Even weak tropical cyclones have grown more intense worldwide – we tracked 30 years of them using currents

Hurricane Nicole was a Category 1 storm, but it caused extensive damage to Florida in 2022. Lauren Dauphin/NASA Earth Observatory

by Wei Mei, University of North Carolina at Chapel Hill and Shang-Ping Xie, University of California, San Diego

Tropical cyclones have been growing stronger worldwide over the past 30 years, and not just the big ones that you hear about. Our new research finds that weak tropical cyclones have gotten at least 15% more intense in ocean basins where they occur around the world.

That means storms that might have caused minimal damage a few decades ago are growing more dangerous as the planet warms.

Warmer oceans provide more energy for storms to intensify, and theory and climate models point to powerful storms growing stronger, but intensity isn’t easy to document. We found a way to measure intensity by using the ocean currents beneath the storms – with the help of thousands of floating beachball-sized labs called drifters that beam back measurements from around the world.

Why it’s been tough to measure intensity

Tropical cyclones are large storms with rotating winds and clouds that form over warm ocean water. They are known as tropical storms or hurricanes in the Atlantic and typhoons in the Northwest Pacific.

A tropical cyclone’s intensity is one of the most important factors for determining the damage the storm is likely to cause. However, it’s difficult to accurately estimate intensity from satellite observations alone.

Intensity is often based on maximum sustained surface wind speed at about 33 feet (10 meters) above the surface over a period of one, two or 10 minutes, depending on the meteorological agency doing the measuring. During a hurricane, that region of the storm is nearly impossible to reach.

For some storms, NOAA meteorologists will fly specialized aircraft into the cyclone and drop measuring devices to gather detailed intensity data as the devices fall. But there are many more storms that don’t get measured that way, particularly in more remote basins.

Map with dots for locations of drifters as of Nov. 28, 2022. The dots are all over the oceans.
Over 1,100 drifters are currently operating around the world. The U.S. (blue dots) operates over 430 of them. France (orange) has about 200. Each typically lasts about a year. NOAA

Our study, published in the journal Nature in November 2022, describes a new method to infer tropical cyclone intensity from ocean currents, which are already being measured by an army of drifters.

How drifters work

A drifter is a floating ball with sensors and batteries inside and an attached “drogue” that looks like a windsock trailing under the water beneath it to help stabilize it. The drifter moves with the currents and regularly transmits data to a satellite, including water temperature and location. The location data can be used to measure the speed of currents.

A sphere about the size of a volleyball with what looks like a windsock attached.
Examples of NOAA’s drifters and the drogue that helps stabilize them. NOAA

Since NOAA launched its Global Drifter Program in 1979, more than 25,000 drifters have been deployed in global oceans. Those devices have provided about 36 million records over time. Of those records, more than 85,000 are associated with weak tropical cyclones – those that are tropical storms or Category 1 hurricanes or typhoons – and about 5,800 that are associated with stronger tropical cyclones.

That isn’t enough data to analyze strong cyclones globally, but we can find trends in the intensity of the weak tropical cyclones.

Here’s how: Winds transfer momentum into the surface ocean water through frictional force, driving water currents. The relationship between wind speed and ocean current, known as Ekman theory, provides a theoretical foundation for our method of deriving wind speeds from the drifter-measured ocean currents.

Explaining Vagn Walfrid Ekman’s theory of currents.

Our derived wind speeds are consistent with wind speeds directly measured by nearby buoy arrays, justifying the new method to estimate tropical cyclone intensity from drifter measurements.

Evidence beneath the storms

In analyzing those records, we found that the ocean currents induced by weak tropical cyclones became stronger globally during the 1991-2020 period. We calculated that the increase in ocean currents corresponds to a 15% to 21% increase in the intensity of weak tropical cyclones, and that intensification occurred in all ocean basins.

In the Northwest Pacific, an area including China, Korea and Japan, a relatively large amount of available drifter data also shows a consistent upward trend in the intensity of strong tropical cyclones.

We also found evidence of increasing intensity in the changes in water temperatures measured by satellites. When a tropical cyclone travels through the ocean, it draws energy from the warm surface water and churns the water layers below, leaving a footprint of colder water in its wake. Stronger tropical cyclones bring more cold water from the subsurface to the surface ocean, leading to a stronger cooling in the ocean surface.

