Climate Change: Hurricanes to Deliver a Bigger Punch to Coasts

By Ryan P. Mulligan, Associate Professor in Civil Engineering, Queen’s University, Ontario. Originally published at The Conversation

When tropical cyclone Idai made landfall near Beira, Mozambique on March 14, a spokesperson for the UN World Meteorological Organization called it possibly the the worst weather-related disaster to hit the southern hemisphere.

This massive and horrifying storm caused catastrophic flooding and widespread destruction of buildings and roads in Mozambique, Zimbabwe and Malawi. Mozambique’s President Filipe Nyusi feared the death toll might rise to more than 1,000 people.

Cyclones, also known as hurricanes or typhoons, are intense wind storms that can take thousands of lives and cause billions of dollars in damage. They generate large ocean waves and raise water levels by creating a storm surge. The combined effects cause coastal erosion, flooding and damage to anything in its path.

Although other storms have hit this African coast in the past, the storm track for cyclone Idai is fairly rare. Warmer-than-usual sea-surface temperatures were directly linked to the unusually high number of five storms near Madagascar and Mozambique in 2000, including tropical cyclone Eline. Warmer ocean temperatures could also be behind the intensity of cyclone Idai, as the temperature of the Indian Ocean is 2 C to 3 C above the long-term average.

Climate change and ocean warming may be linked to the increasing intensity of storms making landfall and to the development of strong hurricanes reaching places not affected in recent history. These regions may not be prepared with the coastal infrastructure to withstand the extreme forces of these storms.

The Role of Climate Change

Scientists are working to improve their forecasts for hurricane winds and waves, and research on ocean and atmosphere interactions is boosting our understanding of the relationship between climate and the formation of hurricanes. Still, there is considerable uncertainty in predicting trends in extreme weather conditions 100 years into the future. Some computer simulations suggest possible changes in these storms due to climate change.

Tropical cyclone Idai rapidly strengthened to a category 3 storm in the warm waters between Mozambique and Madagascar. (NOAA)

For example, scientists have computed detailed simulations of hurricane-type storms for future climate-warming scenarios and revealed that in some cases the hurricane season could be longer. The intensity of storms could also increase so that there are more major hurricanes (categories 4 and 5 on the Saffir-Simpson scale) with winds reaching speeds greater than 209 km/h.

Since these storms are fuelled by ocean heat, warmer ocean conditions will influence their intensity and longevity. This may enable them to travel farther over ocean water at higher latitudes, and farther across the continent after they make landfall.

With global sea level rise expected to continue to accelerate through the 21st century, the impacts of coastal flooding from tropical cyclones is also expected to worsen.

Atlantic Hurricanes

On the Atlantic coast of North America, the hurricane season starts in June and runs to November. We have very recent reminders that these storms can be catastrophic. Hurricane Maria, which struck Puerto Rico in 2017, caused infrastructure damage of US$90 billion and may have killed more than 4,600 people.

Urban areas can take weeks or months to recover from the flooding caused by the storm surge, which can be compounded by heavy rainfall. When the category 4 hurricane Harvey hit Houston in 2017, it caused US$125 billion in damage, mostly due to flooding in the metropolitan area.

Hurricanes that reach places that historically have not been affected have major and long-lasting impacts. An example is hurricane Sandy in 2012, the largest storm on record in the Atlantic Ocean. This storm made a westward turn that is very different from typical tropical hurricane tracks.

Homes in Ortley Beach, N.J. destroyed by Superstorm Sandy. (AP Photo/Mike Groll, File)

Its waves and storm surge pounded the coasts of New Jersey and New York, with a huge impact washing over coastal dunes, eroding beachesand causing flooding in New York City.

It also had a major economic impact, costing US$71 billion with long-term effects on the coastal environment and lasting socioeconomicimpacts in a densely populated area.

Damage to Coasts

Hurricanes can cause severe erosion and breach islands, creating new pathways for water flow between the ocean and back-barrier estuaries. As these storms impact land, they can also create a dangerous multi-hazard environment of fast-moving air, water and debris.

Urban coastal areas are under a major threat, since coastal structures may not have been designed for the waves and surges that these storms generate. Hurricane Katrina, the mega-disaster that took more than 1,200 lives and cost US$161 billion in 2005, taught engineers the hard way that hurricanes can cause unanticipated loads on bridges, buildings and coastal structures.

