won’t be popular, researchers say.

LONDON, 17 January – Geo-engineering – the frustrated climate scientist’s last-ditch solution to global warming – is not likely to be a very popular choice. Members of the public have “a negative view” of deliberate large-scale manipulation of the environment to counteract climate change, according to new research in Nature Climate Change.

Geo-engineering has been repeatedly proposed as a response to the steady build-up of carbon dioxide in the atmosphere, and increasingly cited as a potential necessity as global emissions from fossil fuels have continued to increase. If political action fails, some scientists reason, then perhaps technology could stop global average temperatures from getting too high.

Among these options is the injection of aerosols into the stratosphere to block or dim the sunlight, or the release of reflecting devices in Earth orbit to actually reflect sunlight away from the planet, on the principle that if you can’t turn down the atmospheric temperature, you could at least put up a sunscreen to cool the planet a little.

Such ideas have failed to find universal favour in the scientific community, if only because such action could seriously upset rainfall patterns and trigger disaster in the arid parts of Africa.

Consistent reluctance

But until now, nobody has seriously put the question to the public. Ordinary people don’t like the idea, say Malcolm Wright and Pamela Feetham of Massey University in New Zealand, and Damon Teagle of the University of Southampton, UK.

They consulted large samples of opinion in both Australia and New Zealand, and found “remarkably consistent” responses from both countries, “with surprisingly few variations except for a slight tendency for older respondents to view climate engineering more favourably,” says Pamela Feetham.

The trio report in Nature Climate Change that where there had been engagement with the public, this had been “exploratory, small-scale, or technique-specific.” So the researchers tried another approach, one used by big corporations to evaluate marketing brands. Such approaches use psychological techniques to find out what people associate with different ideas, and have done so successfully for two decades.

The researchers systematically examined and compared in a controlled fashion the public reaction to six potential climate engineering techniques, among them, for instance, robot ships that would spray seawater droplets over the ocean to reflect sunlight – it’s called cloud brightening – and air capture, the design of structures to filter CO2 from the air.

Charcoal is popular

They found that people were not in favour of deflecting or blocking sunlight, but were more likely to have positive reactions to techniques that might reduce carbon dioxide levels.

“It was a striking result and a very clear pattern”, said Professor Wright. “Interventions such as putting mirrors in space or fine particles in the stratosphere are not well received. More natural processes of cloud brightening or enhanced weathering are less likely to raise objections, but the public react best to creating biochar (making charcoal from vegetation to lock in CO2) or capturing carbon directly from the air.”

The message is that if scientists want to save the planet by climate engineering, they had better ask around first. “If these techniques are developed the public must be consulted”, said Professor Wright.

“Our methods can be employed to evaluate the responses in other countries and reapplied in the future to measure how public opinion changes as these potential new techniques are discussed and developed.” – Climate News Network