The U.N. Intergovernmental Panel on Climate Change (IPCC) in its latest report warns that that a large part of the changes that occur on the planet cannot be reversed even after the next few centuries unless carbon dioxide emissions are brought down fast, substantially and kept extremely low for a very long time.

The warning in the final draft of the Summary for Policymakers on the science of climate change reiterates the fact that while tackling short-lived climate changing gases may be an easy option, it could also be too short-sighted.

The summary notes, “it is very likely that more than 20% of emitted CO will remain in the atmosphere longer than 1,000 years after anthropogenic emissions have stopped. CO-induced warming is projected to remain approximately constant for many centuries following a complete cessation of emissions.”

This will have long-lasting impacts on the environment. “It is virtually certain that global mean sea-level rise will continue beyond 2,100 ft, with sea level rise due to thermal expansion to continue for many centuries,” the panel’s final draft of the report says. Though confidence in the finding is low, experts say that if global mean temperatures rise and stay on a sustained basis between 1-4° Celsius, the Greenland ice sheet could all but disappear. The cause: accumulating carbon dioxide emissions.

Scientists have assessed earlier too that cumulative CO emissions in the atmosphere should not accede 1,000 PgC (pentagrams of carbon). Of this, the IPCC report notes, 460-630 PgC of carbon space has already been filled up.

The figures are not new but its insertion in the IPCC report sends a political signal to the developed world. The U.S. has repeatedly warned at earlier climate negotiations that it is not keen to share the burden of reducing emissions with other countries based on the principle of historical responsibility. The EU too has shied away from coming out explicitly agreeing with the ideaLargely their positions at the climate negotiations suggest that they are open to having a burden-sharing formula to limit future emissions. But they are averse to factoring in responsibility for existing accumulated carbon dioxide emissions.

But the idea of an overall carbon budget that is already more than half consumed inequitably will naturally be raised at the climate negotiations by developing countries — especially the emerging and large economies in the developing world.

On India

Among these, India would be in a peculiar position soon. Its per-capita emissions are one of the lowest among the large economies while that of other emerging economies have raced to or already past the levels achieved by the OECD countries. India will require greater carbon space (and therefore time to let its emissions peak) than other developed or emerging economies to cater to the energy needs of a growing nation. The IPCC’s upcoming report on “mitigation” will shed more light on the possible paths towards reducing emissions but for India the challenge will sit in marrying the facts in these reports to the political and geopolitical realities that multilateral negotiations always bring along.

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