Forests, after all, cool the atmosphere by drinking in carbon dioxide from the air. A new study, however, published in Proceedings of the National Academy of Sciences reports that forests' other climatic effects can cancel out their carbon cleaning advantage in some parts of the world. Using a three-dimensional climate model, the research team mimicked full global deforestation and also studied the effects of clear-cutting in different regions of latitude, such as the tropics and boreal zones. Apparently, these natural carbon sinks only do their job effectively in tropical regions; in other areas, they have either no impact or actually contribute to warming the planet. In fact, according to this model, by the year 2100, if all the forests were cut and left to rot, the annual global mean temperature would decrease by more than 0.5 degree Fahrenheit.

How might U.S. national security be threatened by mega-droughts, coastal flooding, killer hurricanes, food scarcity and the other ecological calamities scientists widely predict will occur if global warming continues apace?

No one knows, but Sens. Chuck Hagel, R-Neb., and Dick Durbin, D-Ill., think it's time to find out. Two weeks ago, the bipartisan duo introduced a bill that would require federal intelligence agencies to collaborate on a National Intelligence Estimate to evaluate the security challenges presented by climate change.

The combination of polar bears and melting ice is a heady mix - so much so that the animal's plight has become a rallying cry in the fight against climate change. Simon Garfield reveals how activists have used dramatic pictures of the Arctic's most fearsome predator to give their cause real bite and to ignite an emotive PR campaign.

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One photograph in particular has captured the imagination. In a neat piece of marketing, the Canadian Ice Service made available a stunning image to coincide with the IPCC report. Two bears, probably a mother and her cub, are pictured on a spectacular ice block off northern Alaska that might have been modelled by Henry Moore. They appear to be howling against injustice. The drama is clear: this is truly the tip of an iceberg, the bears are desperately stranded as the water swells around them. The first thought among viewers is surely one of pity and concern, but this is to misjudge the situation: polar bears are reasonable swimmers, and certainly climbed upon such sculptures centuries before we climbed into our 4x4s.

High levels of pesticides are wafting into protected rain forests in Costa Rica, even though the lowland farms being sprayed with the chemicals are miles away, a recent study reports.

Modern pesticides dissolve more easily in water than older, longer-lasting ones, such as DDT. This means the chemicals break down faster in the environment and are less likely to travel long distances.

But because of a unique atmospheric system created by mountain ranges, large concentrations of pesticides are able to drift with the wind and fall with the rain into sensitive habitats previously thought to be unreachable.

"These chemicals have shown they can make it from the places where they are used to the places that are protected," said study leader Frank Wania of the University of Toronto in Canada.

Wania and colleagues reported their findings in two related papers published in the January 10 issue of the journal Environmental Science & Technology.

Wania said the discovery could explain why amphibian extinctions in Costa Rica's protected forests are more common at higher altitudes.

This 2004 incident, reported by Steven Amstrup of the U.S. Geological Survey's Alaska Science Center, was the first report of polar bear cannibalism in two decades of study in the Beaufort Sea area of northern Alaska, and in 30 years of studies in northwestern Canada. Since then, Amstrup has documented two additional cases.

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Some prominent researchers suspect that changes in the climate are a leading threat to polar bear survival. Polar bears are especially vulnerable to rising Arctic temperatures because they hunt, mate and usually make their dens on sea ice. "There is no evidence they can survive on land without sea ice," Williams said.

Sometimes it's good to have bugs in your water.

An increase in the diversity and size of water insects is heralding an improvement in the environmental quality of streams that flow into the Carson River in northern California and Nevada.

The streams run below an abandoned sulfur mine high in the Sierra Nevada mountain range that runs along the border between the two states.

For decades a toxic soup of acids and heavy metals leaked from the mine, coloring the water and rendering the streams nearly lifeless.

In 2000 the U.S. Environmental Protection Agency (EPA) designated the mine as a Superfund site, one of the most polluted spots in the United States.

"The water quality was awful," said Kevin Mayer, the EPA project manager for the mine cleanup.

"And unlike most sites where I work, where groundwater and soil contamination can't be visibly seen, it was extraordinarily disheartening to see the bright orange streams going down miles away from the mine."

