Featured Research

from universities, journals, and other organizations

Protracted Cooling Could Camouflage Effects Of Global Warming

Date:
July 19, 2000
Source:
University Of Illinois At Urbana-Champaign
Summary:
The human contribution to global warming is clearly present and must be controlled, say researchers at the University of Illinois. But there is also another, as-yet-unexplained, cyclic contribution that has important implications for monitoring future climate change

CHAMPAIGN, Ill. -- The human contribution to global warming is clearly present and must be controlled, say researchers at the University of Illinois. But there is also another, as-yet-unexplained, cyclic contribution that has important implications for monitoring future climate change.

Related Articles


"Appearances can indeed be deceiving," said Michael Schlesinger, a UI atmospheric scientist. "If global warming doesn't persist year after year, we shouldn't be fooled into thinking that human effects are no longer of concern. There is something else at work here that we don't yet fully comprehend."

Using a simple climate/ocean model, Schlesinger and his wife, Natalia Andronova -- also an atmospheric scientist at the UI -- calculated the contributions to the observed changes in global-mean, near-surface temperature caused by human and volcano forcing, putative variations in the irradiance of the sun, and the residual temperature change for the years 1856-1997. The researchers published their results in the July 15 issue of Geophysical Research Letters.

"We found that while the human effect has steadily increased -- and is now the dominant external factor -- there also is a residual factor at work within the climate system," Schlesinger said. "This factor played a significant role in the warmings observed during 1904-1944 and 1976-1990."

During both periods, putative variations in solar output played only a minor role in the observed temperature change, the researchers say. Volcanoes were similarly dismissed as the predominant cause.

"Some scientists have conjectured that since there were more volcanoes in the 19th century than in the 20th century, the observed warming trend was due to a decrease in volcanic activity," Andronova said. "But that is not the explanation we came up with. Although volcanic forcing does contribute during 1904-1944, the residual factor is much larger."

The warming observed during 1976-1990 was nearly equally due to human effects and to the residual factor, with volcanoes contributing a cooling, and the sun at most a small warming, Schlesinger said. "The role of the residual factor is even more dominant during 1944-1976, when the human-induced warming was in opposition to the observed cooling."

One plausible explanation for the residual factor was first proposed by Schlesinger and his graduate student Navin Ramankutty six years ago. In the Feb. 24, 1994, issue of Nature, the researchers identified a temperature oscillation that occurred over the North Atlantic Ocean and its adjacent land areas. The oscillation -- which has a period of 65-70 years -- periodically warms and cools the atmosphere, thus sometimes contributing to and sometimes counteracting the greenhouse effect.

"This means there is a very good chance that the present warming will turn around and we will again experience a protracted period of cooling," Schlesinger said. "If we do see that, we should not conclude that the human effect on climate is small or nonexistent -- or that we have eliminated the problem -- and go back to 'business as usual.' We need to be far more intelligent in our response."


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Protracted Cooling Could Camouflage Effects Of Global Warming." ScienceDaily. ScienceDaily, 19 July 2000. <www.sciencedaily.com/releases/2000/07/000719111045.htm>.
University Of Illinois At Urbana-Champaign. (2000, July 19). Protracted Cooling Could Camouflage Effects Of Global Warming. ScienceDaily. Retrieved April 21, 2015 from www.sciencedaily.com/releases/2000/07/000719111045.htm
University Of Illinois At Urbana-Champaign. "Protracted Cooling Could Camouflage Effects Of Global Warming." ScienceDaily. www.sciencedaily.com/releases/2000/07/000719111045.htm (accessed April 21, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Tuesday, April 21, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Going Ape: Sierra Leone Chimpanzees Hail Ebola Retreat

Going Ape: Sierra Leone Chimpanzees Hail Ebola Retreat

AFP (Apr. 21, 2015) As money runs out at Tacugama Chimpanzee Sanctuary in Sierra Leone, around 85 chimps are facing homelessness. The centre closed when the Ebola epidemic was ravaging the country but now that closure is beginning to look permanent. Video provided by AFP
Powered by NewsLook.com
Wild Weather Lashes Sydney Region

Wild Weather Lashes Sydney Region

AFP (Apr. 21, 2015) Sydney and surrounding areas are lashed by wild weather with trees felled, power cuts hitting thousands of homes and sand drifts sweeping inland off the iconic Bondi beach. Duration: 00:50 Video provided by AFP
Powered by NewsLook.com
Deepwater And Dolphins: The Oil Spill's Impact 5 Years On

Deepwater And Dolphins: The Oil Spill's Impact 5 Years On

Newsy (Apr. 20, 2015) Five years on, the possible environmental impact of the Deepwater Horizon spill includes a sustained die-off of bottlenose dolphins, among others. Video provided by Newsy
Powered by NewsLook.com
Pee-Power Toilet to Light Up Disaster Zones

Pee-Power Toilet to Light Up Disaster Zones

Reuters - Innovations Video Online (Apr. 20, 2015) Students and staff are being asked to use a prototype urinal to &apos;donate&apos; urine to fuel microbial fuel cell (MFC) stacks that generate electricity to power lighting. The developers hope the pee-power technology will light toilet cubicles in refugee camps, where women are often at risk of assault in poorly lit sanitation areas. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins