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More CO2 limits plants’ protein output

April 12, 2014 in Agriculture, Carbon Dioxide, Soil, Uncategorized, Vegetation changes, Warming

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The Mojave desert: As CO2levels rose, it took up unexpectedly large amountsofthe gas Image: Rennett Stowe via Wikimedia Commons

The Mojave desert: As CO2 levels rose, it took up unexpectedly large amounts of the gas
Image: Rennett Stowe via Wikimedia Commons

By Tim Radford

With increasing warmth drying more of the Earth, arid soils may absorb more carbon dioxide – but that in turn is likely to limit protein production.

LONDON, 12 April – As global temperatures rise, more than one third of the land surface may become more arid. Although there will be changes in rainfall patterns, heat – and the attendant evaporation of the soil – could extend ever drier conditions to more and more farmland and cities, according to research in the journal Climate Dynamics.

The new study – which excludes Antarctica – is led by Benjamin Cook, a climate scientist both with the University of Columbia’s Lamont-Doherty Earth Observatory and the US space agency Nasa. It is based on climate simulation, and forecasts that 12% of the land surface will be subjected to drought by 2100 just through changes in rainfall. Throw in the increased heat, though, and the drying effect will be spread to 30% of the land.

Even those regions that might be expected to get more rain will be at greater risk of drought. This would be very bad news for the wheat, corn and rice belts of the south-western US and south-eastern China.

“For agriculture, moisture in the soil is what really matters,” said Cook’s co-author, Jason Smerdon. The research confirms previous studies, and the more recent warnings from the Intergovernmental Panel on Climate Change, and other studies, have predicted that extremes of temperature will be bad news for farmers anyway, with yields  likely to be affected.

But nothing in climate research is simple. The extra warming will be a direct consequence of ever-higher levels of carbon dioxide in the atmosphere. A study in Nature Climate Change has just revealed that arid zones offer an unexpected source of what engineers call negative feedback.

Carbon sink

A 10-year experiment in the Mojave desert in the US has shown that as carbon dioxide levels increase, arid areas take up unexpectedly large amounts of the gas.

“They are a major sink for atmospheric carbon dioxide, so as CO2 levels go up, they’ll increase their uptake of CO2 from the atmosphere. They’ll help take up some of that excess CO2 going into the atmosphere. They can’t take it all up, but they’ll help,” says Dave Evans, a biologist at Washington State University.

All land surfaces absorb some carbon. Until now, most attention has been paid to the role of forests as major “sinks” of carbon. But the US experimenters marked out nine octagonal plots of the desert and blew air with current levels of CO2 over three of them, and air with 550 parts per million of CO2, the expected level by 2050, over another three. Three received no extra air at all.

Then the researchers excavated the soils to a depth of a metre to measure the absorbed carbon and were surprised by the gain in carbon during a relatively short exposure in the plots exposed to the extra carbon dioxide.

Arid and semi-arid soils account for a large proportion of the planet’s land surface: overall, they could increase carbon uptake to account for between 15% and 28% of the amount currently being absorbed by land surfaces.

Less protein

This sounds like good news, on balance. It may not be, as far as food supplies are concerned. In the same issue of Nature Climate Change a second study reports on experiments into the effects of elevated levels of carbon dioxide on wheat.

Carbon dioxide is seen as a fertiliser of plants and indeed, without it, there would be no plants. But Arnold Bloom, a plant scientist at the University of California Davis reports that, according to his experiments, elevated levels of carbon dioxide also inhibit the conversion of nitrate into protein in crops.

Wheat provides nearly one fourth of all protein in the global human diet. Other studies have shown the same effect with wheat – and also with rice, barley and potato tubers.

