U.N. group studies impacts, how well humans adapt.
by Miguel Llanos,MSNBC

Bangladeshis have long had to deal with flooding like this event last October and computer models, if they hold up, portend even worse flooding worldwide due to global warming.Feb. 19 — A U.N. climate report, released Monday after months of review, describes a future where the poorest suffer most from global warming. But critics of the report counter that the computer models used to draw the conclusions are too simplistic to reliably predict where Earth is heading.

THE REPORT, released in Geneva by the Intergovernmental Panel on Climate Change, forecasts water and food shortages as well as an increase in disease in some of the poorest parts of Africa, Asia and Latin America.

“Many human settlements will face increased risk of flooding, and tens of millions of people living in deltas, low-lying coastal areas and on small islands will face risk of displacement by sea level rise,” the report says.

People in Europe and North America are expected to be able to adapt, but the climate changes would shift areas best suited for agriculture.


The science behind the report has its critics. Frank Maisano, spokesman for the business group Global Climate Coalition, questioned the reliability of predicting how global warming could be broken down by regions. Such reports are “less than accurate and often overly pessimistic,” he claimed.

Scientific skeptics include Roger Pielke Sr., a Colorado State University atmospheric scientist who believes the computer models used by the U.N. panel to make climate predictions are too simplistic, giving too much credit to carbon dioxide in the warming process.

Pielke said he’s not suggesting climate change isn’t a problem, but that today’s science is not capable of reliably predicting that change.

“People are affecting Earth’s climate but in unpredictable ways,” he said. “It’s surprising we think we can predict 50 years into the future when we can’t predict next year’s weather.”

Pielke said that while the U.N. panel limits its models to the radiative effect of carbon dioxide and other gases, and to how aerosols impact the atmosphere, he and many colleagues look at additional factors like how carbon affects plant biology and thus climate, and how land-use change alters regional and global climate.

“We’re showing that these other effects are at least as significant” as changes in the atmosphere, Pielke added.

A better planning policy, he contended, would be to look at “vulnerability to all kinds of environmental stresses, which includes changes in long-term weather, and then decide where the threats are most serious.”

Anthony Janetos, a climate expert with the World Resources Institute, acknowledged the limitations of modeling but defended it as the best tool available for looking at plausible scenarios of climate change.

Those limitations “certainly shouldn’t be an excuse for people not to do anything,” said Janetos.

And just because land-use factors are hard to include in models, he added, “doesn’t invalidate the models, but it does tell you there is greater sophistication to be had” as modeling techniques improve.

Climate concerns by region

A subgroup of the U.N. climate change panel has drafted its report on potential impacts worldwide.

•Adaptive capacity of humans is low and vulnerability high.

•Food security would diminish if, as projected, grain yields decrease.

•Major rivers are highly sensitive to climate variation. Average runoff and water availability would decrease in Mediterranean and southern countries of Africa.

•The range of infectious diseases would spread.

•Desertification would be exacerbated.

•Increases in droughts, floods and other extreme events would add to stresses on water and health.

•Significant extinctions of species are projected.

•Coastal settlements would be adversely impacted by sea level rise. •Adaptive capacity of humans is low and vulnerability high in Asia's developing countries.

•Arid, tropical and temperate areas face reduced food security if agricultural productivity falls. Northern areas would see more agricultural opportunities.

•Runoff and water supplies would decrease in arid and semi-arid Asia, but increase in northern Asia.

•Health would be threatened by possible increased exposure to vector-borne diseases in some areas.

•Sea level rise and more tropical cyclones as well as rainfall would displace tens of millions of people. •Adaptive capacity of humans is high except for some like indigenous groups, who face high vulnerability.

•Water is likely to be a key issue due to projected drying trends.

•Increases in the intensity of heavy rains and cyclones would raise the risks to life and property.

•Coral reefs, wetlands and alpine systems are among the habitat particularly vulnerable to climate change.

•Adaptive capacity for humans is high, though southern Europe is more vulnerable than the north.

•Summer runoff, water supply and soil moisture are likely to decrease in the already drought-prone south.

•Flood hazards will increase across Europe, with coastal areas also seeing increased erosion and loss of wetlands.