But since then cleanup activities have led to a "dramatic improvement" in the streams' habitats, said David Herbst, a biologist with the Sierra Nevada Aquatic Research Laboratory in California.

Punxsutawney Phil—the groundhog of Groundhog Day fame—emerged from his stump-shaped shelter this morning and didn't see his shadow, traditionally signaling an early spring.

Sun-worshipping humans might welcome the news, but for groundhogs and other hibernating animals, a longer winter could be a blessing.

A recent trend toward increasingly mild winters is disrupting normal hibernation patterns for many high-latitude and high-elevation species—and in some cases it may be a matter of life or death.

From marmots in the Rocky Mountains to bears in the Moscow Zoo, animals are spending less time napping. The change may be placing some species fatally out of synch with their environment.

When animals hibernate they're able to conserve the energy stored in their fat during periods when food is scarce. So when they are abnormally active, they risk using up their stored energy before they can replace it.

It's hard to believe that something as ephemeral as lightning could be frozen in time for thousands of years. But that's just what happens with fulgurites--glassy, hollow tubes that form when lightning melts sand. For the first time, researchers have successfully dated these unusual geological formations, and the findings are providing a unique insight into the long-ago climate and ecology of the Sahara desert.

Fulgurites record the past by providing direct evidence of thunderstorms and rain. But when Rafael Navarro-González, a chemist at the National Autonomous University of Mexico in Mexico City, came across an unusual specimen from the Sahara desert in southwestern Egypt, he realized that some fulgurites may have a much more interesting story to tell. Unlike most fulgurites, this one was rounder and solid, but what really caught his eye were tiny, embedded glass bubbles. He wondered if they might contain gas.

America's addiction to gas-guzzlers is at last poised to receive some treatment. In his annual State of the Union address on Tuesday, President George W Bush announced a plan to cut US gasoline use by 20% over the coming decade.

"For too long our nation has been dependent on foreign oil," Bush told the US Congress. "It is in our vital interest to diversify America's energy supply, and the way forward is through technology."

Three quarters of the proposed cut would be achieved by requiring the use of 35 billion gallons of renewable and alternative fuels – including ethanol and hydrogen – by 2017. This is nearly five times larger than the current target, which must be met by 2012. The rest of the cut in gasoline use would be made by strengthening the Corporate Average Fuel Economy (CAFE) standards for new vehicles.

Aquatic ecosystems in the northeastern U.S. and southern Canada harbor dangerous concentrations of the neurotoxin

Researchers have discovered dangerous levels of the neurotoxin mercury (Hg) in the muscle tissue of perch and in the blood and eggs of the common loon in aquatic ecosystems of the northeastern U.S. and southern Canada. The finding led them to identify five "hot spots" of mercury contamination that pose serious health risks to animals as well as humans. In addition, elevated concentrations of the neurotoxin were found in nine other regions labeled as "areas of concern" in the report published in the January issue of Bioscience. High concentrations of mercury, which accumulate in the food chain, can cause brain and nerve damage in developing fetuses and young children.

In some areas the team of U.S. and Canadian researchers, led by David Evers of the BioDiversity Research Institute in Gorham, Maine, found perch containing mercury levels as high as 20 times greater than the Environmental Protection Agency's (EPA) recommended limits. A survey of other ecosystem members discovered that 75 percent of bass and trout sampled contained mercury levels exceeding the federal limits.

U.S. Government proposes steps to save conservation icon.

The United States has admitted what conservationists have been saying for years — that the polar bear is in danger of losing its battle with habitat loss. A new government proposal suggests that the species be listed as 'threatened' as a result of melting Arctic ice.

Under the plan, unveiled by Secretary of the Interior Dirk Kempthorne yesterday, the US Fish and Wildlife Service will spend a year evaluating the status of the polar bear. If it is listed as threatened, it will come under the protection of the US Endangered Species Act, which sets out recovery plans for endangered wildlife.

"Based on current analysis, there are concerns about the effect of receding sea ice on polar bear populations," Kempthorne said in his announcement. There are thought to be fewer than 25,000 polar bears (Ursus maritimus) remaining.