“When this decline is factored into the respective portion of dietary protein that humans derive from these various crops, it becomes clear that the overall protein available for human consumption may drop by about three per cent as atmospheric carbon dioxide reaches the levels anticipated to occur during the next few decades,” Bloom said. – Climate News Network

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

Warmer winters will limit Olympic snow

March 22, 2014 in Greenhouse Gases, Temperature Increase, Warming

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Is Sochi, home of the 2014 Winter Olympics, now on the skids? Few host cities look likely to survive Image: By Lite via Wikimedia Cpmmons

Is Sochi, home of the 2014 Winter Olympics, now on the skids? Few host cities look likely to survive
Image: By Lite via Wikimedia Cpmmons

By Tim Radford

Only one in three of the cities which have staged the Winter Olympics in the last 90 years is likely to be cold enough to do so as this century draws to its end.

LONDON, 22 March – The future looks cloudy for the Winter Olympics. If the world keeps on burning fossil fuels in the usual way, then of the 19 cities that have staged the event since 1924, only six are likely have enough natural snow and ice by the 2080s.

Daniel Scott, a geographer at the University of Waterloo in Canada and colleagues from Ontario and Innsbruck, Austria report in the journal Current Issues in Tourism that, on average, daytime temperatures in February at the Games sites between 1924 and 1950 were 0°4C. During the 21st century, this had changed dramatically. The average daytime maximum temperatures had reached 7.8°C.

“There are limits to what current weather risk management strategies can cope with. These limits will be increasingly tested in a warmer world,” the authors write.

The Olympic Winter Games are big business. In 1924 there were 250 amateurs from 16 countries competing in 16 medal events. In 2010 in Vancouver, Canada there were 2,500 athletes – amateur and professional – from 82 countries competing in 86 events.

High stakes

Around 1.5 million spectator tickets were sold in Vancouver, and worldwide media broadcast revenues were more than $1.2 billion. Broadcasts reached 200 nations and a potential audience of 3.8 billion. So the Games are now a big tourist attraction, and at the same time a spectacular showcase for the host country as a future destination for pleasure-seekers.

But, say the researchers, it now looks as though artificial snow technology could become more important than ever, and some places that invested heavily in Olympic facilities will become increasingly marginal, high-risk or downright unreliable.

The authors did three things. They considered the pattern of change over the last 90 years. They analysed the minimum requirements in temperature, weather and snowfall for a games venue. And then they considered the likely warming of the next 80 years in two scenarios – one with low greenhouse gas emissions, and one under the notorious “business-as-usual” scenario.

Games planners ideally need the following: daytime maximum temperatures no higher than 10°C in February and minimums of 0°C or below (so that the slush can freeze again); as little rain as possible (because that’s really bad for snow and discouraging for spectators); natural snow deep enough for alpine and cross country skiing; and overall temperature conditions that would make artificial snowmaking possible if the natural snowfall is not enough.

Few candidates left

They distilled all these to two basic requirements: a reliable daily minimum of 0°C and 30 cms of natural snow on the hillsides. And then they checked all these against the predictions for 19 cities and resorts around the world that have already staged the games and watched the candidates eliminate themselves.

Chamonix in France, home of the first-ever games, and a famous winter playground for more than a century, becomes “high-risk/marginal” by mid-century and, under the high emissions scenario, simply “unreliable” by 2080.

The same is true for Grenoble in France, Oslo in Norway and Sarajevo in Bosnia-Herzegovina. Vancouver becomes not reliable under the high emissions scenario by 2050, and thereafter under all cases. Garmisch-Partenkirchen in Germany and Sochi in Russia, home of the 2014 games, become not reliable under all scenarios. By 2050, only 10 places will still be suitable, with reliable snow and ice. By 2080, this total will be down to six

That raises some big questions: what future is there for winter sports? Will new winter sports powers and regions emerge? Could anyone ever devise truly artificial snow – stuff that would not depend on the temperature? In a substantially warmer world, celebrating the second centennial of the Olympic Winter Games in 2124 would become “increasingly challenging,” the researchers say. – Climate News Network

Warmer freshwater emits more methane

March 20, 2014 in Greenhouse Gases, Methane, Warming, Water, Wetlands

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Swamps, marshes, rice paddies and all freshwater ecosystems are sources of methane Image: By vastateparksstaff (Uploaded by AlbertHerring) via Wikimedia Commons

Swamps, marshes, rice paddies and other freshwater ecosystems are sources of methane
Image: By vastateparksstaff (Uploaded by AlbertHerring) via Wikimedia Commons

By Tim Radford

Scientists think the amount of methane emitted to the atmosphere from freshwater ecosystems will increase as the climate warms, triggering further warming.

