UN warming projections may be too optimistic, according to study in Nature Climate Change

UN predicts global warming global “catastrophic” 2.7 ° C by the end of the century, despite the new commitments announced at Cop 26.

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Bad news for the planet. The global warming projections developed by the UN on the basis of commitments and policies to reduce greenhouse gas emissions are more uncertain than one might think, insists a study published on Monday 22 November. in the journal Nature Climate Change.

According to the latest UN estimates, despite new commitments to 2030 announced just before and during the COP26 climate conference, the world is still heading for warming “catastrophic” of 2.7 ° C by the end of the century, far from the objectives of the Paris agreement to limit it well below + 2 ° C, if possible + 1.5 ° C, compared to the pre-industrial era.

The apparent precision of these forecasts is misleading, according to the study, several authors of which also participated in the development of the UN assessment that they implicate. Because of “misleading precision” announcements made during COP26 in Glasgow, “countries might think they are making progress when the reverse is perhaps true”, comments lead author Ida Sognnaes from the CICERO research center in Oslo.

Most climate projections are based on models which start from the desired final temperature for 2100 – + 1.5 ° C or + 2 ° C for example – and seek backwards to establish what levers would be necessary to achieve it, by adjusting variables such as the use of coal or the development of renewables.

Corn “our study is a forecast”, insists Glen Peters, also a researcher at CICERO. “We model where existing policies take us and we look at where we are.” Seven climate modeling groups have used this method to assess the commitments made for 2030 by the 200 or so countries that have signed the Paris Agreement. Result, estimates ranging from + 2.2 ° C to + 2.9 ° C.


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