NEW YORK -- The world's richest countries, which have contributed by far the most to the atmospheric changes linked to global warming, are already spending billions of dollars to limit their own risks from its worst consequences, like drought and rising seas.
But despite longstanding treaty commitments to help poor countries deal with warming, these industrial powers are spending just tens of millions of dollars on ways to limit climate and coastal hazards in the world's most vulnerable regions -- most of them close to the equator and overwhelmingly poor.
On Friday, a new report from the Intergovernmental Panel on Climate Change , a UN body that since 1990 has been assessing global warming, will underline this growing climate divide, according to scientists involved in writing it -- with wealthy nations far from the equator not only experiencing fewer effects, but better able to withstand them.
Two-thirds of the atmospheric buildup of carbon dioxide, a heat-trapping greenhouse gas that can persist in the air for centuries, has come in nearly equal proportions from the United States and Western European countries. These and other wealthy nations are investing in windmill-powered plants that turn seawater to drinking water, in flood barriers and floatable homes, in grains and soybeans genetically altered to flourish even in a drought.
In contrast, Africa accounts for less than 3 percent of the global emissions of carbon dioxide from fuel burning since 1900, yet its 840 million people face some of the biggest risks from drought and disrupted water supplies, according to new scientific assessments. As the oceans swell with water from melting ice sheets, it is the crowded river deltas in Asia and Egypt, along with small island nations, that are most at risk.
"Like the sinking of the Titanic, catastrophes are not democratic," said Henry I. Miller , a fellow with the Hoover Institution at Stanford University. "A much higher fraction of passengers from the cheaper decks were lost. We'll see the same phenomenon with global warming."
Scientists say worldwide precipitation is shifting away from the equator and toward the poles. That will nourish crops in warming regions such as Canada and Siberia while parching countries, like Malawi in sub-Saharan Africa, already prone to drought.
Rich countries are hardly immune from drought and flooding, but their wealth will largely insulate them from harm, at least for the next generation or two, many specialists say.
Cities in Texas, California, and Australia are already building or planning desalination plants, for example. And federal studies have shown that desalination can work far from the sea, purifying water from brackish aquifers deep in the ground.
"The inequity of this whole situation is really enormous if you look at who's responsible and who's suffering as a result," said Rajendra K. Pachauri , chairman of the UN climate panel. In its most recent report, in February, the panel said decades of warming and rising seas were inevitable with the existing greenhouse-gas buildup, no matter what was done about cutting future greenhouse gas emissions.
Miller, of the Hoover Institution, said the world should focus less on trying to rapidly cut greenhouse gases and more on helping regions at risk become more resilient.
Many other specialists insist this is not an either-or situation. They say that cutting the vulnerability of poor regions needs much more attention, but add that unless emissions are curbed, there will be centuries of warming and rising seas that will threaten ecosystems, water supplies, and resources from the poles to the equator, harming rich and poor.
Cynthia E. Rosenzweig , a specialist on climate and agriculture with the National Aeronautics and Space Administration who is a lead author of the UN panel's report, said that while the richer northern nations may benefit temporarily, "as you march through the decades, at some point -- and we don't know where these inflection points are -- negative effects of climate change dominate everywhere."
There are some hints that wealthier countries are beginning to shift their focus toward fostering adaptation to warming outside their own borders. Relief organizations, foreseeing a world of worsening climate-driven disasters, are turning some of their attention toward projects like expanding mangrove forests as a buffer against storm surges, planting trees on slopes to prevent landslides, or building shelters on high ground.