Hurricane Harvey expanded from a tropical storm to a category 4 hurricane in just 48 hours, and is now stalled over eastern Texas and western Louisiana and dropping rainfall in the area at a rate never before witnessed. But why is this? Like Hurricane Katrina and Superstorm Sandy, Harvey expanded to hurricane force with unexpected speed. The reason is that sea-surface waters in the Gulf of Mexico were between 2.7 and 7.2 degrees Fahrenheit above average. Water temperatures in the Gulf have been rising for the past thirty years, with the highest temperatures being recorded in 2011. They then dropped until 2013, and have since been rising again.

Harvey is the only storm to have made landfall west of Florida to have intensified even as it was making landfall. Even Katrina lingered in the Gulf while intensifying. But over the last 12 hours of Harvey’s approach, it displayed an unusual wobbling track that is not yet understood. The storm has so far dropped 15 to 20 trillion gallons of water over southeast Texas, and is expected to double that by Wednesday. The results are likely to be beyond what is now understood by the word "catastrophic."

It’s a fair question to ask whether or not the storm is simply extremely unusual or if it has developed in the way it has due to global warming. Increasing water temperatures around the world have been linked to climate change, but it is necessary for there to be more scientific study of this particular storm to make a determination of its connection, if any, to the temperature anomalies that are being recorded.

The graphic shows Gulf of Mexico temperature anomalies.