Study: Temperate Forests Could Worsen Global Warming

December 5, 2005
Study: Temperate Forests Could Worsen Global Warming

Growing a forest might sound like a good idea to combat global warming, since trees draw carbon dioxide from the air and release cool water from their leaves. But they also absorb sunlight, warming the air in the process. According to a new study from the Carnegie Institution’s Department of Global Ecology and Lawrence Livermore National Laboratory, planting forests at certain latitudes could make the Earth warmer.

Image: New climate modeling research from the Carnegie Institution and Lawrence Livermore National Laboratory shows that northern temperate forests (top) may contribute to global warming, while tropical forests (bottom) can help keep global temperatures cool.

Carnegie’s Ken Caldeira will present the work at the American Geophysical Union Fall Meeting in San Francisco on December 7, 2005.

The researchers used complex climate modeling software to simulate changes in forest cover and then examined the effects on global climate. Their results were surprising. “We were hoping to find that growing forests in the United States would help slow global warming,” Caldeira said. “But if we are not careful, growing forests could make global warming even worse.”

The researchers found that while tropical forests help keep Earth cool by evaporating a great deal of water, northern forests tend to warm the Earth because they absorb a lot of sunlight without losing much moisture. In one simulation, the researchers covered much of the northern hemisphere (above 20° latitude) with forests and saw a jump in surface air temperature of more than 6° F. Covering the entire planet’s land mass with trees led to a more modest increase of about 2° F.

When the scientists restricted the simulation to middle latitudes such as the continental United States, the picture was not quite so clear. At first, cooling due to the uptake of carbon dioxide would offset warming from sunlight absorption. But after several decades, carbon dioxide would begin diffusing from the ocean into the atmosphere, diminishing the cooling effect and warming the Earth in the long term.

Caldeira warns against planting forests on abandoned croplands as a strategy to combat global warming, which some have recommended. But he also recognizes the importance of forests.

“I like forests. They provide good habitats for plants and animals, and tropical forests are good for climate, so we should be particularly careful to preserve them,” Caldeira commented. “But in terms of climate change, we should focus our efforts on things that can really make a difference, like improving efficiency and developing new sources of clean energy.”

The study, authored by Seran Gibbard, Ken Caldeira, Govindasamy Bala, Thomas J. Phillips, and Michael Wickett, will be published online under the title “Climate effects of global land cover change” in the journal Geophysical Research Letters on December 8, 2005.

Source: Carnegie Institution of Washington

Explore further: Are we at a new tipping point in the war on climate change?

Related Stories

Are we at a new tipping point in the war on climate change?

September 3, 2015

For four decades UC San Diego atmospheric scientist Veerabhadran "Ram" Ramanathan has warned that carbon dioxide and other emissions from human activity are heating up the planet. One of the first scientists to predict global ...

Clues from ancient Maya reveal lasting impact on environment

September 3, 2015

Evidence from the tropical lowlands of Central America reveals how Maya activity more than 2,000 years ago not only contributed to the decline of their environment but continues to influence today's environmental conditions, ...

NASA to study Arctic climate change ecosystem impacts

September 1, 2015

As part of a broad effort to study the environmental and societal effects of climate change, NASA has begun a multi-year field campaign to investigate ecological impacts of the rapidly changing climate in Alaska and northwestern ...

Recommended for you

Apple patent looks at fuel cell system for portable device

September 4, 2015

A fuel cell battery to last weeks, not days, is the subject of a patent filed by Apple. According to news reports, the patent is about an energy cell powering a portable electronic device. The Telegraph said this was likely ...

Secrets of a heat-loving microbe unlocked

September 4, 2015

Scientists studying how a heat-loving microbe transfers its DNA from one generation to the next say it could further our understanding of an extraordinary superbug.

Plants also suffer from stress

September 4, 2015

High salt in soil dramatically stresses plant biology and reduces the growth and yield of crops. Now researchers have found specific proteins that allow plants to grow better under salt stress, and may help breed future generations ...

0 comments

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.