Environment Counts | Global Warming and Hurricanes
Author: Rick Higgins – Published At: 2012-03-12 09:59 – (830 Reads)
A study by the Geophysical Fluid Dynamics Laboratory/NOAA concludes it is premature to state that human activity, and particularly greenhouse warming, has already caused a detectable change in Atlantic hurricane activity. However, the study also concludes it is likely that anthropogenic warming by the end of the 21st century will cause hurricanes to have substantially higher rainfall rates and be more intense on average than present-day hurricanes.
- Have humans already caused a detectable increase in Atlantic hurricane activity?
- What changes in hurricane activity are expected for the late 21st century, given the pronounced global warming scenarios from current IPCC models?
The report reviews these questions in the context of published research findings. (Links to the main research papers are included in the study.)
The main conclusions are:
- It is premature to conclude that human activities, and particularly greenhouse gas emissions that cause global warming, have already had a detectable impact on Atlantic hurricane activity. That said, human activities may have already caused changes that are not yet detectable due to the small magnitude of the changes or observational limitations, or are not yet properly modeled (e.g., aerosol effects).
- Anthropogenic warming by the end of the 21st century will likely cause hurricanes globally to be more intense on average (by 2 to 11% according to model projections for an IPCC A1B scenario). This change would imply an even larger percentage increase in the destructive potential per storm, assuming no reduction in storm size.
- There are better than even odds that anthropogenic warming over the next century will lead to an increase in the numbers of very intense hurricanes in some basinsâ€”an increase that would be substantially larger in percentage terms than the 2-11% increase in the average storm intensity. This increase in intense storm numbers is projected despite a likely decrease (or little change) in the global numbers of all tropical storms.
- Anthropogenic warming by the end of the 21st century will likely cause hurricanes to have substantially higher rainfall rates than present-day hurricanes, with a model-projected increase of about 20% for rainfall rates averaged within about 100 km of the storm center.
Tracks of simulated Atlantic Category 4 and 5 hurricanes for the present climate and for a warmer climate condition projected for the late 21st century. The hurricanes were simulated using higher resolution atmospheric models, with large-scale conditions taken from an ensemble of 18 global climate models.
This issue is also the subject of a Science Magazine article by Thomas R. Knutson and others titled Modeled Impact of Anthropogenic Warming on the Frequency of Intense Atlantic Hurricanes– Morris A. Bender et al. http://www.sciencemag.org/content/327/5964/454.full?ijkey=PFX.MzpFJDznM&keytype=ref&siteid=sci