Re-negotiating a planetary boundary

by Oliver Geden | | German Institute for International and Security Affairs
Wednesday, 17 July 2013 16:15 GMT

A NASA handout shows a large presence of stratocumulus clouds photographed by the Expedition 34 crew members aboard the International Space Station above the northwestern Pacific Ocean about 460 miles east of northern Honshu, Japan on January 4, 2013. REUTERS/NASA/Handout

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What happens when we miss the 2 degree target?

Let’s do a little thought experiment. If scientists and policy makers together work out a “scientific climate policy target,” establish it successfully as the threshold for “dangerous climate change,” derive a global carbon budget from it and finally define some emissions reduction paths considered to be feasible – what will happen if global greenhouse gas emissions simply keep rising, year after year after year?

The answer is so simple that nobody dares to talk about it: Politicians will look for just another target!

The very moment the mainstream of climate science comes to the conclusion that the overarching objective of limiting the global temperature increase to two degrees Celsius is no longer achievable, we’ll see a fundamental shift in international climate policy.

And this moment seems not to be far away. If one takes key findings from scientific policy advisers (like UNEP’s annual “Emissions Gap Report”) seriously, emissions will have to be reduced by 10-15 percent between 2010 and 2020 to stay below the 2 degree Celsius limit. But global emissions trends are still moving in the opposite direction and will be impossible to reverse in a matter of just a few years.


We can already observe attempts to avoid the crucial “make-or-break” point of the 2 degree Celsius target—the last possible year in which global emissions would have to peak. Scientists and scientific policy advisors are constantly adjusting core assumptions of climate economics, which is legitimate given the enormous uncertainties that exist within climate and energy system models. But if global emissions keep rising in the coming years, this will not be enough to save the 2 degree Celsius limit.

For politicians, it is quite clear that a target that is obviously unattainable cannot fulfill either a positive symbolic function or a productive governance function. Therefore, they will try to change the primary target of international climate policy.

Since scientists have a very influential position in global climate discourse, and since the current target formula is explicitly “science-based,” policy makers will not be able to modify the target on their own. But this time, agreeing on a “boundary object” between the scientific and the political sphere will be a much more pragmatic process.

Eventually, world leaders will have to decide on a new goal. They could either allow the 2 degree Celsius target to become a benchmark that can be temporarily overshot, accept a less stringent target, or give up on a global stabilisation objective altogether.

It’s highly likely that the European Union will be in favor of the overshoot option, because this would only entail a re-interpretation of the 2 degree Celsius target, not a complete revision. But if policy makers want to decide that 2 degrees Celsius is merely a reference point that will only be achievable in the long term, it would not only require an admission that it is impossible to avoid crossing the 2 degree Celsius mark, but would also put scientists under enormous pressure to redefine the threshold to dangerous climate change.

The foreseeable need to modify the 2 degree Celsius target arises primarily from international climate policy’s lack of success. Yet its failure is also the failure of the dominant approach to policy advice up to now: the attempt to delimit the range of options available to climate policy by establishing “science-based” climate targets. What seemed to be a non-negotiable planetary boundary will be subject to (more or less publicly visible) re-negotiation.

Oliver Geden is a senior research fellow at the German Institute for International and Security Affairs (SWP) in Berlin. A more indepth version of his argument can be found in his recent SWP study “Modifying the 2°C Target: Climate Policy Objectives in the Contested Terrain of Scientific Policy Advice, Political Preferences, and Rising Emissions”