LONDON, 20 March – British scientists have identified yet another twist to the threat of global warming. Any further rises in temperature are likely to accelerate the release of methane from rivers, lakes, deltas, bogs, swamps, marshlands and rice paddy fields.

Methane or natural gas is a greenhouse gas. Weight for weight, it is more than 20 times more potent than carbon dioxide over a century, and researchers have repeatedly examined the contribution of natural gas emitted by ruminant cattle to global warming. But Gabriel Yvon-Durocher of the University of Exeter and colleagues considered something wider: the pattern of response to temperature in those natural ecosystems that are home to microbes that release methane.

They report in Nature that they looked at data from hundreds of field surveys and laboratory experiments to explore the speed at which the flow of methane increased with temperature.

Microbes, algae, freshwater plants and animals are all part of an active ecosystem and take their nourishment from and return waste to the atmosphere. Healthy plants take carbon dioxide from the atmosphere with photosynthesis. Most of the methane in freshwater systems is produced by an important group of microbes called Archaea that live in waterlogged, oxygen-free sediments and play an important role in decay.

Plant uptake of carbon dioxide is affected by temperature, and so is microbial methane production. Respiration also releases carbon dioxide. The questions the researchers set out to answer were: which gas is more likely to be released in greater quantities as temperatures rise? And is the outcome the same whether they examine the Archaea only, or all the microbes in an ecosystem, or the entire package of submerged freshwater life?

More heat, more methane

The answer is, the scientists say, that methane emissions go up with the mercury, and that the ratio of methane to carbon dioxide also goes up in step with temperature. And the result is the same whether you consider the microbes or the whole ecosystem.

“The discovery that methane fluxes are much more responsive to temperature than the processes that produce and consume carbon dioxide highlights another mechanism by which the global carbon cycle may serve to accelerate rather than mitigate future climate change,” says Dr Yvon-Durocher.

This is not the end of the story. All such studies raise as many questions as they answer, and more research is necessary. The next puzzle is how to fit such findings into models of climate change. However, the researchers feel they have cleared up one point. Dr Yvon-Durocher says:

“Our research provides scientists with an important clue about the mechanisms that may control the response of methane emissions from ecosystems to global warming.” – Climate News Network

Europe’s flood risk may double by 2050

March 2, 2014 in Europe, European Union, Extreme weather, Flooding, Weather Systems

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Floods submerge St Mark's Square in Venice: The prospect is for worse to come Image: Wolfgang Moroder via Wikimedia Commons

Floods submerge St Mark’s Square in Venice: The prospect is for worse to come
Image: Wolfgang Moroder via Wikimedia Commons

By Tim Radford

As much of Europe recovers from the severest winter in several centuries, scientists say average annual flood losses could be almost five times greater by mid-century.

LONDON, 2 March – The catastrophic floods that soaked Europe last summer and the United Kingdom this winter are part of the pattern of things to come. According to a new study of flood risk in Nature Climate Change annual average losses from extreme floods in Europe could increase fivefold by 2050. And the frequency of destructive floods could almost double in that period.

About two thirds of the losses to come could be explained by socio-economic growth, according to a team led by Brenden Jongman of the University of Amsterdam in the Netherlands and Stefan Hochrainer-Stigler of theInternational Institute for Applied Systems Analysis in Austria.

That is because more development and investment means there is more at risk from any flooding. But the other third of the increase will be delivered by climate change, and a shift in rainfall patterns in Europe.

From 2000 to 2012, floods in European Union countries averaged €4.9 billion (US $6.8 bn) a year in losses. In the floods of June 2013, losses tipped €12 bn (US $16.6 bn) in nine countries of Central and Eastern Europe. The annual average losses could increase to €23.5 bn (US $32.4 bn) by 2050.

Unprecedented floods like those of 2013 occur on average once every 16 years now. By 2050, the probability will have increased to once every 10 years.