Via the Scientific American Blog:

Scientific evidence demonstrates clearly that human activity is changing the planet's climate. But there are still sceptics who dispute the data and its interpretation. If you don't believe the science, please tell us why and we'll respond to your challenge.

Alan Thorpe of the Natural Environment Research Council and a team of scientists are taking on all comers until January 31. Please do not post questions below as I will not relay them elsewhere for you. Please post questions on the linked debate site. You are welcome to link and repost below after doing so. I will try to provide follow up answers from the debate on your question (or similar).

Local communities can help preserve the world's forests.

For more than a century, the world's forests have been under siege—by the timber industry, by the wild mushroom and maple syrup industries, by agricultural development, and even by millions of indigenous people living at the forests' borders. Disappearing forests mean disappearing habitats for thousands of species.

Ecologists say the loss is especially tragic in the face of our planet's recent warming. Trees act as natural air conditioners: Warm tree leaves release water, the water evaporates, and the atmosphere cools. What's more, today's tropical forests store half a century of global carbon emissions in their trunks.

"Forests have a tremendous amount of biodiversity, both biologically and culturally," said tropical forest ecologist Daniel Nepstad of The Woods Hole Research Center in Massachusetts. "The health of the planet depends on these ecosystems. So the question of how you keep them standing is quite critical."

Forest fires in northern countries may cause regional cooling and not warming, as was previously thought. Researchers say their new findings could mean that on a global scale, forest fires will not affect climate change one way or the other.

Unusually large fires have blazed across Canada, Alaska, Russia, Norway, Sweden and other northern countries over the past decade. Researchers have said that warmer climates, longer summers and generally drier conditions may be increasing their frequency.

It was thought releasing the large amounts of carbon dioxide stored in trees would mean that forest fires would contribute to the greenhouse effect and start a fiery feedback loop. Not so, says a team of 17 US and Australian researchers in Science.

The team took an overall look at the effects of a forest fire that burned about 6.7 hectares (16.5 acres) of the Donnely Flats in central Alaska in June 1999. Some researchers looked changes in how the area reflected radiation from the sun, while others looked at greenhouse gas emissions and changes in vegetation.

They then plugged all their data into a computer model and projected it 80 years forward to see how a single fire would affect climate in the short and medium term.

They found that while temperatures did warm for about one year after the fire, this was reversed within 10 to 15 years. Averaged over 80 years, the overall effect was a cooling of temperatures.

Climate change is having an alarming impact on whales, dolphins, turtles and birds and other rare species that migrate over long distances, the UN Environment Programme (UNEP) has said.

Rising temperatures are already having a dramatic effect on many of these species' food, habitat, health and reproduction, UNEP said Thursday in a report coinciding with UN talks on climate change in the Kenyan capital.

Achim Steiner, executive director of UNEP, said evidence was mounting that when a migratory species dwindled or an exotic species showed up in places where previously it was absent, global warming was to blame.

In the 1810, a remarkable transition happened in Denmark: Forests ceased shrinking and began to expand. The turnaround was driven by several factors, such as migration of people to cities and the abandonment of less fertile fields. Forest area subsequently began to recover in the rest of Europe and the United States. Now, an analysis of global forest data suggests that forests are returning in more and more countries, which leads the authors to predict that the volume of wood in the world's forests will likely stabilize in the coming decades.

The data come from the United Nations Food and Agriculture Organization, which last year released a report on the trends in forests from 229 countries between 1990 and 2005. An international group of researchers led by forest ecologist Pekka Kauppi of the University of Helsinki, Finland, dug into the numbers. In a novel approach, the researchers compared trends in both forest area and forest density for the 50 most-forested nations.

A senior Bush political appointee at the Interior Department has rejected staff scientists' recommendations to protect imperiled animals and plants under the Endangered Species Act at least six times in the past three years, documents show.

In addition, staff complaints that their scientific findings were frequently overruled or disparaged at the behest of landowners or industry have led the agency's inspector general to look into the role of Julie MacDonald, who has been deputy assistant secretary of the interior for fish and wildlife and parks since 2004, in decisions on protecting endangered species.

