By Aaron Kressig, Global Environmental Policy MA candidate
(originally posted on the blog of the Forum for Climate Engineering Assessment, a scholarly initiative of the School of International Service)
Since the Copenhagen Accord in 2009, the goal of the international climate talks has been to hold global warming to a 2 degree Celsius rise above pre-industrial levels.
The start of the 21st Conference of the Parties to the UN Framework Convention on Climate Change in Paris is days away, and intended nationally determined contributions (INDCs) have been submitted by 150 countries. Climate scientists have begun to calculate how we are doing on the 2C goal, and the math is a little frightening. Not only do we have little wiggle room in terms of how much carbon we can emit to have any certainty of staying under this limit, but it will be global actions in the next two decades that determine our fate.
The calculations of planetary warming and average temperatures can be a difficult concept for anyone to get their mind around. One way to understand this topic is through the lens of a global carbon budget. This is the amount of carbon emissions that the planet can release and still stay under our stated goal. The most recent Intergovernmental Panel on Climate Change (IPCC) report estimated from 2011 onwards we would need to emit less than 800 billion tonnes (Gt) of C02e to have a 66% chance of staying under 2C. From 2011 to the end of 2015 the combined effect of greenhouse gas emissions will have reduced our remaining quota to 603 Gt of CO2e. While the exact calculations that go into carbon budget estimations are hotly contested, they all agree on one thing: the budget is disappearing quickly.
In order to understand the magnitude of the 2C challenge, it’s helpful to analyze some models which show how the world could, theoretically, stay under 2C. …