Tuesday, December 1, 2009

Oceans Absorb Less Carbon Dioxide as Marine Systems Change

From: Ben Block, Worldwatch Institute, More from this Affiliate

The oceans are by far the largest carbon sink in the world. Some 93 percent of carbon dioxide is stored in algae, vegetation, and coral under the sea. But oceans are not able to absorb all of the carbon dioxide

released from the burning of fossil fuels. In fact, a recent study suggests that the oceans have absorbed a smaller proportion of fossil-fuel emissions, nearly 10 percent less, since 2000.

The study, published in the current issue of Nature, is the first to quantify the perceived trend that oceans are becoming less efficient carbon sinks. The study team, led by Columbia University oceanographer Samar Khatiwala, measured the amount of human-caused carbon dioxide emissions pumped into the oceans since 1765.

Industrial carbon dioxide emissions have increased dramatically since the 1950s, and oceans have until recently been able to absorb the greater amounts of emissions. Sometime after 2000, however, the rise in emissions and the oceans' carbon uptake decoupled. Oceans continue to absorb more carbon, but the pace appears to have slowed.

The reason is based in part on simple chemistry. Increased concentrations of carbon dioxide have turned waters more acidic, especially nearer to the poles. While carbon dioxide dissolves more readily in cold, dense seawater, these waters are less capable of sequestering the gas as the ocean becomes more acidic. The study revealed that the Southern Ocean, near Antarctica, absorbs about 40 percent of the carbon in oceans.

Article continues: http://www.worldwatch.org/node/6323

Global Salmon Study Shows 'Sustainable' Food May Not Be So Sustainable

From: Science Daily

Popular thinking about how to improve food systems for the better often misses the point, according to the results of a three-year global study of salmon production systems. Rather than pushing for organic or land-based production, or worrying about simple metrics such as "food miles," the study finds that the world can achieve greater environmental

benefits by focusing on improvements to key aspects of production and distribution.

For example, what farmed salmon are fed, how wild salmon are caught and the choice to buy frozen over fresh matters more than organic vs. conventional or wild vs. farmed when considering global scale environmental impacts such as climate change, ozone depletion, loss of critical habitat, and ocean acidification.

he study is the world's first comprehensive global-scale look at a major food commodity from a full life cycle perspective, and the researchers examined everything -- how salmon are caught in the wild, what they're fed when farmed, how they're transported, how they're consumed, and how all of this contributes to both environmental degradation and socioeconomic benefits.

Article continues: http://www.sciencedaily.com/releases/2009/11/091124152803.htm

Friday, September 4, 2009

Ribbon Seal Protection Sought by Activists

From: Dan Joling, AP via Discovery News

Ribbon seals should be listed as threatened or endangered because global warming is quickly melting sea ice, which the seals depend on for several months each year, two environmental groups said in a lawsuit filed against the federal government in San Francisco Thursday.

The National Oceanic and Atmospheric Administration in December denied a listing under the Endangered Species Act for the seals found off the coasts of Alaska and Russia.

The Center for Biological Diversity and Greenpeace sued in U.S. District Court, claiming the agency ignored the best science available on global warming.

Article continues

Climate-change technology risks 'catastrophic' outcome

Risky and unproven climate-changing technologies could have "catastrophic consequences" for the earth and humankind if used irresponsibly, according to a new report.

Yet without drastic further cuts in carbon dioxide emissions, a geoengineering solution may offer the only hope of saving the world from disastrous run-away global warming, experts warned.

A report by the Royal Society, Britain's leading academic institution, looks at the feasibility and potential dangers of technologies designed to cool the earth.

They include artificial "trees" that suck carbon dioxide out of the air, and spraying sulphate particles high in the atmosphere to scatter the sun's rays into space. The scientists concluded that, although some approaches were possible, they had not yet been properly researched and posed serious potential dangers for the planet.

Professor John Shepherd, who chaired the Royal Society geoengineering working group, said: "It is an unpalatable truth that unless we can succeed in greatly reducing carbon dioxide emissions we are heading for a very uncomfortable and challenging climate future, and geoengineering will be the only option left to limit further temperature increases."

"Our research found that some geoengineering techniques could have serious unintended and detrimental effects on many people and ecosystems — yet we are still failing to take the only action that will prevent us from having to rely on them."