The amount of damage a hurricane creates depends on the intensity and characteristics of the storm, combined with the physical and social setting of the coastal area that it hits. Cities face a high risk of hurricane-related disasters, since they contain higher populations and more infrastructure. This can lead to widespread and catastrophic impacts, such as the massive storm surge and flooding generated by typhoon Haiyan, which lead to more than 6,000 deaths in the Philippines in 2013.

Future Impacts

Regardless of changes to the climatic conditions that cause hurricanes to form and intensify, the fact is that these storms already occur frequently. Each year, 80 to 100 tropical storms occur globally. Of these, 40 to 50 are hurricanes, with 10 to 15 classified as major hurricanes.

Hurricane Isabel made landfall on North Carolina’s Outer Banks on Sept. 18, 2003. Its effects were felt as far as western New England and into the eastern Great Lakes. NASA

Climate change projections suggest the number of intense hurricanes will rise. Ocean warming will enable these storms to travel farther, and we may see greater hurricane impacts on coasts in the future.

This could include more storm strikes to northern coasts in places like Atlantic Canada, where hurricane Juan made landfall in 2003.

We may also see more hurricanes reaching large inland lakes such as the Great Lakes, affecting major cities like Toronto and Chicago. Rare events, such as hurricane Ophelia that hit Ireland in 2017, may become more common.

When we build houses, roads and bridges and increase population density in low-lying coastal areas, we walk a fine line if these coastal regions are not prepared for the ferocity of extreme storms in the future.

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    1. Larry

      It would take a storm that deeply inconveniences wealthy power brokers. Let’s say, Manhattan shut down for a month plus. Otherwise, I don’t expect any change because we all know there’s a lot of profit to be had in a natural disaster.

    2. BlueMoose

      Just curious what in your opinion must be done or even can be done? IMHO that horse left the barn a long time ago. Check out Catherine Ingram’s latest: Facing Extinction.

      1. Ignacio

        Whatever can be done. First get serious about CC, second do not embrace derrotist ideas, and third act.

  1. Don cafferty

    The heading of this article delivers a message which is stated in the language of certainty. Throughout the article, however, the professor resorts to “weasel” words – may be, suggest, could be – and undermines the certainty of the message. This style of writing gives decision makers reason not to take action. If we want action to be taken on climate, the message needs to be “believed”. I do believe in the message of this article but frankly there is no new information here. What the author has managed to do, is create uncertainty.

    1. notabanker

      The truth doesn’t fit into convenient political parameters on this topic. We are talking about modeling and forecasting global eco systems and subsequent climates. We can continue to take our chances as the odds stack against us, or do something to move the odds. The idea here is to avoid or at least prepare for the outcomes not wait for them to happen to take action.

      To state definitively that something is or isn’t going to happen undermines the credibility of the science. This is just one report of thousands. In addition to this post, just in the last week on NC:
      $840 million in agricultural losses in NB.
      90% of the $9B citrus crop in Florida is infected with greening disease. Half the acreage has already been abandoned.
      Apple crops across the midwest are dying and we don’t know why.
      60 million Americans are at risk of plain states flooding this spring.
      Record snowfalls in the Sierras, up to 20 feet, are going to melt.
      Historic cyclone hits Mozambique.

      Just in the last week, which is a nanosecond in climate time. Not sure what it’s going to take for people to “believe”.

      1. rd

        We need to differentiate climate change from other anthropogenic problems.

        Citrus greening is greatly increased by an Asian insect that spreads it. This is unrelated to climate change. it is unclear if the apple issue is similar.

        But our poor practices to prevent invasive species, poor control of agricultural and suburban fertilizer runoff, excessive use of pesticides, etc. mean that our ecosystems are being significantly weakened just as a huge stressor (climate change) is starting to hit. Our poor practices unrelated to climate are making us weaker and will make climate change hit even harder.

      2. Susan the other`

        Sunday morning on NPR there was an editorial about a “warmer and wetter climate” and, as usual, the scope of the problem was understated. At least they acknowledged ocean rise was a fact. They interviewed two people from Florida, both dedicated to living in Florida because they love it there and they don’t care about ocean rise. They are prepared to raise sea walls and foundations; dig drainage, and etc. I’d like to hear them do another interview a year or two from now with those same people. After mucking around in knee-deep water and scraping green slime off their walls becomes a way of life. It reminds me of the movie (c. 2000) The Storm about the storm of the century capsizing a New England fishing troller and the final scene is quintessential hubris – the crew is floating around on big waves shouting to each other bravely about high-minded, even poetic, delusions. They look like talking basketballs.

  2. Susan the other`

    Idai looked like it swept up around the northern tip of Madagascar leaving Mozambique without a barrier island for protection. Very agile.

