Millions of Africans could be among the worst hit by global warming, a conference on climate change has heard.
Africa is the world's poorest continent
Nigerian scientist Anthony Nyong said that temperatures could rise by two degrees and rainfall drop 10% by 2050, if current trends continue.
This could mean more droughts and smaller harvests, leaving up to 100 million more Africans hungry.
He called on rich countries to cut their emissions of the greenhouse gases, which worsen climate change.
High population growth and increasing environmental stresses have already made Africa the world's poorest continent.
'Wake up call'
"Africa's high vulnerability is not only due to climate change but a combination of other stresses," said Mr Nyong from Jos University.
"Such stresses include poverty, wars and conflicts, limited technological development, a high disease burden and a rapid population growth rate."
BBC science correspondent Roland Pease says that global warming could also mean malaria-carrying mosquitoes moving to new areas.
The World-Wide Fund for Nature (WWF), which sponsored Mr Nyong's report, said it was a wake-up call to the world.
"If global warming is not tackled, the viability of millions of people's livelihoods in Africa will be undermined," said Catarina Cardoso, head of climate change at WWF-UK.