Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

“Albedo effect” in forests can cause added warming, bonus cooling

20.10.2011
Wildfire, insect outbreaks and hurricanes destroy huge amounts of forest every year and increase the amount of carbon dioxide entering the atmosphere, but scientists are now learning more about another force that can significantly affect their climate impact.

Researchers conclude in a new study that the albedo effect, which controls the amount of energy reflected back into space, is important in the climatic significance of several types of major forest disturbances.

In some cases – mostly in boreal forests with significant snow cover – increases in reflectivity can provide cooling. If the area disturbed by fire or insects is large, this cooling can substantially offset the increase in global warming that would otherwise be caused by these forest disturbances and the release of greenhouse gases. In other cases where the ground itself is unusually dark, albedo decreases can magnify concerns about warming.

Wildfires are not the only disturbance that significantly alters surface albedo, this study concluded. Insect outbreaks and defoliation by hurricanes can also change surface reflectivity, with effects on climate as great as those caused by carbon dioxide release from the disturbed area.

“On a global scale, warming caused by increased carbon dioxide still trumps everything else,” said Beverly Law, a professor in the Department of Forest Ecosystems and Society at Oregon State University. “On a smaller or local scale, however, changes in albedo can be fairly important, especially in areas with significant amounts of snow, such as high latitudes or higher elevations.”

Albedo is a measure of radiation reflected by a surface, in this case the surface of the planet. Lighter colors such as snow reflect more light and heat back into space than the dark colors of a full forest and tree canopy.

“This decreased absorption of heat by the land surface is a local atmospheric cooling effect,” said Tom O’Halloran, a recent postdoctoral research at OSU who is now with the Department of Environmental Studies at Sweet Briar College. “This was clear in one case we studied of trees killed by mountain pine beetles in British Columbia.

“In areas with substantial snow cover, we found that canopy removal due to either fire or insect attack increased reflected radiation and approximately offset the warming that would be caused by increased release of carbon dioxide,” O’Halloran said. “However, we haven’t been able to measure the full impact from the current beetle outbreak, which could take decades to complete.”

This complex phenomenon would be much less in lower latitudes or areas without snow for much of the year, the researchers said. It relates primarily to boreal or colder mid-latitude forests, such as the Canadian insect outbreak over 374,000 square kilometers of forest.

“The impacts of insects on forest carbon dynamics and resulting changes in albedo are generally ignored in large-scale modeling,” Law said.

The study also found that forest disturbance does not always cause an albedo increase. When Hurricane Wilma in 2005 partially defoliated more than 2,400 square kilometers of a mangrove forest in the Florida Everglades, it exposed an underlying land surface darker than the previous forest canopy. In that case, an albedo decrease effectively doubled the warming impact of released carbon dioxide.

All of the forces studied in this research – fire, insect attack and hurricanes – are expected to increase in severity, frequency or extent under climate change scenarios, the scientists said. In the United States alone, these events affect 20,000 to 40,000 square kilometers of forest a year. If Earth system models are to be accurate, this makes it important to more accurately incorporate changes in albedo.

Globally, forest disturbances are a major factor in the carbon cycle and greenhouse gas warming. They can instantly switch forests from carbon sinks into carbon sources for two decades or more. In cold regions where forest recovery is slower, albedo increases can persist for 100 years.

This research was published in Global Change Biology, a professional journal. It was supported by the U.S. Department of Energy, and used data from both the AmeriFlux Network and NASA MODIS sensor on the Terra satellite.

About the OSU College of Forestry: For a century, the College of Forestry has been a world class center of teaching, learning and research. It offers graduate and undergraduate degree programs in sustaining ecosystems, managing forests and manufacturing wood products; conducts basic and applied research on the nature and use of forests; and operates 14,000 acres of college forests.

Media Contact
David Stauth,
541-737-0787
Source
Beverly Law, 541-737-6111

Beverly Law | EurekAlert!
Further information:
http://www.oregonstate.edu

More articles from Earth Sciences:

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

nachricht New atlas provides highest-resolution imagery of the Polar Regions seafloor
25.04.2017 | British Antarctic Survey

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Early organic carbon got deep burial in mantle

25.04.2017 | Earth Sciences

A room with a view - or how cultural differences matter in room size perception

25.04.2017 | Life Sciences

Warm winds: New insight into what weakens Antarctic ice shelves

25.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>