COP21: Why a 2°C target, and will we reach it?

Global temperatures have already risen by around 1° Celsius since the Industrial Revolution of the 19th century. COP21’s stated goal is to ensure that average global temperatures do not rise more than 2° Celsius from what they were before the advent of industry as part of a binding agreement stretching to the year 2100.

But why is the goal set at 2° Celsius and not, say, at 1° or 3°? The target is essentially a compromise between what scientists thinks is necessary to stave off the most dire consequences of global warming and what is realistically achievable.

The target was first put forward by the European Union in 1995, and was gradually adopted as a reasonable objective by governments and intergovernmental organisations.

“It was decided that, with a rise of over 2° Celsius, the risk of hitting a tipping point would be unacceptably high,” says Bob Ward, of the Grantham Institute on Climate Change and the Environment, part of the London School of Economics.

“After that you would start to see things like greater instability of the Greenland ice sheet and methane release – things that would have an irreversible impact,” he told FRANCE 24.

Nevertheless, he says, the target was “essentially a political decision”.

“It’s the politicians who decide what losses, costs and dangers are acceptable.”

‘No precedent’ for a 3°C rise

An even lower target would, unsurprisingly, be preferable. Even with warming of only 2° Celsius, scientists believe the Earth is still in for some major environmental upheaval: increased forest fires, more drought in Africa and the Mediterranean, and sea level rises by some 40cm by the end of the century are just some of the effects scientists predict such a rise in temperature could cause.

All of this still lies within the realms of climate fluctuations that have been observed in the past, going back thousands of years. But if the temperature were to rise by 3° Celsius, the Earth would start to head into new, potentially cataclysmic territory.

“We have no precedent for rises of 3° Celsius or above. The last time it happened was millions of years ago, so it’s difficult to say what would happen,” says Ward. “But it would probably overwhelm our ability to adapt to the changes to the planet.”

Keeping global warming down to just 2° Celsius is already a monumental task. The Intergovernmental Panel on Climate Change (IPCC) estimates global CO2 emissions will have to fall by between 40% and 70% to make hitting the 2° Celsius target “likely”, but even then there is no guarantee.

If nothing is done and CO2 emissions continue to rise at their current rate, the IPCC believes the Earth could warm up by between 3.7° Celsius to 4.8° Celsius by 2100 compared to the pre-industrial level – a scenario that would be devastating to the planet.

Climate pledges fall far short

So, will the great and powerful gathered in Paris for the next 10 days come up with the necessary goods to stop the planet from heading down an irreversible path towards climate apocalypse?

Unfortunately, probably not. Ahead of the talks, participating nations – of which there are 195 – were asked to draw up pledges outlining the targets for cutting emissions and how they would achieve them. Only 180 have done so.

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To have just a 50/50 chance of keeping to the 2° Celsius target, those pledges would need to see carbon emissions cut to 36 billion tones by 2030. But the Grantham Research Institute’s analysis of the pledges found that, even if the promises are fully implemented, carbon emissions will still be at around 53 billion tonnes a year by that date.

“The pledges are a long way from being consistent with what would be needed if the 2° Celsius target is to be achieved,” says Ward, who co-authored the institute’s report.

But that doesn’t mean the world should resign itself to a future of flood, famine and environmental disaster.

If countries commit to reviewing the actions they are taking to cut carbon commissions after Paris, and strive to make future reductions, it may yet be enough to avert full-scale catastrophe. And the fact that for the first time there appears to be a global will to tackle the problem of climate change is reason to be optimistic.

“It’s not impossible that we’ll hit the 2° Celsius target if countries commit to making further changes in the future,” says Ward.“The fact that we have on the table pledges from 180 countries is a significant achievement already.”