Does Climate Change cause more powerful and frequent hurricanes?

Scientists have been trying to understand why these events have become more violent, and seemingly more frequent. Their main challenge: they need to understand it as the phenomenon unfolds.

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These past summers have been a long for environmentalists, thirsty creatures of all realms, and simple people who like normal temperatures. In 2019, raging fires in the two largest tree reserves we have — the Amazon and the Boreal forests — have contested headline news to rolling back of US environmental regulations or some of the first city-wide consequences of man-made climate change. For years now, man-made environmental events reporting have become a large part of our news cycles.

In Indonesia, the capital city of Jakarta is sinking so fast into the ocean that the central government has decided to establish a new centre of power… in the middle of pristine Borneo jungle. New Dehli, in India, has been choking under temperatures over 50°C and smog that would make 19th century London look like a clear mountain morning.

From August to September, hurricane season hits the coasts of the Northern hemisphere. During the Rugby World Cup, two games — including European classic England vs. France — had to be cancelled due to a “super typhoon” called Hagibis. The typhoon was the most powerful to make landfall in years on the Japanese Archipelago.

Hurricane Irma seen here making landfall on Haiti and Cuba (Credit: NASA)

Meanwhile during the same summer, hundreds of kilometres away, Hurricane Dorian’s uncertain path caused major confusion in the US, with a burlesque exchange between the NOAA and Trump about whether or not the storm was going to hit Alabama. It did not. Yet, the expanding range of hurricanes is a reality. Last year, Ireland witnessed for the first time in its history a sub-tropical hurricane. And if there is a country that has known storm, it has got to be Ireland.

Climatology is not the easiest of sciences, but we, the humans, also have a few smart people working on the issue. This catastrophic series does not come as such a surprise for the scientific community. Here is what they can tell you about hurricanes, their future, and also ours. We found answers to the questions we were too embarrassed to ask about hurricanes. Thanks, science!

How do hurricanes appear?

A well-known fact thing about climate change: the general temperature of the planet is rising. Fast. This means that oceans are getting warmer too, which in turn means there is more water vapour in the air. Water vapour is like the fuel of tropical thunderstorms. The hotter it gets, the more this water-heavy air becomes reactive. Heating triggers an upward movement, which causes the molecules that make up air (O2, CO2, H2O…) to bump into each other and create tall, hot, wet clouds. The stage is set for stormy weather.

In practice: humid air shooting up to form a barrel (Credit: Wikimedia/CC)

Warmer air particles over the surface of the ocean are sucked up all the way up to the high atmosphere, about 15km high. This forms a particular type of cloud called cumulonimbus. If the formation doesn’t disperse under its powerful inner rotating winds, then you have yourself a storm system.

What is the difference between hurricane, typhoons and cyclones?

A storm becomes a “hurricane” when the closed circulation becomes an eye, and sustained winds reach at least 65 knots or 119km/h. By the way, tropical storms are hurricanes when they are in the North Atlantic and Northeast Pacific oceans, but are called typhoons in the Northwest Pacific. The word cyclone is used for storm systems happening in the Southern Pacific and Indian oceans.

Past the speed limit, storms receive a name by the World Meteorological Organisation (WMO). At first exclusively female names, the organisation switched to a male and female nomenclature in 1978.

Are hurricanes getting more frequent?

The frequency and intensity of these events have augmented significantly in the last 30 years. The 2017 season is not the most intense though. 2005 was the record year, which saw the passing of 26 cyclonic phenomena, including two category 5 hurricanes.

In 2017, there have been 13 storms in the North Atlantic, which is not that unusual. What is weird about this season is that four powerful hurricanes washed over the Caribbean over a particularly short period of time. In recent meteorological history, some of these islands had never experienced powerful hurricanes, as they normally pick up power when they reach the Caribbean sea, beyond the islands. On that year, they’ve had 4 in one season.

Are hurricanes getting more powerful?

