The issues raised by climate change in the wake of Hurricane Dorian

Bryan Dyne

The destruction caused by Hurricane Dorian lends weight to the prediction of climate scientists in the United States and internationally that as global warming continues unabated, hurricanes will increase in severity and intensity.

Hurricane Dorian made landfall in the Bahamas as one of the strongest storms on record, with a storm surge of up to 23 feet and sustained wind speeds of 185 miles per hour. At least $7 billion of damage was caused across the country, at least 43 people have died and potentially thousands more will be uncovered, buried alive in the rubble.

The scale of the disaster in the Bahamas is immense and among the events that have been predicted for several years as part of the broader research studying the impact of climate change. One such recent study is the Fourth National Climate Assessment published last October, which warns that key factors of hurricanes Harvey and Maria were “consistent with what might be expected as the planet warms.”

In particular, the report focused on the rapid increase of wind speeds and the intensity of heavy rain. Hurricane Irma in particular broke records for wind speed and duration for which such intensity was maintained. Harvey and Maria both were distinguished for record levels of rainfall, including single- and multi-day totals that exceeded any known storms across the United States. One study estimated that human-induced climate change caused a rainfall increase of between 19 and 28 percent.

These problems were exacerbated by the slow speeds at which these hurricanes moved over land, which increases the devastation inflicted on a specific area through wind and flooding. While a link between stalled hurricanes and global warming is still a very active area of scientific research, it is known that the speed and trajectory of hurricanes is governed by wind and ocean currents which have been shown to be directly influenced by rising ocean and atmospheric temperatures.

Similar assessments are already being made about Hurricane Dorian. One of its principal features was that it stalled over the Bahamas and moved barely more than one mile per hour for more than a day, essentially drowning parts of the islands in a continuous deluge. It has also set new records for size, rainfall and lifetime. It is only chance that Dorian did not do to a major city in the US or Canada—or to Nassau, a city of nearly 300,000 only 100 miles south—what it did in the northern Bahamas.

Dorian also made landfall as far north as Nova Scotia, an indication that global weather patterns are more broadly shifting warmer air and water toward the poles, another prediction made by those studying the impact of climate change.

Counterintuitively, global warming is not predicted to produce more hurricanes. Such events, even in the most radical climate models, are still governed by natural variability. What is expected, however, is that the hurricanes that are formed will become more intense. The 2017 Atlantic hurricane season witnessed four hurricanes in Category 5, the most powerful classification of storm, a record for the number of such storms in a year. This past February became the first month a super typhoon in the Pacific Ocean exceeded sustained winds of 160 miles per hour. These catastrophic weather events are shifting from anomalies to the new normal.

These storms also belie the claims, such as those recently put forward in Forbes (and other right-wing media outlets) that attempt to downplay the link between hurricanes and climate change by claiming that there is still not enough data to confidently say that every aspect of hurricanes and typhoons is being made worse by hurricanes. The argument is then made that policy decisions should not be made based on assuming that storms like Harvey, Maria and Dorian are more likely in the future.