  3. Evil Wizard Glick

    I’m confused because this article doesn’t actually substantially link Hurricanes and Climate change.
    Since when is “Researchers cannot say, however, that global warming is to blame for the specifics of the latest storm,”, why certainly it is the cause?
    I have noticed a lot of could and maybes morph into definitely is lately. No matter what science or politics.
    Scientists are increasingly confident of the links between global warming and hurricanes.

    In a warming world, they say, hurricanes will be stronger, for a simple reason: Warmer water provides more energy that feeds them.

    Hurricanes and other extreme storms will also be wetter, for a simple reason: Warmer air holds more moisture.

    And, storm surges from hurricanes will be worse, for a simple reason that has nothing to do with the storms themselves: Sea levels are rising.

    Researchers cannot say, however, that global warming is to blame for the specifics of the latest storm, Hurricane Michael, which grew to Category 4 with sustained winds of 155 miles an hour, as it hit the Florida Panhandle on Wednesday. Such attribution may come later, when scientists compare the real-world storm to a fantasy-world computer simulation in which humans did not pump billions of tons of carbon dioxide into the atmosphere.

    1. Susan the other`

      After watching Dan Britt’s “Orbits and Ice Ages” speech from 2012, I’m not sure we are using the best narrative. It is possible that CO2 is less of a culprit than we thought. Not to suggest that we continue to use fossil fuels at the current pace, but some warming beats a new glaciation. Which will probably happen anyway. We need an honest conversation on all of this.

      1. Ignacio

        We are not witnessing “some warming” but a climate change so fast and so dramatic that it is almost certainly unprecendented on earth.

        1. Susan the other`

          Yes, you are correct. But the speed of the change has more to do with (according to Dan Britt, who may be off in left field for all I know) with the cooling of the sun and the Earth’s orbit cycles. So all I am speculating about is the information we are spoon fed. I’m skeptical.

            1. Susan the other`

              One reason I revert to digging in my heels is that no one utters the verboten words “ice age” even tho’ this is the recurring condition of the planet over hundreds of millions of years… and no one even discusses tidbits like ice core evidence that before each glaciation there was a brief episode of interglacial warming – and one comment now long-forgotten by an ice scientist was that all the previous ice cores showed a level of warming much less than we currently have… leaving the question open on the possibility that this chaotic weather to come only needs a few degrees of cold to begin a new glaciation that due to all the moisture in the atmosphere from our extra CO2 warming could be the mother of all ice ages… sorry… not to get too hysterical here. I hope I’m just weird, as usual.

              1. notabanker

                I’ve watched Britt’s videos. He’s a geologist. It’s very important to look at this presentation in the context of timeframes. The money chart for me was when he showed orbital cooling cycles and the warming divergence from historical norms beginning with the start of human civilization. Going back thousands of years.

                His presentations are from 2012. Much has been learned since then. Models have greatly improved, feedback loop science is still nascent, and, the most aggressive of forecasts since 2012 have been woefully conservative compared to actual results. Britt’s conclusions only address sea level rise, which is consistent with a general consensus back in 2012. He flat out does not address permafrost melting, methane releases, extreme weather cycles, ocean deadspots, deforestation, inland flooding, jet stream changes, oceanic stream changes, ice cap reflection and the impacts on agriculture / food supply or water sources. He also does not address global dimming and the impact of particulate matter in the atmosphere. He’s simply looking at the divergence of orbital climate cycles from historic norms over millions of years.

                I don’t see anything that would support a conclusion that a reduction in use of fossil fuels and emissions of GHG’s would result in cooling to ice age levels. His own data says the divergence started thousands of years before industrialization, and does not account for the rapid acceleration of GHG’s since 2012. I think we have a long, long way to go before we need to worry about CO2 PPM dropping to 1870 levels, let alone thousands of years ago. Conversely, I see a lot of flaws / incomplete thinking in his analysis, which is understandable given he is a geologist, not a climate scientist.

                1. Susan the other`

                  Thank you. You confirm my indecision. But who isn’t conflicted? I think an open discussion would at least help. I’m going nuts trying to find an explantation I can live with.

                  1. Ignacio

                    Bear in mind that you are giving the same weigth to a geologist in one side and to a group of thousands of climatologists on the other. Of course future is uncertain, but terribly uncertain if we don’t stop burning fossil fuels some day.