•Agriculture will expand in northern Europe, decrease in the south.

•Some species would be threatened by a shift north of certain habitats.

•Heat waves might change summer destinations, less reliable snow might impact winter tourism.

•Adaptive capacity of humans is low and vulnerability high.

•Retreat of glaciers along the Andes would reduce water supply in some areas.

•Floods and droughts would become more frequent, degrading water quality in some areas.

•The range of vector-borne diseases would spread south and to higher elevations.

•Crop yields would decrease in many areas, subsistence farming in northeastern Brazil would be threatened.

•Mangrove ecosystems would be harmed by sea level rise.

•The rate of biodiversity loss would increase.

•Adaptive capacity of humans is high but indigenous groups are more vulnerable.

•Farming output in the U.S. Great Plains and Canada's Prairies would decline, while some areas would benefit.

•Western watersheds that rely on snowmelt would peak earlier in spring, possibly reducing summer flows.

•Prairie wetlands, alpine tundra and cold water ecosystems would be at risk and effective adaptation is unlikely.

•Sea level rise would cause erosion, flooding, loss of wetlands and storm surges, especially in Florida and much of the Atlantic Coast.

•Indigenous peoples have little capacity and few options for adaptation.

•Climate change here is expected to be among the greatest of any region on Earth, and would last centuries.

•Species might begin to migrate.

•Adaptive capacity of humans is generally low and vulnerability high.

•These are among the countries likely to be most seriously impacted.

•Coral reefs would see higher die-offs, affecting reef fisheries as well.

•Rising seas would affect tourism and local water supplies.


The latest conclusions are drawn from from a 1,000-page report on impacts that a working group of the U.N. climate change panel has spent two years putting together. The group’s findings are based on its review of research from around the world.A separate group on the panel earlier issued a report on what the science says about temperature trends. And a third group will issue a report in March looking at options for dealing with climate change.

The reports are part of the U.N.-sponsored talks aimed at implementing an international climate change treaty.

The talks broke off last November over differences between the United States and Europe. The United States wanted to use carbon trading and other flexible tools to reach the targets, while Europe insisted the targets be met by actual reductions.

The Bush administration last month asked that the next round be delayed until July so that it could review the U.S. policy.

The official in charge of the talks said last week that they would resume either in late June or early July, but he did not set a place.

The sun's energy, after traveling 93 million miles to get to Earth, hits the upper atmosphere at about the intensity of three 100-watt bulbs per square yard. A third is reflected back into space, two thirds warms the planet and drives its weather engine. 

The atmosphere
Earth gets its livable temperature (on average 59 degrees Fahrenheit) thanks to a delicate balance of gases that create a "greenhouse" effect by trapping heat inside the atmosphere. Greenhouse gases -- water vapor, carbon dioxide, methane, nitrous oxide, and others -- absorb heat energy, then re-radiate a portion of it back to the surface. 

The oceans
Covering two thirds of the planet, oceans are the key source of moisture in the air and they store heat efficiently, transporting it thousands of miles. The oceans and marine life also consume huge amounts of carbon dioxide. 

The water cycle
Higher air temperatures can increase water evaporation and melting of ice. And while water vapor is the most potent greenhouse gas, clouds also affect evaporation, creating a cooling effect. 

They both cool Earth by reflecting solar energy and warm Earth by trapping heat being radiated up from the surface. 

Ice and snow
The whiteness of ice and snow reflects heat out, cooling the planet. When ice melts into the sea, that drives heat from the ocean. Northern Hemisphere snow cover has declined 10 percent in two decades, but no significant melting of the Antarctic ice sheet has been detected. 

Land surface
Mountain ranges can block clouds, creating ‘dry’ shadows downwind. Sloping land allows more water runoff, leaving the land and air drier. 
A tropical forest will soak up carbon dioxide, but once cleared for cattle ranching, the same land becomes a source of methane, a greenhouse gas.

Human influences
Humans might be magnifying warming by adding to
the greenhouse gases naturally present in the atmosphere.
Fuel use is the chief cause of rising carbon dioxide levels.
On the other hand, humans create temporary, localized cooling
effects through the use of aerosols, such as smoke and sulfates
from industry, which reflect sunlight away from Earth.

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