Article continues: http://www.birminghampost.net/birmingham-business/birmingham-business-news/other-uk-business/2009/09/01/climate-change-technology-risks-catastrophic-outcome-report-65233-24585797/

Schwarzenegger to Obama cabinet: Water... please!

From: Peter Henderson, Reuters

Schwarzenegger to Obama cabinet: Water... please!

SAN FRANCISCO (Reuters) - California Governor Arnold Schwarzenegger has demanded that President Barack Obama's cabinet rethink federal policy that would divert water from parched farms and cities to threatened fish, his administration said on Wednesday.

California's rivers used to brim with salmon and sturgeon, but a massive system of canals diverted water that fed farms and cities, now suffering through a third year of drought.

Schwarzenegger has gained credibility as an environmentalist for his push to curb greenhouse gases but he argued that federal plans to save fish will worsen a water crisis that has cost farmers more than $700 million and caused mandatory rationing in cities of the most populous state.

Article continues

Abrupt reversal detected in Arctic cooling trend

David Perlman, Chronicle Science Editor

The Arctic climate has been warmer over the past decade than during any 10-year period in 2,000 years, according to a study by an international research team that adds powerful new evidence that human-generated greenhouse gases have speeded the pace of the planet's recent warming.



The report from an international team of climate scientists concludes that climate change in the Arctic has accelerated since the Industrial Revolution, abruptly reversing a long-term worldwide cooling trend.

"The study provides a clear example of how increased greenhouse gases are now changing our climate," said Caspar Ammann of the National Center for Atmospheric Research in Boulder, Colo., a co-author of the report published Thursday in the journal Science.

To deduce the Arctic's decade-by-decade climate trend over the centuries, the leading scientists in the international study analyzed sediment cores in 14 Arctic lakes that revealed the varied growth rates of long-buried plants. They also studied Arctic tree rings to determine their growth rates and ages as well as ice cores from glaciers across the Arctic that showed patterns of relative warm and cold.

Researchers at other institutions, seeking to look for patterns of climate change even further back in time, used astronomical records to study the well-known wobble of the globe as it spins on its axis. They found that the Northern Hemisphere has long been moving away from the sun's warmth. During the summer solstice, the Northern Hemisphere is now a million kilometers - about 621,000 miles - farther away from the sun than it was 2,000 years ago, according to the scientist's computer models.

The result was a global period of relative cold that would have continued, the scientists found. But about 1850, at the beginning of the Industrial Age, the planet's climate began overcoming the cooling trend, and the Arctic climate has warmed decade by decade ever since as greenhouse gas emissions have increased, the scientists say.

Stephen Schneider, a Stanford climate expert and biologist who did not participate in the study, called the seven-year study, involving seven major research institutions in three nations, "a heroic effort."

The study, he said, "shows that nature has been, unfortunately, cooperating with theory and showing us on a long-time scale of millennia that the mainstream view is once again bolstered."

It is clear again, Schneider said, that anthropogenic influences - the increasing emission of greenhouse gases into the Earth's atmosphere - are the prime cause of global warming.


For the rest of the article go to:

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/09/04/MNB219HIRT.DTL&tsp=1

Tuesday, August 11, 2009

Vast expanses of Arctic ice melt in summer heat

From Japan Today

TUKTOYAKTUK, Northwest Territories —

The Arctic Ocean has given up tens of thousands more square kilometers of ice on Sunday in a relentless summer of melt, with scientists watching through satellite eyes for a possible record low polar ice cap.

From the barren Arctic shore of this village in Canada’s far northwest, 2,414 kilometers north of Seattle, veteran observer Eddie Gruben has seen the summer ice retreating more each decade as the world has warmed. By this weekend the ice edge lay some 128 kilometers at sea.

“Forty years ago, it was 40 miles (64 kilometers) out,” said Gruben, 89, patriarch of a local contracting business.

Global average temperatures rose 1 degree Fahrenheit (0.6 degree Celsius) in the past century, but Arctic temperatures rose twice as much or even faster, almost certainly in good part because of manmade greenhouse gases, researchers say.

