But members of both modeling teams said their results were so robust, and the match to the rise in greenhouse gases was so clear, that more detail was unlikely to make a difference.

April 13, 2001

Studies Tie Rise in Ocean Heat to Greenhouse Gases

By ANDREW C. REVKIN

sing two different computer simulations of climate and the oceans, separate research teams have concluded that a buildup of heat in the seas over the last five decades was almost certainly caused by the heat- trapping effect of greenhouse gases released into the air by human activities.

The findings provide new evidence that people, mainly through the burning of fossil fuels, have caused at least a substantial portion of a global warming measured since the 1950's, several independent experts on climate models said.

The work is described in two papers in today's issue of the journal Science. The raw data on the oceans' rising heat were published last year, but the two new studies were the first to offer an explanation for what influence, natural or otherwise, accounted for them.

The computer models used in the research were among the world's most advanced efforts to recreate the behavior of earth's climate system and so study how changes in the atmosphere might change weather patterns. Even so, they are relatively rough sketches of the real world.

In fact, some climate experts said the papers' conclusions were overstated, a result, they said, of the computer models' lacking sufficient detail to deal with small but potentially important changes in ocean conditions.

But an author of one study, Dr. Tim P. Barnett, said the findings were strong enough to overcome his long skepticism about the models' ability to pinpoint a human influence amid all the naturally chaotic ups and downs of climate.

Dr. Barnett, a marine physicist at the Scripps Institution of Oceanography, in San Diego, said in an interview that he was now convinced that people were contributing to global warming.

"I was maybe 60-40 before, but I'm at least 90-10 now," he said. "The chances that our model could have done this by itself are virtually nil."

He added that the ability of the two computer simulations to reproduce the warming actually measured in the oceans in recent decades indicated that these models were valid tools for projecting how the continuing emission of greenhouse gases might spur further climate changes in coming decades.

This is important because the models, and others like them, are the basis for many of the forecasts being used by experts to recommend how forcefully societies must move to reduce emissions of carbon dioxide and other greenhouse gases.

At least one aspect of the new studies bears directly on that question. Dr. Barnett and other scientists said the analyses supported the idea that by absorbing most of the heat trapped by greenhouse gases in the air above, the oceans could act as a strong buffer against abrupt climate warming.

"The immediate impact may not be as great, because the oceans may slow things down a little," he said. But eventually that heat will be released from the ocean's surface back into the air, he and others said.

The other modeling study was led by Dr. Sydney Levitus, director of the National Oceanic and Atmospheric Administration's ocean climate laboratory, in Silver Spring, Md. It was Dr. Levitus who collated the millions of accumulated temperature measurements, taken around the world's oceans, that detected the heat rise.

Other scientists said the new analyses showed the importance of Dr. Levitus's decade-long effort.

"In putting together this global data set, he's like a national treasure," said one expert on computer climate models, Dr. Andrew Weaver, a professor of atmospheric science at the University of Victoria, in British Columbia.

Dr. Weaver said previous efforts to identify human interference with the climate system had focused on changes in air temperature, which varies enormously day to day, year to year, in ways that hide clues.

The oceans, in sharp contrast, are a vast long-term repository for heat absorbed from the air, and so exhibit little confounding variability, he said.

"This is a much more convincing approach," he said. "It's not only consistent with the land-based detection schemes, but it doesn't suffer from the problems of being clouded by the noise that critics always focus on."

Even so, some scientists said they were concerned that such similar results could emerge from models that deal very differently with forces affecting climate. For example, the model used by Dr. Levitus's group included the sun-blocking effect of volcanic emissions that have punctuated recent decades, while the model used by Dr. Barnett did not.

Others had different criticisms. Chris N. Hill, a designer of ocean computer models at the Massachusetts Institute of Technology, said, "The models being used, although state of the art, still represent the ocean as a viscous oil-like fluid, rather than the turbulent and highly variable real ocean."

