New study suggests tropical storms will become more intense
Tropical storms may become less frequent as the planet warms up, but those that do form could be increasingly powerful, according to a new study published in the journal Science last week.
How global warming will affect tropical storm formation in the decades ahead has been the subject of intensive research. The new study says that, so far, the warming effects of greenhouse gases on tropical cyclones have been hard to discern because of natural variability and also because air pollution has been masking the impacts.
Aerosol particles, which cool the atmosphere by reflecting sunlight, have cancelled the effects of greenhouse gas pollution on tropical storm formation, the study found. But that compensating effect won’t last much longer if greenhouse gas warming keeps increasing, the scientists said in the study.
As vehicles and power plants added filters and scrubbers to reduce their impact on human health, and levels of man-made aerosols in the atmosphere began to decline. At the same time, greenhouse gas concentrations continued to rise.
With a new climate modeling effort, the new study recalculates the cancelling effects of aerosols and greenhouse gases on tropical cyclones worldwide. T
“The fact that global warming’s fingerprints don’t yet jump out at us when we look at hurricanes isn’t surprising – it’s what current science tells us we should expect,” said lead author Adam Sobel, a professor at Columbia University’s Lamont-Doherty Earth Observatory and School of Engineering. “The same science tells us that those fingerprints will show up eventually in more ultra-powerful storms.”
The scientists reviewed existing studies and data on tropical storm formation, specifically looking at potential intensity. Their new global calculations of the cancelling effect follow a 2015 study led by Lamont’s Mingfang Ting, with Suzana Camargo, also a coauthor on the new paper, that showed similar effects over the North Atlantic, where hurricanes that make landfall in the United States form.
Basic atmospheric physics suggest that hurricanes and cyclones will get stronger as the oceans heat up, since ocean warmth is the primary fuel for such storms.
Less well understood is how climate change will influence the number of tropical cyclones that form each year. Computer models indicate that while the total number of cyclones should decline in a warming climate, more intense, highly destructive storms like Super Typhoon Nepartak are likely to become more common.
Super-strong tropical storms have taken a toll in recent years, including
Typhoon Haiyan, also known as Yolanda, which killed more than 6,300 people as it devastated parts of the Philippines as a Category 5 storm in 2013. Last year, Hurricane Patricia became the second most-intense tropical cyclone on record when its sustained winds reached 215 mph before weakening to hit Mexico with winds still powerful at 150 mph.
The new study found that the largest increases in tropical cyclone potential intensity are expected to be at the margins of the tropics, particularly in the Atlantic and Pacific. The amount of rain that tropical storms bring is also expected to increase as the planet warms, due to increasing water vapor; and coastal flooding from storm surges that accompany tropical storms are expected to become more of a problem as sea levels rise.
The scientists also describe a shift in tropical cyclone tracks toward the margins of the tropics, noting that it is unclear if the shift is a response to warming. Simulations for the western North Pacific suggest that it is, at least in part.