In late July the mercury soared to almost 86 degrees Fahrenheit (30 degrees Celsius) in this settlement of 900 Inuvialuit, the name for western Arctic Eskimos.

“The water was really warm,” Gruben said. “The kids were swimming in the ocean.”

As of Thursday, the U.S. National Snow and Ice Data Center reported, the polar ice cap extended over 6.75 million square kilometers after having shrunk an average 106,000 square kilometers a day in July—equivalent to one Indiana or three Belgiums daily.

The rate of melt was similar to that of July 2007, the year when the ice cap dwindled to a record low minimum extent of 4.3 million square kilometers in September.

In its latest analysis, the Colorado-based NSIDC said Arctic atmospheric conditions this summer have been similar to those of the summer of 2007, including a high-pressure ridge that produced clear skies and strong melt in the Beaufort Sea, the arm of the Arctic Ocean off northern Alaska and northwestern Canada.

In July, “we saw acceleration in loss of ice,” the U.S. center’s Walt Meier told The Associated Press. In recent days the pace has slowed, making a record-breaking final minimum “less likely but still possible,” he said.

Scientists say the makeup of the frozen polar sea has shifted significantly the past few years, as thick multiyear ice has given way as the Arctic’s dominant form to thin ice that comes and goes with each winter and summer.

The past few years have “signaled a fundamental change in the character of the ice and the Arctic climate,” Meier said.

Ironically, the summer melts since 2007 appear to have allowed disintegrating but still thick multiyear ice to drift this year into the relatively narrow channels of the Northwest Passage, the east-west water route through Canada’s Arctic islands. Usually impassable channels had been relatively ice-free the past two summers.

“We need some warm temperatures with easterly or southeasterly winds to break up and move this ice to the north,” Mark Schrader, skipper of the sailboat Ocean Watch, e-mailed The Associated Press from the west entrance to the passage.

The steel-hulled sailboat, with scientists joining it at stops along the way, is on a 40,232-kilometer, foundation-financed circumnavigation of the Americas, to view and demonstrate the impact of climate change on the continents’ environments.

Environmentalists worry, for example, that the ice-dependent polar bear will struggle to survive as the Arctic cap melts. Schrader reported seeing only one bear, an animal chased from the Arctic shore of Barrow, Alaska, that “swam close to Ocean Watch on its way out to sea.”


(The rest of the article is available at: http://www.japantoday.com/category/world/view/vast-expanses-of-arctic-ice-melt-in-summer-heat)

Arctic Ocean may be polluted soup by 2070

From: Kate Ravilious, NewScientist

WITHIN 60 years the Arctic Ocean could be a stagnant, polluted soup. Without drastic cuts in greenhouse-gas emissions, the Transpolar Drift, one of the Arctic's most powerful currents and a key disperser of pollutants, is likely to disappear because of global warming.

The Transpolar Drift is a cold surface current that travels right across the Arctic Ocean from central Siberia to Greenland, and eventually out into the Atlantic. It was first discovered in 1893 by the Norwegian explorer Fridtjof Nansen, who tried unsuccessfully to use the current to sail to the North Pole. Together with the Beaufort Gyre, the Transpolar Drift keeps Arctic waters well mixed and ensures that pollution never lingers there for long.

To better understand the dispersal of pollution in the Arctic Ocean, Ola Johannessen, director of the Nansen Environmental and Remote Sensing Center in Bergen, Norway, and his colleagues studied the spread of radioactive substances such as strontium-90 and caesium-137 from nuclear testing, bomb factories and nuclear power-plant accidents. Measurements taken between 1948 and 1999 were plugged into a high-resolution ocean circulation model and combined with a climate model to predict Arctic Ocean circulation until 2080.

Article continues

Flying frogs and the world's oldest mushroom: a decade of Himalayan discovery

From: Felicity Carus, The Guardian UK

A pretty ultramarine blue flower which changes colour in response to temperature, a flying frog and the world's oldest mushroom preserved in amber are among the 350 new species discovered in the Eastern Himalayas over the past 10 years. But experts warn the new discoveries are under pressure from demand for land and climate change.

A report published today by the WWF, The Eastern Himalayas — Where Worlds Collide, lists 242 new types of plants, 16 amphibians, 16 reptiles, 14 fish, two birds and two mammals and 61 new invertebrates. The cache, quality and diversity of species newly discovered between 1998 and 2008 make the mountainous region one of the world's most important biological hotspots.