It’s important to remember that even weak tropical cyclones can have devastating impacts. Tropical Storm Megi, called Agaton in the Philippines, triggered landslides and was blamed for 214 deaths in the Philippines in April 2022. Early estimates suggest Hurricane Nicole caused over $500 million in damage in Volusia County alone when it hit Florida as a Category 1 storm in November 2022.

The 2022 Atlantic hurricane season officially ended on Nov. 30 with 14 named storms and eight hurricanes. It isn’t clear how rising global temperatures will effect the number of tropical cyclones that form, but our findings suggest that coastal communities need to be better prepared for increased intensity in those that do form and a concurrent rise in sea level in the future.

Wei Mei, Assistant Professor of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill and Shang-Ping Xie, Roger Revelle Professor of Climate Science, Scripps Institution of Oceanography, University of California, San Diego

This article is republished from The Conversation under a Creative Commons license. Read the original article.

We’re decoding ancient hurricanes’ traces on the sea floor – and evidence from millennia of Atlantic storms is not good news for the coast

Deep ‘blue holes,’ like this one off Belize, can collect evidence of hurricanes. The TerraMar Project, CC BY

by Tyler Winkler, Woods Hole Oceanographic Institution

If you look back at the history of Atlantic hurricanes since the late 1800s, it might seem hurricane frequency is on the rise.

The year 2020 had the most tropical cyclones in the Atlantic, with 31, and 2021 had the third-highest, after 2005. The past decade saw five of the six most destructive Atlantic hurricanes in modern history.

Then a year like 2022 comes along, with no major hurricane landfalls until Fiona and Ian struck in late September. The Atlantic hurricane season, which ends Nov. 30, has had eight hurricanes and 14 named storms. It’s a reminder that small sample sizes can be misleading when assessing trends in hurricane behavior. There is so much natural variability in hurricane behavior year to year and even decade to decade that we need to look much further back in time for the real trends to come clear.

Fortunately, hurricanes leave behind telltale evidence that goes back millennia.

Two thousand years of this evidence indicates that the Atlantic has experienced even stormier periods in the past than we’ve seen in recent years. That’s not good news. It tells coastal oceanographers like me that we may be significantly underestimating the threat hurricanes pose to Caribbean islands and the North American coast in the future.

The natural records hurricanes leave behind

When a hurricane nears land, its winds whip up powerful waves and currents that can sweep coarse sands and gravel into marshes and deep coastal ponds, sinkholes and lagoons.

Under normal conditions, fine sand and organic matter like leaves and seeds fall into these areas and settle to the bottom. So when coarse sand and gravel wash in, a distinct layer is left behind.

Imagine cutting through a layer cake – you can see each layer of frosting. Scientists can see the same effect by plunging a long tube into the bottom of these coastal marshes and ponds and pulling up several meters of sediment in what’s known as a sediment core. By studying the layers in sediment, we can see when coarse sand appeared, suggesting an extreme coastal flood from a hurricane.

With these sediment cores, we have been able to document evidence of Atlantic hurricane activity over thousands of years.

One sediment core with dates showing high levels of sand deposits and a photo of one section showing the sand layer.
The red dots indicate large sand deposits going back about 1,060 years. The yellow dots are estimated dates from radiocarbon dating of small shells. Tyler Winkler

We now have dozens of chronologies of hurricane activity at different locations – including New England, the Florida Gulf Coast, the Florida Keys and Belize – that reveal decade- to century-scale patterns in hurricane frequency.

Others, including from Atlantic Canada, North Carolina, northwestern Florida, Mississippi and Puerto Rico, are lower-resolution, meaning it is nearly impossible to discern individual hurricane layers deposited within decades of one another. But they can be highly informative for determining the timing of the most intense hurricanes, which can have significant impacts on coastal ecosystems.

It’s the records from the Bahamas, however, with nearly annual resolution, that are crucial for seeing the long-term picture for the Atlantic Basin.

Why The Bahamas are so important

The Bahamas are exceptionally vulnerable to the impacts of major hurricanes because of their geographic location.

In the North Atlantic, 85% of all major hurricanes form in what is known as the Main Development Region, off western Africa. Looking just at observed hurricane tracks from the past 170 years, my analysis shows that about 86% of major hurricanes that affect the Bahamas also form in that region, suggesting the frequency variability in the Bahamas may be representative of the basin.

Satellite view of Atlantic showing tracks of each storm, most starting off Africa, heading west and then curving northward.
Atlantic hurricane tracks from 1851 to 2012. Nilfanion/Wikimedia

A substantial percentage of North Atlantic storms also pass over or near these islands, so these records appear to reflect changes in overall North Atlantic hurricane frequency through time.

