Why 5 degrees really matters

Methane hydrate gasification

In 2002 a BBC2 'Horizon' documentary, 'The Day the Earth Nearly Died,' summarized some recent findings and speculation concerning the Permian extinction event. Paul Wignall examined Permian strata in Greenland, where the rock layers devoid of marine life are tens of meters thick. With such an expanded scale, he could judge the timing of deposition more accurately and ascertained that the entire extinction lasted merely 80,000 years and showed three distinctive phases in the plant and animal fossils they contained. The extinction appeared to kill land and marine life selectively at different times. Two periods of extinctions of terrestrial life were separated by a brief, sharp, almost total extinction of marine life. Such a process seemed too long, however, to be accounted for by a meteorite strike. His best clue was the carbon isotope balance in the rock, which showed an increase in carbon-12 over time. The standard explanation for such a spike – rotting vegetation – seemed insufficient.

Geologist Gerry Dickens suggested that the increased carbon-12 could have been rapidly released by upwellings of frozen methane hydrate from the seabeds. Experiments to assess how large a rise in deep sea temperature would be required to sublimate solid methane hydrate suggested that a rise of 5°C would be sufficient. Released from the pressures of the ocean depths, methane hydrate expands to create huge volumes of methane gas, one of the most powerful of the greenhouse gases. The resulting additional 5°C rise in average temperatures would have been sufficient to kill off most of the life on earth.

Sudden release of methane hydrate has also been hypothesized as a cause of the Paleocene-Eocene Thermal Maximum extinction event.

Moderate Resolution Imaging Spectroradiometer (MODIS)

This NASA Aqua satellite handout image of millions of tiny ocean plants called phytoplankton, shows the bright blue and green swirls that the Moderate Resolution Imaging Spectroradiometer (MODIS) detected off the coast of Vancouver Island, Canada. A giant growth of algae in the waters off Canada's west coast, so huge it can be seen from space, may be linked to climate change, say scientists who hope to collect samples 30 June 2006.(AFP/NASA-HO/Jeff Schmaltz)

Northeast floods stir global warming debate

Easton Pa., left, and Phillipsburg N.J., right, are seen flooded by the Delaware River in an aerial photo Thursday, June 29, 2006. Swollen rivers produced by relentless rain the last few days have caused extensive flooding across the Northeast.(AP Photo/Matt Rourke)

BOSTON (Reuters) - Images of swamped homes in the U.S. Northeast deepened suspicions over global warming, giving ammunition to scientists and others who say greenhouse gas-spewing cars and factories are fueling extreme weather.

Meteorologists cautioned that no one should read too much into one storm. But the Atlantic Ocean is unusually warm for this time of year, they said, creating excess moisture in the atmosphere that can swiftly build a powerful rainstorm.

Paul Epstein, associate director of Harvard Medical School's Center for Health and the Global Environment, said the Atlantic is warming faster than scientists projected even a decade ago, and he expects such storms as the one seen this week from Virginia to New York to become common.

"Scientists and climatologists are looking at one another and we're just stunned because no one, even in the 1990s, projected the magnitude of the storms and degree of warming in the Arctic that we are seeing," he said.

Pennsylvania flooding forces evacuations

WILKES-BARRE, Pa. - Up to 200,000 people in the Wilkes-Barre area were ordered to evacuate their homes Wednesday because of rising water on the Susquehanna River, swelled by a record-breaking deluge that had killed at least 12 people across the Northeast.

Thousands more were ordered to leave their homes in New Jersey, New York and Maryland. Rescue helicopters plucked residents from rooftops as rivers and streams surged over their banks, washed out roads and bridges, and cut off villages in some of the worst flooding in the region in decades.

Earlier this week, floodwaters in the nation's capital closed the National Archives, the IRS, the Justice Department and other major government buildings. The National Archives, several Smithsonian museums and some government office buildings were still closed Wednesday.

