March 30th, 2021
Key Findings
- Warming of the surface ocean from human-induced climate change is likely fueling more powerful tropical cyclones (TCs).
- The destructive power of individual TCs through flooding is amplified by rising sea level, which very likely has a substantial contribution at the global scale from anthropogenic climate change.
- TC precipitation rates are projected to increase due to enhanced atmospheric moisture associated with anthropogenic global warming.
- The proportion of Category 4 & 5 TCs has increased, possibly due to anthropogenic climate change, and is projected to increase further.
- Most climate model studies project the total number of TCs each year to decrease or remain approximately the same.
- Additional observed changes include the poleward migration of the latitude of maximum intensity, increasing rates of rapid intensification, and a slowing of the forward motion of TCs in places, though there are challenges in attributing these past observed changes to anthropogenic forcing.
Thomas R. Knutson, Maya V. Chung, Gabe Vecchi, Jingru Sun, Tsung-Lin Hsieh and Adam J. P. Smith. ScienceBrief Review by ScienceBrief.org.
This ScienceBrief presents a summary of the state of the science on tropical cyclones (tropical storms, hurricanes, and typhoons) and climate change. The authors assessed more than 90 peer-reviewed scientific articles, with a focus on articles describing observations of, or projected future changes to, the frequency and intensity of tropical cyclones (TCs) globally or in key regions, as well as changes in tropical cyclone-related rainfall and storm surge.
Warming of the surface ocean from anthropogenic (human-induced) climate change is likely fueling more powerful TCs. The destructive power of individual TCs through flooding is amplified by rising sea level, which very likely has a substantial contribution at the global scale from anthropogenic climate change. In addition, TC precipitation rates are projected to increase due to enhanced atmospheric moisture associated with anthropogenic global warming. The proportion of severe TCs (category 4 & 5) has increased, possibly due to anthropogenic climate change. This proportion of intense TCs is projected to increase further, bringing a greater proportion of storms having more damaging wind speeds, higher storm surges, and more extreme rainfall rates. Most climate model studies project a corresponding reduction in the proportion of low-intensity cyclones, so the total number of TCs each year is projected to decrease or remain approximately the same.
Additional changes such as the poleward migration of the latitude of maximum intensity, increasing rates of rapid intensification, and a slowing of the forward motion of TCs have been observed in places, and these may be climate change signals emerging from natural variability. While there are challenges in attributing these past observed changes to anthropogenic forcing, models project that with global warming, some regions will experience increases in rapid intensification, slowing of the forward motion of TCs, or a poleward migration of the latitude of maximum intensity, in coming decades.
Since 2013, models have been able to replicate observations with greater skill, utilizing higher resolution atmospheric−oceanic general circulation models and improved downscaling techniques. This has increased confidence in the sign and magnitude of projected future changes in some TC metrics. State-of-the-art models and multi-decadal satellite observation records suggest that in some cases, the signal of human-caused influence on TCs may be beginning to emerge from natural variability.
This ScienceBrief is meant to provide an accessible, understandable summary as part of a series on “Critical Issues in Climate Change Science” prepared for the COP26 climate conference to be held in Glasgow in 2021. The summary relies on a recent WMO assessment with additional, more recent references included. Reliable scientific information on possible future changes in tropical cyclone activity will help inform climate change mitigation decision-making as well as climate change adaptation efforts in hurricane-prone regions.