A scientific model will answer questions like 'what is a honeybee worth?' and measure the economic costs and benefits of ecosystems to human life, Canadian and US scientists said.

Researcher Kai Chan of the University of British Columbia said the model will help estimate the dollar value to people of such ecosystem services as mangroves and wetlands.

Such modeling could allow decision-makers to include the costs and benefits of nature conservation when planning developments such as housing, agriculture zones or hydroelectric dams.

Conservation often seems to boil down to preserving the environment versus economic opportunity. If a given patch of land is saved, then a farmer will go hungry. If a marine reserve is created, then fisherfolk will lose their jobs. But two new studies demonstrate that intact ecosystems offer a variety of economic benefits, and preserving the environment may do more economic good than bad.

Robin Naidoo and Taylor Ricketts of the World Wildlife Fund (WWF) performed a classic cost-benefit analysis of the Mbaracayú Forest Nature Reserve in eastern Paraguay, part of the disappearing Atlantic woods of South America. In the past 30 years this protected region has lost 34 percent of its tree cover to agriculture and cattle ranching as well as timber harvesting. The researchers rated the economic benefits derived from five ecosystem services: sustainable bush meat hunting; timber harvest; bioprospecting for pharmaceuticals; carbon storage; and so-called existence value, or the intrinsic value of nature as a source of wonder and inspiration, the researchers write in the paper presenting their finding published yesterday in PLoS Biology. As for costs, the researchers calculated this as the agricultural value the land would have provided if deforested.

A building boom that would add scores of new coal-fired power plants to the nation''s power grid is creating a new dilemma for politicians, environmentalists and utility companies across the United States.

Should power companies be permitted to build new plants that pollute more but are reliable and less expensive? Or should regulators push utilities toward cleaner burning coal plants, even if it means they will cost more and are based on newer, yet still unproven, technology?

How those questions are answered will have huge implications over the next few decades. It could determine how Americans light, heat and cool their homes and business, the rate of return on utility investments and the potential environmental impact of the new plants.

In a debt for nature swap, the United States has agreed to forgive about 20 percent of the 108 million dollars owed by Guatemala. In exchange, the Central American country will invest 24.4 million dollars to protect species-rich subtropical and tropical ecosystems.

The recently announced agreement is the largest of ten such deals the U.S. government has undertaken in recent years under the Tropical Forest Conservation Act of 1998.

Under the deal, the Guatemalan government is to fund conservation efforts with money it would have otherwise used to begin to pay back the tens of millions of dollars it has borrowed from the U.S.

Loggers, tour companies, farmers, developers, and hunters have battered Guatemala's wildlands, conservationists say. They hope the swap will help protect coastal mangrove swamps, high-altitude cloud forests, and rain forests in Guatemala, a country about the size of Tennessee.

Mammal species do not seem to last very long in the grand scheme of things, persisting for an average of 2.5 million years, according to the fossil record. By studying the fossilized teeth of rodents over a span of 22 million years, Jan van Dam of Utrecht University in the Netherlands and his colleagues confirmed this cycle of rodent species rise and fall. But they also found that it closely matched variations in Earth's orbit--and may have definitively linked the two. If you have seven or eight of these in a row all showing the same pattern, it becomes extremely unlikely that it can be reduced to chance, explains paleoecologist Paul Olsen of Columbia University.

When it comes to climate change, what's love got to do with it? A lot, according to a study of shifts in bird migrations in response to global warming. Competition for females may be helping some species adapt to climate change more quickly.

The timing of bird migrations appears to be extremely sensitive to climate change. Many migrating species have been arriving earlier by the year as warmer springs thaw the snows ever sooner than in the past. But wWhat remains to be explained is why some species of birds are far more affected than are others in the same geographic range. Answering this question could help scientists better anticipate global warming's impact on biodiversity and allow them to prioritize conservation efforts.

The infamous snakehead, once dubbed the Frankenfish, is in the U.S. to stay, experts say. Fortunately, the Asian import seems to be coexisting peacefully with native species—for now.

