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 Six-decade-old space mystery solved with shoebox-sized satellite called a CubeSat
15.12.2017 | National Science Foundation

nachricht NSF-funded researchers find that ice sheet is dynamic and has repeatedly grown and shrunk
15.12.2017 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>