Scientists Warn of Abrupt World Climate Change

SAN FRANCISCO (Reuters) - Global climate change, often seen as a process stretching over thousands of years, could in fact occur abruptly and unexpectedly -- quickly pushing up temperatures by as much as 18 degrees Fahrenheit and wreaking havoc on human society, scientists warned on Wednesday.

``Climate change is not always smooth. Sometimes it is abrupt,'' said Richard Alley, a climate expert at Pennsylvania State University and lead author of a new National Academy of Sciences report on the threat of rapid climactic shifts.

``If you have a very large, abrupt change, a lot of people and a lot of ecosystems are going to notice,'' he said. ``The bigger and faster it is, the harder it will be to deal with.''

The new National Academy of Sciences report, released this week, warns that gradual global warming coupled with other human impacts on the environment could ``trip the switch'' for sudden climate change.

At the American Geophysical Union meeting on Wednesday, Alley and other environmental scientists said the geological evidence indicated that such rapid climate shifts had occurred frequently in the past -- moving temperatures drastically in the space of just a few decades.

``This can happen in less than a human generation, and then it will persist for thousands of years,'' said David Battisti, an atmospheric scientist at the University of Washington.

The most immediate dangers posed by abrupt climate change range are devastating droughts and floods which could seriously affect both water supply and agriculture across vast stretches of the planet.

Longer term impacts could include changes in the basic systems which determine regional global temperatures. Scientists believe that the Gulf Stream, a current of warm Atlantic water which now keeps much of Northern Europe temperate, could theoretically reverse direction if enough cool fresh water runs into the north Atlantic from melting ice, a change that would quickly impact European weather.

Researchers briefing the AGU meeting said it was clear that the world's oceans play a major role in queuing up rapid climate changes, but that thus far the mechanics of such changes were poorly understood.

``It's like being blindfolded and walking toward the edge of a cliff,'' said Wallace Broeker, a professor of environmental sciences at Columbia University. ``We don't understand (the factors) so we don't really know what to look for.''

Using ice cores drilled from glaciers and other ice sheets, the researchers have developed a model showing world temperatures spiking and dipping with unsettling frequency over the past 110,000 years.

While some of the changes have been slow and steady, such as the end of the last Ice Age some 12,000 years ago, others have been swift and unexpected, such as the rapid warming of the North Atlantic from 1920 to 1930 and the Dust Bowl drought of the 1930s.

The most drastic temperature changes -- believed to be as much as 18 degrees Fahrenheit over the space of just a few years -- exceed any recorded in human history, they said.

Alley said the report was not intended to alarm the public, but that he hoped it would spur policy makers to prepare for the possibility of rapid temperature flux.

Greenhouse gases, emitted by fossil fuels such as oil and coal, have been linked by many researchers to a rise in global temperatures. A 1997 Kyoto treaty on global warming sought to cut emissions of such gasses by developed nations, but the Bush administration this year spurned the treaty, saying pollution controls would be too costly for the U.S. economy.

The NAS panel called for research to identify what it described as ``no-regrets'' measures that would cost relatively little and would be good policies regardless of the extent of environmental change.

Such measures could include regulations to reduce damage to water, air and land, or slow climate change, or helping societies cope with abrupt climate change by developing new financial instruments such as weather derivatives and catastrophe bonds to reflect the risks, it said.

``Societies have faced both gradual and abrupt climate changes for millennial and have learned to adapt through various mechanisms, such as moving indoors, developing irrigation for crops, and migrating away from inhospitable regions,'' the report said. ``It is important not to be fatalistic about the threats posed by abrupt climate change.''

Well, according to one paragraph in the article

rise of mean temperature of the world ->

melting northern polar ice cap ->

Europe turns into Siberia (or Kamtchaka).

This warm temperature brings really cold weather in the Europe. Then, are we have global warming or global cooling preceded by small global warming ?

It is my guess that initial rise of mean temperature of Earth will create different changes in different parts of Earth. Once I watched a PBS NOVA documentary where a Princeton professor, who was the leading authority in climate modeling, has climate maps which agrees with this idea. Initial temperature change is viewed as a perturbation to the world climate system which are interlocked together. Europe's drastic cooling may be coupled with warming of Manchuria due to Ocean current changes in Pacific. The resulting mean temperature can be anywhere. Climate system is not a terribly stable system. Small changes can create wild gyrations before it settles in a new pattern for a while. Even without human releasing CO2 gas in the atmosphere, the system itself could just well escape out of old pattern on its own after a while.

