Why Paris Climate Pledges Need to Overdeliver to Keep Warming to 2C

Last year’s Paris Agreement is considered a major global step in addressing the threat of climate change.
...
But accompanying this success came a set of puzzling questions:  what do the INDCs add up to in terms of global emissions reductions?  Are they sufficient to keep warming to well below 2C?  If not, what temperature increase are we heading for?  What about 1.5C?  And, are the INDCs at least a step in the right direction?

An added complication is that INDCs don’t all follow the same approach.  Some countries’ emissions pledges are conditional on receiving funding, for example, while others depend on the growth of their economy.  This is why various studies (pdf) addressing these questions have often come up with different answers.

Our new paper, just published in Nature, provides some clarity on this issue by carrying out a “meta-analysis” to see what conclusions we can draw from ten of these studies.

And to cut a long story short, the INDCs alone do not keep warming to well below 2C.

Similar level of effort
The current INDCs cover the period up to 2030.  To estimate warming over the entire 21st century, scientists have to make assumptions about what happens beyond the INDCs.
...
But the bottom line is that the level of climate action in the INDCs do not keep global temperature rise below 2C.  And they present an almost 10% risk that temperature rise hits 4C by 2100.

Read more at Why Paris Climate Pledges Need to Overdeliver to Keep Warming to 2C