Warm ocean waters fuel tropical systems, fueling stronger hurricanes that intensify faster.
The 2020 Atlantic hurricane season is already the second-busiest on record, and the entire list of storm names has been exhausted. As a result, the remaining storms of this season will take their Greek alphabet names. The only other time this happened was in 2005, when there was four storms that reached Category 5 – Emily, Katrina, Rita and Wilma. While there are year-to-year variations in weather patterns and water temperatures that lead to one season being more active than another, climate change is making storms worse once they develop.
Despite the fact that the total number of hurricanes each year no increases, there is a significant increase in the probability that a hurricane will reach a higher hurricane intensity (Category 3-5) during its lifetime. A NOAA CIMSS study earlier this year he reexamines global satellite data from 1979 to 2017. Using regular intensity estimates that are available every 6 hours, scientists found that the probability of a hurricane reaching Category 3 or higher has increased by about 8 percent per decade globally. When examining just the North Atlantic, that number jumped to 49 percent per decade. Combined over 3-year periods, the proportion of intensity estimates indicating a major hurricane jumped from about 32 percent to 39 percent globally, and from about 15 to 38 percent in the North Atlantic.
Water temperatures in the tropical Atlantic during hurricane season have increased about 1.85 ° F in the last hundred years. When combined with the warming atmosphere, this means that storms have greater strengthening potential, sometimes quickly, which leads to greater impacts. More water evaporates in storms, allowing for heavier rain. There is also evidence that the speed of translation of storms is slowing down, thus increasing the accumulated rainfall over a particular place and increasing the risk of flooding inland. And with an average level of sea level 7 inches Higher than a century ago, coastal storm surge flooding is already deeper and traveling further inland.
No reductions in greenhouse gas emissions these trends will continue with higher levels of coastal flooding, higher rainfall rates and a higher percentage of storms reaching higher hurricane intensity.