Hurricane Harvey was the first major hurricane to make landfall in the United States since 2005, but its winds were not the only historic variable associated with Harvey. Millions were impacted by deadly flooding, and on Wednesday, the National Weather Service (NWS) officially confirmed that 64.58 inches of rain fell with Hurricane Harvey near Beaumont, Texas (in Nederland). This is a new record for the heaviest rainfall ever recorded in the United States during a tropical cyclone. The previous record occurred in Hawaii in which 52 inches was recorded. To show the magnitude of Harvey, the NWS confirmed that at least seven weather stations recorded more than 51 inches of rainfall with Harvey in Texas.
Was Harvey Caused By Climate Change?
Many people on social media have made statements along the lines of: “this is because of climate change” and “Harvey was caused by climate change”. But, this is not the appropriate way to view Harvey and its impacts. Climate change reflects a change in the background state in which all weather exists. Climate change, in itself, does not cause an individual tropical cyclone. Climate change can make impacts of a tropical cyclone worse. A few ways in which climate change can make the impacts worse are: I) rising sea levels due to melting ice, II) warming ocean waters, and III) more atmospheric moisture. I) As ice melts, the sea levels will rise. This can cause sea water inundation to be a bigger threat for coastal areas during a storm surge. II) As the atmosphere warms, and warms the ocean waters, it can increase the intensity of tropical cyclones. This is because the warm waters are food for the hurricanes (but one of many ingredients needed for a tropical cyclone to develop and intensify). And III), as the atmosphere warms, it can hold more moisture. This can allow for more moisture to be evaporated and more rain to fall with tropical cyclones. So, to blame the development of Hurricane Harvey, and its impacts, solely on climate change is not the appropriate.
The impacts of climate change on tropical activity continue to be heavily researched and are not fully conclusive.