One way of looking at emissions targets is as a fixed budget amount, or quota. This countdown shows one estimate of how long it will take to reach an amount of greenhouse gas emissions beyond which 2C of warming will be likely.
How is this calculated?
To have a good chance of keeping global warming under 2C, there is only a finite amount of carbon pollution the world can emit – this amount can be thought of as a fixed budget amount, or quota.
Our countdown clock shows one estimate of how long it will take to reach an amount of greenhouse gas emissions beyond which 2C of warming will be likely.
The total carbon budget remaining figure used is 2900 GtCO2-e (within a range of 2550 to 3150 depending on various factors). This is one estimate of the amount emissions need to stay under to limit total human-induced warming to less than 2C relative to the period 1861–1880 with a probability of >66%.
Full details of how this figure was determined are in the IPCC Synthesis Report here.
The rate of emissions is based on the most recent year of global emissions from the Global Carbon Project, and assumes no increase or decrease in emissions year-to-year as a ‘business as usual’ scenario.
For further information, please refer to the Guardian article, first published Thursday 19 January 2017