Do Hurricanes Feel The Effects Of Climate Change?

Do Hurricanes Feel The Effects Of Climate Change?
Satellite image on Sept. 7, 2017 shows three hurricanes: Irma in the center just north of the island of Hispaniola, Katia on the left in the Gulf of Mexico and Jose in the Atlantic Ocean on the right.

Hurricane Harvey, with its historical amount of rainfall over Texas, followed by a string of Hurricanes Irma, Jose and Katia in the North Atlantic basin in 2017, has triggered longstanding questions about any linkage between hurricanes and climate.

Can we really blame these recent hurricanes on climate changes? Or are they simply a coincidence of nature happening once every few decades, similar to the triple of Hurricanes Beulah, Chloe and Doria back in 1967?

Answering these questions lies at the heart of the current hurricane climate research that atmospheric scientists are trying to understand. There are signs that climate change can influence hurricanes in several different ways. However, these signals are inconclusive due to our inadequate understanding of how hurricanes interact with the environment.

Link to ocean temperature

Much as a flu virus morphs in different environments and becomes more infectious in cold winter temperatures, hurricanes depend on the ambient environment for their existence and motion. To what extent the surrounding environment affects hurricane development is indeed among the most extensively studied topics in hurricane research.

Evidence of the environment’s role on hurricane development has been noted since the early 1950s, yet a major milestone was achieved by Kerry Emanuel at MIT in his studies of hurricane dynamics in the late 1980s.

His idea was to consider hurricanes as heat engines that can extract heat from the ocean surface and exhaust it at the upper troposphere. In this way, Emanuel was able to obtain a mathematical expression showing how the maximum potential intensity a hurricane can attain in a given environment depends on sea surface temperature and temperature near the top of the atmospheric troposphere around 14 kilometers, or 8.8 miles, above the sea. A warmer sea surface temperature would result in a higher intensity, according to Emanuel’s formulation.

The ‘fuel’ for hurricanes comes from the energy in the ocean’s heat.
The ‘fuel’ for hurricanes comes from the energy in the ocean’s heat.

In essence, Emanuel’s relationship between hurricane intensity and sea surface temperature dictates how strong a hurricane can be for a given environmental condition. Numerous studies have then confirmed the importance of sea surface temperature in controlling hurricane maximum intensity, and suggest an increase of 2-3 percent in hurricane strength per 1 Celsius degree increase in sea surface temperature under favorable conditions.

From this perspective, it is thus very tempting to assert that hurricane intensity variations must be connected to the global climate due to the vital role of ocean temperatures in hurricane development. Indeed, many studies of hurricane intensity climatology consider ocean temperature as a main proxy to detect the future trend in hurricane intensity change.

The common consensus among these studies is a conclusion that future hurricanes will tend to be stronger than those in the present-day climate, assuming that sea surface temperature will continue its current warming trend into the future.

Looking at extremes for clues

While we can expect an increase in hurricane intensity as a result of rising ocean temperatures, how to interpret this result to one specific hurricane turns out to be very different.

For an intuitive illustration of how difficult this can be, consider how climate change can affect aspects of our weather, such as the daily variation of temperature.

For instance, a future air temperature warming of 0.5 degrees in the next 10 years would be mostly masked out by any daily temperature variation, which is in the range of 10 degrees between day and night. In this sense, it would be hasty to jump to a conclusion that the high intensity of Hurricane Harvey or Irma is caused by climate changes, simply because fluctuations in local weather conditions could contribute much more than climate change signals.

On top of the day-to-day intensity fluctuations due to local environmental conditions, hurricanes may also possess chaotic behaviors that cause their intensity to highly vary. A recent study showed internal variations of hurricane intensity could be as large as 10-18 miles per hour, which is larger than what would be induced by climate change.

On the other hand, one should not naively deny any claim that the extreme impacts of Hurricane Harvey or Irma are symptoms of climate changes.

08 29 hurricane harvey
Extreme events, such as the rain associated with Hurricane Harvey, provide an opportunity for researchers to study the effects of climate change because they are outside the day-to-day variability of weather.
AP Photo/David J. Philip

Some research has indicated that the change in global climate could lead to a shift of the jet stream behaviors over North America. Flooding related to Harvey was unusual in part because the storm stalled over Texas for much longer than any other hurricane. So while our current knowledge does not allow us to connect Harvey’s intensity to any specific changes in climate, the abnormality of the Harvey stalling for a long period over land could be a manifestation of the shift in global circulation in a warmer climate.

Likewise, the emergence of triple hurricanes in the Atlantic basin during September 2017 could be another potential signal of the more favorable conditions for hurricane formation from climate change.

From the climatological perspective, it is the frequency and magnitude of these abnormal extremes, such as the prolonged period over land of Hurricane Harvey or the extreme intensity of Hurricane Irma, that are often of utmost interest to researchers. This is because these extremes are signals of climate changes that can be distinguished from day-to-day variations.

