The figure quoted most often in climate change literature is a further warming of 0.6 ºC. This is unavoidable warming-in-the-pipeline, over and above the 1ºC rise the world has touched in 2015. This is not to minimise the political significance of the demand of 1.5 ºC, but to point out that it has already been breached.
Of the numerous issues being discussed at the COP21, the most crucial is mitigation – the reduction of greenhouse gas emissions – and the accompanying limit on the rise in global average temperatures. The draft being negotiated in Paris, as it currently stands (on 9 December), offers three options in Article 2 (1a): “… To hold the increase in the global average temperature to below 2 degrees C above pre-industrial levels; … well below 2 degrees C … and below 1.5 degrees C.” One of these three will be in the final draft. The recent deluge in Chennai – likely a consequence of climate change, and at only 1 ºCelsius warming currently – makes amply clear that this is not merely an issue of arcane law or abstract science.
Two ºC has been for a while the most widely accepted benchmark for dangerous levels of warming among scientists and policymakers. It’s hugely significant for two reasons: were the planet to cross 2 ºC of average surface warming above pre-industrial temperatures for long enough, important ecosystems get locked into irreversible damage. What’s more, and this is the most crucial concern, at 2 ºC of warming, there’s a much greater likelihood that multiple climate feedbacks – the Earth’s responses to warming that in turn cause further warming – would amplify each other, taking global warming to levels too fearful to contemplate.
A 1.6º C headstart
Two degrees as the benchmark has been questioned from a number of perspectives that cover the past, present and future. In a landmark paper in 2008, ‘Target Atmospheric CO2: Where Should Humanity Aim?’ the well-known climate scientist James Hansen and colleagues argued from a palaeo-climatic perspective that atmospheric CO2 levels ought to be brought down to 350 parts per million (it’s 400 ppm currently), with a correspondingly lower temperature threshold. He was less measured in an interview on Australia’s ABC Radio earlier this year: “We know that the prior interglacial period, about a 120,000 years ago, was less than 2 degrees warmer than pre-industrial conditions and sea level was at least 6-8 metres higher … so it is crazy to think that 2 degrees is a safe limit”.
The group associated with RealClimate said a few years ago: “[Given current impacts] after only 0.8 degrees of warming, calling 2 degrees C a danger limit seems to us pretty cavalier.” The Alliance of Small Island States that face submergence due to sea level rise – including Maldives, Jamaica, Tuvalu, the Bahamas and forty others – has been reminding us for some years now that many of those nations would not survive a 2 ºC rise. At the Paris COP, they and a large number of other nations have been pushing for 1.5 ºC as the benchmark to be adopted. This target was also what was demanded by countries, people’s movements and NGOs attending the People’s Conference on Climate Change in Cochabamba, Bolivia in April 2010, after the failed COP in Copenhagen, 2009.
It may be a huge political victory for climate justice movements if 1.5 ºC is enshrined as the target, but we need to be extremely cautious, for two reasons. One, we are actually already effectively at 1.6 ºC above pre-industrial levels. Much of the excess heat trapped by greenhouse gases is absorbed by the oceans. Oceans slowly release the heat they have absorbed, or transport it back to the ocean’s surface via ocean currents. Due to this thermal inertia of the oceans, there is a long lag between carbon emissions and warming. The most oft-quoted figure in the climate change literature is a further warming of 0.6 ºC. This is unavoidable warming-in-the-pipeline, over and above the 1 ºC rise we have touched in 2015. This is not to minimise the political significance of the demand of 1.5 ºC, but just to point out that it has already been breached.
Clear and present danger
The second reason is this: even though the final text may set a threshold of 1.5 or less than 2 ºC of warming – which political elites will present as a negotiating triumph – what we actually have on the table takes us way higher. The disaggregated, bottom-up approach adopted in COP meetings of the past 4-5 years, of each nation voluntarily submitting Intended Nationally Determined Contributions (INDCs), though more inclusive in covering emissions by China, the US and India, dismantled the prior ceiling set by the Kyoto Protocol at 2 ºC. The respected World Resources Institute scrutinised many studies that have examined all the INDCs submitted to the UNFCCC; these studies suggest we are on course to a warming of 3 ºC. Though the process allows for a ratcheting up of emission pledges (and possibly of financial and technology transfers as well), the nearest date for a review is almost a decade away, in 2024, and even that date is being contested. What happens in or after 2024 is anybody’s guess.
It is a failure because significant decision-makers have known for thirty years now the dangers of pushing the planet significantly above 1 ºC of warming. Three degrees’ warming is outside anything that human civilisation has ever experienced. Though it would take very long for its furies to reveal themselves fully, it would be good to know what a 3º world looks like. In his book Six Degrees, Mark Lynas presented peer-reviewed research which suggests that at three degrees, the Indus – inordinately dependent on glacier melt for its water flows, much more than the Ganga or Brahmaputra – dries up (which would be catastrophic for the people of Pakistan and Ladakh). Sea levels rise 25 metres higher than the present inundating vast coastal regions in India and all over the world. Worryingly, the Arctic region is completely free of ice, and warmer soils release carbon dioxide instead of absorbing them as they do presently, both ensuring that warming rises even further.
Clearly, we need to act with much greater urgency to prevent the world crossing into dangerous levels of warming. Every fraction of a degree’s rise above that has huge consequences for communities and species everywhere. What we do now – not just ten or fifteen years from now – will determine what kind of world we bequeath to generations of the foreseeable future.
Nagraj Adve works and writes on issues related to global warming.