How much of a difference will the Paris Agreement make?

MIT study projects end-of-century climate under different scenarios.

Signed in December by climate negotiators from around the globe, the Paris Agreement centers on pledges from 188 countries to reduce their human-made greenhouse gas emissions, with the ultimate goal of capping the rise in global mean surface air temperature (SAT) since preindustrial times at 2 degrees Celsius. Toward that end, these pledges, which cover the years 2020-2030, are expected to be reviewed and strengthened periodically, but do not commit nations to any course of action after 2030. As a result, projections of the long-term climate impact of the Paris Agreement vary widely. 

A useful way to assess that impact is to simulate the effects of policies that extend the Agreement's 188 pledges (known as Nationally Determined Contributions, or NDCs) to the end of the century. In a new study that takes this approach, a team of climate scientists and economists from the MIT Joint Program on the Science and Policy of Global Change led by research scientist Andrei Sokolov finds that by 2100, the Paris Agreement reduces the SAT considerably, but still exceeds the 2°C goal by about 1°C.

One of the study's co-authors, Joint Program Principal Research Scientist Erwan Monier, discussed the team's results at the General Assembly of the European Geosciences Union on April 21 in a panel/press conference, "Historical Responsibilities and Climate Impacts of the Paris Agreement." 

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"The Paris agreement is certainly a step in the right direction, but it is only a step," said Monier. "It puts us on the right path to keep warming under 3°C, but even under the same level of commitment of the Paris agreement after 2030, our study indicates a 95 percent probability that the world will warm by more than 2°C by 2100."

Source: MIT News