Climate change will reverse decades of social and economic progress across Asia, campaigners claim.
Extreme weather events are likely to become more frequent
A report by a coalition of environment and aid agencies calls for urgent action to avert the threat.
The Working Group on Climate Change and Development says industrialised countries must cut carbon emissions massively by mid-century.
The coalition calls on the UK government to set an example by championing renewable energy.
The report - Up In Smoke? Asia and the Pacific - says Asia is "effectively on the front line of climate change", as it is home to almost two-thirds of the world's population.
And with half of this population living near the coast, billions are directly vulnerable to sea-level rise driven by a warming world.
The report says Asia is where the "human drama of climate change" will largely be played out.
The report's author, Andrew Simms of the New Economics Foundation (Nef), said: "If those painfully won improvements in social and economic conditions can be blown away in a few but increasingly frequent and extreme weather events, we have to rethink about how we go about meeting people's basic needs."
The coalition's 21 members include ActionAid International, Christian Aid, Friends of the Earth, Greenpeace, Oxfam and WWF.
Nef, together with the International Institute for Environment and Development, organised the report's production.
The coalition previously published a study in October 2004 saying global warming threatened poverty reduction and urged industrial countries to cut their carbon emissions dramatically. It said such action now was "even more pressing".
The report comes as world leaders prepare for UN climate change talks in Bali next month.
Nazmul Chowdhury, from the Disappearing Lands project, says: "Before the Bali meeting, we must make our voices heard, and demand international leaders take urgent and ambitious action.
"Without this, Asia's vulnerable will continue to suffer, as will communities worldwide who are contributing least to climate change."
Andrew Simms said he hoped the talks would help bring a "paradigm shift in the attitude of developing countries".
"We need to start talking about emissions reduction targets that are in line with the science rather than in line with what negotiators think they can get away with," he told BBC News.
As well as cutting global emissions by at least 80% by 2050, the report calls on richer countries to lead by example and champion renewable energy.
The coalition says Asian countries need to be convinced not to go down the fossil fuel energy route of "get rich quick, stay poor long".
Mr Simms said: "Practical difficulties and a lack of rich country leadership on climate change mean Asia is unlikely to abandon fossil fuels in the near future."
He added: "It is useless to turn around and point a finger at China's rising emissions if we are not showing the will and making the resources available to provide the changes necessary."