wild places | wild happenings | wild news
make a difference for our wild places

home | links | search the site
  all articles latest | past | articles by topics | search wildnews
wild news on wildsingapore
  Yahoo News 10 Apr 07
Deforestation effects depend on location
By Randolph E. Schmid, AP Science Writer

BBC 10 Apr 07
Snowy forests 'increase warming'

Channel NewsAsia 10 Apr 07
Some deforestation may help offset global warming: study

WASHINGTON : Planting new trees in snow-covered northern regions may actually contribute to global warming as they have the counter-effect of tropical forests, according to a study out Monday.

While rainforests cool the planet by absorbing carbon dioxide and producing clouds that reflect sunlight, the dark canopy of Canadian, Scandinavian and Siberian forests catches sunrays that would be reflected back to space by the snow, the study said.

The study, published Monday in the online edition of the Proceedings of the National Academy of Sciences, found that reforestation projects in the tropics would help mitigate global warming but would be "counterproductive" in high latitudes.

"Our study shows that only tropical rainforests are strongly beneficial in helping slow down global warming," Govindasamy Bala, who led the research, said in a statement.

"It is a win-win situation in the tropics because trees in the tropics, in addition to absorbing carbon dioxide, promote convective clouds that help to cool the planet," he said. "In other locations, the warming from the albedo effect (sunlight absorption) either cancels or exceeds the net cooling from the other two effects," said Bala, an atmospheric scientist at the Lawrence Livermore National Laboratory.

Reseachers used a three-dimensional computer simulation to study the effects of large-scale deforestation and look at the positive and negative effects of tree cover at different latitudes.

"When it comes to rehabilitating forests to fight global warming, carbon dioxide might be only half of the story; we also have to account for whether they help to reflect sunlight by producing clouds, or help to absorb it by shading snowy tundra," said study co-author Ken Caldeira.

However, the authors did not endorse deforestation of the boreal forests as a measure against global warming.

"Preservation of ecosystems is a primary goal of preventing global warming, and the destruction of ecosystems to prevent global warming would be a counterproductive and perverse strategy," said Caldeira, of the Carnegie Institution. Researchers from Stanford University in California and Universite Montpellier II in France contribute to the study. - AFP/ch

Yahoo News 10 Apr 07
Deforestation effects depend on location
By Randolph E. Schmid, AP Science Writer

The effect of deforestation on climate depends on three things — location, location and location.

Environmentalists concerned about global warming have long encouraged preservation of forests because they absorb carbon dioxide, the most abundant greenhouse gas in the atmosphere.

But the issue, like most things, may be more complicated than it first appears.

New research in this week's online edition of Proceedings of the National Academy of Sciences, confirms the effectiveness of tropical forests at reducing warming by absorbing carbon.

But it suggests that in snowy latitudes, forests may actually increase local warming by absorbing solar energy that would otherwise be reflected back out into space.

That doesn't mean forests in cold areas should be chopped down, stressed Ken Caldeira of the Carnegie Institution department of global ecology, located at Stanford University in Palo Alto, Calif.

"I am a little concerned about this being misapplied as an excuse to chop down the forests in the name of saving the environment," said Caldeira, a co-author of the report.

"A primary reason we are trying to slow global warming is to protect nature. It just makes no sense to destroy natural ecosystems in the name of saving natural ecosystems," he said.

But, he added, efforts to increase the forested areas in northern regions may be ineffective in combating warming and can be a distraction from the real answer, which is the need to reform our system of energy production.

The result does suggest "it's more important to preserve and restore tropical forests than had been previously recognized," he added.

Tropical forests help cool the planet in two ways, Caldeira pointed out — by absorbing carbon dioxide and by drawing up soil moisture which is released into the air forming clouds. Those clouds reflect solar energy back into space, he said, while reducing the amount reaching the ground.

Steven W. Running, a professor of ecology at the University of Montana, praised the researchers, but questioned their conclusion.

"I don't think the conclusions they draw are ready for prime-time policy, and particularly their conclusion that reforestation in high latitudes might be counterproductive," Running said in a telephone interview. "What they are doing is sparking a lively scientific discussion that is very necessary and I applaud them for that," he said.

But until the scientific community can "chew this over" it shouldn't be used in setting policy, he said.

"This is challenging work" said Running, who was not part of the research team. "This is a real top group of scientists and they are doing some really intriguing earth systems model analysis that is exceedingly difficult to do," he added. It shows how complex Earth system feedback is.

Govindasamy Bala of Lawrence Livermore National Laboratory, a co-author of the paper, added: "Apart from their role in altering the planet's climate, forests are valuable in many other aspects. Forests provide natural habitat to plants and animals, preserve the biodiversity, produce economically valuable timber and firewood, protect watersheds and indirectly prevent ocean acidification."

The research was funded by the Energy Department.

BBC 10 Apr 07
Snowy forests 'increase warming'

Planting trees in snowy areas may worsen global warming as their canopies absorb sunlight which would otherwise be reflected by the snow, a study says.

The report in US journal Proceedings of the National Academy of Sciences says the pine forests of Europe, Siberia and Canada may contribute to warming.

Only tropical forests effectively cool the earth by absorbing carbon dioxide and creating clouds, the report says.

But the report's authors stress they are not advocating chopping down trees. They say forests are a valuable resource and remain vital for bio-diversity, providing a home for animals and plants.

'Lively discussion'

Scientists have long argued that planting and preserving forests helps reduce global warming because trees absorb carbon dioxide from the atmosphere and convert it to oxygen. Trees also absorb water from the ground, helping to form clouds that shield the earth from sunlight.

But the report's findings, discussed last year at an American Geophysical Union meeting and now published in the Proceedings of the National Academy of Sciences, suggest planting forests indiscriminately may be counter-productive.

"Our new study shows that only tropical rainforests are strongly beneficial in helping slow down global warming," Govindasamy Bala of the Lawrence Livermore National Laboratory says.

In cooler areas of the earth, tree cover helps store sunlight reflected by snow on the ground and this "cancels or exceeds" the net cooling effect, Mr Bala told the AFP news agency.

Another author of the report, Ken Caldeira of the Carnegie Institution, said the report suggested it is "more important to preserve and restore tropical forests than had been previously realised".

But, he told the Associated Press news agency, he was "a little concerned about this being misapplied as an excuse to chop down the forests in the name of saving the environment".

Computer models produced by the report's authors suggested deforestation in higher latitudes could reduce global warming.

Steven W Running, a professor of ecology at the University of Montana, praised the report's authors for "sparking a lively scientific discussion". But Mr Running, who was not involved in the report, said it was too early to base policy on the report's conclusion that certain types of reforestation might be counter-productive.
links
Related articles on Global: Climate change
about the site | email ria
  News articles are reproduced for non-profit educational purposes.
 

website©ria tan 2003 www.wildsingapore.com