Hurricane scientists and research meteorologists are intensively studying how storms like the powerful and historic Hurricane Ian are impacted by the warming globe. Some impacts of climate change are certain — such as more rain, flooding, and storm surge. Others are being investigated, and Hurricane Ian will add to the sum of this growing scientific evidence.
Mashable spoke with the scientists below following the destructive Hurricane Ida, which struck Louisiana in 2021.
Heavier deluges and more serious flooding
Hurricanes are producing heavier rains because the warming climate has amped the odds for storms to produce more rain, Brian Tang, an atmospheric scientist at the University of Albany who researches hurricanes, told Mashable.
As Mashable previously reported: "When air temperature is warmer, the atmosphere can naturally hold more water vapor (heat makes water molecules evaporate into water vapor(opens in a new tab)), meaning there's more water in the air, particularly in many humid or rainy regions. For every 1.8 degrees Fahrenheit of warming (or one degree Celsius), the air holds about seven percent more water vapor(opens in a new tab). Earth has warmed by just over 2 degrees Fahrenheit since the late 1800s(opens in a new tab), resulting in more storms significantly juiced with more water. This means storms now have boosted odds of dumping significantly more rain.
"You're loading the dice," Tang emphasized.
"You're loading the dice."
Since the 1950s, the heaviest rains have increased over most areas where climate scientists have good data (like North America, Europe, and many other regions), a major UN Intergovernmental Panel on Climate Change (IPCC) report recently concluded.
So far, Earth has warmed by some 1.1 degrees Celsius, or about 2 degrees Fahrenheit, above 19th-century levels. If Earth warms to 2 C (or 3.6 F), which is an increasingly likely outcome, hurricane scientists expect rainfall rates within 100 kilometers(opens in a new tab) (62 miles) of a storm's center to increase by 10 to 15 percent. That portends major flooding during hurricanes.
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Higher storm surge
Hurricanes can push violent, destructive surges of seawater into the coast. A hurricane's powerful winds drive these surges. Ida's surge was potent(opens in a new tab). But, crucially, sea levels are increasing as Earth's great ice sheets melt into the ocean. That inevitably means higher storm surges.
"Sea level is rising," Phil Klotzbach, an atmospheric scientist at Colorado State University who researches hurricanes, told Mashable. He noted how this results in more coastal areas inundated with damaging saltwater.
"Sea level is rising."
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Sea levels have already risen by some eight to nine inches(opens in a new tab) since the late 1800s. And as Mashable previously reported: "Sea levels rose faster in the 20th century than in any prior century over the last three thousand years(opens in a new tab), the IPCC found, based on research of fossilized coastal creatures(opens in a new tab). By this century's end, under intermediate (not extremely high or low) carbon emission scenarios, the IPCC predicts sea levels will rise by another 1.5 to 2.5 feet, and then continue rising."
Already, hurricanes produce more destruction and property damage(opens in a new tab) than they would have a century ago. Areas like Florida, the Texas coast, and other Gulf states now have considerably more infrastructure and homes. Hurricanes have more targets. "They're causing more damage," emphasized Klotzbach. "There's more people and stuff in harm's way."
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Intensifying storms?
An actively researched question in atmospheric science today is how the changing climate will impact the intensity of storms (meaning sustained wind speeds). There is evidence, for example, that storms in the Atlantic Ocean have had a detectable increase in intensification events(opens in a new tab) between 1982 and 2009, and that tropical storm intensity has increased globally(opens in a new tab) over the last few decades. Of particular interest to storm researchers are the conditions that stoke tropical storms to "rapidly intensify," meaning a storm's winds increase by at least 35 mph in a 24-hour period.
Yet many tropical storm researchers emphasize that more storm observation is necessary, in the years and decades ahead, to truly know how climate change is affecting hurricane intensity.
For a foolproof way to say with certainty how climate change affects hurricane intensity, we need to wait decades and see how the trend evolves, said Falko Judt, a research meteorologist at the National Center for Atmospheric Research(opens in a new tab). "As usual, hindsight is 20/20."
"It's something that requires more research to understand," added Tang, but also noted it seems like there's been a recent uptick in the number of storms that have rapidly intensified(opens in a new tab). What's more, the frequency of strong Atlantic tropical storms (Category 3 or higher) have increased since 1979(opens in a new tab).
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Yet the uncertainty lies in how scientists observe storms today, versus humanity's limited view of storms before the 1980s. Today, scientists have state-of-the-art weather satellites(opens in a new tab) and a fleet of aircraft gathering all sorts of information about hurricanes(opens in a new tab). But this 40-year-long, increasingly detailed observation period is much shorter than other climate records, like records for global temperature, drought, and wildfires. So when recent years show evidence of stronger storms, is it because they're happening, or are scientists now seeing them happen with more advanced tools?
"There are indications that rapid intensification episodes have increased over the last decades," said Judt. "This could be a sign of climate change 'supercharging' the ocean and atmosphere. But we're also detecting rapid intensification better than say 40 years ago. So is this trend real or an artifact of better technology?"
It's an open, evolving question.
Atmospheric scientists, however, can potentially tease out the impact climate change had on a storm like Ian or Ida with "attribution studies." These are complex hypothetical computer simulations that assess "what would have happened if there was no global warming," noted Judt. They show the influence climate change had on an extreme event. These attributions are often done with heat waves(opens in a new tab).
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Warming oceans may influence storms
The oceans are heating up as the climate warms, and warm oceans are "jet fuel for hurricanes," explained Klotzbach. (Warmer oceans fuel tropical storms as more water naturally evaporates into the air, giving storms energy and moisture to intensify.) The extremely absorbent oceans soak up over 90 percent of the heat that humans, due to fossil fuel burning, trap on Earth. The seas will continue warming well beyond this century.
This ocean warming seems like it should easily portend stronger hurricanes. Hurricane Ida in 2021 definitely passed through some extremely warm waters(opens in a new tab). But when it comes to extremely dynamic processes like relatively short-lived, churning cyclones, it's not that simple. "It's pretty clear that — everything else equal — hurricanes intensify faster in a warmer world," said Judt. "But everything else is not equal." Future storms are a complicated mix of an atmosphere and ocean that are both interacting and changing. Wind patterns change too, said Judt. And warmer temperatures may actually act to stabilize the atmosphere(opens in a new tab), which isn't good for storms (tropical storms form in unsettled, disturbed atmospheric environments), explained Klotzbach.
As the years and decades pass, however, the warming ocean may indeed win out over other factors, resulting in more intense storms, said Klotzbach. For example, in a world considerably warmer than Earth today (a 2 C world, where we're almost certainly headed), climate projections currently suggest there may be a greater proportion of higher intensity storms(opens in a new tab). Yet, crucially, there's currently no evidence there will be more storms overall.
This story will be updated with significant hurricane and climate research.
