Global warming over the next 50 to 80 years could jeopardise food security for the world's poorest people, warn scientists.
Extreme climate conditions — such as floods and droughts — resulting from global warming could greatly damage crop yields in developing countries, they explained.
The researchers were addressing a gathering of climatologists, policymakers, economists and sociologists at the Royal Society, the United Kingdom's science academy.
Martin Parry, co-chair of a working group of the Intergovernmental Panel on Climate Change, said that although global figures appear to suggest that food security is not at risk, they hide regional differences.
Locally, the risk to food production is much greater said Parry, particularly in Asia but even more so in Africa — a view all delegates agreed with.
Global warming threatens crops in several ways. Rising sea levels threaten to flood fields in low-lying coastal areas, such as those in Bangladesh and Egypt.
In sub-Saharan Africa, crop yields are expected to fall in regions predicted to become hotter and drier.
Researchers are also concerned that climate change could reduce the farming workforce by increasing the area in which malaria is endemic.
But simply identifying the threat to food security is not enough, said Tony Nyong of the University of Jos, Nigeria. What we need, he says, is the answer to the question "If the crops fail, what do you do about it?"
The delegates discussed approaches of reducing or adapting to the effects of climate change to ease the threat to food security.
Lin Erda of the Chinese Academy of Agricultural Sciences suggested that China could adapt to climate change and boost crop yields using 'carbon dioxide fertilisation', where the gas is pumped into greenhouses.
However, his data also showed that carbon dioxide fertilisation decreased the protein content of wheat.
Reducing the threat to the global water supply, said Parry, will require reducing carbon dioxide emissions far more than what is required by the Kyoto Protocol on climate change.
By and large, however, delegates agreed on the need to adapt to the effects of climate change in ways that would offset the threat to food security.
Parry said this was not a question of devising new technologies, but making adequate use of existing ones.
"We could mop up the decline in crop productivity with adaptation measures," said Parry. "But then, we could also mop up the problem of those who are dying of hunger now. We don't but we could."
The meeting's conclusions will be presented at July's G8 summit of leaders of the world's most industrialised nations.
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