Featured Research

from universities, journals, and other organizations

Tropical Ocean Warming Drives Recent Northern Hemisphere Climate Change

Date:
April 6, 2001
Source:
National Center For Atmospheric Research
Summary:
A progressive warming of tropical oceans, likely due to the buildup of greenhouse gases in the atmosphere, is driving major climate changes observed in the Northern Hemisphere since 1950, according to a new study published in the April 6 issue of the journal Science.

BOULDER -- A progressive warming of tropical oceans, likely due to the buildup of greenhouse gases in the atmosphere, is driving major climate changes observed in the Northern Hemisphere since 1950, according to a new study published in the April 6 issue of the journal Science.

Related Articles


"We believe the link between tropical ocean warming and the Northern Hemisphere climate trend may be a signal of human-induced climate change that has just begun to emerge in the last 50 years," say lead authors James Hurrell of the National Center for Atmospheric Research (NCAR) and Martin Hoerling of the Commerce Department's National Oceanic and Atmospheric Administration (NOAA).

The key player in this climate trend is the North Atlantic Oscillation (NAO), an atmospheric pressure seesaw between Iceland at one end and Spain and Portugal at the other.

Studies of predicted early impacts of increased greenhouse gases have shown a warming trend in the tropical oceans. Observations have revealed such a trend beginning around 1950. By analyzing results of a number of experiments using global climate models, Hoerling and Hurrell have found a correlation between these warmer sea-surface temperatures and climate changes in the Northern Hemisphere winter over the same period.

The experiment indicates that warmer waters, especially in the Pacific and Indian Oceans, produce more equatorial rain, which heats the tropical atmosphere. "It turns out that this exerts a strong control on the atmospheric pressure pattern and winds over the North Atlantic and North Pacific," says Hoerling, of NOAA's Climate Diagnostics Center. "In fact, it has forced the NAO to maintain a single phase in recent decades." Resulting changes in circulation have warmed land surfaces and shifted storm tracks farther north.

"The Northern Hemisphere surface temperature has shown a warming trend over the past several decades to values that are perhaps unprecedented over the past 1,000 years," write the authors, and the NAO change has been a key player in this.

Gradually, additional effects on climate have emerged. Winters in northern Europe and Scandinavia have grown wetter, while those in southern Europe and the Middle East have become dryer. European farmers have encountered an earlier and longer growing season. The habitats and life cycles of many marine and terrestrial species have changed.

Hoerling and Hurrell are now trying to find the physical mechanism that accounts for the tropical oceans' long-distance effects on northern atmospheric circulation. A critical component is the NAO, which controls winter weather in Europe and over much of the Northern Hemisphere.

"Until recently scientists believed the NAO was entirely chaotic, random, and unpredictable," says Hurrell. "No one paid much attention to it." All that changed in 1995 when Hurrell found that the NAO's winter-to-winter variations cloaked an underlying trend extending over several decades. That trend was soon correlated to changes in weather, agriculture, and wildlife from Canada to Siberia and from the Arctic to northern Africa.

Through the 1980s and 1990s, the NAO entered and maintained a largely "positive" phase characterized by stronger-than-average westerly winds across the middle latitudes of the Atlantic Ocean and into Europe, southerly flow over the eastern United States, and northerly flow across western Greenland, the Canadian Arctic, and the Mediterranean. Building on several attempts to explain the shift from its "negative" phase during the 1950s and 1960s, Hoerling and Hurrell have now found warming tropical oceans to be the driver.

NOAA's Office of Global Programs funded the study. NCAR's primary sponsor is the National Science Foundation.


Story Source:

The above story is based on materials provided by National Center For Atmospheric Research. Note: Materials may be edited for content and length.


Cite This Page:

National Center For Atmospheric Research. "Tropical Ocean Warming Drives Recent Northern Hemisphere Climate Change." ScienceDaily. ScienceDaily, 6 April 2001. <www.sciencedaily.com/releases/2001/04/010406073554.htm>.
National Center For Atmospheric Research. (2001, April 6). Tropical Ocean Warming Drives Recent Northern Hemisphere Climate Change. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2001/04/010406073554.htm
National Center For Atmospheric Research. "Tropical Ocean Warming Drives Recent Northern Hemisphere Climate Change." ScienceDaily. www.sciencedaily.com/releases/2001/04/010406073554.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) — Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) — A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber 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