April 11, 2000 - AP

U.S. and European researchers have discovered a greenhouse gas with frightful characteristics - it is 18,000 to 22,200 times more powerful than carbon dioxide, and it has an atmospheric life estimated at 3,500 years.

Ole John Nielsen of the Chemical Institute at Copenhagen University presented the findings at a recent conference on greenhouse gases hosted by the Society of Danish Engineers' chemistry group. A paper has been submitted to the journal Science.

The gas, SF5CF3 -- or trifluoromethylsulphur pentafluoride -- lurks in the atmosphere between 5 and 20 miles above the Earth's surface. It was first noted in an analysis of stratospheric air samples as an unexpected reading close to SF6, or sulphur hexafluoride, a more common industrial gas.

Like SF6, SF5CF3 is a gas that can absorb heat radiating from the Earth's surface, what scientists call greenhouse gases.

Traces of SF5CF3 and SF6 were also found in deep snow in remarkably similar concentrations. SF6 concentrations have been measured for a number of years, leading the researchers to conclude that the concentration of SF5CF3 has grown from almost nothing in the late 1960s to 0.12 parts per trillion -- 10 to power of 12 -- in 1999.

Tim Wallington of the Ford Motor Company's chemical laboratories, one of the researchers, says, "... We don't know where SF5CF3 comes from, which is worrying. But it must be connected with human activity."

They think the new greenhouse gas may be a by-product of the manufacture or decomposition of SF6, an electrical insulator in transformers and similar high-voltage electrical equipment. It may derive from CF4, which is released in aluminum production.

"Most of the important greenhouse gases -- carbon dioxide, methane and nitrous oxide -- occur naturally. While we're pumping more of them into the atmosphere, there are natural processes that can remove them, allowing the atmosphere to regain its natural balance," says Vincent Gauci of the department of earth sciences and the Center for Ecology and Hydrology at Britain's Open University.

"However, this new molecule is unnatural and seems to be extremely stable, so the atmosphere has a hard time breaking it down. While it doesn't seem to be having much of an effect right now, the fact that it has such a long lifetime means that unless its production is prevented it will continue to accumulate and so may have a larger effect in the future," Gauci says.

The researchers come from the Ford Motor Company, Germany's Max Planck Institute and J. W. Goethe University, the British universities of Reading and East Anglia, the CNRS Laboratoire de Glaciologie et Geophysique de l'Environment in France, and the British Antarctic Survey.

February 17, 2000 - BBC

Studies of temperature records preserved deep in underground rocks show that the Earth has been gradually warming over at least the last 500 years.

And the studies, by scientists in the US and Canada, show that the trend accelerated markedly during the 20th Century, which was the warmest of the past five centuries.

Since 1500, the Earth's temperature has increased by about one degree Celsius, with half of that increase occurring in the last century.

Trend picks up

The warming trend is speeding up

Almost 80% of the net temperature increase observed occurred in the 19th and 20th centuries.

In the Northern Hemisphere, the five-century change has been 1.1 degrees, with 0.6 recorded since 1900.

The studies, reported in the science journal Nature, are based on analysis of borehole temperatures from 616 sites on every continent except Antarctica.

The scientists lowered sensitive thermometers into holes drilled down from ground level to discover how surface temperature altered in the past. A typical borehole was measured at 10-metre depth intervals down to as far as 600 m.

Records preserved

The technique is possible because of heat conduction, which means that temperature changes at the surface generate "signals" that penetrate subterranean rocks.

The signals from short-term daily or seasonal variations penetrate only a few metres and are rapidly lost. But changes over centuries are preserved in deeper rock, although the signals travel very slowly, penetrating only about 500 metres in 1,000 years.

One of the team, Professor Henry Pollack of the University of Michigan, said: "The upper 500 metres is an archive. Like any historical archive, there are of course missing pages, and the ink has run in a few places.

"But in principle, if you drilled a borehole anywhere on a continent, you could observe a temperature profile and be able to reconstruct what had happened at that location."

The team's work involved calculating averages from all the boreholes investigated, and built on a previous analysis of borehole temperature data from 358 sites.

The scientists also compared their results with those obtained from other methods of estimating past temperature change, including studies of tree rings, ice cores, lake sediments and coral growth.

"All the methods generally show a very unusual 20th Century, and ours does too," said Professor Pollack. "It is the warmest century of the last five, and the one which is most rapidly changing."

Forecast re-inforced

"What we show that is somewhat different is that the total temperature change over the past five centuries has been greater than some of the other methods are showing."

In an accompanying article in Nature, Jonathan Overpeck, of the University of Arizona, Tucson, says the team's results re-inforce the forecast for this century: continued warming ahead.

"But they also provide unsettling indications that human alteration of the climate system over the past century will make the reliable prediction of climate change an even tougher business than expected.

"Their analysis is the latest of several to indicate that late 20th Century warming is without precedent in the past 400 to 1,000 years.

