Why should countries like India, Brazil and China - from which activists take part in a debate here on openDemocracy - care about climate change? One answer is that the possible impacts, while uncertain, could be highly detrimental and undermine social and economic progress.

As The Economist, favourite reading of capitalism-hating environmental cultists, notes: it was the second worst year for the destruction of the rainforest since satellite surveys began (The economy booms, the trees vanish, 19 May).

Short term economic gains from deforestation may impose significant economic costs in the medium and longer term (as well as both short and longer term social costs - see A Thin Red Line on Brazil's landless movement in the 19 May Economist).

The Third Assessment Report from the Intergovernmental Panel on Climate Change is cautious, but has some strong warnings regarding neo-tropical forests:

'Unless appropriate action is taken, mismanagement of these ecosystems will, in turn, make climate change impacts more severe.

...if tropical forests were replaced by degraded pastures, there would be significant increases in surface temperature and decreases in evapotranspiration and precipitation in the Amazon basin. Furthermore, increases in the length of the dry season would make reestablishment of forests difficult. The global carbon cycle also could be altered...the effect of climate change on carbon sequestration in tropical soils can be very complex...9-18% more carbon [can be] stored in the soil under pasture than under the original forest'.

However as temperatures rise even further with more clearance a different scenario could arise. ("Positive feedbacks could reverse sinks"). Desertification and interruption of continental weather systems has not been counted out.

In the case of China (and temperate Asia as a whole), the IPCC says:

'The most critical area of uncertainty is the lack of credible projections of the regional climate in Temperate Asia. In particular, the effect of climate change on the Asian monsoon or the ENSO phenomenon is unknown. Presently, there are two diametrically opposite projections: one showing a strengthening and the other a weakening of the Asian monsoon, which would result in completely opposite impacts on hydrology and water resources'.

Some scenarios for China point to exacerbation of already severe water shortages (on the current situation see China's Water Crisis, also from the 19 May edition of The Economist).

Climate change in China could lead to changing patterns of migration within China and beyond its borders.

Better judgement as to the regional impacts of climate change is likely to have to wait until the IPCC's fourth assessment, due in 2006/7. If existing and further study suggests that once feedbacks commence it is too late to stop them, it may be wise to do what is possible to prevent them where possible, and where not to mitigate and prepare to adapt to them before they begin.

Caspar Henderson