Nairobi, Kenya ? Government officials, scientists and activists from around the world converged on drought-stricken Kenya for today’s opening of the U.N. conference on climate change, the first such session in sub-Saharan Africa, the continent at greatest risk as the world warms.

A U.N. report Sunday forecast a dire future if global temperatures continue to rise.

One-third of Africa’s species may lose their habitats by 2085 as climate zones shift, it said. In some areas, 30 percent of coastal infrastructure may be wrecked by rising seas. On the world’s hungriest continent, cereal crop yields are projected to decline.

The U.N. Environment Program chief sees an issue of basic fairness. “The problem was not caused on the African continent, and yet it’s Africa that has to adapt,” Achim Steiner told a news conference.

A leading African environmentalist was more blunt.

“It’s the luxury emissions of the United States versus our survival emissions,” Grace Akumu of Climate Network Africa said.

The 189 parties to the 1992 U.N. climate treaty gathering here for their annual meeting are divided into two groups: the 165 that have ratified the treaty’s 1997 Kyoto Protocol mandating cutbacks in greenhouse gases, and a handful of others, led by the U.S., that do not accept Kyoto.

The atmospheric accumulation of carbon dioxide, methane and other such heat-trapping gases – byproducts of power plants, automobiles and other industrial and agricultural sources – is blamed by scientists for at least some of the 1-degree-Fahrenheit rise in global temperatures during the past century.

Under the Kyoto accord, 35 industrial countries are obliged to reduce their emissions by 5 percent below 1990 levels by 2012. President Bush rejected the Kyoto deal in 2001, saying it would hamstring the U.S. economy and objecting that it excluded poorer countries from its mandates.

In Nairobi, the Kyoto countries will continue backroom talks on what kind of emissions targets and timetables should follow 2012. But many are waiting to see whether the biggest emitter – the United States, which accounts for 21 percent of the world’s greenhouse gases – will submit to a mandatory regime of cutbacks.

“What I see happening in the United States is, first of all, a lot of action at the state level,” said Yvo de Boer, head of the U.N. climate treaty secretariat, referring to such steps as California’s decision to rein in emissions there. But he cited no movement by the Bush administration, and few here expect any dramatic shift in the U.S. position.

Many experts are saying industrialized nations must cut emissions by as much as 80 percent by midcentury to head off temperature increases as high as 10 degrees Fahrenheit by 2100.

The Intergovernmental Panel on Climate Change, the U.N. network of climate scientists, says rising temperatures will expand oceans via heat and runoff of melting land ice; shift climate zones, disrupting agriculture; and lead to more frequent and intense climate events, such as the drought now in its fourth year in East Africa.