Invited review article
Multidecadal modulations of key metrics of global climate change

https://doi.org/10.1016/j.gloplacha.2020.103149Get rights and content
Under a Creative Commons license
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Highlights

  • Global climate change metrics vary naturally over multidecadal periods.

  • These metrics may track global mean surface temperature in counterintuitive ways.

  • The global warming hiatus provided a focus for rapid scientific progress.

  • Pacific and Atlantic decadal variability played a key role in recent modulations.

Abstract

Widespread public and scientific interest in the recent global warming hiatus and related multidecadal climate variability stimulated a surge in our understanding of key metrics of global climate change. While seeking explanations for the nearly steady global mean temperature from late 1990s through the early 2010s, the scientific community also grappled with concomitant and seemingly inconsistent changes in other metrics. For example, over that period, Arctic sea ice experienced a rapid decline but Antarctic sea ice expanded slightly, summertime warm extremes continued to rise without evidence of a pause, and the expanding Hadley cell trend maintained its course. In this article, we review recent advances in understanding the multidecadal variability of these metrics of global climate change, focusing on how internal multidecadal variability may reconcile differences between projected and recently observed trends and apparent inconsistencies between recent trends in some metrics. We emphasize that the impacts of global scale, naturally occurring patterns on multidecadal timescales, most notably the Pacific and Atlantic Multidecadal Variability, tend to be more regionally heterogeneous than those of radiatively forced change, which weakens the relationship between local climate impacts and global mean temperature on multidecadal timescales. We conclude this review with a summary of current challenges and opportunities for progress.

Keywords

Global warming slowdown
Climate change metrics
Pacific decadal variability
Atlantic multidecadal variability
Polar amplification
Warm Arctic/cold continents
Hadley cell expansion

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