But members of both modeling teams said their results were so robust, and the match to the rise in greenhouse gases was so clear, that more detail was unlikely to make a difference.

Copyright 2001 The New York Times Company

-- Real Science (for@change.com), April 13, 2001

Answers

Environment & Climate News April 2001 Contents New evidence casts doubt on global warming

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Claims are "based on false data," international team of scientists says

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by Robert Matthews

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Fresh doubt has been cast on evidence for global warming following the discovery that a key method of measuring temperature change has exaggerated the warming rate by almost 40 percent.

Studies of temperature records dating back more than a century have seemed to indicate a rise in global temperature of around 0.5C, with much of it occurring since the late 1970s. This has led many scientists to conclude global warming is under way, with the finger of blame usually pointed at man-made emissions of such greenhouse gases as carbon dioxide.

Now an international team of scientists, including researchers from the Met Office in Bracknell, Berkshire, United Kingdom, has found serious discrepancies in the temperature measurements, suggesting that the amount of global warming is much less than previously believed.

Measuring water, not air

The concern focuses on the temperature of the atmosphere over the oceans, which cover almost three-quarters of the Earth's surface. While scientists use standard weather station instruments to detect warming on land, they have been forced to rely on the crews of ships to make measurements over the vast ocean regions.

Crews have taken the temperature by dipping buckets into the sea or using water flowing into the engine intakes. Scientists have assumed there is a simple link between the temperature of seawater and that of the air above it.

However, after analyzing years of data from scientific buoys in the Pacific that measure sea and air temperatures simultaneously, the team has found no evidence of a simple link. Instead, the seawater measurements have exaggerated the amount of global warming over the seas, with the real temperature having risen less than half as fast during the 1970s than the standard measurements suggest.

Reporting their findings in the influential journal Geophysical Research Letters, the scientists say the exact cause of the discrepancy is not known. One possibility is that the atmosphere responded faster than the sea to cooling events such as volcanic eruptions.

A big cut

The findings have major implications for the climate change debate because sea temperature measurements are a key part of global warming calculations. According to the team, replacing the standard seawater data with the appropriate air data produces a big cut in the overall global warming rate during the last 20 years, from around 0.18C per decade to 0.13C.

This suggests that the widely quoted global warming figure used to persuade governments to take action on greenhouse gas emissions exaggerates the true warming rate by almost 40 percent. The team is now calling for climate experts to switch from seawater data to sea- air temperature measurements.

One member of the team, David Parker, of the Hadley Centre for Climate Prediction and Research at the Met Office, said the discovery of the discrepancy "shows we don't understand everything, and that we need better observations--all branches of science are like that." Yet according to Parker, the new results do not undermine the case for global warming: "It is raising questions about the interpretation of the sea-surface data."

Even so, the findings will be seized on by skeptics as more evidence that scientists have little idea about the current rate of global warming, let alone its future rate. Climate experts are still trying to explain why satellites measuring the temperature of the Earth have detected little sign of global warming, despite taking measurements during supposedly the warmest period on record.

Some researchers suspect the fault may again lie with the ground- based temperature measurements. They say many of the data come from stations surrounded by growing urban sprawl, whose warmth could give a misleading figure. A study of data taken around Vienna, Austria, between 1951 and 1996 found that the air temperature rose by anything from zero to 0.6C, depending on precisely where the measurements were made.

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Robert Matthews is a staff reporter for the UK Telegraph, with whose permission this article is reprinted.

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Return to April 2001 contents.

-- Carlos (riffraff@cybertime.net), April 13, 2001.

I guess everybody can just walk to work. Admit it - the ones who would scream the loudest about losing their standard of living are the most left-wing entitlement sucking bunch. Barbara Streisand would last all of one hour without her limos and mansions.

-- libs are idiots (moreinterpretation@ugly.com), April 13, 2001.

OK, I'm sorry, I'll stop peeing in the ocean.

-- Uncle Deedah (unkeed@yahoo.com), April 14, 2001.