By coupling coastal sediment records from the Bahamas with records from sites farther north, we can explore how changes in ocean surface temperatures, ocean currents, global-scale wind patterns and atmospheric pressure gradients affect regional hurricane frequency.

As sea surface temperatures rise, warmer water provides more energy that can fuel more powerful and destructive hurricanes. However, the frequency of hurricanes – how often they form – isn’t necessarily affected in the same way.

Satellite image of a hurricane over The Bahamas, marked on the map, next to  Florida.
Hurricane Dorian sat over the Bahamas as a powerful Category 5 storm in 2019. Laura Dauphin/NASA Earth Observatory

The secrets hidden in blue holes

Some of the best locations for studying past hurricane activity are large, near-shore sinkholes known as blue holes.

Blue holes get their name from their deep blue color. They formed when carbonate rock dissolved to form underwater caves. Eventually, the ceilings collapsed, leaving behind sinkholes. The Bahamas has thousands of blue holes, some as wide as a third of a mile and as deep as a 60-story building.

They tend to have deep vertical walls that can trap sediments – including sand transported by strong hurricanes. Fortuitously, deep blue holes often have little oxygen at the bottom, which slows decay, helping to preserve organic matter in the sediment through time.

Images showing the depth of a blue hole
Hine’s Blue Hole in the Bahamas is about 330 feet (100 meters) deep. Seismic imaging shows about 200 feet (60-plus meters) of accumulated sediment. Pete van Hengstum; Tyler Winkler

Cracking open a sediment core

When we bring up a sediment core, the coarse sand layers are often evident to the naked eye. But closer examination can tell us much more about these hurricanes of the past.

I use X-rays to measure changes in the density of sediment, X-ray fluorescence to examine elemental changes that can reveal if sediment came from land or sea, and sediment textural analysis that examines the grain size.

To figure out the age of each layer, we typically use radiocarbon dating. By measuring the amount of carbon-14, a radioactive isotope, in shells or other organic material found at various points in the core, I can create a statistical model that predicts the age of sediments throughout the core.

So far, my colleagues and I have published five paleohurricane records with nearly annual detail from blue holes on islands across the Bahamas.

Each record shows periods of significant increase in storm frequency lasting decades and sometimes centuries.

A map showing hurricane frequency from 1850 to 2019, with parts of Florida, Louisiana and North Carolina showing nine to 10 storms.
The red dots show the sites of high-resolution paleohurricane records. The map shows the frequency of hurricanes ranked Category 2 or above from 1850 to 2019. Tyler Winkler

The records vary, showing that a single location might not reflect broader regional trends.

For example, Thatchpoint Blue Hole on Great Abaco Island in the northern Bahamas includes evidence of at least 13 hurricanes per century that were Category 2 or above between the years 1500 and 1670. That significantly exceeds the rate of nine per century documented since 1850. During the same period, 1500 to 1670, blue holes at Andros Island, just 186 miles (300 kilometers) south of Abaco, documented the lowest levels of local hurricane activity observed in this region during the past 1,500 years.

Spotting patterns across the Atlantic Basin

Together, however, these records offer a glimpse of broad regional patterns. They’re also giving us new insight into the ways ocean and atmospheric changes can influence hurricane frequency.

While rising sea surface temperatures provide more energy that can fuel more powerful and destructive hurricanes, their frequency – how often they form – isn’t necessarily affected in the same way. Some studies have predicted the total number of hurricanes will actually decrease in the future.

Eight chronologies of hurricane evidence stacked to show corresponding periods of higher hurricane frequency.
Comparing paleohurricane records from several locations shows periods of higher frequency. The highlighted periods cover the Little Ice Age, a time of cooler conditions in the North Atlantic from 1300 to 1850, and the Medieval Warm Period, from 900 to 1250. Tyler Winkler

The compiled Bahamian records document substantially higher hurricane frequency in the northern Caribbean during the Little Ice Age, around 1300 to 1850, than in the past 100 years.

That was a time when North Atlantic surface ocean temperatures were generally cooler than they are today. But it also coincided with an intensified West African monsoon. The monsoon could have produced more thunderstorms off the western coast of Africa, which act as low-pressure seeds for hurricanes.

