Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

“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 Natural regeneration of tropical forests helps global climate mitigation and forest restoration
23.05.2016 | National Science Foundation

nachricht Researchers find that Earth may be home to 1 trillion species
23.05.2016 | 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: FS POSEIDON startet zur 500. Expedition

Das am GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel beheimatete Forschungsschiff POSEIDON startet diese Woche zu seiner 500. Expedition. Während der Jubiläumsfahrt untersuchen und kartieren Meeresgeologen des MARUM – Zentrum für Marine Umweltwissenschaften der Universität Bremen den Kontinentalhang vor der südfranzösischen Hafenstadt Nizza. Ziel der Arbeiten ist es, die Gefahr von Hangrutschungen und letztendlich auch Tsunamis besser abschätzen zu können.

Am kommenden Mittwoch heißt es wieder einmal „Leinen los“ für die POSEIDON. Von Catania auf Sizilien aus nimmt das 60 Meter lange Forschungsschiff Kurs auf die...

Im Focus: Spinströme: Riesengroß und ultraschnell

Mit einer neuen Methode der TU Wien lassen sich extrem starke Spinströme herstellen. Sie sind wichtig für die Spintronik, die unsere herkömmliche Elektronik ablösen könnte.

In unseren Computerchips wird Information in Form von elektrischer Ladung übertragen. Elektronen oder andere Ladungsträger werden von einem Ort zum anderen...

Im Focus: Researchers demonstrate size quantization of Dirac fermions in graphene

Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices

Quantum mechanics is the field of physics governing the behavior of things on atomic scales, where things work very differently from our everyday world.

Im Focus: Graphene: A quantum of current

When current comes in discrete packages: Viennese scientists unravel the quantum properties of the carbon material graphene

In 2010 the Nobel Prize in physics was awarded for the discovery of the exceptional material graphene, which consists of a single layer of carbon atoms...

Im Focus: Könnten Dämme die schwindenden Gletscher Europas ersetzen?

Stauseen könnten in Zukunft den Wassermangel lindern, der angesichts schwindender Gletscher im Sommer zu erwarten ist. Dies berichtet ein Forscherteam der Eidg. Forschungsanstalt WSL, das die Auswirkungen des Klimawandels auf die Gletscher in den europäischen Alpen simuliert hat. Es kommt zum Schluss, dass zwei Drittel der im Sommer fehlenden Wassermenge durch ein aktives Wassermanagement kompensiert werden könnte.

Viele Flüsse Europas werden von Wasser aus Schnee und Gletschern gespeist. Steigen die Temperaturen, werden schneebedeckte Gebiete kleiner und über kürzere...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Manövrieren sehr großer Schiffe

23.05.2016 | Veranstaltungen

Strategien für die deutsche Produktionsforschung

23.05.2016 | Veranstaltungen

Gesundheit 2.0: Wie Big Data die moderne Medizin verändert

20.05.2016 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

FS POSEIDON startet zur 500. Expedition

23.05.2016 | Geowissenschaften

Neue Prozesskette für Topologieoptimierung im Zerspanungsprozess

23.05.2016 | Verfahrenstechnologie

DFKI-Projekt erfolgreich abgeschlossen – Tauchfahrt in die Tiefen von Jupiters Eismond Europa

23.05.2016 | Messenachrichten