http://www4.nas.edu/news.nsf/isbn/0309074347?OpenDocument

Date: Dec. 11, 2001

Contacts: Bill Kearney, Media Relations Officer

Andrea Durham, Media Relations Assistant

(202) 334-2138; e-mail < news@nas.edu>



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.

Read the full text of Abrupt Climate Change: Inevitable Surprises on the Internet at < http://www.nap.edu>. Copies of the report will be available for purchase early next year from the National Academy Press; tel. (202) 334-3313 or 1-800-624-6242. Reporters may obtain a pre-publication copy from the Office of News and Public Information (contacts listed above).

homepage: homepage: http://www.prototista.org/E-Zine/climatechange.htm

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add a comment on this article

"............societies have learned to adapt....." 03.May.2005 11:08

Messenger link

They adapted alright! In the most recent "Mini Ice Age" about 500 years ago they were forced to eat rotting maggot filled dead horses and roots before many thousands died of starvation.

The "surprise" this article talks about is how suprised you will be how many people turn to canniblism. That is what we or most likely our children and grandchildren have to look forward to.

But our government feels it needs more study.

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That's a fact! 03.May.2005 12:10

D. Burbeck link

The mini ice age lasted less than ten years, but the growing season failed all over Europe and scientists found evidence of severe drought in North America.

They believe now that these events are all closely tied to the Atlantic Conveyor which, if it shuts down, fails to circulate tropical warmth to the upper lattitudes.......and the growing season is sharply reduced.

This idea of abrupt climate change needs no further study at all. What needs study is why people are not marching on Washington DC demanding immediate changes!

This knowledge is why we now have a neo-con take over of the Federal Government changing things for the filthy rich........who are beginning to worry about the future finally.

A repeat of the Dust Bowl? Ah, I can see it now - a repeat of the Grapes of Wrath with BA, Fresca and the other Cheetos Boys on their way from wherever they live to Bakersfield in various jalopies, hoping to find work picking fruit. Doubtless they will run out of water and food and be forced to stop at various encampments of Mexican or Chicano farmworkers (perhaps undocumented) in order to beg for provisions. Brutal sheriff's deputies will run them out of town in cities like Wasco and Taft, suspecting them of being Okie drifters. Once they reach Bakersfield they will be put to work in the nearby grape or cotton fields, and they will get to find out what unregulated capitalism is really like for workers. So maybe even the horror of sudden climatic change might have at least some positive results.

i have 20 that the liberals develop a fetish over this.

You right-wingers have a fetish for Ann Coulter's legs and for gas-hog suvs.

coulters legs are probably awesome, based on what i seen of the rest, don't you think?

gas hog suvs, naaaah i got a beatup ole pickup(ford), little maintenance and just dump the gas in and drive. I drive a pickup for the guns(lotta feudin) and groceries(19 kids) and the bibles.

What you drive?

I use public transit or I walk.

And those of us who don't use cars if we can possibly avoid it should pay more and more taxes for an ever-growing freeway/expressway system, right? When any construction of rapid transit trains or purchase of public buses is viewed as shocking extravagance. And 18 year old kids who often could not afford a car even if they wanted one should go on getting killed in Iraq to secure the fuel supply.

If I developed the same "winning qualities" and positive attitude that you have I'd be sitting in my Mom's home posting messages that blame immigrants, Muslims, labor union members and "leftists" for my problems and faiures in life. And I would be trying to convince other people that my own prejudices and bigotry represent reality, not the sick product of my churning, malfunctioning, hate-filled brain.

filcher: "What do I drive? A BMW 530i 2002"

...playing with Hot Wheels cannot be called "driving"...

If I developed the same "winning qualities" and positive attitude that you have I'd be sitting in my Mom's home posting messages that blame immigrants, Muslims, labor union members and "leftists" for my problems and faiures in life.

Obviously, the Right isn’t waiting for government handouts, as you claim. Quite the opposite...we’re the prime movers, builders and entrepreneurs of this society.

The drag on the economy is caused by professional parasites of the left who have made a living off of whining like spoiled children.

Thank God you're out of power.

William F. Buckley Jr., Ann Coulter, George Bush 1 and George Bush 2, also Jeb Bush all had rich daddies who paid for their Ivy League educations. But they all think that other people should pull themselves up by their bootstraps - perhaps by serving in Iraq to get the "privelege" of a higher education at a state university or community college. One set of rules for spoiled brats born with silver spoons in their mouths, another for everyone else.