* Adapting to climate change can be better than cutting CO2

* $10 trillion spent gives $16 trillion in benefits

By Alister Doyle, Environment Correspondent

OSLO, Aug 21 (Reuters) - Helping developing nations to adapt to climate change such as floods or heatwaves can give bigger economic benefits than a focus on deep cuts in greenhouse gas emissions, a study indicated on Friday.

A total of $10 trillion spent on adaptation, ranging from research into drought-resistant crops to measures to limit a spread of diseases such as malaria, would provide $16 trillion of economic benefits over the coming century, it said.

"We talk immensely about cutting carbon emissions, but there are many other ways to deal with climate change," said Bjorn Lomborg, Danish author of "The Skeptical Environmentalist" who commissioned the study by Italian researchers.

"Everyone pays lip service to adaptation but in reality we rarely talk as much about it as cutting carbon emissions," he told Reuters of the study, meant to provoke debate about a new U.N. climate treaty to be agreed in Copenhagen in December.

"The authors find that...adaptation achieves more than mitigation in terms of reducing the damage from climate change," he said. Mitigation means curbing emissions of greenhouse gases and often gets most attention at U.N. climate negotiations.

The study said that the highest economic benefits would come if adaptation went hand in hand with moderate curbs on emissions. In the best case, $9 trillion spent would give $19 trillion of benefits, it said.

"The optimal strategy to deal with climate change entails the adoption of both adaptation and mitigation measures," Carlo Carraro of the University of Venice and co-authors from the Fondazione Eni Enrico Mattei in Italy wrote.

MARKET FORCES

The study also said that the impacts of climate change could also be muted by adaptation, driven by market forces. In developed nations, for instance, farmers could turn to new crops to match water availability and temperatures.

"If it rains less you will adapt and you will use drip irrigation," said Lomborg, who is head of the Copenhagen Consensus Center. "If it rains more you will grow more crops and you will end up being more productive."

Other low-cost measures could include insulation of older buildings, building new homes with higher steps to avoid flooding or siting new infrastructure inland to avoid storm surges from a creeping rise in sea levels.

"The problem from global warming is not going to be in the developed world, it will be in the developing world," he said.

Taking account of the natural market-driven adaptation, climate change could have a fractional net positive impact in developed nations, totalling a 0.1 percent gain in gross domestic product by 2100, the study said.

And in poor nations, such adaptation could limit overall economic losses to 2.9 percent of GDP from 5.3 percent.

The authors say that their study does not include feared costs of catastrophic damages or "tipping points", irreversible shifts in the climate system that could, for instance, bring an irreversible melt of Greenland's ice that drives up sea levels. (Editing by Matthew Jones)

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