How climate change makes powerful storms like Hurricane Melissa more likely

Hurricane Melissa now holds a place in Atlantic basin record books as one of the most powerful tropical cyclones to develop and make landfall.The storm became a hurricane at 11 a.m. Saturday with peak winds of 75 mph. Just 24 hours later, the storm’s strength had nearly doubled with eyewall winds estimated at 140 mph. Less than a day after that, the storm slammed into Jamaica with eyewall winds estimated to be at 185 mph. Meteorologists call this massive jump in wind speeds rapid intensification. Three other Atlantic hurricanes experienced this phenomenon this season: Hurricanes Erin, Gabrielle and Humberto.While many factors can play a role in the development and strengthening of a tropical cyclone, two large scale patterns stand out as possible influences this hurricane season. La NiñaEarlier this month, scientists at NOAA officially declared a weak La Niña pattern was present in the eastern tropical Pacific. A La Niña pattern is marked by cooler the normal water temperatures in that specific region of the Pacific Ocean, but atmospheric impacts of La Niña are often seen over the Atlantic basin. A major marker of La Niña in the South Atlantic is weaker upper level winds. When those winds are weaker, wind shear is reduced. Hurricanes struggle to stay organized if wind shear is high, but this past week had weak wind shear conditions in the area where Hurricane Melissa strengthened to the south of Jamaica.Climate ChangeWhen we talk about climate change, we often talk in terms of rising air temperatures because that’s what we experience in our day-to-day lives.But research from NOAA, NASA and many other international meteorological organizations shows that 90% of the excess heat generated by increasing greenhouse gasses is absorbed by the oceans. That extra heat raises global ocean temperatures and elevates sea levels. Sea surface temperatures in the Atlantic and Caribbean have been running a couple of degrees warmer than normal this fall. Warm ocean waters are the fuel that hurricanes need to develop and gain strength. In general, a sea surface temperature around 80 degrees is plenty.Water temperatures where Melissa strengthened were about two to three degrees warmer than the long term average, with temperatures of 85 to 87 degrees extending down to about 300 feet. These conditions gave Hurricane Melissa a literal well of energy to tap into hours before its first landfall. Of course, weather is complicatedHurricane Melissa likely would have developed without the influence of climate change and possibly without the ongoing La Niña. However, both of these patterns put the proverbial thumb on the scale, tipping the odds in favor of a destructive storm spinning up just a couple of days before landfall.A 2023 study found that the number of rapidly intensifying hurricanes has doubled in the last 30 years. Warmer ocean temperatures are highlighted as the main cause. See more coverage of top California stories here | Download our app | Subscribe to our morning newsletter | Find us on YouTube here and subscribe to our channel