In comments marking the entry into force of the Kyoto Protocol, the landmark treaty requiring cuts in gas emissions that cause global warming, Klaus Töpfer said the problem could be far worse than originally feared and lamented that Africa would probably bear the brunt of its damage.

Africa "is where the hammer of global warming will, if unchecked, likely hit hardest," the German said, noting that climate change would further hinder efforts to promote development on the chronically impoverished continent.

Töpfer spoke of a "specter at the feast" for the Kyoto Protocol's taking effect, referring to new scientific data that found earlier dire predictions about global warming may have significantly underestimated the problem. "Climate change is the specter at the feast, capable of undermining our attempts to deliver a healthier, fairer and more resilient world," he said.

He noted a study published last month in Britain that concluded that global temperatures could rise by as much as 11 C (19.8 F) by the middle of the century, twice the earlier accepted figure of up to 5.8 degrees (9.0 F). And, Töpfer pointed to the recent conclusions of the International Climate Change Task Force, that even a two degree Celsius rise could take the planet past a point of "no return."

"These two reports make terrifying reading, a vision of a planet spinning out of control," he said, adding: "I certainly hope that these new calculations are proven wrong. "However, it seems that many of the past theoretical forecasts are sadly coming to pass."

Töpfer: must do more

Töpfer is to host more than 100 environment ministers in Nairobi next week to review UNEP's plans for the future and he said he would use the occasion to press the need to see the link between global warming and development.

"Let us enjoy this special day as the Kyoto Protocol passes into force, but celebrate with the certain knowledge that we must do much more to achieve climatic stability and thus the MDGs (millennium development goals)," he said.

Kyoto took effect earlier Wednesday with the support of 141 nations but boycotted by the world's biggest polluter, the United States, as well as Australia. The 34 industrialized countries to have ratified the treaty are legally bound to slash output of greenhouse gases before 2012, with targets set for each nation based on their 1990 levels.

Töpfer urged critics, who argue the US boycott makes the treaty impotent, not to focus on Washington's refusal to join, noting that some American states were acting on their own to curb greenhouse gas emissions. Instead, he called for redoubled efforts to improve on Kyoto's goals.

"We must act swift and sure to go beyond Kyoto," Töpfer said. "We must put the planet on course for the up to 60 per cent cuts in greenhouse gas emissions needed to conserve the climate."