The Intergovernmental Panel on Climate Change’s (IPCC) new Summary for Policymakers on the science of climate change is set to feed in to a key concern at the climate negotiations which will take place this November: should the global community prioritise the fight against the short-lived climate change gases or straight-up tackle the biggest contributor to climate change — carbon dioxide emissions? The decision on this could end up determining which set of countries should take early action to reduce emissions and which can breathe easy for a while.

The final draft report, accessed by The Hindu weeks ahead of its final release, notes that carbon dioxide emissions accumulating in the atmosphere since 1750 make the largest contribution to the net radiative forcing (in other words caused the greatest warming of the planet). But the emissions of another, much more potent but short-lived gas methane (CH) have increased by 150 per cent as compared to CO emissions that rose by 40 per cent between 1750-2011.

The panel’s scientists have concluded that the impact of methane on the climate is much higher than had been assessed when IPCC put out its last report in 2007. The report also notes that the impact of aerosols on climate change remains the least understood.

Politically important

These scientific assessments of the IPCC are politically important for countries trying to negotiate a new global agreement to fight climate change. The largest contribution of carbon dioxide emissions so far has come from industrialised countries. Once emitted, carbon dioxide, tends to stay in the atmosphere much longer, accumulating and causing ever more heating of the planet.

Short-lived greenhouse gases, such as methane and halocarbons (which are often used as gases in the refrigerant businesses) are more potent but tend to dissipate faster in the atmosphere. Methane emissions are rising from coal production in China and have been recorded at high levels in both China and India due to wet paddy agriculture and livestock.

Several developed countries have pushed for the global community to address these short-lived gases as a priority as it would give the world some headroom to tackle carbon dioxide emissions later.

Most developing countries pitch strongly against this prioritisation. They claim that if carbon emissions from the developed world had not accumulated unchecked so far, methane and other short-lived emissions whose levels go up and down constantly would not take the global temperatures to tipping point.

They have long taken a stance, with rare exceptions, that methane emissions are “subsistence emissions” coming from much poorer agrarian economies and that the farmers of the developing world would be hard hit if asked to adopt new and costlier alternative technologies while the developed world gets away easy. This, they contend, is against the U.N. convention that requires an equitable burden sharing formula for reducing emissions.

The IPCC report also makes it clear that the science on aerosols and black carbon — for which the developing world is increasingly being blamed — is yet unclear. In various interactions with other gases in the atmosphere and clouds, aerosols can cause cooling as well as heating but the net affect of this set of chemicals is still not understood well.

Indian programme

To counter the earlier research which suggests high climate changing impact of aerosols and black carbon emanating from developing countries, India has set up its own research programme specifically for these chemicals

At the meeting of more than 190 countries under the umbrella of the U.N. Framework Convention on Climate Change to be held in Warsaw this November, it is expected that the developed world, including the U.S., will make a strong pitch that the short-lived gases be addressed first and fast. The negotiations for the 2015 global agreement, which is to address climate change holistically, are yet to take-off with full force and are likely to do so only in 2014.

The pressure to produce some face-saving “deliverables” in November has brought the issue of short-lived gases to the table in the pre-Warsaw confabulations. In Poland, parties are going to use the data from the IPCC report in a manner that suits their strategic position best.

nitin.sethi@thehindu.co.in

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