THEY ALREADY ARE

Hurricanes in 100 years could be far more devastating, study finds

By Mark Puleo, Accuweather.com

Cars are left stranded on the Long Island Expressway due to flooding from a massive downpour of rain from Hurricane Ida at the 2021 U.S. Open Tennis Championships in New York City on September 1. File Photo by John Angelillo/UPI | License Photo

Our understanding of hurricane formations and tracks has changed dramatically in the past century, but what do we know about the next century of storms?

A team of climate scientists from Rowan University in New Jersey set out to answer that question, using more than 35,000 computer simulations to study the evolution of storm tracks and better understand storm behaviors in the future. The scientists' findings were particularly concerning for one specific region of the United States.

Andra Garner, the study's lead researcher, told AccuWeather the climate models she used to analyze storm behavior evolution show that storm systems will only become more unforgiving in the decades to come."A couple of key things we found were that, over time, hurricanes seem like they're forming closer to the U.S. southeast coast, which means less time for those northeast cities to prepare for those storms to arrive," she told AccuWeather. "The other thing that happens is that over time, we see hurricanes moving their slowest when they're along the U.S. East Coast, which means that those communities being impacted by them see a longer duration of the storm impacts."


Garner said her team was motivated for years to study specifically the future of hurricane-influenced flooding in New York City. This was long before Ida, which had transitioned from a hurricane at landfall on the Gulf Coast to a tropical rainstorm as it traveled north, tearing through the eastern United States and New York City in August and September.

The study's main findings show that future hurricanes won't be a worry just in historically susceptible areas.

Using storm tracks from the pre-industrial era (850-1800) and the modern era (1970-2005), the team simulated the future tropical scenario (2080-2100) under a very high-emissions scenario to simulate the future climate.

In a future high-emissions scenario, as used by the study, the output of greenhouse gases caused by the heavy use of fossil fuels continues to add additional warming to the climate.

A building in downtown New Orleans is destroyed in the aftermath of Hurricane Ida on August 30. File Photo by AJ Sisco/UPI | License Photo

"Tropical cyclone (TC) track characteristics in a changing climate remain uncertain," the study's abstract reads.

Although Garner said her team's initial motivations were to study the future tropical impacts on New York City, the findings revealed that a few East Coast cities should also be concerned.

"As the climate warms, TCs also form closer to the U.S. southeast coast, reach their slowest forward speed along the U.S. Atlantic coast and persist farther north and east in the Atlantic basin," the study said. "The time required for TCs to reach cities such as Boston, Norfolk and New York City is reduced, and the typical duration of TC conditions increases at each of these locations."

It may soon be time for those in the Northeast to call up their Gulf Coast friends and family to ask for some safety tips. However, the future changes will require more adaptations than simply boarding up windows and filling sandbags.

Garner said her findings should also influence the way these East Coast cities plan for the future. Simply put, the current setup may not fly.

"We're really living in a society that has been developed and adapted for a climate state that maybe is no longer the case, and we're now dealing with this rapidly changing climate," she said, adding that tropical systems like Hurricane Ida showed just how hard it is to prepare for something people haven't seen before. "It's definitely something we need to be thinking about -- How we can adapt our communities?"



As Ida painfully highlighted in August and September, rethinking community infrastructure is a matter of life or death.

For cities like New York and Philadelphia, where flooded-ravaged subways and buildings turned into death traps from Ida's intense rainfall, Garner said her study's findings should send a clear message about the urgency of strengthening coastal infrastructure ahead of these future storms.

"We need to be thinking about that now and coming up with ways that we can make those communities more resilient," she said. "Protecting against things like sea-level rise and storm surge, updating our infrastructure like with some of the problems we consistently see in New York City with the subways flooding and things like that. We need to be thinking about those kinds of issues."


4 / 5A man walks past a giant live oak tree that was blown down in the Mid-City area of New Orleans during Hurricane Ida, Tuesday, August 31, 2021. Photo by AJ Sisco/UPI | License Photo

On top of simply forecasting the future with her simulation models, Garner said, her research shows how we've already seen great changes from the pre-industrial era to the present.

