Hurricane Irma during its peak intensity moving over the Virgin Islands. Photo credit: NASA Worldview.

By Anders Lorenzen

When Hurricane Sandy made landfall in the US in 2012, just before the US election, I wrote that climate change had arrived in the country. When Obama started his second term in office, it became a term dominated by a policy focus on tackling climate change. Arguably, it is unlikely that Obama would have pushed so hard on climate change, had Sandy not happened.

The destructive powers of Harvey and Irma

Five years down the line, events are underway that will undoubtedly be far more damaging and severe than Sandy ever was. An epic climate-fuelled scenario of extreme weather is taking place. First, Hurricane Harvey struck Texas, with a force at least as damaging as Sandy. And the cost of the damage is set to far exceed that of Sandy. Hardly had Harvey disappeared before Hurricane Irma appeared. After wrecking several Caribbean islands as a category 5 hurricane, the highest rating for a hurricane (both Sandy and Harvey were category 4), it finally made landfall in Florida as a category 4 hurricane. And due to the size of the superstorm (so large that the area of the whole hurricane was the size of the entire state of Florida), the damage is set to far outweigh that of Harvey. In terms of the damage, it could even become close to matching the 2005 catastrophic Hurricane Katrina. However, as forecasting and warning systems have become so much better, the death tally for both Harvey and Irma will not get close to that of Katrina. It was known over a week in advance that it was going to hit so evacuation and preparation plans could be put in place.

There were worries about another hurricane, Jose, which had formed behind Irma. But thankfully those islands affected by Irma narrowly avoided it. And it has now weakened from a category 4 to a category 2 hurricane, though it could still impact parts of the US east coast.

Hurricanes are becoming more violent and extreme

Of course, hurricanes are normal on the US east coast every year, and it is unclear whether there has been an increase in frequency. However, we do seem, at least this year, to have reached a peak of hurricanes in the Atlantic Hurricane Season. But there has been a significant increase in the frequency of superstorms, aka the category 3,4 and 5 hurricanes. Those so-called hundred- or thousand-year storms now occur on a more frequent basis. If you look at the frequency of the last major storms Katrina, Sandy and now Harvey, the gaps in between are becoming less. And this will be the first time ever in US hurricane history that two category 4 hurricanes or above have hit in the same season. And the fact that Harvey and Irma are occurring so close to each other is absolutely staggering and moving above an explanation of natural variability. Fuelled by a warming world, the ongoing trend is that US storms are becoming more violent. That is a scientific fact and it is in line with climate predictions for a warmer world. It is important to factor in the climate change link. Yes, climate change did not create Harvey and Irma, but climate change made them into superstorms of epic and fatal proportions with huge economic impact.

Let’s talk about climate change

Therefore the simple best tool to limit such killer storms is to start taking climate change seriously. We urgently need to start reducing emissions. The answer is not, as US President Trump advocates, to exit the Paris Agreement, or to revive the coal industry, one of the largest contributors to climate change. Nor is it cutting the funding to the Federal Emergency Management Agency (FEMA), tearing apart the powers of the Environmental Protection Agency (EPA). The climate-denying rhetoric of Texas Governor, Greg Abbott, and Florida Governor, Rick Scott, the two states who were primarily hit by Harvey and Irma is not a solution either. And what Mr Scott is pursuing is inconsistent with that of the many mayors in coastal cities and communities in his state, who see the impact of climate change day in and day out and who just want state leadership on the biggest mass killer in the state. As Irma prepared to make landfall in Florida, the Republican Mayor of Miami Tomás Regalado attacked Donald Trump for ignoring the link to climate change.

Harvey and Irma and whatever the 2017 Hurricane Season throws at the US, must be a wake-up call like Sandy was a wake-up call to Obama. An urgent reversal of policies must be made. But with a climate-denying White House, and with climate deniers in Congress having an overall majority it does not look promising. Meanwhile, Harvey and Irma speak for themselves.