Global warming likely to hurt poorest nations most, researchers say

Colo. scientists contribute to updated report

Jim Erickson, Rocky Mountain News

Saturday, March 24, 2007

Everyone on the planet will be touched by global warming, but the poorest nations may be hardest hit because they lack the resources to adapt to the harmful changes ahead, Boulder climate researchers say.

Consider Bangladesh, a country of 147 million people packed into a mostly flat delta region slightly smaller than Iowa.

As the world warms, sea levels could rise 2 feet, or more, by 2100.

"Even a rise of one foot will put a huge amount of that entire country under water permanently," said geographer Susi Moser.

She is among National Center for Atmospheric Research scientists who contributed to an upcoming international report on the likely worldwide impacts of climate change.

"And these are not the same people who live in Laguna Beach," said Moser, who works at NCAR's Institute for the Study of Society and Environment in Boulder.

"These are people whose entire livelihood depends on the agriculture in those coastal regions," she said. "Millions would be displaced."

Impact on snowpacks

Five of the NCAR institute's 11 researchers contributed to Climate Change 2007: Impacts, Adaptation and Vulnerability, the second of four updates to be issued this year by the authoritative Intergovernmental Panel on Climate Change, or IPCC.

A summary of the new 20-chapter report will be presented April 6 in Brussels, Belgium.

Specific findings are embargoed until then, but NCAR researchers agreed to talk in general terms about some of the topics addressed in the report.

The document looks at the likely impacts of climate change on societies, as well as ecosystems.

Topics range from coastal flooding and erosion to the spread of disease, changes in crop yields, dwindling urban water supplies, drought, heat waves and the threat of famine.

Even residents of the world's most prosperous nations won't be able to avoid the effects of global climate change, according to the Boulder researchers.

"It's not just the other guy's problem. It will affect us right here in our own backyard," said Kathleen Miller, an NCAR economist.

In the West, one frequently cited impact of warming is a projected decline in mountain snowpacks, a critical source of the region's water.

"In the West, nature gave us one of the best reservoirs you could get, and that's our snowpack," Miller said.

"And we're basically pulling the plug on that reservoir."

Effects on U.S. crops

U.S. agriculture also will be affected by warming.

In a report issued Feb. 2, the IPCC projected a global temperature increase of 2 degrees to 11.5 degrees Fahrenheit by 2100, with a "best estimate" of 3.2 degrees to 7.2 degrees.

The projected warming is blamed largely on the ongoing buildup of heat-trapping gases such as carbon dioxide, released during the combustion of fossil fuels.

Carbon dioxide has a fertilizing effect on some plants, promoting growth. So crops such as soybeans and wheat could benefit from some extra CO2 , said Linda Mearns, director of the NCAR institute.

And a bit of warming could help crops such as winter wheat, extending its range north through the Dakotas into the southern Canadian plains, Mearns said.

But at some critical warming point - which will vary from region to region - the gains from increased fertilization are outweighed by problems caused by rising temperatures and increased water demand from crops.

Studies have shown that a global warming of 3.6 degrees likely would reduce soybean and corn yields in the southeastern U.S.

Southwest to get hotter

Corn yields in Africa, where the crop is a staple across much of the continent, also would decline, raising the possibility of widespread famine.

"In Africa, one of the sad things is that they're going to suffer much more (than residents of developed countries) when they have not caused the problems," Mearns said.

"Their contribution to increased emissions has been trivial compared to that of Western nations."

One key concept the NCAR researchers have explored is the idea of multiple stresses.

Basically, it means that warming won't occur in a vacuum: It will combine with other factors to exacerbate pre-existing problems.

Climate simulations suggest, for example, that the Southwest is likely to get hotter and drier in coming decades.

Future water problems

As it does, the population of cities such as Phoenix will continue to grow, increasing competition for limited Western water resources.

At the same time, flows in the Colorado River - which supplies water to Phoenix and much of the West - are projected to decline, adding to the water woes.

And piling more concrete and asphalt onto the sprawling Phoenix metropolitan area will intensify the so-called urban heat island effect, which means the city will retain even more of its oppressive heat.

"We are not trying to alarm people. We just want to raise awareness of how difficult this issue is and that we need to be more proactive," said NCAR sociologist Paty Romero Lankao.

The upcoming report is not all doom and gloom.

There's still time to avert some of the most damaging impacts of climate change, if the world's nations act soon to reduce emissions of heat-trapping "greenhouse" gases such as carbon dioxide, the NCAR researchers say.

"The question is, 'What are we going to do to slow down global warming so that we give ourselves a chance?' " Moser said. "We need to contain the impacts, so that we can adapt."

Climate change findings

Key findings of Climate Change 2007: The Physical Science Basis, issued Feb. 2 in Paris by the Intergovernmental Panel on Climate Change. A summary of the second volume in the series, Climate Change 2007: Impacts, Adaptation and Vulnerability, is due to be released April 6 in Brussels.

• The planet has warmed 1.3 degrees Fahrenheit over the past century, an observation scientists consider "unequivocal."

• Most of the observed warming since the mid-20th century is "very likely" due to increases in human-caused emissions of heat-trapping gases such as carbon dioxide. "Very likely" is defined as a likelihood greater than 90 percent.

• Global temperatures are projected to rise 2 degrees to 11.5 degrees Fahrenheit by 2100, with a best-guess estimate of 3.2 to 7.2 degrees.

• Sea levels are projected to rise 7.2 inches to 23.6 inches by 2100, though some scientists consider the IPCC predictions overly conservative.

ericksonj@RockyMountainNews.com or 303-954-5129