Steering winds and vertical wind shear likely also affect a region’s hurricane frequency over time. The Little Ice Age active interval observed in most Bahamian records coincides with increased hurricane strikes along the U.S. Eastern Seaboard from 1500 to 1670, but at the same time it was a quieter period in the Gulf of Mexico, central Bahamas and southern Caribbean.

Records from sites farther north tell us more about the climate. That’s because changes in ocean temperature and climate conditions are likely far more important to controlling regional impacts in such areas as the Northeastern U.S. and Atlantic Canada, where cooler climate conditions are often unfavorable for storms.

A warning for the islands

I am currently developing records of coastal storminess in locations including Newfoundland and Mexico. With those records, we can better anticipate the impacts of future climate change on storm activity and coastal flooding.

In the Bahamas, meanwhile, sea level rise is putting the islands at increasing risk, so even weaker hurricanes can produce damaging flooding. Given that storms are expected to be more intense, any increase in storm frequency could have devastating impacts.

Tyler Winkler, Postdoctoral Researcher in Oceanography, Woods Hole Oceanographic Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Barrier islands are natural coast guards that absorb impacts from hurricanes and storms

Cumberland Island National Seashore off the coast of Georgia. NPS, CC BY-SA

by Anna Linhoss, Auburn University

When storms like Hurricane Ian make landfall, the first things they hit often are barrier islands – thin ribbons of sand that line the U.S. Atlantic and Gulf coasts. It’s hard to imagine how these narrow strips can withstand such forces, but in fact, many of them have buffered our shores for centuries.

Barrier islands protect about 10 percent of coastlines worldwide. When hurricanes and storms make landfall, these strands absorb much of their force, reducing wave energy and protecting inland areas.

They also provide a sheltered environment that enables estuaries and marshes to form behind them. These zones serve many valuable ecological functions, such as reducing coastal erosion, purifying water and providing habitat for fish and birds.

Many barrier islands have been developed into popular tourist destinations, including Florida’s Sanibel Island and South Carolina’s Pawleys Island, both of which suffered heavy damage from Hurricane Ian. Islands that have been preserved in their natural state can move with storms, shifting their shapes over time. But many human activities interfere with these natural movements, making the islands more vulnerable.

Ocean City, Maryland is built on Fenwick Island, an Atlantic barrier island. USACE

Islands on the move

Barrier islands are made of sandy, erodible soil and subject to high-energy wave action. They are dynamic systems that constantly form and reform. But this doesn’t necessarily mean the islands are disappearing. Rather, they migrate naturally, building up sand in some areas and eroding in other areas.

New islands can form out in the ocean, either because local sea level drops or tectonics or sediment deposition raises the ocean floor. Or they may shift laterally along the shore as currents carry sediments from one end of the island toward the other. On the East Coast, barrier islands usually move from north to south because longshore currents transport sand in the same direction.

And over time many barrier islands move landward, toward the shore. This typically happens because local sea levels rise, so waves wash over the islands during storms, moving sand from the ocean side to the inland side.

How longshore drift moves sediment along a beach.

1=beach. 2=sea 3=longshore current direction 4=incoming waves 5=swash 6=backwash USGS

Building on shifting sands

Building hard infrastructure such as homes, roads and hotels on barrier islands interrupts their lateral migration. Needless to say, beach communities want their dunes to stay in place, so the response often is to build control structures, such as seawalls and jetties.

This protects buildings and roads, but it also disrupts natural sand transportation. Blocking erosion up-current means that no sediments are transported down-current, leaving those areas starved of sediment and vulnerable to erosion.

Many sandy tourist beach towns along the East Coast also turn to beach nourishment – pumping tons of sand from offshore – to replace sand lost through erosion. This does not interrupt natural sand transportation, but it is a very expensive and temporary fix.

For example, since the 1940s Florida has spent over US$1.3 billion on beach nourishment projects, and North Carolina has spent more than $700 million. This added sand will eventually wash away, quite possibly during the next hurricane to hit the coast, and have to be replaced.

What kind of protection?

In some cases, however, leaving barrier islands to do their own natural thing can cause problems for people. Some cities and towns, such as Miami and Biloxi, are located behind barrier islands and rely on them as a first line of defense against storms.

And many communities depend on natural resources provided by the estuaries and wetlands behind barrier islands. For example, Pamlico Sound – the protected waters behind North Carolina’s Outer Banks – is a rich habitat for blue crabs and popular sport fish such as red drum.