"We do not know of any combination of natural mechanisms that can explain this phenomenon. So we are left with the likelihood that human-induced global warming is under way."

And he adds a warning. "The results show yet again that the 20th Century record of climate variability is too short and cloaked with human-induced influences to provide a clear indication of natural climate variability.

"Earlier studies may have underestimated the full amplitude of natural decade-to century-scale climate variability."

March 26, 1999 - AP - Washington

A temperature change of only a few degrees can disrupt a community of animals, according to a researcher who studied how hot and cold affects the delicate balance of starfish and mussels in Oregon's tidal waters.

Eric Sanford of Oregon State University said his study, published today in the journal Science, suggests that if a key species in a community of animals is particularly sensitive to temperatures, a slight warming or cooling can start a whole cascade of rapid changes affecting every animal in an ecosystem.

Sanford said in an interview that he found a 5-degree change in temperature is enough to change dramatically the feeding habits of the starfish, a five-armed creature that feeds mainly on mussels and is common along the Pacific coast of the United States. The finding, said Sanford, has important implications for understanding the effects of global warming.

``Many people have assumed that the effects of climate change would be gradual,'' the researcher said in an interview. ``But this shows that if an important species in a community is highly sensitive to temperature, then the effects of a small temperature change can happen rapidly.''

In his study, Sanford tracked the feeding patterns of starfish kept in the laboratory at different temperatures. He checked his results by manipulating the population of starfish and mussels in two areas along the Oregon coast. Sanford found that a temperature drop of 5 degrees caused the starfish to virtually stop feeding on the mussels. This allows the mussels to rapidly expand in population. Conversely, when the water temperature was increased by 5 degrees, Sanford said starfish went on a feeding binge, quickly reducing the population of mussels. Either way, he said, there are dramatic changes in the tidal community of animals.

When mussels are not controlled by starfish, said Sanford, their population explodes. The mussels attach themselves to every surface in the near-shore tidal zone, crowding out barnacles, algae and other organisms.

When starfish eat too much, he said, the reef-like mussel communities quickly start falling apart. These reefs, Sanford said, are homes for crab, sea cucumbers and worms, all important parts of the ecosystem.

Temperatures along the Oregon coast are affected by upwelling, cold deep waters surging to the surface. The frequency of upwellings, said Sanford, is determined by winds that, in turn, are affected by global temperatures.

If cold upwellings become less frequent, starfish may eat more mussels, said Sanford; if the upwellings happen more often, thus cooling the tidal waters, starfish will eat less, allowing the mussel population to suddenly explode.

Reuters - Washington - March 10, 1999

The 1990s were the warmest decade of the millennium, with 1998 the warmest year so far, researchers said Wednesday. The study adds to a growing body of evidence that the global climate has been getting steadily warmer, especially the last half of the 20th century.

"Temperatures in the latter half of the 20th century were unprecedented," Raymond Bradley of the University of Massachusetts said in a statement.

Their report, published in Geophysical Research Letters, shows that temperatures dropped an average of 0.02 degrees C (0.04 degree F) per century for the 900 years before the 20th century.

Because human climate records only go back a few hundred years, and do not cover the whole globe, the team at the University of Massachusetts and the University of Arizona looked at measurements other scientists have made of tree rings, ice cores and other "proxy indicators" that record climate variations.

They heavily relied on three sets of 1,000-year-long tree-ring records from North America, as well as tree rings from northern Scandinavia, northern Russia, Tasmania, Argentina, Morocco, and France.

The ice cores they studied came from Greenland and the Andes mountains in South America.

"As you go back farther in time, the data become sketchier," Michael Mann of the University of Massachusetts said. "One can't quite pin things down as well, but our results do reveal that significant changes have occurred, and temperatures in the latter 20th century have been exceptionally warm compared to the preceding 900 years."

He said the records were not perfect, but complete enough to show "startling revelations." "If temperatures change slowly, society and the environment have time to adjust," he said. "The slow, moderate, long-term cooling trend that we found makes the abrupt warming of the late 20th-century even more dramatic.

"The cooling trend of over 900 years was dramatically reversed in less than a century. The abruptness of the recent warming is key, and it is a potential cause for concern."

In January the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) said they had established that 1998 was the warmest year on record. But their finding was based on records only going back 120 years.

In January the American Geophysical Union, which publishes Geophysical Research Letters, called for continued efforts to curb human-made carbon emissions to stop global warming.

In December the World Meteorological Organization (WMO) said the earth's mean surface temperature in 1998 was 0.58 degrees C above the average for the benchmark period 1961-90. For the century, global temperatures were almost 0.7 degrees C above those at the end of the 19th century.

A warmer global climate melts the ice caps, raising sea levels, and disturbs weather patterns, causing droughts, severe storms, tornadoes, hurricanes and blizzards.

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