Earth Science News  





. Like It Or Not, Uncertainty And Climate Change Go Hand-In-Hand

While the new equation will help scientists quickly see the most likely impacts, it also shows that far more extreme temperature changes - perhaps 15 degrees or more in the global mean - are possible, though not probable. That same result also was reported in previous studies that used thousands of computer simulations, and the new equation shows the extreme possibilities are fundamental to the nature of the climate system. Much will depend on what happens to emissions of carbon dioxide and other greenhouse gases in the future. Since they can remain in the atmosphere for decades, even a slight decrease in emissions is unlikely to do more than stabilize overall concentrations, Roe said.
by Staff Writers
Tacoma WA (SPX) Oct 26, 2007
Despite decades of ever more-exacting science projecting Earth's warming climate, there remains large uncertainty about just how much warming will actually occur. Two University of Washington scientists believe the uncertainty remains so high because the climate system itself is very sensitive to a variety of factors, such as increased greenhouse gases or a higher concentration of atmospheric particles that reflect sunlight back into space.

In essence, the scientists found that the more likely it is that conditions will cause climate to warm, the more uncertainty exists about how much warming there will be.

"Uncertainty and sensitivity have to go hand in hand. They're inextricable," said Gerard Roe, a UW associate professor of Earth and space sciences. "We're used to systems in which reducing the uncertainty in the physics means reducing the uncertainty in the response by about the same proportion. But that's not how climate change works."

Roe and Marcia Baker, a UW professor emeritus of Earth and space sciences and of atmospheric sciences, have devised and tested a theory they believe can help climate modelers and observers understand the range of probabilities from various factors, or feedbacks, involved in climate change. The theory is contained in a paper published in the Oct. 26 edition of Science.

In political polling, as the same questions are asked of more and more people the uncertainty, expressed as margin of error, declines substantially and the poll becomes a clearer snapshot of public opinion at that time. But it turns out that with climate, additional research does not substantially reduce the uncertainty.

The equation devised by Roe and Baker helps modelers understand built-in uncertainties so that the researchers can get meaningful results after running a climate model just a few times, rather than having to run it several thousand times and adjust various climate factors each time.

"It's a yardstick against which one can test climate models," Roe said.

Scientists have projected that simply doubling carbon dioxide in the atmosphere from pre-Industrial Revolution levels would increase global mean temperature by about 2.2 degrees Fahrenheit. However, that projection does not take into account climate feedbacks - physical processes in the climate system that amplify or subdue the response. Those feedbacks would raise temperature even more, as much as another 5 degrees F according to the most likely projection. One example of a feedback is that a warmer atmosphere holds more water vapor, which in itself is a greenhouse gas. The increased water vapor then amplifies the effect on temperature caused by the original increase in carbon dioxide.

"Sensitivity to carbon dioxide concentration is just one measure of climate change, but it is the standard measure," Roe said.

Before the Industrial Revolution began in the late 1700s, atmospheric carbon dioxide was at a concentration of about 280 parts per million. Today it is about 380 parts per million and estimates are that it will reach 560 to 1,000 parts per million by the end of the century.

The question is what all that added carbon dioxide will do to the planet's temperature. The new equation can help provide an answer, since it links the probability of warming with uncertainty about the physical processes that affect how much warming will occur, Roe said.

"The kicker is that small uncertainties in the physical processes are amplified into large uncertainties in the climate response, and there is nothing we can do about that," he said.

While the new equation will help scientists quickly see the most likely impacts, it also shows that far more extreme temperature changes - perhaps 15 degrees or more in the global mean - are possible, though not probable. That same result also was reported in previous studies that used thousands of computer simulations, and the new equation shows the extreme possibilities are fundamental to the nature of the climate system.

Much will depend on what happens to emissions of carbon dioxide and other greenhouse gases in the future. Since they can remain in the atmosphere for decades, even a slight decrease in emissions is unlikely to do more than stabilize overall concentrations, Roe said.

"If all we do is stabilize concentrations, then we will still be risking the highest temperature change shown in the models," he said.

Community
Email This Article
Comment On This Article

Related Links
University of Washington
Climate Science News - Modeling, Mitigation Adaptation




Tempur-Pedic Mattress Comparison

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News
White House defends 'health benefits' of climate change
Washington (AFP) Oct 25, 2007
The White House on Thursday defended its prediction that climate change would bring some "health benefits" to humans, a forecast unlikely to endear it to critics of the US environmental record.

.
Get Our Free Newsletters Via Email
  



  • Study Shows Housing Development On The Rise Near National Forests
  • On fires, Bush looks to smother Katrina debacle
  • Healing The Wounds Of War: Novel Phytochemical Agent Enhances, Improves Process Of Wound Healing
  • White House: Katrina lessons applied to California fires

  • White House defends 'health benefits' of climate change
  • Like It Or Not, Uncertainty And Climate Change Go Hand-In-Hand
  • North Atlantic Slows On The Uptake Of CO2
  • Rise In Atmospheric CO2 Accelerates As Economy Grows, Natural Carbon Sinks Weakening

  • NASA Views Southern California Fires And Winds
  • A Roadmap For Calibration And Validation
  • GeoEye Contract With ITT Begins Phased Procurement Of The GeoEye-2 Satellite
  • Key Found To Moonlight Romance

  • Sarkozy backs 'carbon tax' to fight climate change
  • Darfur rebel group kidnaps foreign oil workers
  • Analysis: Nigeria mulls oil-deal review
  • Analysis: Azerbaijan looks to stash cash

  • AIDS stunting southern Africa's prospects: Malawi president
  • After extinction fears, Botswana learns to live with AIDS
  • West Nile Virus Spread Through Nerve Cells Linked To Serious Complication
  • New Model Predicts More Virulent Microbes

  • Meteor No Longer Prime Suspect In Great Extinction
  • St. Bernard Study Casts Doubt On Creationism
  • Life's Early Vision
  • Researchers Studying How Singing Bats Communicate

  • Space Sensors Shed New Light On Air Quality
  • Pitt Professor Says Harmful Byproducts Of Fossil Fuels Could Be Higher In Urban Areas
  • Analysis: Olympics and Beijing pollution
  • Scientists Estimate Mercury Emissions From US Fires

  • Video Game Shown To Cut Cortisol
  • Researchers Find Earliest Evidence For Modern Human Behavior In South Africa
  • Family trees flourish on the Internet
  • Genetic Ancestral Testing Cannot Deliver On Its Promise

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement