There are always two sides to the story.
Hurricanes are one of the most powerful natural phenomena that occur on the planet. Along with generating winds that can gust over 250 kilometers per hour (155 miles per hour), they can also result in torrential downpours, coastal flooding, structural damage, human injuries, and loss of life.
So not surprisingly, hurricanes are a constant source of worry for residents of the southeastern United States. However, new research suggests that hurricanes also have an unexpected, but major upside — counteracting global warming.
Ana Barros, an environmental engineer from Duke University, has shown that tropical cyclones that make landfall result in an increase of forest photosynthesis and growth in the southeastern United States. In fact, these forests capture hundreds of times more carbon than is released by all vehicles in the US in a given year.
"Our results show that, while hurricanes can cause flooding and destroy city infrastructure, there are two sides to the story," said Barros in a Duke University news release. "The other side is that hurricanes recharge the aquifers and have an enormous impact on photosynthesis and taking up carbon from the atmosphere."
For the study, published in the Journal of Geophysical Research - Biogeosciences, Lauren Lowman, a doctoral student in Barros’s laboratory, used a hydrologic computer model to simulate the ecological impacts of tropical cyclones between the years 2004 and 2007. The earlier years experienced a high number of tropical cyclone landfall events, while the latter only had a few.
By comparing the low- and high-activity years, Lowman calculated the effect tropical cyclones have on the rates of photosynthesis and carbon uptake in forests located in the southeastern United States.
"It's easy to make general statements about how much of an impact something like additional rainfall can have on the environment," said Lowman. "But we really wanted to quantify the amount of carbon uptake that you can relate to tropical cyclones."
Unfortunately, it is extremely difficult to predict if the number of tropical cyclones that form in the Atlantic ocean will increase or decrease each year, and especially, how many of those that do form will even make landfall.
In fact, a recent study has shown that although the number of hurricanes that form in the Atlantic do not seem to be increasing year-after-year, their categorical strengths are. This is because hurricanes are fueled by warm ocean water, and the warmer the sea is, the more energy the hurricane has to ramp up.
But one thing is definitely clear — the regularity and number of hurricanes making landfall is a vital ecological and climatic process, albeit a sometimes dangerous one to humans.
Barros concluded, "If droughts do become worse and we don't have these regular tropical cyclones, the impact will be very negative. And regardless of climate change, our results are yet one more very good reason to protect these vast forests."
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