Thomas Knutson, Suzana J. Camargo, Johnny C. L. Chan, Kerry Emanuel, Chang-Hoi Ho, James Kossin, Mrutyunjay Mohapatra, Masaki Satoh, Masato Sugi, Kevin Walsh, and Liguang Wu

Bulletin of the American Meteorological Society

Published date May 28, 2019

Tropical Cyclones and Climate Change Assessment: Part I

  • Looks at whether changes in tropical cyclone activity can be detected compared to natural variability and/or attributed to human-caused climate change
  • Assesses the evidence for detectable anthropogenic influence on tropical cyclone activity while seeking to reduce the chance of Type II errors (i.e., missing or understating anthropogenic influence or detection)
  • For a change to be considered detectable from the Type II error perspective, the authors adopt the criteria of p=0.1 (less than 1 in 10 chance of being wrong) for statistical significance and also assess whether the balance of evidence suggests that a detectable change has been identified
  • Attribution statements made from the Type II error perspective indicate the authors found there is a balance of evidence (more than 50% chance) that anthropogenic climate change contributed nontrivially in a specified direction to an observed change

NOTE: all the statements below are from a Type II perspective requiring less convincing levels of evidence

  • All authors agree there is a detectable poleward migration of the lifetime maximum intensity of cyclones in the western North Pacific, and most (9 out of 11) agree human-caused climate change contributed to the migration
  • Ten out of 11 authors conclude the balance of evidence suggests there is a detectable increase in the global average intensity of the strongest tropical cyclones since the early 1980s; eight of 11 say humans contributed to the increase
  • Eight of 11 authors concluded that the balance of evidence suggests an anthropogenic contribution to the 2015 western North Pacific TC season
  • All authors concluded that the balance of evidence suggests there has been a detectable long-term increase in occurrence of Hurricane Harvey-like extreme precipitation events in the eastern Texas region, and that human-caused global warming has contributed to this increase
  • All authors found the balance of evidence suggests an increase in the frequency of post-monsoon season extremely severe cyclone storms over the Arabian Sea, and most authors (eight of 11) say human-caused warming has contributed to the increase
  • All authors concluded that the balance of evidence suggests the observed increase in Category 4-5 proportion in recent decades represents a detectable change; most (eight of 11) concluded the increase resulted in part from human-caused warming