Vegetation Growth May Quickly Raise Arctic Temperatures

Sep 09, 2005

Warming in the Arctic is stimulating the growth of vegetation and could affect the delicate energy balance there, causing an additional climate warming of several degrees over the next few decades.

A new study indicates that as the number of dark-colored shrubs in the otherwise stark Arctic tundra rises, the amount of solar energy absorbed could increase winter heating by up to 70 percent.

The research will be published 7 September in the first issue of the Journal of Geophysical Research-Biogeosciences, published by the American Geophysical Union.

The study in western Alaska during the winters in 2000-2002 shows how the increasing abundance of high-latitude vegetation, particularly shrubs, interacts with the snow and affects Earth's albedo, or the reflection of the Sun's rays from the surface.

The paper, which also analyzes the ramifications of continued plant growth in the tundra regions, written by researchers at the U.S. Army Cold Regions Research and Engineering Laboratory and at Colorado State University. It presents the first evidence that shrub growth could alter the winter energy balance of the Arctic and subarctic tundra in a substantial way.

The authors measured five adjacent sites in subarctic Alaska. They included areas covered by continuous forest canopy, others dotted with shrubs, and some of barren tundra. They found that mid-winter albedo was greatly reduced where shrubs were exposed and that melting began several weeks earlier in the spring at these locations, as compared to snow-covered terrain.

The researchers note, however, that the shrubs' branches produced shade that slowed the rate of melting, so that the snowmelt finished at approximately the same time for all the sites they examined.

Matthew Sturm, lead author of the study, notes that warming in the region seems to have stimulated shrub growth, which further warms the area and creates a feedback effect that can promote higher temperatures and even more growth. This feedback could, in turn, accelerate increases in the shrubs' range and size over the four million square kilometer [1.5 million square mile] tundra and effect significant changes over the region.

"Basically, if tundra is converted to shrubland, more solar energy will be absorbed in the winter than before," Sturm says. And while previous research has shown that warmer temperatures during the Arctic summer enhance shrub growth, "our study is important because it suggests that the winter processes could also contribute to and amplify the rate of the [growth]."

Sturm cites satellite and photographic evidence showing increasing plant growth across the Alaskan, Canadian, and Euro-Asian Arctic and notes that continued warming will likely produce thicker stands of brush that protrude above the snow. The new, brushy landscape would replace the smooth, white environment that currently dominates the Arctic during its 8-10 month winter.

In addition, the increasing shrub cover would impact more than just the energy balance in the Arctic. With nearly 40 percent of the world's soil carbon is stored in Arctic soils, any change in vegetation and energy is likely to trigger a response in the Arctic carbon budget.

Scientists are still trying to understand the nature of this response, but Sturm and his coauthors conclude that the feedback effects they describe would undoubtedly accelerate its rate. They conclude that combined effects of increasing shrubs on both energy and carbon could change the Arctic in a way that affects the rest of the world.

Copyright 2005 by Space Daily, Distributed United Press International

Explore further: Successful engine test enables SpaceX Falcon 9 soar to space station in Jan. 2015

add to favorites email to friend print save as pdf

Related Stories

UN climate report offers stark warnings, hope (Update)

Nov 02, 2014

Climate change is happening, it's almost entirely man's fault and limiting its impacts may require reducing greenhouse gas emissions to zero this century, the U.N.'s panel on climate science said Sunday.

Signatures of selection inscribed on poplar genomes

Aug 24, 2014

One aspect of the climate change models researchers have been developing looks at how plant ranges might shift, and how factors such as temperature, water availability, and light levels might come into play. ...

Government publishes UK Antarctic science strategy

Jul 17, 2014

A framework document, 'UK Science in Antarctica 2014-2020,' is published today (Wednesday 16 July). Prepared by the UK National Committee for Antarctic Research on behalf of the UK Antarctic community it ...

Recommended for you

The top 101 astronomical events to watch for in 2015

Dec 24, 2014

Now in its seventh year of compilation and the second year running on Universe Today, we're proud to feature our list of astronomical happenings for the coming year. Print it, bookmark it, hang it on your ...

NASA image: Frosty slopes on Mars

Dec 24, 2014

This image of an area on the surface of Mars, approximately 1.5 by 3 kilometers in size, shows frosted gullies on a south-facing slope within a crater.

Can astronomy explain the biblical Star of Bethlehem?

Dec 24, 2014

Bright stars top Christmas trees in Christian homes around much of the world. The faithful sing about the Star of Wonder that guided the wise men to a manger in the little town of Bethlehem, where Jesus was ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.