Survey images of barrier islands of Alabama, Mississippi and southeast Louisiana, collected to document changes resulting from Hurricane Isaac in August 2012. USGS

Unmanaged, some of these islands may not move the way we want them to. For example, a storm breach on a barrier island that protects a city would make that city more vulnerable.

Here in Mississippi, a string of uninhabited barrier islands off our coast separates Mississippi Sound from the Gulf of Mexico. Behind the islands is a productive estuary, important wetlands and cities such as Biloxi and Gulfport.

Because the Mississippi River has been dredged and enclosed between levees to keep it from spilling over its banks, this area does not receive the sediment loads that the river once deposited in this part of the Gulf. As a result, the islands are eroding and disappearing.

To slow this process, state and federal agencies have artificially nourished the islands to keep them in place and preserve the cities, livelihoods and ecological habitats behind them. This project filled a major breach cut in one island by Hurricane Camille in 1969, making the island a more effective storm buffer for the state’s coast.

When to retreat?

Geologically, barrier islands are not designed to stay in one place. But development on them is intended to last, although critics argue that climate change and sea level rise will inevitably force a retreat from the shore.

Reconciling humans’ love of the ocean with the hard realities of earth science is not easy. People will always be drawn to the coast, and prohibiting development is politically impractical. However, there are some ways to help conserve barrier islands while maintaining areas for tourism activities.

First, federal, state and local laws can reduce incentives to build on barrier islands by putting the burden of rebuilding after storms on owners, not on the government. Many critics argue that the National Flood Insurance Program has encouraged homeowners to rebuild on barrier islands and other coastal locations, even after suffering repeated losses in many storms.

Aerial view of a causeway with water and sediment flowing through a gap in the center
Hurricane Ian breached the causeway connecting Sanibel Island, Florida to the mainland, forcing residents to leave by boat after the storm passed. Image taken Sept. 30, 2022. Ricardo Arduengo/AFP via Getty Images

Second, construction on barrier islands should leave dunes and vegetation undisturbed. This helps to keep their sand transportation systems intact. When roads and homes directly adjacent to beaches are damaged by storms, owners should be required to move back from the shoreline in order to provide a natural buffer between any new construction and the coastline.

Third, designating more conservation areas on barrier islands will maintain some of the natural sediment transportation and barrier island migration processes. And these conservation areas are popular nature-based tourism attractions. Protected barrier islands such as Assateague, Padre and the Cape Cod National Seashore are popular destinations in the U.S. national park system.

Finally, development on barrier islands should be done with change in mind and a preference for temporary or movable infrastructure. The islands themselves are surprisingly adaptable, but whatever is built in these dynamic settings is likely sooner or later to be washed away.

Anna Linhoss, Associate Professor of Engineering, Auburn University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This 100% solar community endured Hurricane Ian with no loss of power and minimal damage

Read the full story from CNN.

Anthony Grande moved away from Fort Myers three years ago in large part because of the hurricane risk. He has lived in southwest Florida for nearly 19 years, had experienced Hurricanes Charley in 2004 and Irma in 2017 and saw what stronger storms could do to the coast.

Grande told CNN he wanted to find a new home where developers prioritized climate resiliency in a state that is increasingly vulnerable to record-breaking storm surge, catastrophic wind and historic rainfall.

What he found was Babcock Ranch — only 12 miles northeast of Fort Myers, yet seemingly light years away.

Babcock Ranch calls itself “America’s first solar-powered town.” Its nearby solar array — made up of 700,000 individual panels — generates more electricity than the 2,000-home neighborhood uses, in a state where most electricity is generated by burning natural gas, a planet-warming fossil fuel.

Hurricane Ian capped 2 weeks of extreme storms around the globe: Here’s what’s known about how climate change fuels hurricanes

Hurricane Ian’s water vapor on Sept. 28, 2022, meant heavy rainfall for large parts of Florida. NOAA

by Mathew Barlow, UMass Lowell and Suzana J. Camargo, Columbia University

When Hurricane Ian hit Florida, it was one of the United States’ most powerful hurricanes on record, and it followed a two-week string of massive, devastating storms around the world.

A few days earlier in the Philippines, Typhoon Noru gave new meaning to rapid intensification when it blew up from a tropical storm with 50 mph winds to a Category 5 monster with 155 mph winds the next day. Hurricane Fiona flooded Puerto Rico, then became Canada’s most intense storm on record. Typhoon Merbok gained strength over a warm Pacific Ocean and tore up over 1,000 miles of the Alaska coast.

