Climate change and severe weather

As the United States counts the cost of a series of violent tornadoes raging across Mid-Western states, National Oceanic and Atmospheric Administration (NOAA) has issued a warning that the upcoming hurricane season could be equally devastating for the Atlantic coast. In the United States, where there is a powerful lobby of climate sceptics, a bitter debate is already raging between sceptics and scientists and environmentalists about whether these catastrophes and other extreme events are connected to climate change. 

On May 22 a giant tornado took 124 lives as it hit the town of Joplin in south west Missouri. With winds of up to 200 miles an hour, it left much of the town in ruins and has been ranked as one of the 10 deadliest tornados on record. In subsequent days, tornadoes killed at least 13 people in the states of Kansas, Oklahoma and Arkansas and left several hundred homeless and thousands more without electricity supplies. Several hundred people are still missing and the death toll in the devastated towns is likely to rise. The region is currently experiencing torrential thunderstorms with the likelihood that weather conditions will generate further tornadoes.

The US has already experienced catastrophic wildfires and flooding this year, in addition to the tornadoes, but the material and human risks of severe weather events in the United States are not over, according to NOAA. Last year’s hurricane season was also severe, but the hurricanes did not hit populated areas. This year’s season is likely to be equally severe, according to NOAA’s Climate Prediction Center, a division of the National Weather Service, and there are no guarantees about how many hurricanes will make landfall or where they will hit. 

The hurricane season on the Atlantic Basin begins on June 1 and lasts six months. The Climate Prediction Center is forecasting a 70% likelihood of between three and six major hurricanes of Category 3, 4 or 5, with winds of 111 miles per hour (about 178 kilometres per hour) or higher, a prediction that puts this year well above normal for hurricane risk.

A number of factors inform these predictions, which tally with the views of other experts. Some are short term factors – whether it is an El Niño or a La Niña year, for instance. Other factors are longer term and related to climate change: while scientists are reluctant to attribute any single weather event to climate-change effects, they have long predicted that the warming of the planet will generate more extreme weather. In particular the warming of the Atlantic  Ocean is an important factor in the strength and frequency of hurricanes. Despite a widespread public misconception, it is also likely that exceptionally heavy winter snow is related to climate change. Warmer temperatures mean that more moisture is taken up into the atmosphere and in winter this falls as snow. Weather is not the same as climate, but they are connected and if the scientific predictions are correct, we can expect many more such extreme events in the future, with all the material loss and human misery that such events bring.