"We absolutely need to be taking those steps now to try to make our communities more resilient and able to handle those kinds of impacts."

Garner told AccuWeather the study highlighted three key locations for future storm scenarios -- The Battery (NYC), Norfolk, Va., and Boston.

"Where the colors are warmer," Garner said, noting the red, yellow and pink parts of the map seen above, "there are more storm tracks in the future compared to the pre-industrial era." The parts of the map where the colors are cooler, with shades of blue denoted that there will be "fewer storm tracks in the future compared to the pre-industrial era."


Rather than curving into the Big Apple, she said, the models show storms lingering out at sea and presenting bigger worries for cities like Boston. On top of that, she continued, her team was also surprised not only by the destination of these storms but also by the areas of formation and the speed of trajectory.

According to Garner, the study found storms moving along the East Coast are likely to slow down, or even stall, in their forward progress, allowing even heavier loads of tropical rain and storm surge to inundate communities.

The researcher also told AccuWeather that the study focused mainly on the evolution of tropical cyclone tracks and not any changes to the intensity of those future storms, changes in the frequency of those storms or the distribution of storms between hurricanes and tropical storms.

However, she did add that their findings could signal danger to the projected cities like Norfolk and Boston because of how near the storms could form to the U.S. coast.

"The proportion of storms forming farther west and closer to our coastline seems to be increasing, and the number of storms we have forming there is going up," she said. "It needs to be a warning to us to be ready to, perhaps, prepare more quickly and have those warning systems in place and good communication in the event that a storm does develop near our coast."

All confidence in a safe future doesn't need to be cast away, however. Although the data may seem full of despair, the hope lies in an altered scenario.

According to Garner, the future studies simulations were conducted using a "very high future emissions scenario." In the decades to come, she said, communities need to work to lower greenhouse gas emissions so that we can limit how bad the impacts of the storms become in the future.

"I always like to remind people that I think there's a lot of hope for the future, too," she said, striking an optimistic tone. "We know that we are the cause of climate change. We didn't get a chance to look at lower emission scenarios, but I think there's a good chance that if we did look at those lower emission scenarios, perhaps we see less drastic changes in storms. That's something we should all be working toward, working to take those larger-scale actions to lower our emissions so that we can avoid some of the worst-case future scenarios."

Hurricanes in the North Atlantic are increasing in frequency, says study

Scott Sutherland
Thu., December 9, 2021

New research confirms what historical records have been telling us — that hurricane activity in the North Atlantic has been increasing over the past 150 years.

Today, with the array of satellites we have in space, no hurricane, typhoon, or tropical cyclone escapes our attention. Detailed imagery from orbit, along with data collected via ocean buoys, ships, ground stations, and aircraft reconnaissance, give scientists unparalleled insights into the frequency and strength of these storms.

However, going through the full historical record of hurricanes, researchers point out a noticeable trend.

"As you go back in time, the observations become more and more sparse," Dr. Kerry Emanuel, a meteorologist and climate scientist at the Massachusetts Institute of Technology, explained to Reuters.

Regular observations of hurricanes via satellite began in the 1970s, and since the 1940s aircraft have been making dedicated reconnaissance flights into storms. Unfortunately, prior to that, records only came from ships, or from islands that the storms passed over. So, for roughly the first century of the historical record, collecting data on hurricanes essentially depended on luck.

Therefore, a storm that did not cross any of the established shipping lanes of the time, or that followed a track which avoided all islands, would not show up in the historical record.

"Undoubtedly, we missed some storms," Emanuel concluded.

Now, Emanuel is the author of a new study published in Nature Communications, in which he used climate simulations to reconstruct hurricane activity over the past 150 years.