The National Archives moved in giant dehumidifiers to preserve its historic documents. "The threat to the records is not floodwater, but humidity from the lack of air conditioning," spokeswoman Susan Cooper said Wednesday.

Alberto prompts evacuation on Fla. coast

CEDAR KEY, Fla. - More than 20,000 people along Florida's Gulf Coast were ordered to clear out Monday as Alberto — the very first tropical storm of the new hurricane season — unexpectedly picked up steam and threatened to come ashore as a hurricane.

If Alberto came ashore as a hurricane, it would be the earliest hurricane in 40 years to hit the United States, according to the

National Hurricane CenteR

Polar bears may be turning to cannibalism

ANCHORAGE, Alaska - Polar bears in the southern Beaufort Sea may be turning to cannibalism because longer seasons without ice keep them from getting to their natural food, a new study by American and Canadian scientists has found.

The study reviewed three examples of polar bears preying on each other from January to April 2004 north of Alaska and western Canada, including the first-ever reported killing of a female in a den shortly after it gave birth.

"During 24 years of research on polar bears in the southern Beaufort Sea region of northern Alaska and 34 years in northwestern Canada, we have not seen other incidents of polar bears stalking, killing, and eating other polar bears," the scientists said.

Environmentalists contend shrinking polar ice due to global warming may lead to the disappearance of polar bears before the end of the century.

Study Reveals Ancient Arctic Climate Swings

http://www.livescience.com/environment/060531_arctic_climate.html

Scientists have uncovered the Arctic region's history of climate change buried beneath layers of ocean ice from a newly collected sediment core.

The 1,312-foot-long cylindrical sediment core sample provides a 56-million-year record of the continent's temperature trends. It reveals that approximately 45 million years ago, the Arctic went from being a warm greenhouse to the frosty ice-covered continent that we know today.

The sediment sample also revealed abundant remains of a freshwater fern known as Azolla, dating back to about 49 million years ago, which indicate that there was freshwater flowing from the Arctic Ocean as far south as the North Sea. Without an inflow of salty waters, any excess precipitation compared with evaporation created a freshwater environment in the Arctic Ocean.

New Forecast: Hot and Hotter

Dangerous emissions.
Experiments at this meadow in the Colorado Rockies show that, under the temperatures corresponding to climate models estimates for about 2050, soils release carbon dioxide.

Credit: JOHN HARTE

If Earth's past climate cycles are any indication, temperatures could be significantly hotter by the end of the century than current climate models predict. New research suggests that current atmospheric models underestimate future global warming. Scientists say the estimates don't account for soil decomposition and other natural processes that are expected to escalate in response to ongoing warming, thus amplifying greenhouse gas production.

Currently, the Intergovernmental Panel on Climate Change estimates that the global average temperature could increase as much as 5.8 degrees Celsius by the end of the 21st century. But these estimates don't factor in some feedback mechanisms that may be triggered by rising temperatures. For instance, accelerated decomposition in soils and changes in ocean chemistry may add considerably to greenhouse gases and further intensify warming. Two studies published 26 May in Geophysical Research Letters attempt to translate these potential impacts into hard numbers.

In the first study, biogeochemists Margaret Torn of Lawrence Berkeley National Laboratory in California and John Harte of the University of California, Berkeley, used Antarctic ice cores to estimate the amount of greenhouse gases released into the atmosphere over the past 420,000 years, allowing them to predict the impact of future climate-CO₂ feedbacks. Combining these estimates with standard assumptions from climate models, they calculated the amplification in global temperatures attributable to greenhouse gas feedback. They found that a doubling of current CO₂ levels would boost temperatures by 1.6 to 6 degrees Celsius, and by 2100 the gain could be as much as 7.7 degrees C.

Torn notes that many feedback mechanisms remain poorly understood, and uncertainties abound in trying to predict their effects on climate. But she believes the findings indicate "that we will experience more severe, not less severe, climate change than is currently forecast."