When it comes to climate change, experts say few things have been as tricky to predict as its impact on hurricanes.
A new report in the ScienceBrief Review website published last week now suggests that many regions affected by hurricanes will likely experience storms of greater intensity as a result of Earth’s changing climate. Maximum wind speeds in hurricanes could rise five per cent if the planet warms by 2 C by 2100, the review of more than 90 peer-reviewed studies found.
And that highlights a need for cities and governments — including those in Canada — to plan ahead for a future where they may be dealing with climate issues they have not had to deal with in the past, experts say.
“It’s important that governments look at how you need to adapt to climate change,” said Canadian researcher Corinne Le Quéré, a Royal Society professor of climate change at the University of East Anglia, who edited the report. “Some of these events will occur in places where perhaps they have not seen hurricane-force winds before. And therefore, you need to develop coping measures to have these alert systems.”
The report, which analyzed peer-reviewed literature, was published as part of a series on climate change issues ahead of the United Nations’ COP26 climate conference scheduled for Nov. 1–2 in Glasgow.
In the U.S. and Canada, hurricanes are categorized using the Saffir-Simpson scale that classifies them from a Category 1 to a Category 5.
To put the five per cent potential rise in maximum wind speeds into perspective, a Category 3 hurricane produces sustained wind speeds ranging from 178 to 208 km/h. A Category 5 produces speeds of 252 km/h or higher. Hurricanes from Categories 3 to 5 are considered major or severe hurricanes.
Not a clean-cut story
The impact of climate change on hurricanes has been tricky to quantify because there are many aspects to the system involved in creating and sustaining a hurricane. And it is hard to separate how much of that is caused by natural or man-made reasons.
The report said the intensity of hurricanes will “probably” increase as a result of climate change, but it is hard to be certain due to several factors, including a lack of historical data. Since 1979, hurricanes of Category 3 or higher have increased by roughly five per cent, but it’s difficult to say how much of a role climate change has played in this.
“The reason why the picture seems … a bit murky when we present things is because it’s not as clean-cut a story as we have for something like global mean temperature, where we have these clear records going back to the late 1800s,” said Tom Knutson, division leader at the National Oceanic and Atmospheric Administration’s (NOAA) Geophysical Fluid Dynamics Laboratory, who led the review.
“But we can contrast that with this case for hurricanes and hurricane activity where, first of all, there are lots of different ways of looking at hurricanes, lots of different metrics, lots of different regions, and things like that. But in no case, really, do we have a comparable confidence to what we have for global mean temperature.”
While the intensity of hurricanes is likely to increase, it’s also important to note that not all of these storms will necessarily reach inland.
Canada should look at hurricane threat
There are more complications with hurricanes. Climate change is warming sea surface temperatures, which help fuel hurricanes. There is also more moisture available to produce and sustain hurricanes, which results in heavier rainfall.
In addition, research has found that hurricanes are moving towards the North and South poles by roughly 56 kilometres, or about one degree of latitude, per decade and that they are also moving further inland.
With the increase in hurricane intensity, greater rainfall volumes, hurricanes that are moving further inland and poleward, countries including Canada may need to evaluate the potential fallout in the future.
“Certainly Canada should look at whether [hurricanes] are a threat … If they are more intense, then they also have potential to affect bigger areas,” Le Quéré said. “Certainly the changes in the storm tracks and in the weather patterns is something that Canada should be looking at to see if there is a need [to adapt].”
Deanna Hence, an assistant professor at the University of Illinois Urbana-Champaign’s department of atmospheric sciences, said the report highlights the difficulties predicting hurricanes in a changing climate.
“The biggest thing that comes across from this article that is that when it comes to climate change or tropical cyclones, it’s a really complicated set of interactions and a very complicated set of possible impacts,” said Hence, who was not involved in the study.
“Essentially what people want to know is, if you live in a certain part of the world will hurricanes or typhoons or tropical cyclones hurt you more. That’s I think what really the root question comes down to … And the answer is yes, kind of, sort of.”
It’s just exactly how that is the remaining question. But Hence said that it’s time for all stakeholders to start planning ahead, especially in light of already aging infrastructure that may not be able to handle more precipitation, more storm surge or stronger winds associated with hurricanes.
Overall, climatologists agree that more research needs to be done, and that only time will tell how people will be affected.
“Humans are changing the climate system. And so we’re sort of running this experiment, whether we like it or not, this global warming experiment, and we’re going to find out — as we continue along with this trajectory of warming — we’re going to find out how various things do or don’t change,” Knutson said. “We’ll get more information coming as we continue to alter the climate system.”