The WWF is asking the governments of Bhutan, India and Nepal to commit to cooperate on conservation efforts in the geographic region that transcends the borders of the three countries to protect the landscape and the livelihoods of people living in the Eastern Himalayas.

Population growth, deforestation, overgrazing, poaching, the wildlife trade, mining, pollution, and hydropower development have all contributed to the pressures on the fragile ecosystems in the region, the report says. Only 25% of the original habitats in the region remain intact and 163 species that live in the Eastern Himalayas are considered globally threatened.

Article continues

Saturday, August 8, 2009

More wildfire, more bad air

From: Bettina Boxall, LA Times

Harvard University scientists are predicting some forms of air pollution could increase significantly across the West as more of the region's wildlands burn as a result of rising temperatures.

Smoke from wildfires contains two main kinds of carbon particles: black soot, or elemental carbon, and lighter-colored particles, called organic carbon aerosols, which are a mix of chemicals.

"In large quantities, downwind of fires, organic carbon aerosols are hazardous," said senior research fellow Jennifer Logan, who led a study examining rising wildfire rates and the impact on air quality. "The particles irritate lung tissue and the chemicals they carry are toxic. But even at low concentrations, these aerosols may be dangerous. We don't know. There is no known threshold where damage begins."

Article continues

Can national parks be saved from global warming?

From: Margot Roosevelt, LA Times

The federal government must take decisive action to avoid "a potentially catastrophic loss of animal and plant life," in the national parks, according to a new report that details the effect of global warming on the country's most treasured public lands.

The 53-page report from the National Parks Conservation Assn., a Washington-based advocacy group, contains a litany of concerns related to climate change in the parks, from the bleaching of coral reefs in Florida to the disappearance of high-altitude ponds that nurture yellow-legged frogs in California.

The group, which has offices in California and 10 other states, called on the National Park Service to come up with a detailed plan and funding to adapt to temperature-related ecosystem changes.

"Right now, no national plan exists to manage wildlife throughout their habitat, which often is a patchwork of lands managed by multiple federal agencies, states, tribes, municipalities and private landholders," wrote Tom C. Kiernan, president of the group.

Article continues

How to Get Cancer: Move to the United States

From: Live Science

he risk of cancer for Hispanics living in Florida is 40 percent higher than for those who live in their native countries, a puzzling new study finds.

The finding holds even after researchers corrected for the increase detection rates in the United States. And access to health care

did not make things better.

"This suggests that changes in their environment and lifestyles make them more prone to develop cancer," said Dr. Paulo S. Pinheiro, a researcher in the Department of Epidemiology at the University of Miami Miller School of Medicine.

Cancers of the colon and rectum among Cubans and Mexicans who moved to the United States was more than double that in Cuba and Mexico. Lung cancer among Mexican and Puerto Rican women living in Florida was also double the rates in their countries of origin.

Article continues

Alaskan Glaciers REALLY are Shrinking

"Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change."

Beginning in 1957, the USGS has taken annual measurements of the South Cascade Glacier in Washington state, and followed shortly thereafter monitoring the Gulkana Glacier on the coast of Alaska and Wolverine Glacier in Alaska's interior.

All three glaciers have shrunk and thinned, the report says, with the mass loss rapidly accelerating over the past 15 years. The South Cascade Glacier has lost nearly 25% of its weight, and the two Alaskan glaciers about 15%.


Between 1987 and 2004 all three glaciers consistently lost more snow and ice each summer as compared to years prior, the report says. Combined with less snowfall the loss has led to the net decline of the glaceirs.
The study raises concerns about diminishing freshwater runoff and the future availability for fresh drinking water in areas that depend on the glaciers for water supply as they continue to shrink - some possibly disappearing entirely. The shrinkage also changes water temperatures, effecting the habitat of fish, insects, and other animals downstream, says USGS scientist Shad O'Neel.

Photo shows the South Cascade Glacier in 1928 (top) and now (bottom).

