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Climate change signal in Atlantic tropical cyclones today and near future
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  • Chia-Ying Lee,
  • Adam H Sobel,
  • Michael K Tippett,
  • Suzana J. Camargo,
  • Marc Wüest,
  • Michael F Wehner,
  • Hiroyuki Murakami
Chia-Ying Lee
Columbia University

Corresponding Author:[email protected]

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Adam H Sobel
Columbia University
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Michael K Tippett
Columbia University
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Suzana J. Camargo
Marie Tharp Lamont Research Professor, Ocean and Climate Physics Division, Lamont-Doherty Earth Observatory, Columbia University
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Marc Wüest
Swiss Re
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Michael F Wehner
Lawrence Berkeley National Laboratory (DOE)
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Hiroyuki Murakami
GFDL
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Abstract

This manuscript discusses the challenges in detecting and attributing recently observed trends in the Atlantic hurricanes and the epistemic uncertainty we face in assessing future hurricane risk. Data used here include synthetic storms downscaled from five CMIP5 models by the Columbia HAZard model (CHAZ), and directly simulated storms from high-resolution climate models. We examine three aspects of recent hurricane activity: the upward trend and multi-decadal oscillation of the annual frequency, the increase in storm wind intensity, and the downward trend in the forward speed. Some datasets suggest that these trends and oscillation are forced while others suggest that they can be explained by natural variability. Future projections under warming climate scenarios also show a wide range of possibilities, especially for the annual frequencies, which increase or decrease depending on the choice of moisture variable used in the CHAZ model and on the choice of climate model. The uncertainties in the annual frequency lead to epistemic uncertainties in the future hurricane risk assessment. Here, we investigate the reduction of epistemic uncertainties on annual frequency through a statistical practice – likelihood analysis. We find that historical observations are more consistent with the simulations with increasing frequency but we are not able to rule out other possibilities. We argue that the most rational way to treat epistemic uncertainty is to consider all outcomes contained in the results. In the context of hurricane risk assessment, since the results contain possible outcomes in which hurricane risk is increasing, this view implies that the risk is increasing.
20 Feb 2023Submitted to ESS Open Archive
27 Feb 2023Published in ESS Open Archive