Recommended temperature metrics for carbon budget estimates, model evaluation and climate policy


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Date

2019-12

Publication Type

Journal Article

ETH Bibliography

yes

Citations

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Data

Abstract

Recent estimates of the amount of carbon dioxide that can still be emitted while achieving the Paris Agreement temperature goals are larger than previously thought. One potential reason for these larger estimates may be the different temperature metrics used to estimate the observed global mean warming for the historical period, as they affect the size of the remaining carbon budget. Here we explain the reasons behind these remaining carbon budget increases, and discuss how methodological choices of the global mean temperature metric and the reference period influence estimates of the remaining carbon budget. We argue that the choice of the temperature metric should depend on the domain of application. For scientific estimates of total or remaining carbon budgets, globally averaged surface air temperature estimates should be used consistently for the past and the future. However, when used to inform the achievement of the Paris Agreement goal, a temperature metric consistent with the science that was underlying and directly informed the Paris Agreement should be applied. The resulting remaining carbon budgets should be calculated using the appropriate metric or adjusted to reflect these differences among temperature metrics. Transparency and understanding of the implications of such choices are crucial to providing useful information that can bridge the science–policy gap.

Publication status

published

Editor

Book title

Volume

12 (12)

Pages / Article No.

964 - 971

Publisher

Nature

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Climate and Earth system modelling; Projection and prediction

Organisational unit

03777 - Knutti, Reto / Knutti, Reto check_circle

Notes

It was possible to publish this article open access thanks to a Swiss National Licence with the publisher.

Funding

820829 - LC-CLA-08-2018 | RIA | Constraining uncertainty of multi decadal climate projections (EC)

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