Article continues: http://www.globalwarmingisreal.com/blog/2009/08/07/usgs-report-shows-a-dramatic-decline-in-us-glaciers/

Saturday, July 25, 2009

Greenwash: easyJet's carbon claims written on the wind

EasyJet says its flights have a smaller carbon footprint than a Toyota Prius hybrid car. Let's do the maths…

easyjet

EasyJet claims its flights have smaller carbon footprints than a Toyota Prius. Photograph: Philippe Hays/Rex Features

You probably weren't watching BBC3 at 4am on Monday morning. Not if you had a job to go to in the morning, anyhow. So you probably missed a nice little programme called Britain's Embarrassing Emissions.

It door-stepped the budget airline easyJet about claims on the company's website that it is greener than a hybrid car. Or, more particularly, that its emissions were less than those of a Toyota Prius. It's greenwash, of course. As, I discovered, are several of its other environmental claims.

The crux of the matter is the company's website, which highlights a graph showing that its emissions "based on one person" are 95.7g/km, whereas those for a Prius are 104g/km. As the programme pointed out, this is not comparing like with like. EasyJet doesn't say so, but its "typical comparison" is very atypical. It assumes that the plane is full and its emissions are shared out among all the passengers, while the Prius is presumed to have only one occupant.

EasyJet may succeed in its aim of completely filling up every flight (though it is not true in my experience). But all British official stats on car emissions reckon on an average of 1.6 passengers in a car. Eastjet presumably didn't follow this convention, because it would show even a full easyJet flight emitting 47% more per passenger-kilometre than an averagely full Prius. And of course a full easyJet flight would emit close to for four times as much per passenger as a full Prius carrying four people.

In the programme, which I'm guessing was filmed recently, the hapless easyJet spokesman appeared to promise to try and get the website changed to reflect reality. Not so far, it hasn't. The greenwash persists. And if the claims are repeated in any of easyJet's advertising perhaps someone fancies contacting the Advertising Standards Authority...

But the environment pages of easyJet's site contain other slippery claims. They repeatedly proclaim that "aviation's carbon dioxide emissions... only account for 1.6% of global greenhouse gas emissions", citing as the source Lord Stern's famous review of the economics of climate change. But the company ignores the next sentence in Stern's text, which says that "the impact of aviation on climate change is greater than these figures suggest because of other gases released by aircraft... for example water vapour". These emissions roughly double the effect, says Stern. So make that 3.2%.

Oddly enough, easyJet's seems seems not to trust its headline claims. Its own report on corporate and social responsibility quotes a figure of 3.5% contained in a report from the Intergovernmental Panel on Climate Change in 1999.

In any event, both Stern and the IPCC report are out of date. Stern's data come from someone else's report in 2005, which in turn cites data for 2002. Since when global aircraft emissions have grown by about 40%. And IPCC scientists now quote a figure for aviation's contribution to global warming of almost 5%.

Whatever aviation's true contribution to global warming, it is not 1.6%.

What else does easyJet offer to reassure its growing number of passengers that it is green to fly? Naturally, since it doesn't fly to the US, the company flags up how flying to Europe is better. So it says in big letters: "Flying from London to Nice produces 10 times fewer CO2 emissions than flying London to Miami."

Leaving aside the ugly English, I am not sure this stands up. Since easyJet doesn't fly to Miami, we can't check the stat on its own carbon calculator. But a couple of others I went to, including Climate Care, show the difference at a bit over eight times.

The comparison is misleading in a more important way, however. If I need to get to Miami, I have little choice other than to fly. Whereas if i need to get to Nice, I can catch a train. It might take a bit longer, but it will save on carbon. Thanks to the nuclear power-running Eurostar and the French railways, my emissions would be, very roughly, one-tenth those of flying. With easyJet or anyone else.

China dust cloud circled globe in 13 days

China dust cloud circled globe in 13 days


Dust clouds generated by a huge dust storm in China's Taklimakan desert in 2007 made more than one full circle around the globe in just 13 days, a Japanese study using a NASA satellite has found.

When the cloud reached the Pacific Ocean

the second time, it descended and deposited some of its dust into the sea, showing how a natural phenomenon can impact the environment far away.

"Asian dust is usually deposited near the Yellow Sea, around the Japan area, while Sahara dust ends up around the Atlantic Ocean and coast of Africa," said Itsushi Uno of Kyushu University's Research Institute for Applied Mechanics.