I think that initial global warming may create cascade climate changes which can be drastic. But it is too much a leap to conclude that we will surely drown ice water from both poles because initial warming will surely results in more temperature increase.

URL for the full report and National Academy of Sciences Press Release (link supplied):

Full Report:

Abrupt Climate Change: Inevitable Surprises

Press Release: Possibility of Abrupt Climate Change Needs Research and Attention

Most climate-change research has focused on gradual changes, such as the processes by which emissions of greenhouse gases lead to warming of the planet. But new evidence shows that periods of gradual change in Earth's past were punctuated by episodes of abrupt change, including temperature changes of about 10 degrees Celsius, or 18 degrees Fahrenheit, in only a decade in some places. Severe floods and droughts also marked periods of abrupt change.

A new report from the National Academies' National Research Council says greenhouse warming and other human alterations of the climate system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events. Researchers do not know enough about such events to accurately predict them, so surprises are inevitable.

If the planet's climate is being forced to change -- as is currently the case -- it increases the number of possible mechanisms that can trigger abrupt events, the report says. And the more rapid the forced change that is taking place, the more likely it is that abrupt events will occur on a time scale that has immediate human and ecological consequences.

There is no need for undue alarm, however, about the possibility of sudden climate change, because societies have learned to adapt to these changes over the course of human history, said the committee that wrote the report. Nevertheless, the committee said research into the causes, patterns, and likelihood of abrupt climate change is the best way to reduce its impact. Overall, research should be aimed at improving modeling and statistical analysis of abrupt changes. An important focus of the research should be on mechanisms that lead to sudden climate changes during warm periods, with an eye to providing realistic estimates of the likelihood of extreme events. Poor countries may need more help preparing for abrupt climate change since they lack scientific and economic resources.

The planet's past climate record also needs to be understood better, according to the report. Scientists have a variety of means to study what the climate was like thousands of years ago. For example, researchers look at tree rings to examine the frequency of droughts and analyze gas bubbles trapped in ice cores to measure past atmospheric conditions. With such techniques, scientists have discovered repeated instances of especially large and abrupt climate changes over the last 100,000 years during the slide into and climb out of the most recent ice age. For instance, the warming at the end of the last ice age triggered an abrupt cooling period, which finished with an especially abrupt warming about 12,000 years ago. Since then, less dramatic -- though still rapid -- climate changes have occurred, affecting precipitation, hurricanes, and the El Niño events that occasionally disrupt temperatures in the tropical Pacific. Examples of abrupt change in the past century include a rapid warming of the North Atlantic from 1920 to 1930 and the Dust Bowl drought of the 1930s.

Simulating abrupt climate changes using computer models is particularly difficult because most climate models respond in a linear manner in which a doubling of the factor forcing change -- greenhouse gases, for instance -- doubles the response. However, abrupt climate changes show that a small forcing may cause a small change, or may force the climate system across a threshold and trigger huge change. A massive discharge of fresh water from lakes dammed by melting ice sheets, which suddenly changes climate conditions worldwide, is an example of threshold-crossing. Chaotic behavior in the climate also may push it across a threshold without any apparent external forcing.

The collapse of some ancient civilizations has been associated with abrupt climate changes, especially severe droughts, but humans have shown great resilience as well. Fast changes make adaptation more difficult, so research should be pursued to identify strategies that reduce vulnerabilities and increase the adaptability of economic and ecological systems, the committee said. It noted that many proactive policies might provide benefits regardless of whether abrupt climate change occurs. Some steps that deserve careful scrutiny include reducing emissions to slow global warming, improving climate forecasting, slowing biodiversity loss, and improving water, land, and air quality.

The report was sponsored by the U.S. Global Change Research Program, with additional support from the National Bureau of Economic Research Program on International Environmental Economics at Yale University. The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering. It is a private, nonprofit institution that provides science and technology advice under a congressional charter. A committee roster follows [click link].

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I say IF it changes THAT much we are all dead so why worry????

I am just a stranger here anyway, Heaven is MY home!