Study: Temperate Forests Could Worsen Global Warming

Dec 05, 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: Experts examine bones as Spain hunts for Cervantes' remains (Update)

add to favorites email to friend print save as pdf

Related Stories

UM researcher helps NASA get the dirt on soil moisture

Jan 15, 2015

During the early-morning hours on Tuesday, Jan. 29, NASA will launch a satellite that will peer into the topmost layer of Earth's soils to measure the hidden waters that influence our ecosystems weather and ...

Bet-hedging dry forest resilience to climate-change threats

Jan 14, 2015

New research shows that the most significant current threat to western dry forests is from insect outbreaks and droughts, not wildfires; and historically abundant small trees offer the greatest hope for forest survival and ...

NASA finds good news on forests and carbon dioxide

Jan 05, 2015

A new NASA-led study shows that tropical forests may be absorbing far more carbon dioxide than many scientists thought, in response to rising atmospheric levels of the greenhouse gas. The study estimates ...

The ants that conquered the world

Dec 24, 2014

About one tenth of the world's ants are close relatives; they all belong to just one genus out of 323, called Pheidole. "If you go into any tropical forest and take a stroll, you will step on one of these ...

Recommended for you

Study calls for audit transparency

6 hours ago

As major accounting companies increasingly outsource audit work to other firms, a new study from the University of Colorado Denver Business School says greater transparency is needed to help investors assess the quality of ...

Girls lead boys in academic achievement globally

6 hours ago

Considerable attention has been paid to how boys' educational achievements in science and math compare to girls' accomplishments in those areas, often leading to the assumption that boys outperform girls ...

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.