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 In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Hochpräzise Verschaltung in der Hirnrinde

Es ist noch immer weitgehend unbekannt, wie die komplexen neuronalen Netzwerke im Gehirn aufgebaut sind. Insbesondere in der Hirnrinde der Säugetiere, wo Sehen, Denken und Orientierung berechnet werden, sind die Regeln, nach denen die Nervenzellen miteinander verschaltet sind, nur unzureichend erforscht. Wissenschaftler um Moritz Helmstaedter vom Max-Planck-Institut für Hirnforschung in Frankfurt am Main und Helene Schmidt vom Bernstein-Zentrum der Humboldt-Universität in Berlin haben nun in dem Teil der Großhirnrinde, der für die räumliche Orientierung zuständig ist, ein überraschend präzises Verschaltungsmuster der Nervenzellen entdeckt.

Wie die Forscher in Nature berichten (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005), haben die...

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Wundermaterial Graphen: Gewölbt wie das Polster eines Chesterfield-Sofas

Graphen besitzt extreme Eigenschaften und ist vielseitig verwendbar. Mit einem Trick lassen sich sogar die Spins im Graphen kontrollieren. Dies gelang einem HZB-Team schon vor einiger Zeit: Die Physiker haben dafür eine Lage Graphen auf einem Nickelsubstrat aufgebracht und Goldatome dazwischen eingeschleust. Im Fachblatt 2D Materials zeigen sie nun, warum dies sich derartig stark auf die Spins auswirkt. Graphen kommt so auch als Material für künftige Informationstechnologien infrage, die auf der Verarbeitung von Spins als Informationseinheiten basieren.

Graphen ist wohl die exotischste Form von Kohlenstoff: Alle Atome sind untereinander nur in der Ebene verbunden und bilden ein Netz mit sechseckigen Maschen,...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

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

11. BusinessForum21-Kongress „Aktives Schadenmanagement"

22.09.2017 | Veranstaltungen

Internationale Konferenz zum Biomining ab Sonntag in Freiberg

22.09.2017 | Veranstaltungen

Die Erde und ihre Bestandteile im Fokus

21.09.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

11. BusinessForum21-Kongress „Aktives Schadenmanagement"

22.09.2017 | Veranstaltungsnachrichten

DFG bewilligt drei neue Forschergruppen und eine neue Klinische Forschergruppe

22.09.2017 | Förderungen Preise

Lebendiges Gewebe aus dem Drucker

22.09.2017 | Biowissenschaften Chemie