Major storms hit from the Philippines in the western Pacific to the Canary Islands in the eastern Atlantic, to Japan and Florida in the middle latitudes and western Alaska and the Canadian Maritimes in the high latitudes.

A lot of people are asking about the role rising global temperatures play in storms like these. It’s not always a simple answer.

Record-setting cyclones in late September 2022. Mathew Barlow

It is clear that climate change increases the upper limit on hurricane strength and rain rate and that it also raises the average sea level and therefore storm surge. The influence on the total number of hurricanes is currently uncertain, as are other aspects. But, as hurricanes occur, we expect more of them to be major storms. Hurricane Ian and other recent storms, including the 2020 Atlantic season, provide a picture of what that can look like.

Our research has focused on hurricanes, climate change and the water cycle for years. Here’s what scientists know so far.

Rainfall: Temperature has a clear influence

The temperature of both the ocean and atmosphere are critical to hurricane development.

Hurricanes are powered by the release of heat when water that evaporates from the ocean’s surface condenses into the storm’s rain.

A warmer ocean produces more evaporation, which means more water is available to the atmosphere. A warmer atmosphere can hold more water, which allows more rain. More rain means more heat is released, and more heat released means stronger winds.

Simplified cross section of a hurricane. Mathew Barlow

These are basic physical properties of the climate system, and this simplicity lends a great deal of confidence to scientists’ expectations for storm conditions as the planet warms. The potential for greater evaporation and higher rain rates is true in general for all types of storms, on land or sea.

That basic physical understanding, confirmed in computer simulations of these storms in current and future climates, as well as recent events, leads to high confidence that rainfall rates in hurricanes increase by at least 7% per degree of warming.

Storm strength and rapid intensification

Scientists also have high confidence that wind speeds will increase in a warming climate and that the proportion of storms that intensify into powerful Category 4 or 5 storms will increase. Similar to rainfall rates, increases in intensity are based on the physics of extreme rainfall events.

Damage is exponentially related to wind speed, so more intense storms can have a bigger impact on lives and economies. The damage potential from a Category 4 storm with 150 mph winds, like Ian at landfall, is roughly 256 times that of a category 1 storm with 75 mph winds.

Two women stand in a wind-damaged kitchen looking up at the sky through a missing section of roof.
Hurricane Ian tore up roofs on homes, businesses and at least one hospital. Bryan R. Smith / AFP via Getty Images

Whether warming causes storms to intensify more rapidly is an active area of research, with some models offering evidence that this will probably happen. One of the challenges is that the world has limited reliable historical data for detecting long-term trends. Atlantic hurricane observations go back to the 1800s, but they’re only considered reliable globally since the 1980s, with satellite coverage.

That said, there is already some evidence that an increase in rapid intensification is distinguishable in the Atlantic.

Within the last two weeks of September 2022, both Noru and Ian exhibited rapid intensification. In the case of Ian, successful forecasts of rapid intensification were issued several days in advance, when the storm was still a tropical depression. They exemplify the significant progress in intensity forecasts in the past few years, although improvements are not uniform.

There is some indication that, on average, the location where storms reach their maximum intensity is moving poleward. This would have important implications for the location of the storms’ main impacts. However, it is still not clear that this trend will continue in the future.

Storm surge: Two important influences

Storm surge – the rise in water at a coast caused by a storm – is related to a number of factors including storm speed, storm size, wind direction and coastal sea bottom topography. Climate change could have at least two important influences.

Homes across entire neighborhoods seen from a helicopter are surrounded by floodwater.
The day after Hurricane Ian made landfall, homes were surrounded by water in Fort Myers, Fla. AP Photo/Marta Lavandier

Stronger storms increase the potential for higher surge, and rising temperatures are causing sea level to rise, which increases the water height, so the storm surge is now higher than before in relation to the land. As a result, there is high confidence for an increase in the potential for higher storm surges.

Speed of movement and potential for stalling

The speed of the storm can be an important factor in total rainfall amounts at a given location: A slower-moving storm, like Hurricane Harvey in 2017, provides a longer period of time for rain to accumulate.

There are indications of a global slowdown in hurricane speed, but the quality of historical data limits understanding at this point, and the possible mechanisms are not yet understood.

Frequency of storms in the future is less clear

How the number of hurricanes that form each year may change is another major question that is not well understood.

There is no definitive theory explaining the number of storms in the current climate, or how it will change in the future.

