In the devastation left behind by hurricanes Harvey and Irma over the past weeks in the United States and the Caribbean, we are left shocked and stunned by their intensity: Harvey deposited 33 trillion gallons of water onto U.S. land, and Irma had as much cyclonic energy as an entire average hurricane season. How two such incredible storms occurred almost one directly after the other is a question posed to scientists and climatologists, about whether the impact of years of climate-change talk is finally coming to light.
Simply put, yes: hurricanes are low-pressure tropical storms that get their energy as they pass over warm ocean waters, and ocean warming is one of the consequences of climate change. The warmer the ocean, the more likely a tropical storm will gather hurricane-level wind speeds. Politicians alike have released statements about the urgency of addressing the human impact on weather patterns, and the role of greenhouse gas emissions on the environment.
There are, however, those who believe it is premature to say that hurricanes and climate change directly correlate. The
released a report graphing the intensity of hurricanes since 1970 and predicting them to 2100. They created them using both indicators of ocean temperatures and hurricanes frequencies and intensities, and the results show a clear upward trend in the past few decades:
Although there is clearly an increase in hurricane occurrences, the report doesn’t consider it as water-tight evidence for proving that warmer oceans caused by climate change are the concluding cause for these trends. Although it does not discredit human activity on weather patterns, it predicts that that impact will be felt for decades to come, rather than now. It pointed to the stable pattern of hurricanes that made landfall, in comparison to the increase in their occurrence and says that other weather patterns are more likely the cause of such an increase in hurricane activity.
Nevertheless, this debate is an on-going back-and-forth discussion, and there are as many sceptics as there as activists on the issue. The North Atlantic is more prone to tropical storms in any case, and places such as the South Atlantic basin – which includes the southern tip of Africa – will not likely ever experience hurricanes of the same intensity even if climate change is behind it. Warmer waters are of course one of the reasons why hurricanes occur, but “shears” are also an important factor that
Warmer waters are of course one of the reasons why hurricanes occur, but “shears” are also an important factor that makes hurricanes in South Africa very unlikely. Shears are essentially the difference between wind speeds in the upper troposphere and the sea surface level, and in the South Atlantic, these vertical shears are too strong, which will rip tropical storms apart before they can form.
That being said, the consequences of climate change for weather patterns are difficult to predict because of uncertainty regarding what effects built-up human influence will have.
Either way, President Trump’s continued denial of climate change is doing little to protect U.S. citizens from future natural disasters – regardless of whether they’re caused by us or not.