The Potomac River, which runs through West Virginia, Virginia, Maryland, and Washington, D.C., on its way to the Atlantic, has seen a thriving population of snakeheads arise after several of the fish were released into Virginia's Dogue Creek in Fairfax County.

But so far the snakeheads appear to have had little discernable impact on the native ecosystem, to the relief of scientists and anglers alike.

We have not seen any adverse effects, said fisheries biologist Steve Owens, with Virginia's Department of Game and Inland Fisheries in Fredericksburg.

But surveys also show that northern snakehead populations are booming in the Potomac.

Salmon farming practices have come under fire for polluting oceans and damaging marine ecosystems. Now a new study heaps more criticism on the farms, suggesting that parasitic sea lice that flourish in salmon farms can kill as many as 95% of migrating wild Pacific salmon. The study, the first that attempts to quantify the effect of sea lice infection on wild Pacific salmon populations, further fuels an ongoing controversy over salmon farming practices in the United States and Canada.

The soon-to-be-launched and much-hyped Mercedes-Benz E320 Bluetec has reportedly failed to meet emissions criteria in the important states of California, Maine, Massachusetts, New York and Vermont.

Mercedes said its E320 CDI was the cleanest diesel vehicle in the world, but apparently not clean enough for U.S. regulators.

Despite their popularity in Europe, diesels have never been commonplace in the United States and have a reputation as a technology for big rigs only. But there's a more ecological explanation for the lukewarm reception. Diesel is actually more harmful to the environment than gasoline because it generates more nitrogen oxides (NOx), gases that play a major role in the formation of acid rain and haze.

A team of scientists based in Japan and Germany has found an unusual lake of liquid carbon dioxide beneath the ocean floor.

On Earth's surface carbon dioxide (CO2) is normally a gas, but in the cold, high-pressure ocean depths it cools and becomes a liquid.

Because CO2 in the atmosphere plays a major role in global warming, some scientists have suggested disposing of the gas by injecting it deep beneath the seabed, where it could be stored in liquid form.

The newly found CO2 lake, a rare natural formation, could offer clues to whether such a plan might work and how it might affect undersea ecosystems.

Climate change appears to be awakening a toxic Rip van Winkle in North America's northern peatlands. A new study concludes that more frequent fires promoted by the warming atmosphere are releasing mercury sequestered in the soils at levels up to 15 times greater than previous estimates.

Peatlands are boreal forest ecosystems rich in thick organic soil layers. Because of their chemical makeup, they are efficient at binding and storing mercury. That helps keep the chemical from accumulating in animals such as fish, where high levels can cause nervous system damage in humans who eat them.

Forest fires threaten peat's ability to protect. Between 1960s and the 1990s, the annual area burned in western Canada and Alaska doubled, a result consistent with global climate change, which researchers believe causes more frequent droughts. Previous studies have shown that forest fires release nearly all the mercury stored in ground litter and soils and inject it into the atmosphere.

Hurricane Katrina has had a devastating impact on the environment of south-east Louisiana, experts report almost a year after the violent storm smashed the city of New Orleans, causing floods that killed nearly 2000 people. Researchers say poor land management and badly planned infrastructure had exacerbated the extent of the ecological devastation.

Over 24 hours on 29 August 2005, Hurricane Katrina destroyed more than 200 square kilometres (77 square miles) of wetlands east of the Mississippi River, reported Carlton Dufrechou, head of the Lake Pontchartrain Basin Foundation in Metarie, Louisiana, US. Freshwater marsh plants were rolled up like a carpet by the storm, Gary Shaffer at Southeastern Louisiana University told New Scientist.

In the face of the coming onslaught of pollutants from a rapidly urbanizing China and India, the task of avoiding ecological disaster may seem hopeless, and some environmental scientists have, quietly, concluded that it is. But Americans are notoriously reluctant to surrender their fates to the impersonal outcomes of an equation. One by one—and together, in state and local governments and even giant corporations—they are attempting to wrest the future from the dotted lines on the graphs that point to catastrophe. The richest country in the world is also the one with the most to lose.

