A new study of satellite data suggests that what has been perceived as a “century-scale increase” in hurricane activity in recent decades may just be a rebound from a lull caused in part by aerosol pollution.
Published in the journal Nature Communications, the study provides “a new complete record of Atlantic hurricanes from 1851 to 2019, adding in hurricanes that were likely missed by pre-satellite observation methods,” writes Carbon Brief.
The move to update the global hurricane picture has enabled researchers to identify a decrease in hurricane activity during the 1970s and ’80s, a lull the authors say was likely caused by “some combination of multi-decadal [natural] climate variability…and/or non-greenhouse gas forcing, such as variations in anthropogenic or natural aerosols.”
The surprising connection between the two factors comes down to how aerosols act to reduce the amount of sunlight arriving at the ocean surface, explained Princeton University geoscience professor Gabriel Vecchi.
The study adds that the variations in aerosol levels “probably masked century-scale greenhouse gas warming contributions to North Atlantic major hurricane frequency.” The authors were careful to stress that the findings “are specific to the Atlantic and should not be generalized” for storm systems in other parts of the world, and should not necessarily be taken to mean that emissions have had a “marginal” effect on cyclone or hurricane development.
Princeton atmospheric scientist Shuai Wang, who was not involved in the study, told Carbon Brief the lesson from these findings is that he and his fellow researchers “should take extra caution to not over-interpolate a relatively short period of storm trend.”
Hiroyuki Murakami, a scientist at the University Corporation for Atmospheric Research (UCAR), praised the study authors for doing a “great job” in reconstructing the dataset.
“These findings highlight the complex nature of long-term changes in storm activity in the North Atlantic,” he said. “I agree that multi-decadal internal variability, anthropogenic aerosols, and greenhouse gases have all played important roles for the long-term changes in storm activity.”