Above: SST heat loss from Hurricane Irene
The title is sarcasm, but it does present an interesting quandary for alarmists. What’s more acceptable – hurricanes and the loss of life and property they bring, or loss of coral reef systems? My guess is that given the dislike for humankind often demonstrated by the environmental movement, they’d go for more hurricanes, and then use them to squall about “increasing extreme weather”. Fortunately, as Dr. Ryan Maue has shown us again and again, there is no upward trend in hurricane frequency.
From the AGU weekly highlights:
Preventing coral bleaching, one hurricane at a time
In recent decades, sea surface temperatures and the occurrence of heat stress in coral communities have soared.
High surface water temperatures lead coral populations to evict their symbiotic, and colorful, algal residents. The photosynthesizing algae are what feed the coral, and the process-known as bleaching-can eventually kill it, leaving parched white exoskeletons in place of formerly vibrant reefs. However, not all coral reefs seem equally affected by mass bleaching at the hands of global warming. Some processes, like deep water upwelling, are known to offset rising temperatures locally, but Carrigan and Puotinen investigate a novel mechanism that they suggest may be responsible for protecting some susceptible populations.
Tropical cyclones (TCs) induce ocean mixing. Their strong winds whisk heat away from the sea surface, cooling surface temperatures by up to 6 degrees Celsius (10.8 degrees Fahrenheit) in an area typically spanning hundreds of kilometers from the eye of the storm. Though the strong waves associated with TCs are known to damage coral reefs, the extent of the cooling effect far exceeds the localized damage. Using historical TC storm tracks and the National Oceanic and Atmospheric Administration’s Coral Reef Watch’s records of thermal stress from 1985 to 2009, the authors analyze whether or not the cooling effect of TCs could temporarily alleviate escalating sea surface temperatures, staving off coral bleaching. At the basin scale, they find that TCs play a significant role in mitigating thermal stress for coral reefs in the North Atlantic. Further, their analysis suggests that TCs are likely important for the Great Barrier Reef, along with coral communities in western Australia, Japan, and the southwest Indian Ocean, though the spatial and temporal resolution of their model is not detailed enough to make a definitive statement. The authors note that their investigation only considered the effect of TCs on reef ecosystems that were already experiencing thermal stress. They raise the possibility that cyclones could play a preventative role, cooling the ocean waters before the corals’ heat threshold is exceeded.
Source: Geophysical Research Letters, doi: 10.1029/2011GL049722, 2011 http://dx.doi.org/10.1029/2011GL049722
Title: Assessing the potential for tropical cyclone induced sea surface cooling to reduce thermal stress on the world’s coral reefs
Authors: A. D. Carrigan and M. L. Puotinen: Institute for Conservation Biology and Environmental Management and School of Earth and Environmental Sciences, University of Wollongong, New South Wales, Australia and School of Earth Sciences, Ohio State University, Ohio, USA.