Limits of our understanding

Along with direct impacts of climate on hurricane intensity, another conceivable influence of climate on hurricanes is the shift of the hurricane track pattern in the future climate.

In principle, a change in global air circulation patterns could influence the steering flows that guide hurricane movement, much like a leaf carried away by a river. As such, variations in global circulations associated with climate change could introduce another degree of variability to hurricane impacts that we have to take into account.

A recent climatological study led by James Kossin at University of Wisconsin suggested a poleward shift of the hurricane maximum intensity location in a warming climate. But unlike the connection between hurricane intensity and the ambient environment, the linkage between global circulation change and hurricane movement is much harder to quantify at present.

While research on hurricanes gives us a good sense of how hurricanes would change in a warmer climate, measuring this change and, in particular, tying a unique feature of one specific hurricane to climate change are beyond the current level of confidence.

In reality, there are several other factors that could strongly interfere with hurricane development, such as the change of atmospheric temperature with height. These factors directly affect the interaction of hurricanes with the surrounding environment. However, these are very difficult to quantify in the context of climate change due to the different time scales between hurricane development – measured on the order of days and weeks – and climate change, which occurs over decades.

The ConversationFrom a scientist’s perspective, the lack of understanding of climate impacts on hurricanes is disappointing, if not irritating. On the other hand, these uncertainties continue to motivate us to search for any possible link between hurricanes – including their intensity, frequency, time of formation and location – and climate. Better understanding of hurricane-climate relation is needed, as ultimately that knowledge can help serve society.

Chanh Kieu, Assistant Professor of Atmospheric Science, Indiana University

This article was originally published on The Conversation. Read the original article.

Related Books



Blue Ocean Event : Game Over?
by Just Have a Think
A Blue Ocean Event, or Ice-Free Arctic, is the source of almost fever pitch speculation in the climate science world.…
Climate Change - The Facts by Sir David Attenborough
by David Attenborough, BBC
After one of the hottest years on record, Sir David Attenborough looks at the science of climate change and potential…
Why it’s time to think about human extinction
by Kerwin Rae
After listening to this ep with Dr David Suzuki, you’ll never be the same again. The environmentalist, activist,…
Record Temperatures 20-25C Above Norm in far North
by Paul Beckwith
The Northwest Territories of Canada had March temperatures above 20C for the first time (hit 21.6C or 71F); breaking…
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
Why New CO₂ Capture Technology Is Not The Magic Bullet Against Climate Change
by Chris Hawes
According to a recent major UN report, if we are to limit temperature rise to 1.5 °C and prevent the most catastrophic…
Why Climate Change Will Dull Autumn Leaf Displays
Why Climate Change Will Dull Autumn Leaf Displays
by Matthew Brookhouse
Every autumn we are treated to one of nature’s finest seasonal annual transitions: leaf colour change and fall.
Climate denial isn’t stopping climate action.
by David Wallace-Wells
Climate change denial draws headlines. But is it actually an obstacle to climate action? A great majority of Americans…
Energy Storage: How to store renewable energy?
by Total
Under your bed, in the attic even on your mobile phone, it seems there's never enough storage. It turns out it's also…


Crops at risk from changing climate
Crops at risk from changing climate
by Tim Radford
Global warming could bring yet more challenges to a hungry world. New studies have identified precise ways in which a…
Seeing The Planet Break Down In Climate Crisis Is Depressing – How To Turn Your Pain Into Action
Seeing The Planet In Climate Crisis Is Depressing – Turn Your Pain Into Action
by Cameron Brick
Environmentalism can feel like a drag. People trying to reduce their environmental impact often feel stressed and…
Global Inequality Is 25% Higher Than It Would Have Been In A Climate-stable World
by Nicholas Beuret
Those least responsible for global warming will suffer the most. Poorer countries – those that have contributed far…
Jason Kenney's Victory Means We'll All Pay The Price For Fossil Fuel Emissions
Jason Kenney's Victory In Alberta Means We'll All Pay The Price For Fossil Fuel Emissions
by D.T. Cochrane
Jason Kenney has led the United Conservative Party to victory in Alberta. There were manyobjectionablecomponents to the…
How Can Trees Really Cool Our Cities Down?
How Can Trees Really Cool Our Cities Down?
by Roland Ennos, University of Hull
In cities around the world, trees are often planted to help control temperatures and mitigate the effects of the “urban…
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
Beto O’Rourke Releases $5 Trillion Climate Change Proposal
by Global Warming & Climate Change
But Varshini Prakash, executive director of the Sunrise Movement, a youth-led activist group that has advocated for the…
Should The Sahara Desert Be Turned Into A Huge Solar Farm?
Should The Sahara Desert Be Turned Into A Huge Solar Farm?
by Amin Al-Habaibeh
Whenever I visit the Sahara I am struck by how sunny and hot it is and how clear the sky can be.
How Retreating From The Sea Level Rise Will Affect Our Health?
How Retreating From The Sea Level Rise Will Affect Our Health?
by Jackson Holtz
Managed retreat in the face of sea level rise will be a mixed bag, researchers predict.