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COP21 daily report: Can we limit global warming to 1.5C?

Cabot Institute Director Professor Rich Pancost will be attending COP21 in Paris as part of the Bristol city-wide team, including the Mayor of Bristol, representatives from Bristol City Council and the Bristol Green Capital Partnership. He and other Cabot Institute members will be writing blogs during COP21, reflecting on what is happening in Paris, especially in the Paris and Bristol co-hosted Cities and Regions Pavilion, and also on the conclusion to Bristol’s year as the European Green Capital.  Follow #UoBGreen and #COP21 for live updates from the University of Bristol.  All blogs in the series are linked to at the bottom of this blog.
One of the most stunning developments in the climate negotiations of COP21 – perhaps of the entire 20 years of negotiations – has been the emergence of major push to raise the accord’s ambitions.

After years of watering down language and creating flexible and non-binding targets, many of us anticipated that the pressure of compromise would weaken the COP21 accord. It might still be weakened in many respects.  And yet, in the past 72 hours, a group of 100 nations, including the European Union, the United States and dozens of developing nations, has emerged to propose the nearly unimaginable: to reduce the acceptable limit to human-caused global warming from 2C to 1.5C.

This has, for lack of a better word, stunned the scientific community.  Here in Paris, these raised ambitions resulted in applause and celebration – especially when they remained in place in the second draft circulated Wednesday.  But those of us who study climate change wonder whether this is possible.  Already this year, global warming reached 1C, and several more decimal places of warming are already baked into the system due to the slow response of the climate system. In short, there is some chance that our current 400 ppm CO2 is already enough to push the globe past 1.5C.

Ensuring even a 50:50 chance of staying below 1.5C will require urgent action – far more urgent than what nations have committed through their INDCs which will only limit warming to 2.7 to 3C.  In fact, it will almost certainly require achieving zero emissions, a complete cessation of all fossil fuel use, in the next several decades – and then negative emissions. We will have to capture and store carbon dioxide (CCS) either through biology  or technology; and as I mentioned in yesterday’s blog, the UK has actually cancelled potential CCS projects.
It is laudable that countries want to push for a stronger global warming limit, but they must be honest about the distance between their ambitions and their policies.  By policies I mean not only the insufficient INDCs to which they are committing, but the actual policies back home to achieve them.  Many nations’ policies will help achieve 40% reductions – the low-hanging fruit – but are they really investing in the innovation and infrastructure to achieve a 100% reduction in any timeframe, let alone a timeframe to limit warming to 1.5C?  If 1.5C requires an almost complete decarbonisation with the next several decades, how can that be achieved when global shipping and aviation are not even in the current draft of the accord?

Consequently, many of my colleagues around the globe are as stunned and confused about the political agenda as I am.  Are the politicians idealistic and naïve?  Out of touch with the science? Grandstanding?

I am cautious about jumping to conclusions.

The underlying politics are complex. Maybe the leaders are caught up in the moment.  More likely, they are caught up in their needs; this initiative has been led by small island states – especially Tony de Brum, Foreign Minister of the Marshall Islands – and these nations do face an existential threat from 2C warming, and some even from 1.5C warming.  They have been demanding this increased ambition for over a decade; they are living on the sharp end of climate uncertainty (as we learned when hosting many of them last summer) and they know what is coming.

It is surprising that others have joined them.

If I had to guess, I think this change is designed to strengthen post-COP21 policy both internationally and domestically.  It could be related to putting stronger pressure on the ratcheting up process of the accord, the mechanism by which nations will impose more demanding targets on themselves.  It could also be related to enshrining more robust compensation for those nations that will be most impacted by climate change. Or it could also be the confidence-building statement that investors and businesses have been demanding all week long. It is too soon to say.

Nonetheless, there is a large disconnection between these targets and our commitments and between our commitments and our policies. I’d be more comfortable about a step-up in our targets, if these gaps were being more openly discussed.

Prof Rich Pancost

This blog is by Prof Rich Pancost, Director of the Cabot Institute at the University of Bristol.  For more information about the University of Bristol at COP21, please visit

This blog is part of a COP21 daily report series. View other blogs in the series below:

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