In the recent annual report from the Global Carbon Project (GCP) we are warned that if emissions continue to climb at current rates, we will not be able to keep global warming to less than two degrees Celsius. The research suggests that if we wish to limit global warming (to 2 degrees) we will have to stay below 3,200 billion tonnes of carbon dioxide.
But at current rates, the world will have already exhausted all that carbon by 2045 because carbon dioxide emissions continue to track the high end of emission scenarios, thus eroding the chances of keeping warming below 2 degrees Celsius.
Image: The IPCC's Fifth Assessment Report collated from the peer-reviewed literature almost 1200 scenarios of future emissions, each scenario having a different 'story' of how the future might unfold. The scenarios can be grouped according to which of the four Representative Concentration Pathways (RCPs) they are most similar to, based on peak concentration of greenhouse gases.