Article continues

Ocean current switch due to warming could be slower than feared

CHICAGO — The nightmare global warming scenario which provided the plot for a Hollywood blockbuster -- the Atlantic Ocean current that keeps Europe warm shuts down and triggers rapid climate change -- has long worried scientists.

But a study published Thursday in the journal Science found it may not occur as quickly as previously feared.


There is evidence that this current has shut down with some regularity in the past -- and sometimes quite rapidly -- in response to large influxes of fresh water from melting glaciers.

However, it appears as though the current rate of glacial melt is occurring at a more gradual pace which will "give ecosystems more time to adjust to new conditions," said study coauthor Peter Clark, a professor of geosciences at Oregon State University.

Article continues

NOAA Reports Record Ocean Surface Temperatures for June

From: , Global Warming is Real, More from this Affiliate
Published July 21, 2009 07:30 AM

The National Oceanic and Atmospheric Administration (NOAA) has reported findings of preliminary analysis from the agency's National Climatic Data Center in Asheville, North Carolina that shows global ocean surface temperatures for June broke the previous record set in 2005.

The combined average global/land and ocean surface temperature for June was the second warmest on record, 1.12 degrees Fahrenheit (0.62 degrees Celsius) above the 20th century average of 59.9 degrees F.

Ocean surface temperatures for June '09 were the warmest on record, 1.06 degrees F (0.59 degrees C) above the 20th century average of 61.5 degrees F.

The global land surface temperature for June was 1.26 degrees F above the 20th century average, and the sixth warmest June on record.

Article continues: http://www.globalwarmingisreal.com/blog/2009/07/20/noaa-reports-record-ocean-surface-temperatures-f

How Clouds Over the Oceans Affect Our Climate

How clouds over the ocean affect our climate, and how climate change

may be affecting THEM, is not well known. There is no network of observing stations like on land, and climate models have not been shown to really simulate clouds well. They may be just too fine a detail for models that cover such large scale phenomenon as oceanic circulation. But clouds over the oceans have been thought be important in our understanding of what drives our climate.


In a study published in the July 24 issue of Science, researchers Amy Clement and Robert Burgman from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and Joel Norris from Scripps Institution of Oceanography at UC San Diego begin to unravel this mystery. Using observational data collected over the last 50 years and complex climate models, the team has established that low-level stratiform clouds appear to dissipate as the ocean warms, indicating that changes in these clouds may enhance the warming of the planet.
The result of their analysis was a surprising degree of agreement between two multi-decade datasets that were not only independent of each other, but that employed fundamentally different measurement methods. One set consisted of collected visual observations from ships over the last 50 years, and the other was based on data collected from weather satellites.


"The agreement we found between the surface-based observations and the satellite data was almost shocking," said Clement, a professor of meteorology and physical oceanography at the University of Miami and winner of the American Geophysical Union's 2007 Macelwane Award for her groundbreaking work on climate change. "These are subtle changes that take place over decades. It is extremely encouraging that a satellite passing miles above the earth would document the same thing as sailors looking up at a cloudy sky from the deck of a ship."
Together, the observations and the Hadley Centre model results provide evidence that low-level stratiform clouds, which currently shield the earth from the sun's radiation, may dissipate in warming climates, allowing the oceans to further heat up, which would then cause more cloud dissipation.


"This is somewhat of a vicious cycle potentially exacerbating global warming," said Clement. "But these findings provide a new way of looking at cloud changes. This can help to improve the simulation of clouds in climate models, which will lead to more accurate projections of future climate changes. "

For more information: http://www.universityofcalifornia.edu/news/article/21575

Friday, July 3, 2009

Drax protesters found guilty of obstructing coal train

Climate change protesters face community service after judge rejects justification defence

Climate change protesters who ambushed and hijacked a power station coal train failed to convince a jury today that their actions were justified by the "imminent threat" of devastation from global warming.

The 22 men and women, including a senior university lecturer, teachers and film-makers, were convicted - after less than two hours of deliberation - of obstructing the service carrying 42,000 tonnes of coal to Drax in North Yorkshire last June.