In the last 100 years, 13 of the 35 category-5 hurricanes that have occurred in the Atlantic have happened in the XXIst century, and 2019 in the fourth consecutive year to feature at least one of these superstorms. A tropical storm becomes category-5 when wind speeds exceed 137 knots or 252km/h. This means it is big enough to cause massive structural damage to any human construction. Most recently, superstorms threatening to break records have triggered some politicians and observers to argue for a sixth category to include recent freak storm such as Mitch (1998, deadliest hurricane since 1780) Patricia (2005, most powerful winds ever at 345 km/h) or Irma (2017, most googled term of the year).

Meteorological models predict a 20% rise in the intensity of hurricanes. Intensity, in this instance, means wind power, levels of precipitation, timespan on a given zone and destructive power. In August 2019, the Bahamas Islands were devastated by hurricane Dorian, the same one that was supposedly going to hit Alabama but ended up flirting with North Carolina instead.

Are human activities responsible for natural disasters?

Hurricanes, natural disasters in general, have always been part of the planet’s natural cycles. Some of these catastrophic events are still very mysterious to us. Although we have established causality between warming oceans and atmosphere to the formation of storm systems, the reason why scientists have been weary to link punctual weather events (especially the most extreme ones) to a deep meteorological trend.

Over time, however, we can observe a clear trend.

A clear correlation exists between global temperatures and hurricane power release (Credit: Aslak Grinsted, Niels Bohr Institute)
A clear correlation exists between global temperatures and hurricane power release (Credit: Aslak Grinsted, Niels Bohr Institute)

We know earthquakes and volcanic eruptions stem from the movement of tectonic plates dancing on an actual floor of lava but we do not know for sure what triggers the outbreak. Comparatively, there have been no rise in the frequency or intensity of these natural phenomena.

What have emissions got to do with hurricanes?

Human emissions have contributed to raising the concentration of greenhouse gasses in our atmosphere by an astonishing 25% in less than fifty years. Natural barriers in the meantime like forests or mangroves have been replaced by risky urban settlements. The removal of natural protections, including the replacement of natural ground by concrete, has made humans much more vulnerable to tropical storms. And since human settlements are mostly on the coast, we are feeling these changes acutely.

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A recent multi-agency report on climate change was considered so alarming by its makers that they decided to leak it to the press, for fear of official censorship. It sheds some light on our eventual trajectory:

“Both physics and numerical modelling simulations indicate an increase in tropical cyclone intensity in a warmer world, and the models generally show an increase in the number of very intense tropical cyclones. […] Increases are projected in precipitation rates and intensity. The frequency of the most intense of these storms is projected to increase.”

Leaked US Climate Change report, 2017, published by the New-York Times

Indirectly, the human influence over the environment, and especially the disruption of the temperature regulation mechanism of our planet, does create more favourable conditions for their formation and induces more extreme weather events. That’s more powerful hurricanes, over a longer season and over a larger geographical scope.

Is this our life now?

The world is not ending, it’s changing. As it is simpler for a teacher to predict the average score of his class than an individual’s exact result, climatologists can only take this new season into account, and try to make better sense of what we should be doing to lower the incumbent risks. There will be a rise in the average number and strength of extreme weather events.

This summer is what is a globally warmed age looks like. It’s sadly time to stop speaking in the future tense about climate change, and start looking at resilience strategies. Gardens of Eden such as the Caribbean rim, or the Pacific Islands, will become uninhabitable or disappear under the repeated assaults of the elements. Humans, animals and plants alike have to adapt to new settings, and new conditions of life.

Climate change is now part of every story. We are now well into the 6th major extinction event of our planet’s history. The previous one was the downfall of dinosaurs, and guess who took over? Mammals, and by extension, us. Can we make sure the bugs don’t take over, at least?

From “The Far Side Gallery“ by Gary Larson
From “The Far Side Gallery“ by Gary Larson

This article was originally published on Plan A.

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