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 23, 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 23, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Raw: Buffalo Residents Digging Out, Helping out

Raw: Buffalo Residents Digging Out, Helping out

AP (Nov. 22, 2014) Hundreds of volunteers joined a 'shovel brigade' in Buffalo, New York on Saturday, as the city was living up to its nickname, "The City of Good Neighbors." Video provided by AP
Powered by NewsLook.com
Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
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