Developed countries should step up their efforts in assisting African countries adapt to the devastating effects of climate change, a United Nations senior official said here Tuesday.

UN Environment Programme Executive Director Achim Steiner said poor nations especially in Africa are experiencing natural calamities as a result of climate change caused by greenhouse gas emissions mainly by the rich states.

"Some measures of climate change is however a reality that the world must already live with. That reality requires assistance for Africa to adapt," Steiner told journalists in Nairobi during the release of the regional report by Working Group II of the Intergovernmental Panel on Climate Change in Nairobi.

The UNEP chief said climate change is already affecting many parts of Africa and will get worse if the global community does not commit itself immediately to combat that change.

He said many of the African countries are not doing enough to adapt and cope with climate change, which he said, is complex and requires financial investment.

"It requires investment but equally requires climate proofing of economies now and in the future. This is as much about investment in careful and considered planning — so that climate change becomes central to the developmental process — as it is about financial investment," said Steiner.

"Africa is the continent that is probably most vulnerable to the negative effects of climate change, and the one that faces the greatest challenges to adapt. This issue (climate change) is so serious that everyone has to wake up," he said.

Citing the droughts and floods experienced in Kenya in recent past, Steiner said African countries suffered from a cause they least contributed to and urged governments to address the climate change a domestic responsibility.

The IPCC report says Africa requires urgent assistance to adapt to climate change and action by industrialized countries to deliver deep cuts in emissions if the continent and its people are to thrive in the 21st century.

The report, which was released by Anthony Nyong, the coordinating lead author for Africa Chapter predicts that continued increase in greenhouse gases will later this century put up to 1.8 billion more people in Africa at risk of water stress.

Although the climates of Africa have always been erratic, the latest scientific research indicates new and dangerous extremes, continual warming and more unpredictable weather patterns.

The success or failure of one rainy season, or even several, cannot be attributed to global warming. But, says the report, Africa is steadily warming and the climate is changing.

"The report underlines the enormous costs facing Africa as a result of unchecked climate change — costs that are wholly unacceptable for the 800 million people alive today and for the generations to come," said Steiner.

"It is the continent with the least responsibility for the climate change and yet is perversely the continent with the most at risk if greenhouse are not cut," he added.

The IPCC report says a modest temperature rise could lead to falls in water flows in some river systems equally in volume to one large dam being lost annually.

Tourism, much of which is based on nature, is also likely to be hard hit with 25 percent to 40 percent of animal species like zebra in the national parks of sub-Saharan Africa set to become endangered.

The report says sea level rise, especially on the east African coast, will increase flooding with the adaptation bill rising to up to 10 percent of Gross Domestic Product.

Dr Nyong, the lead author noted that natural disasters and calamities are costing the continent dearly in its effort to reverse their implications.

"These calamities should be used to educate the local communities that climate change is real. It is important to think about new technologies to avert these effects of climate change," he said.

The IPCC report says between 2080 and the end of the century, average annual rainfall is very likely to decrease along Africa's Mediterranean coast by a fifth with the fall also experienced in the northern Saharan and the northern West African coast.

It also acknowledges that uncertainties in models and future governance make it tough to know how flows in the Nile will be affected.

The report says other factors could be investigated to "enhance resilience to shocks such as droughts, which include national grain reserves, grain futures markets, weather insurance, cash transfers and school feeding schemes."