Their hopes of repeating the "Kingsnorth Six" judgment last September, when activists who defaced a power station chimney were acquitted by a Kent jury, were dashed by a judge, who refused to admit arguments that the hijack was "necessary and proportionate to prevent the greater crime of carbon pollution".

Although he eventually allowed an unexpectedly large amount of evidence about climate change to be heard, Judge James Spencer refused to let expert witnesses such as Nasa scientist, Prof James Hansen, address the seven women and five men on the jury at Leeds crown court. In a pre-trial ruling he said that to do so would allow the protesters "to hijack the trial process as surely as they hijacked the coal train".

He did however compliment the group, who conducted their own defence, on making an "eloquent, sincere, moving and engaging" case to the court. After the verdicts, he said that sentencing in early September would definitely not include jail terms, but was likely to be community service.

The 22, plus a further five protesters who earlier pleaded guilty and two who are ill but expected to submit guilty pleas in due course, will however face hefty financial penalties. The crown is applying for both its costs and £36,000 compensation for cleaning up coal shovelled on to the tracks during a 16-hour standoff with police.

After the verdict, one of the 22, Dr Louise Hemmerman, 31, said: "The judge declared from day one that climate change was irrelevant to the trial, despite the fact that it was the sole reason for doing what we did."

Another of the group, Jonathan Stevenson, 27, who works for a development charity, said: "This won't be the last case where climate protesters are in court for taking peaceful direct action, and while some judges may think climate change is irrelevant, they won't be able to hold back the tide forever."

Stevenson asked the judge after the verdicts if an order banning the defendants from power stations would apply more widely, to include roads. Judge Spencer replied with a smile: "I would steer clear of demonstrations, all of you, until this case is completely over. Try to find some other activities to do on your holidays."

Hansen, head of Nasa's Goddard Institute for Space Studies, whom the defendants had intended to call to the stand to speak about the science of climate change, said: "Civil resistance is not an easy path, but given abdication of responsibility by the government, it is an essential path."

Hansen was arrested last week for his part in a protest over mountaintop coalmining in West Virginia. He has previously said that direct action is necessary because the democratic process is not bringing about policy change fast enough.

The chief crown prosecutor for North Yorkshire, Rob Turnbull, said: "While the CPS [crown prosecution service] respects the rights of individuals to lawfully protest, it takes a serious view of criminal activity which targets those carrying out lawful activities." He defended Judge Spencer's pre-trial ruling on the grounds that no one was in such immediate danger from global warning that hijacking a coal train was "proportionate".

"The judge said that if the power station contributed to global warming, and all that entailed, it was for the government to attend to and not the protesters. He also said that no reasonable jury could conclude that the crime these defendants allegedly committed was either reasonable or proportionate when there were democratic processes available in this country for political change."

The 22 were acquitted of actually stopping the train, after evidence that no one knew which of them had donned fake railwaymen's uniforms and used red flags to bring it to a halt. The ambush stopped the train right on a bridge over the river Aire, whose girders gave protesters the means to clamber up and use 15 shovels to start unloading coal.

Passenger and freight services in the area were disrupted for two days, but Drax generated power normally throughout.

Those convicted were: Theo Bard, 24, Amy Clancy, 24, Brian Farelly, 32, Grainne Gannon, 26, Bryn Hoskins, 24, Jasmin Karalis, 25, Ellen Potts, 33, Bertie Russell, 24, Alison Stratford,26, Jonathan Stevenson, 27 and Felix Wight, all of London, Melanie Evans,25, Matthew Fawcette, 34, Robin Gillett, 23, Kristina Jones 22, Oliver Rodker, 40 and Thomas Spencer,23, all of Manchester, Paul Chatterton, 36, and Louise Hemmerman, 31, of Leeds, Melanie Evans, 25, of Stockport, Paul Morozzo, 42, of Hebden Bridge, Christopher Ward, 38, of Newport Pagnell and Elizabeth Whelan of Glasgow.

The five who pleaded guilty earlier were: Theo Brown, 22 and Clemmie James, 24, of London, Malcolm Carroll, 53, of Stafford, Thomas Johnstone, 25, of Liverpool and Paul Mellett, 29, of Colerne, Wiltshire. The two have indicated they will plead guilty when well are Caroline Williams, 25, of London and Sam Martingell, 24, of Leeds.