Besides having the right environmental conditions to fuel a storm, the storm has to form from a disturbance in the atmosphere. There is currently a debate in the scientific community about the role of these pre-storm disturbances in determining the number of storms in the current and future climates.

Natural climate variations, such as El Niño and La Niña, also have a substantial impact on whether and where hurricanes develop. How they and other natural variations will change in the future and influence future hurricane activity is a topic of active research.

How much did climate change influence Ian?

Scientists conduct attribution studies on individual storms to gauge how much global warming likely affected them, and those studies are currently underway for Ian.

However, individual attribution studies are not needed to be certain that the storm occurred in an environment that human-caused climate change made more favorable for a stronger, rainier and higher-surge disaster. Human activities will continue to increase the odds for even worse storms, year over year, unless rapid and dramatic reductions in greenhouse gas emissions are undertaken.

Mathew Barlow, Professor of Climate Science, UMass Lowell and Suzana J. Camargo, Lamont Research Professor of Ocean and Climate Physics, Columbia University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Heavy rain could cause toxic waste spills at industrial sites in Ian’s path

Read the full story in the New York Times.

Heavy rainfall and high winds from Hurricane Ian could cause some of Florida’s industrial sites to spill dangerous contaminants into local waterways, environmentalists warned on Wednesday.

Two giant wastewater ponds at phosphate mines east of Tampa were of the greatest concern.

Climate change makes storms like Ian more common

Read the full story at NPR.

Heat is the fuel that makes hurricanes big, powerful and rainy. As humans burn fossil fuels and release huge amounts of carbon dioxide and other greenhouse gasses, the amount of heat trapped on Earth rises steadily. The air gets hotter, and the ocean water gets hotter. When a baby hurricane forms in the Atlantic, all that heat is available to help the storm grow.

That’s what happened to Ian. When the storm first formed, it was relatively weak. But as it moved over very hot water in the Caribbean and Gulf of Mexico, it grew very quickly.

The Wall of Wind can blow away buildings at Category 5 hurricane strength to help engineers design safer homes – but even that isn’t powerful enough

The Wall of Wind can create Category 5 hurricane winds for testing life-size structures. Margi Rentis/Florida International University

by Richard Olson, Florida International University; Ameyu B. Tolera, Florida International University; Arindam Chowdhury, Florida International University, and Ioannis Zisis, Florida International University

In an airplane hangar in Miami, engineers are recreating some of the most powerful hurricane winds to ever strike land. These Category 5 winds can shatter a test building in the blink of an eye.

Yet they aren’t powerful enough to keep up with nature.

When engineers built the Wall of Wind test facility 10 years ago at Florida International University, it was inspired by Hurricane Andrew, a monster of a storm that devastated South Florida in 1992.

The facility was designed to test structures’ ability to withstand winds up to 160 miles per hour (257 kilometers per hour). Now, we’re seeing the likes of Hurricane Dorian, which shredded neighborhoods in the Bahamas with 184 mph (296 km/h) winds in 2019, and Hurricane Patricia, with winds clocked at 215 mph (346 km/h) off the coast of Mexico in 2015.

A person jumps over debris next to what remains of a home. Its roof is missing, and the walls are askew.
Hurricane Dorian’s Category 5 winds tore apart communities in the Bahamas. AP Photo/Ramon Espinosa

Studies show tropical storms are ramping up in intensity as the climate changes and ocean and air temperatures rise. Designing homes and infrastructure to withstand future storms like Dorian will require new test facilities that go well beyond today’s capabilities – for what we believe should be called Category 6 storms.

The Wall of Wind

There is currently only one life-size test facility at a U.S. university capable of generating Category 5 winds, currently the most powerful level of hurricane. That’s the Wall of Wind.

At one end of the facility is a curved wall of 12 giant fans, each as tall as an average person. Working together, they can simulate a 160 mph hurricane. Water jets simulate wind-driven rain. At the other end, the building opens up to a large field where engineers can see how and where structures fail and the debris flies.

The powerful tempests that we create here allow us and other engineers to probe for weaknesses in construction and design, track failures cascading through a building and test innovative solutions in close to real-world storm conditions. Cameras and sensors capture every millisecond as buildings, roofing materials and other items come apart – or, just as important, don’t fail.

Ten years of research here have helped builders and designers reduce the risk of damage. That’s helpful when forecasters warn, as they do for 2022, of a busy hurricane season with several major hurricanes.