Hurricane Laura 2020-08-26 2300Z NOAA

2020's Hurricane Laura reached its peak intensity off the US East Coast on August 26, as seen here in imagery from the GOES-16 geostationary weather satellite. Credit: NOAA

Looking at the full record from 1851 to the present day, there is a noticeable uptick in the frequency of hurricanes in the North Atlantic Ocean. With the apparent sparsity in the first century of the record, though, climate researchers have avoided using this trend when trying to determine the impact of global warming on hurricane activity.

"Nobody disagrees that that's what the historical record shows," Emanuel stated in an MIT press release. "On the other hand, most sensible people don't really trust the historical record that far back in time."

There have been attempts to fill the gaps in the earliest parts of the record, of course.

Studies have compared modern storm tracks to old shipping routes, to see if there were ones that would have been missed in those early years. While these studies did suggest that hurricane activity may not have increased, Emanuel considered there to be two key issues with this approach. Firstly, there's no telling if hurricanes back in the late 1800s and early 1900s would have followed the same tracks that they do in modern times. Indeed, recent research has found that Atlantic hurricanes are reaching their peak strength farther north, so there may be significant differences in their tracks, today, compared with 100 to 150 years ago. Secondly, some of the oldest shipping routes are still not yet digitized into the record. If those routes were added to the studies, their conclusions may have changed.

So, instead of relying on the historical records, Emanuel chose to instead reconstruct the past using climate simulations. This method — known as 'reanalysis' — is when real data is fed into a climate model to simulate the past, rather than the future. This has been very successful, in general, because model results can be directly compared to the weather conditions that actually occurred.

For this study, in particular, Emanuel left out aircraft and satellite data, and only fed surface observations from ships and islands into his reanalysis models. This kept the type of records consistent and gave an accurate account of the weather and sea surface conditions for the full span of the historical data. Into those models he then scattered hurricane 'seeds' — the basic conditions that can cause a hurricane to form — and watched what happened.

Across the three climate simulations that he used, they all revealed the same thing. While there was no noticeable increase in hurricane activity on the global scale over the past 150 years, there was a definite increase in activity specifically for hurricanes in the North Atlantic.

The overall number of hurricanes increased over time, the number of major hurricanes increased, and the number of landfalls also went up.

North Atlantic Hurricanes climate reanalysis - Emanuel, Nature Communications

These graphs show the results from all three models used in the study. Each graph contains the actual historical hurricane records from the International Best Track Archive for Climate Stewardship (IBTrACS) database (blue line), which produce a positive trend (blue dashed line). The red line in each represents the results from Emanual’s MIT study, which also reveal a positive trend (red dashed line) for hurricanes, for major hurricanes, and for hurricane landfalls. Credit: Emanuel, 2021/Nature Communications

As shown in the graphs above, the simulations did "find" a significant number of missed North Atlantic hurricanes, with some of those likely becoming major hurricanes. The models also accurately reproduced a noticeable 'peak' in hurricane activity seen in the 1940s, and the 'hurricane drought' that was experienced in the 1970s and 1980s. Emanuel's research group attributes this drought to the cooling effects of sulfate aerosols from fossil fuel burning. The presence of these sulfate aerosols in the atmosphere would have meant more sunlight being reflected back into space, thus cooling the surface and limiting the impacts of global warming. As regulations were put into place to limit sulfur dioxide emissions (due to the public health risk they posed), this cooling effect was removed.

"The general trend over the last 150 years was increasing storm activity, interrupted by this hurricane drought," Emanuel stated in the MIT press release.

Given that these simulations showed no overall increase in the global trend of tropical cyclone activity, it is difficult to make broad assumptions about the cause of the specific uptick in activity in the North Atlantic.

From the study, Emanuel stated that "most of the variability of North Atlantic tropical cyclone activity over the last century was directly related to regional rather than global climate change."

Thus, rather than being driven by the overall impacts of global warming, it may be the smaller scale impacts — changes in North Atlantic sea surface temperatures, and changes in the strength and position of ocean currents — that are driving this increased activity.

"That is still a mystery," Emanuel noted, "and it bears on the question of how global warming might affect future Atlantic hurricanes."