Floods widespread

The team looked at monthly peak river discharges in more than 1,000 river sub-basins to begin making their estimates: they also matched these peak flows with atmospheric circulation patterns. The point of the study was to deliver more accurate information.

“We brought together expertise from the fields of hydrology, economics, mathematics and climate change adaptation, allowing us for the first time to comprehensively assess continental flood risk and compare the different adaptation options,” said Brenden Jongman.

And Dr Hochrainer-Stigler said the new study for the first time accounted for the correlation between floods in different countries. Risk-assessment models tended to consider river basins as independent entities. “But in actuality, river flows across Europe are closely correlated, rising and falling in response to large-scale atmospheric patterns that bring rains and dry spells to large regions.”

All of this points to greater strains on the pan-European Solidarity Fund that finances recovery from disaster within the European Union. “If the rivers are flooding in Central Europe, they are also likely to be flooding in eastern European regions,” he said. – 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

Geo-engineering ‘could mean more heat’

February 19, 2014 in Adaptation, Forecasting, Geoengineering, Technology, Temperature Increase

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Another way to cooling: Removing trees from snowy slopes would increase reflectivity Image: Thomas Maier via Wikimedia Commons

Another way to cooling: Removing trees from snowy slopes would increase reflectivity
Image: Thomas Maier via Wikimedia Commons

By Tim Radford

Finding a technology that would let us counteract the effects of climate change is a cherished dream. But if there is a cure, it could be worse than the disease, scientists say.

LONDON, 19 February – The geo-engineers just cannot win, it seems. First, scientists demonstrated that ambitious plans to cool the planet by dimming solar radiation could have unintended and unwelcome consequences. And now they have shown something even more alarming: any programme to block the sunlight could precipitate even more dramatic global warming once it stopped, according to Environmental Research Letters.

Geo-engineering as a fallback strategy has been on the climate science agenda for decades. Almost all climate researchers argue, and have argued for 30 years, that the most effective response to global warming and the threat of climate change is a drastic reduction in the use of fossil fuel, everywhere on the planet.

Although many governments have agreed, and have even introduced attempts to control greenhouse gas emissions, levels of carbon dioxide and other greenhouse gases keep rising.

So researchers have suggested other possible solutions: “artificial trees” to absorb atmospheric carbon dioxide; the fertilisation of the oceans to accelerate algal photosynthesis; and even the injection of sulphate particles into the stratosphere to block the incoming sunlight. Such things happen naturally, during occasional violent volcanic eruptions, and global cooling has been observed to follow.

This last deliberate technological response might create other kinds of unwelcome climate change, among which would be an alarming change in rainfall patterns, other scientists have argued.

But now Kelly McCusker of the University of Washington in the US and colleagues have proposed yet another reason for limiting discharges into the upper atmosphere. Whatever benefits might follow the technique known as solar radiation management or SRM would be wiped out once the management stopped.

Worse when you stop

Quite simply the technology could ultimately make climate change more dramatic and global warming more alarming. If solar radiation management techniques were applied for a few decades and then halted, global temperature increases would more than double. The consequential heat would be worse than that expected if the sun-block had never been applied at all.

All such research is conducted with computer simulations. There remains no practical way of modelling such an experiment in real time and in the real world on a pilot scale.

But climate simulations seem to accurately “hindcast” real climates of the last 50 years, and the bet is that therefore they can forecast with reasonable accuracy the climate patterns to come.

The University of Washington team modelled a future climate in which the world went on increasing the rate of emissions in such a way that global average temperatures were 1°C above the average for 1970-1999.

Then, in the same simulation, the hypothetical geo-engineers stepped in and kept on loading the upper atmosphere with sulphate particles for 25 years. And then, for some hypothetical political or economic reason, or some notional technological failure, the solar radiation management plan came to a sudden halt.

And at that point, the models showed, global average temperatures would rise steeply, by 4°C. Over the same time frame, without the sun-block experiment, global average temperatures would have risen only 2°C.

Penalising the poor

The new rate of temperature rise would be on average 1°C per decade, about six times faster than the average over the last 40 years. This sustained warming, the authors say, would be “well outside 20th century climate variability bounds.”

