#ClimateAgreement: The Paris Agreement has solved a troubling problem

By endorsing a limit of 1.5 °C, the climate negotiations have effectively defined what society considers dangerous, says Simon L. Lewis.

The Paris Agreement for tackling climate change opens for governments to sign this week, four months after it was agreed. The momentum created by the deal, described as a multilateral political triumph, looks set to continue: China and the United States are among the 130-odd countries expected to bring the agreement into force early by adding their signatures on the first day.
Is this the beginning of the end of the fossil-fuel age, as some suggest? It could be — its influence is certainly being felt. Peabody Energy, the largest private coal company, lost 12.6% of its value the day after the Paris deal was agreed. It filed for bankruptcy last week. But even before countries queue up to sign, the Paris Agreement could already have solved one of the most troublesome problems in the climate arena, one that has plagued scientists and policymakers for almost a quarter of a century. And yet almost nobody — scientists included — seems to have noticed.
The Paris Agreement has finally defined the threshold for ‘dangerous’ climate change. It is 1.5 °C above pre-industrial levels. True, this definition is not explicitly spelled out in the agreement text. It is a de facto definition. But it is there all the same. And that is hugely significant.

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