Lessons from hurricane testing

We’ve found in destructive testing that a structure will often rip apart in less than a second. All it takes is the wind penetrating the weakest point.

When Hurricane Dorian hit the Bahamas, many less-well-constructed homes turned into shrapnel, creating another problem. Once a building fails, even nearby homes built to withstand higher winds are in trouble because of the flying debris. Our testing has shown how debris from one building, under continuous winds of 130-140 mph or more, can take out the next building, and then that takes out the next building.

Roofs are often that weakest link. A roof is subjected to uplift force during a storm, so wind hitting the surface of the building needs to be able to escape. When wind runs into objects in that path, it can cause damage.

New designs are improving how buildings stand up to extreme winds. For example, storms can create powerful vortices – winds that swirl almost like a corkscrew at a building’s edge – that can strip away roofing material and eventually lift the roof itself. One innovation uses a horizontal wind turbine along the edge of a roof to diffuse the wind and generate power at the same time, a double benefit.

When wind blows up the side of a building it can create vortices that strip off roofing materials. Horizontal wind turbines attached to rood edges can suppress these vortices, as shown here using smoke, and can also generate power. FIU

The shape of buildings can also either create weaknesses or help deflect wind. You’ll notice that most modern high-rises avoid sharp corners. Testing shows that more trapezoidal or rounded edges can reduce wind pressures on buildings.

And better safety doesn’t have to be costly. One experiment showed how just US$250 in upgrades was the difference between a small, shed-size building standing up to a Category 3 storm – or not. Hurricane straps attach a roof truss to the perimeter of the house. Ring shank nails, which have threads around the shank to grasp the wood, can resist wind forces better than smooth nails. Hurricane shutters also block entry points where the wind can penetrate and trigger catastrophic failure.

Installation also matters, and helps explain why roofs that appear to meet building code requirements can still fail and go flying in hurricanes.

Experiments we conducted have shown how an edge system – the metal elements between walls and the roof – that is installed just half an inch too high or low can prematurely fail at low winds, even though the system was designed to withstand a Category 5 hurricane. Roofers installing asphalt shingles and roofing tiles may need to go beyond the current code when sealing edges to keep them from failing in a storm.

A neighborhood of homes with shredded roofs, some missing most of their roof tiles or shingles, others with parts of the roof missing entirely.
In August 1992, Hurricane Andrew hit South Florida with sustained winds as high as 165 mph. AP Photo/Mark Foley

Expanding testing: 200 mph winds + storm surge

While engineers have been gaining knowledge through testing, the nature of storms is changing as the planet warms.

Warmer temperatures – fueled by increasing greenhouse gas emissions from human activities – enable the air to hold more moisture, and warmer oceans provide more energy to fuel hurricanes. Research shows that bigger and more intense storms that are heavier with water and moving more slowly are going to hammer the areas they hit with more wind, storm surge, flooding and debris.

Storms like these are why we’re working with eight other universities to design a new facility to test construction against 200 mph winds (322 km/h), with a water basin to test the impact of storm surge up to 20 feet (6 meters) high plus waves.

Computers can model the results, but their models still need to be verified by physical experiments. By combining wind, storm surge, and wave action, we’ll be able to see the entire hurricane and how all those components interact to affect people and the built environment.

Disaster testing is finding ways to make homes safer, but it’s up to homeowners to make sure they know their structures’ weaknesses. After all, for most people, their home is their most valuable asset.

Richard Olson, Director of the Extreme Events Institute, Florida International University; Ameyu B. Tolera, Research Assistant at Florida International University – College of Engineering & Computing, Florida International University; Arindam Chowdhury, Professor of Civil Engineering, Florida International University, and Ioannis Zisis, Associate Professor of Civil Engineering, Florida International University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Study shows human-induced climate change is affecting hurricane severity

Read the full story from Stony Brook University.

A study that analyzed the entire 2020 North Atlantic hurricane season — in conjunction with human activity that affects climate change — found that hourly hurricane rainfall totals were up to 10 percent higher compared to hurricanes that took place in the pre-industrial (1850) era. Led by Kevin A. Reed, an associate professor in the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University, the study findings, which are published in Nature Communications, are another indicator of the effect of climate change on rainfall totals.

After Ida, Louisiana struggles to tally the environmental cost. Activists say officials must do better

Read the full story at Inside Climate News.

The state was still recovering from five named storms in 2020 when the Category 4 hurricane walloped the Gulf Coast with 150 mph winds.