We know that global warming is taking place and its main cause is increasing levels of carbon dioxide in the atmosphere.

The Paris climate agreement provides a rallying call to nations to limit carbon emissions and to keep global temperature rise well below 2°C above the pre-industrial period. This would significantly reduce the risks and impact of climate change.

What is important for policymakers is - how much time is left before we reach the Paris warming targets?

If there is only a few years, we'll need to focus on mitigation. Whereas if we have many decades, then there is more opportunity to develop and implement new technologies and policies for a more carbon-efficient future.

 Many previous simulations of global warming do not work well if you try to get them to simulate what has happened in the past. We think that is an important test for a simulation - if it can't replicate the past, it probably is less reliable for projecting the future.

To get our results, we ran 100 million simulations of carbon emissions and warming. Then we took only the results that recreated past climate accurately, which left us with about 30,000 projections for the next century.

When do we reach 2°C? It all comes down to emissions

To keep below 2°C of warming, we found that the total amount of carbon emitted from the start of 2018 needs to remain less than 1,300 to 1,830 gigatonnes of carbon dioxide. The sooner we emit that much carbon, the sooner we reach 2°C.

To view the resulting timeline predictions see the full article on the NERC website.