Environmentalism waxes and wanes in importance in American politics, but it appears to be on the upswing now. Membership in the Sierra Club is up by about a third, to 800,000, in four years, and Gallup polling data show that the number of Americans who say they worry about the environment a great deal or a fair amount increased from 62 to 77 percent between 2004 and 2006. (The 2006 poll was done in March, before the attention-getting release of Al Gore's global-warming film, An Inconvenient Truth.) Americans have come to this view by many routes, sometimes reluctantly; Carl Pope, executive director of the Sierra Club, thinks unhappiness with the Bush administration's environmental record plays a part, but many of the people NEWSWEEK spoke to for this story are Republicans. Al Gore can't convince me, but his data can convince me, venture capitalist Ray Lane remarks ruefully. Lane is a general partner in the prominent Silicon Valley firm of Kleiner Perkins Caufield & Byers, which has pledged to invest $100 million in green technology. He arrived at his position as a Republican environmentalist while pondering three trends: global warming, American dependence on foreign oil and the hypermodernization of Asian societies.

When scientists try to gauge the impact of humans on bird populations since 1500--the time Europeans began to explore the world in earnest--they often cite estimates that, on average, one species has gone extinct every 4 years. Now, a group of researchers says that figure may be far too low. The good news is that conservation efforts in the 20th century have prevented many extinctions, but the authors warn that continued destruction of habitat makes even more birds likely to vanish forever in the next 100 years.

Climate change has led several migrating bird species to re-set their travel clocks. In a new study, researchers claim that the earlier onset of spring in northern Europe seems to affect long-distance bird migrants, most of which winter in Africa, more than it does Europe's short-distance avian vacationers. Researchers say the findings suggest that these birds' earlier migration may result from evolutionary changes driven by the warming climate.

How technology is leading environmentalism out of the anti-business, anti-consumer wilderness.

For decades, environmentalists have warned of a coming climate crisis. Their alarms went unheeded, and last year we reaped an early harvest: a singularly ferocious hurricane season, record snowfall in New England, the worst-ever wildfires in Alaska, arctic glaciers at their lowest ebb in millennia, catastrophic drought in Brazil, devastating floods in India - portents of global warming's destructive potential.

Green-minded activists failed to move the broader public not because they were wrong about the problems, but because the solutions they offered were unappealing to most people. They called for tightening belts and curbing appetites, turning down the thermostat and living lower on the food chain. They rejected technology, business, and prosperity in favor of returning to a simpler way of life. No wonder the movement got so little traction. Asking people in the world's wealthiest, most advanced societies to turn their backs on the very forces that drove such abundance is naive at best.

He invented the Internet (sort of). He became President (almost). Now Al Gore has found his true calling: using the power of technology to save the world.

Al Gore? Five and a half years after leaving the political stage, only the fourth man in US history to win the popular vote for president without being inaugurated, Gore has deftly remade himself from an object of pity into a fearless environmental crusader. The new Gore is bent on fixing what he calls the "climate crisis" through a combination of public awareness, federal action, and good old-fashioned capitalism. He's traveling the globe, delivering a slide show that, by his own estimate, he's given more than a thousand times over the years. His one-man campaign is chronicled in a new documentary, An Inconvenient Truth, which made Gore the unlikely darling of the Sundance Film Festival earlier this year and will be released on May 26 by Paramount Classics. He has also written a forthcoming companion volume of the same name, his first book on the subject since the 1992 campaign tome Earth in the Balance: Ecology and the Human Spirit.

Along the way, Gore has become a neo-green entrepreneur, taking his messianic faith in the power of technology to stop global warming and applying it to an ecofriendly investment firm. The company, Generation Investment Management, which he cofounded nearly two years ago, puts money into businesses that are positioned to capitalize on the carbon-constrained economy Gore and his partners see coming in the near future. All the while, he has been busy polishing his reputation as the ultimate wired citizen: Not far from the Stanford campus, Gore sits on the board of directors at Apple and serves as a senior adviser to Google. Farther up Highway 101 are the San Francisco headquarters of Current TV, the youth-oriented cable network he cofounded with legal entrepreneur Joel Hyatt.