The researchers say the temperature changes would be greatest in winter in the high latitudes – this seems to be the same in all global warming scenarios – but even in the tropics in the summer, once the sun-block was abandoned, the changes would be pronounced.

This would hit the world’s poorest, who are concentrated in the tropics, and at the same time pose a threat to the world’s richest centres of biodiversity, once again in the tropics. There would be a pronounced increase in rain and snow fall, but half of all land areas would also experience an increase in aridity.

All this of course is based on a set of simulations, and these incorporate the assumption that the injection of sulphate particles into the upper atmosphere would be technically possible, economically feasible, and truly effective: none of this is for certain.

The research does not deliver an accurate picture of the future. But it certainly does not deliver any encouragement to believe that a “technological fix” could counter the consequences of the steady increase in greenhouse gas emissions in the atmosphere.

“The only way to avoid creating the risk of substantial temperature increases through SRM, therefore, is concurrent strong reductions of GHG emissions”, says McCusker. – Climate News Network

Cities’ twin heat problems face relief

February 15, 2014 in Population, Temperature Increase, Urban Heat

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A hot day in Beijing's Tiananmen Square: Cities are usually hotter than the countryside Image: Tactesh882 via Wikimedia Commons

A hot day in Beijing’s Tiananmen Square: Cities are usually hotter than the countryside
Image: Tactesh882 via Wikimedia Commons

By Tim Radford

Climate change aside, cities tend to be warmer than the surrounding ciuntryside. Now researchers in the US have found ways that may lessen the effects of both problems.

LONDON, 15 February – Even without global warming, atmospheric temperatures are likely to rise later in the century: the expansion of the cities will see to that.

Climate scientists and meteorologists long ago recognised the “heat island” effect created by the cities, and made sure routine measurements were not distorted by urban sprawl. But Matei Georgescu of Arizona State University and colleagues think that as populations grow, and cities begin to spread, temperatures will rise anyway.

So, they report in the Proceedings of the National Academy of Sciences, they have tested a few strategies to mitigate the rise of city temperatures and perhaps at the same time turn down the rate of rise in greenhouse temperatures as well.

The argument goes like this: roofs, paved roads, pipes, wiring, traffic, central heating and air conditioning, industry and commerce and other such urban trappings could raise temperatures by 1°C to 2°C.

And cities are certain to expand: the population of the US is expected to grow to somewhere between 422 million to 690 million by 2050, with up to 260,000 square kilometers of land newly covered by roofs and roads.

Winter problems

Global urban area is expected to grow by 185% by 2030; much of that will be in China and India. In that same time Africa could see the greatest proportional increase: African cities are expected to expand sixfold.

“Urban expansion within these areas will almost certainly be highly concentrated, exposing highly vulnerable populations to land use-driven climate change,” the authors say.

So the researchers started to think about some simple changes that could reduce urban temperatures. The first conclusion was that adaptations needed to be tailored to local climates and needs.

One simple answer is the “cool roof” – paint it white so it reflects the sunlight, and in California’s Central Valley, at least, the temperature levels fall. In other simulated environments, the measure didn’t work so well: reflective roofs lowered the temperature too well in winter, necessitating extra investment in heating fuels.

“Green” roofs, covered with turf or planted with transpiring foliage, were more effective in other urban climates: these highly transpiring structures did not compromise summertime energy savings by demanding additional energy in winter.

Horses for courses

With judicious planning and careful choice of design, it could be possible not only to counteract urban growth temperature increases but even offset the effect of greenhouse gas warming as well, not just over the cities, but beyond the cities as well.

But there was no simple, one-size-fits-all answer. Geography played an important role in any such calculations.

The study delivered unexpected results. In Florida, the team’s simulations significantly reduced rainfall, a result that would have implications for water supply and local ecosystems.

“For Florida, cool roofs may not be the optimal way to battle the urban heat island because of these unintended consequences,” Georgescu said.

“We simply wanted to get all these technologies on a level playing field and draw out the issues associated with each one, across place and across time.” - 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