In the North Atlantic hurricanes have typically formed in the tropics, between a latitude of 5 and 30 degrees north of the equator. A 2014 study found that this area was expanding northwards by about half a degree of latitude, about 33 miles, each decade – a change matched in the southern tropics. In an analysis of the damage wrought by Hurricane Harvey last year, Michael Mann, a professor of atmospheric science at Penn State University, noted that the sea temperatures in which the storm intensified were about 1-1.5C warmer than their average a few decades ago, which meant 3-5 per cent more moisture in the atmosphere, which in turn led to greater rainfall and coastal flooding. Sea levels were also half a foot higher, he said. Weaker prevailing winds – another factor predicted in climate change models – caused the storm to grind to a halt over Houston, greatly increasing the damage it wrought. A study published in Nature last year suggested that man-made climate change caused more rain near the centres of tropical cyclones and that hurricanes were making slower progress. The speed at which the weather systems move had decreased by 10 per cent between 1949 and 2016. James Kossin, an atmospheric research scientist at the National Ocean and Atmospheric Administration and author of the paper, reported a slow-down of 16 per cent over land areas in the North Atlantic region, and named Hurricane Harvey’s “stall” over Texas as a notable example.
Times 3rd Sept 2019 read more »
Climate crisis: Rising sea levels and catastrophic storm surges could displace 280m people, UN warns.
Independent 31st Aug 2019 read more »