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Proc Natl Acad Sci U S A. 2017 May 9;114(19):4881-4886. doi: 10.1073/pnas.1618082114. Epub 2017 Apr 24.

Quantifying the influence of global warming on unprecedented extreme climate events.

Author information

1
Department of Earth System Science, Stanford University, Stanford, CA 94305; diffenbaugh@stanford.edu.
2
Woods Institute for the Environment, Stanford University, Stanford, CA 94305.
3
Department of Earth System Science, Stanford University, Stanford, CA 94305.
4
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964.
5
Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, CA 94305.
6
NASA Goddard Institute for Space Studies, New York, NY 10025.
7
Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208.
8
Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095.
9
Department of Statistics, University of California, Los Angeles, CA 90095.
10
Department of Statistics, Stanford University, Stanford, CA 94305.

Abstract

Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent.

KEYWORDS:

climate change; climate extremes; event attribution; global warming

PMID:
28439005
PMCID:
PMC5441735
DOI:
10.1073/pnas.1618082114
[Indexed for MEDLINE]
Free PMC Article

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