                    1. Evil Wizard Glick

                      Not really. You just are not reading the “other side”.
                      I’m skeptical of ALL climate claims.
                      I’ve seen compelling arguments from both sides.
                      I’m also bothered that we are only examining a relatively small section of Earths climate History and claiming we definitely fully comprehend the amazingly complex nature of the situation.
                      One interesting example, blamed on climate change, is the Antarctic melting glacier. The doom story about a rapidly growing hole. Yet few people cite the volcanism happening beneath the glacier. And that volcanism has been known to exist for nearly a decade. As with the hole.
                      I’m unimpressed that so much money and reputation relies on agreement. There is no “pure” science.

      2. drumlin woodchuckles

        I remember in the 1970s that the climatologists of that day were predicting a coming Frosty Chill Age . . . maybe even an Ice Age. Certainly a Cool Down.

        Very few people in the late 70s were saying that based on Svant Arrhenius’s discovery work about CO2 re-reflecting certain wavelengths of earth-sent out-going infrared light back to earth surface itself or sideways to neighboring atomolecules in the atmosphere . . . that earth was kept at a higher temperature than if atmosphere contained zero CO2 AND that if atmosphere gained MORE CO2, that breakeven temperature of earth-surface systems would be raised higher.

        More people started studying this issue in the 1980s and beyond. The people predicting that more heater-gases in the air would mean more global heating made certain predictions from that hypothesis. Those predictions have come true as predicted. Basic things like . . . the Arctic will warm up faster than the non-Arctic.

        The correctness of the predictions of the man-made global heating theorists makes me think the man-made global heating theory is reality-based and a good guide to what actions to take, if we feel like taking the appropriate actions.

        Of course if the heater-gas skyload remains high or goes higher, and the sun remains at the same light-output level, and reflecto-particle pollution remains the same over many years to come , and yet we get a multi-year cooldown in the teeth of all those other things being equal; then I would feel the man-made global heating theory has been shown to be a lot weaker than I thought.

        But I don’t feel it is safe just to wait and see. It would be safer, if even possible any more , to lower the airborn heater-gas skyload, and suck down the excess skycarbon into plants and the soil they grow in, in order to get some man-made global re-cooling under way than to simply wait another few decades to see if the Frosty Cool Age Coming theorists are right in the end.

    2. Tomonthebeach

      Global warming cannot be directly linked to any bad weather because bad weather just IS. Nearly all scientists who study climate change do agree that climate change caused by humans shitting in their own nests amplifies the impact of weather events by making storms larger and more violent. We humans resist change.


      What has Houston done to prevent future flooding? Zip. Did Florida force citizens of Mexico Beach to enforce its wind-mitigation building codes? Nope. Are developers still draining the Florida swamps to build retirement homes in floodplains? Yes. Aside from Central Florida counties, where else are wood power poles being replaced with concrete wind-resistant poles that feed individual homes via underground cables? Nowhere. What has Manhattan and Miami done to prevent regular tidal flooding in their downtowns? Thought about it.

      Looking west, California still builds homes on mudslide hills and fire-prone regions. There are still many Paradises in California without evacuation routes or fire mitigation. The US Midwest has fertile soil due to periodic floods like they are experiencing right now. Over the past century, no effective measures have been taken to manage that water to advantage? Given that tornadic winds flatten mobile homes and kill their occupants even when there is no direct hit, they are still being manufactured?

  4. rd

    Sandy, Harvey, and Florence have had very unusual west-hooking and/or drifting movements once they get close to shore or just inland. This may be the biggest impact that climate change has on hurricanes if it increases the frequency of these very destructive tracks. There are very few places on Earth that can withstand 10 inches per day of rain for days.

  5. Evil Wizard Glick

    Don cafferty
    “however, the professor resorts to “weasel” words – may be, suggest, could be”

    They use those words because they know what they state are vague and tenuous links at best. The Replication crisis exists across ALL science.

    If they post a certainty and it is proven incorrect their papers get pulled and they lose funding. Obviously, Scientists can only suggest there may be links. BUT they can not DEFINITELY prove them.

    Personally, I would like to see an international debate involving both sides, instead of the single side which is accepted as fact today. Which according to the language of various climate papers is definitely NOT fact but speculation. Those weasel words as you call them.

    1. pretzelattack

      no they use such words because they are being careful to be accurate. there arent two scientific sides to this, there is a political side funded by the fossil fuel companies, and a scientific side. what replication crisis exists in climate science? post your evidence, please.

  6. Ignacio

    Sligthly off topic I strongly recommend “The Boy That Harnessed the Wind”, a story in Malawi based on real life events.

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