The fierce, roaring winds and heavy rain of hurricanes are extremely dangerous and frightening. However, to the people living in the Carolinas, this terror is a reality. Hurricane Florence first made landfall near Wrightsville Beach in North Carolina. It brought 92 mph winds, which is the highest wind gust since Hurricane Donna in 1960. It is also forecasted to drop record-breaking amounts of rain. While Hurricane Florence now has calmed to be a tropical storm, it still has claimed a total of five lives and left over 600,000 homes and businesses without power. Besides forecasting the storm itself, a group of scientists took on the new, daunting task of running experiments, based on Hurricane Florence, to see if hurricanes are worsening due to human-induced global warming.
The experiments were led by Kevin Reed of Stony Brook University. He originally used a simulation to forecast Hurricane Florence by replicating the atmospheric and weather conditions from September 18th, the day the storm formed. He then observed the simulation throughout the projected duration of the storm. To serve as a comparison, he redid the simulation and subtracted global warming’s effects from the atmospheric and weather conditions. The artificial world without global warming was created by an international project C20C+, which models climate over the past 100 years without human-created greenhouse gases. In the counterfactual simulation, the storm looks entirely different.
In comparison to the storm without global warming, Hurricane Florence dumped 50% more rain, and it is much bigger. The diameter of Florence is approximately 80 kilometers wider in comparison to the model without climate change. Reed postulated that these effects are due to more available moisture in the air and warmer sea surface temperatures, which are all factors caused by global warming. His findings have startled the scientific community because humans can potentially increase the chances and magnitude of dangerous weather conditions.
How Does Climate Change Affect Hurricanes?
Reed and his team observed that climate change is causing slower slowing down the storms, which makes it dump more rain over an area. Over the past 70 years, scientists found that hurricanes have slowed by 10%. Reed believes this occurs because the atmospheric temperatures are steadily increasing, and warmer air can hold more moisture. This allows the clouds to drop more rain. Furthermore, Reed believes that climate change affects areas of high atmospheric pressure more in comparison to low atmospheric pressure areas. Both these effects allow hurricanes to become stronger and slower.
Additionally, climate change is causing an overall increase in water temperatures, and the melting of the polar ice caps is raising the sea level. This makes hurricanes stronger and bigger. The accumulation of effects can be observed in Hurricane Harvey, which devastated the people of Texas in August of 2017. In comparison to the simulated data without the effects of global warming, Harvey moved significantly slower and, therefore, dropped 35% more rain.
While many people support Reed’s findings, others have contrasting ideas behind the destructive nature of Hurricane Florence. While Reed claims that global warming is the primary contributor to hurricanes slowing down, others believe that it is due to the jet streams retreating north. This denies storms of essential currents that direct their path and speed. Without the jet streams, the rainstorms slow down and dump more rain in a single location.
Other contrasting arguments provide alternative reasons why the storms are increasing in size and strength. Many scientists claim that they are due to unpredictable weather patterns rather than climate change. To them, weather is random, and the increase in strength and size is due to natural storm cycles. They support this idea using sediment samples from the coastal lakes along the Gulf of Mexico. These samples suggest that there were more frequent and intense hurricanes 1,000 to 2,000 years ago in comparison to today. Since human-induced global warming occurred in more recent years, they postulate that random weather cycles are the culprit.
Additionally, other data show that hurricane intensity is not increasing over time. Rather, the monetary costs of the damages increased dramatically. This is due to increases in population and infrastructure.
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Resources: https://www.sciencenews.org/article/how-climate-change-fueling-hurricane-florence, https://www.usatoday.com/story/opinion/2018/09/14/hurricane-florence-climate-change-global-warming-weather-greenhouse-flood-column/1289272002/, https://www.cbsnews.com/news/hurricane-florence-how-climate-change-could-be-impacting-storms/, https://arstechnica.com/science/2018/09/first-ever-pre-storm-study-looks-at-climate-change-and-hurricane-florence/, https://www.npr.org/2018/09/13/647559489/what-hurricane-florence-tells-us-about-climate-change, https://www.cbsnews.com/live-news/tropical-storm-florence-hurricane-latest-weather-forecast-path-flood-zone-warnings-live-updates/
Picture Resources: https://www.mediawiki.org/wiki/File:Hurricane_Florence_Viewed_from_the_Space_Station.jpg, https://www.mediawiki.org/wiki/File:Hurricane_Florence_Approaching_Coast_(30801665718).gif, https://pixabay.com/en/beach-blue-caribbean-clouds-84531/, https://www.mediawiki.org/wiki/File:Staring_Down_Hurricane_Florence.jpg