Featured Research

from universities, journals, and other organizations

Climate change from black carbon depends on altitude

Date:
April 14, 2011
Source:
Carnegie Institution
Summary:
Scientists have known for decades that black carbon aerosols add to global warming. These airborne particles made of sooty carbon are believed to be among the largest human-made contributors to global warming because they absorb solar radiation and heat the atmosphere. New research quantifies how black carbon's impact on climate depends on its altitude in the atmosphere.

Scientists have known for decades that black carbon aerosols add to global warming. These airborne particles made of sooty carbon are believed to be among the largest human-made contributors to global warming because they absorb solar radiation and heat the atmosphere. New research from Carnegie's Long Cao and Ken Caldeira, along with colleagues George Ban-Weiss and Govindasamy Bala, quantifies how black carbon's impact on climate depends on its altitude in the atmosphere.

Their work, published online by the journal Climate Dynamics, could have important implications for combating global climate change.

Black carbon is emitted from diesel engines and burning wood, among other sources. In the atmosphere, it acts as an absorbing aerosol -- a particle that absorbs the sun's heating rays. (Other types of aerosols reflect the sunlight back out into space, providing a cooling effect.) The climate effect of black carbon is difficult to quantify because these particles heat the air around them, affecting clouds even before they begin to heat the land and ocean surface.

The team's research involved idealized simulations of adding a theoretical megatonne of black carbon uniformly around the globe at different altitudes in the atmosphere. They found that the addition of black carbon near the land and ocean surface caused the surface to heat. As the altitude of black carbon increased, surface warming decreased. The addition of black carbon to the stratosphere caused the land and oceans to cool. This cooling occurred despite the fact that the black carbon caused Earth as a whole to absorb more energy from the sun. When black carbon is high in the atmosphere, it can lose its energy to space while helping to shade the land and ocean surface.

"Black carbon lower in the atmosphere is more effective at warming the surface, even though black carbon particles at higher altitudes absorb more solar radiation," said Ban-Weiss, formerly of Carnegie and currently at Lawrence Berkeley National Laboratory. He continued: "Just analyzing instantaneous changes in absorption of radiation from black carbon cannot accurately predict changes in surface temperatures. If we want a consistent framework for predicting changes in surface air temperature from black carbon we need to account for rapid atmospheric responses in things like clouds."

Black carbon also had varying effects on precipitation. In the lower layers it increased precipitation and in the upper layers it decreased precipitation, a result of changes in atmospheric stability.

"We showed that black carbon near Earth's surface has the greatest effect on global warming. Unfortunately, this is exactly where we are putting most of the black carbon that we add to the atmosphere," Caldeira said. "This black carbon also often causes health problems, so cleaning up these emissions would help both the environment and human health."

Major sources of black carbon emissions into the lower atmosphere include forest fires, cooking stoves, and emissions from trucks and automobiles. Aircraft are a notable source of emissions to the upper atmosphere.

"This study points out the importance of understanding the complexities of how human activities affect the globe. If we want humans to live well while protecting the environment, we need to understand how our activities affect climate," Caldeira said.


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Journal Reference:

  1. George A. Ban-Weiss, Long Cao, G. Bala and Ken Caldeira. Dependence of climate forcing and response on the altitude of black carbon aerosols. Climate Dynamics, April 2011 DOI: 10.1007/s00382-011-1052-y

Cite This Page:

Carnegie Institution. "Climate change from black carbon depends on altitude." ScienceDaily. ScienceDaily, 14 April 2011. <www.sciencedaily.com/releases/2011/04/110414104215.htm>.
Carnegie Institution. (2011, April 14). Climate change from black carbon depends on altitude. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2011/04/110414104215.htm
Carnegie Institution. "Climate change from black carbon depends on altitude." ScienceDaily. www.sciencedaily.com/releases/2011/04/110414104215.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Virginia Governor Tours Tornado Aftermath

Virginia Governor Tours Tornado Aftermath

AP (July 25, 2014) Virginia Gov. Terry McAuliffe toured the Cherrystone Family Camping and RV Resort on the Chesapeake Bay today, a day after it was hit by a tornado. The storm claimed two lives and injured dozens of others. (July 25) Video provided by AP
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
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:
from the past week

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