Warming Climate Could Make East Coast Hurricanes Stronger

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https://phys.org/news/2019-05-climate-barrier-east-coast-hurricanes.html

A new study suggests that climate change could soon eliminate an atmospheric barrier that protects much of the U.S. East Coast from powerful hurricanes.

Severe hurricanes can cost up to hundreds of billions of dollars in damages. The destruction left in the wake of Atlantic hurricanes has been increasing over time in recent decades, according to scientific studies. However, it has been difficult to predict whether and how hurricanes will continue to increase in intensity and impacts.

There are two main factors that contribute to hurricane development and intensity: sea surface temperature and vertical wind shear. Vertical wind shear is the difference in wind speed or direction between the upper and lower troposphere. Warmer sea surface temperatures and low wind shear (meaning the wind speeds and directions are similar throughout the column of air) both raise the potential intensity of a hurricane. Scientists knew that ocean temperatures are heating up, but until now it has not been clear how climate change would impact wind shear.

A new paper, published today in Scientific Reports, finds that climate change could alter wind shear in a way that could deliver more powerful hurricanes to the East Coast. The study is authored by scientists from Columbia University's Lamont-Doherty Earth Observatory and the National Oceanic and Atmospheric Administration.

The new paper builds off of a talk NOAA's James Kossin gave at an Extreme Weather and Climate Initiative meeting at Columbia University in 2017. Kossin spoke about how, as hurricanes move northwestward out of the tropical Atlantic, a strong vertical wind shear along the East Coast prevents the storm from gaining strength, thus providing a protective barrier to strong landfalling hurricanes. Lamont Research Professor Mingfang Ting had the idea to build upon Kossin's findings with the application of her own modeling to explore how a changing climate might affect this wind shear pattern.

Ting and Kossin, along with Lamont researchers Suzana Camargo and Cuihua Li, used model simulations to examine the effects of climate change on hurricanes in the United States. The group found that these hurricanes will be affected in two different ways. As earlier studies have shown, rising sea surface temperatures will lead to an increase in hurricane intensity. But this study was the first to find that rising anthropogenic greenhouse gases in the atmosphere will weaken the vertical wind shear along the East Coast which will, in turn, enable further intensification of hurricanes that make landfall in this region.

"Once the natural protection is eroded by greenhouse gas warming, we may experience unprecedented hurricane intensification along the East Coast that can lead to stronger landfalling storms and higher storm surges in the future," Ting explains. "This is on top of the stronger tropical cyclone strength expected from the warmer sea surface temperature that we are already aware of. Home owners and policy makers have to take this into account when planning for coastal development and protections."

Although climate change is typically a slow process, the models point to the possibility of these anthropogenic effects emerging quickly. One of the models with a larger number of simulations indicated that these effects could start to be seen around the year 2040. A timeline like that only gives us about 20 years to try to change course by taking actions to reduce climatechange and, at the very least, prepare for more extreme weather events.

More information: Mingfang Ting et al. Past and Future Hurricane Intensity Change along the U.S. East Coast, Scientific Reports (2019). DOI: 10.1038/s41598-019-44252-w

Journal information: Scientific Reports 

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Turbocharged: How Michael got 55 percent stronger in 1 day (Update)

 

 

[etudiant]

There is no indication that the warming thus far has actually produced increased hurricane intensity. So the premise for this model needs further justification before becoming actionable.

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29 minutes ago, etudiant said:

There is no indication that the warming thus far has actually produced increased hurricane intensity. So the premise for this model needs further justification before becoming actionable.

 

https://www.washingtonpost.com/amphtml/climate-environment/2019/02/07/hurricanes-are-strengthening-faster-atlantic-climate-change-is-big-reason-why-scientists-say/?tid=ss_tw&utm_term=.ea7a43a93988&__twitter_impression=true

https://www.nature.com/articles/s41467-019-08471-z

A group of top hurricane experts, including several federal researchers at the National Oceanic and Atmospheric Administration, published striking new research Thursday suggesting that hurricanes in the Atlantic Ocean have grown considerably worse, and climate change is part of the reason why.

The study focused on rapid intensification, in which hurricanes may grow from a weak tropical storm or Category 1 status to Category 4 or 5 in a brief period. They found that the trend has been seen repeatedly in the Atlantic in recent years. It happened before Hurricane Harvey struck Texas and before Hurricane Michael pummeled the Gulf Coast with little warning last fall. Hurricane Michael, for example, transformed from a Category 1 into a raging Category 4 in the span of 24 hours.

The study, published in Nature Communications, describes its conclusion in blunt language, finding that the Atlantic already has seen “highly unusual” changes in rapid hurricane intensification, compared to what models would predict from natural swings in the climate. That led researchers to conclude that climate change played a significant role.

“Natural variability cannot explain the magnitude of the observed upward trend,” they wrote. The research was led by Kieran Bhatia, who conducted the research as a postdoctoral researcher at Princeton University and NOAA’s Geophysical Fluid Dynamics Laboratory.

 “There’s just a whole host of issues that come along with rapid intensification, and none of them are good,” said Jim Kossin, one of the study’s authors and also a hurricane expert with the National Oceanic and Atmospheric Administration.

https://phys.org/news/2018-10-turbocharged-michael-percent-stronger-day.html

Moist air, warm waters in the Gulf of Mexico, and ideal wind patterns supercharged Hurricane Michael in the hours before it smacked Florida's Panhandle.

Hurricane Michael was barely a hurricane Tuesday morning, with winds of 90 mph. A little over a day later, it had transformed into a monster. When it made landfall Wednesday afternoon, it was blowing at 155 mph. That's a 72 percent increase in wind speed in less than 33 hours.

"Michael saw our worst fears realized, of rapid intensification just before landfall on a part of a coastline that has never experienced a Category 4 hurricane," University of Miami hurricane researcher Brian McNoldy said Wednesday morning.

Hurricanes have something called a potential intensity. That's how strong a storm can get if all other factors are aligned, said National Oceanic and Atmospheric Administration climate and hurricane expert Jim Kossin said. Michael had nothing holding it back.

"Everything was there for it to reach its potential and it did," Kossin said.

As Michael's eye started coming ashore, it boasted the third lowest central pressure of any storm to hit the United States, behind only a 1935 Labor Day storm and 1969′s Camille.

Meteorologists first got a sense something big could be happening by watching how Michael's eye changed shape. Early Tuesday, it was oddly shaped and ragged. Later in the morning it started to get better organized, and by Tuesday night real-time satellite imagery was showing the eye getting stronger and scarier by the minute.

Another factor: Its pressure, the measurement meteorologists use to gauge a hurricane's strength. The lower the pressure, the stronger the storm. Before landfall, Michael's pressure fell so low it looked like the winds were sure to pick up fast, said Ryan Maue, a meteorologist for weathermodels.com.

And none of the factors that hold a storm back were present, especially something called "wind shear." Wind shear is when there's a mismatch either in speed or direction between winds near the surface and those five to six miles (8 to 10 kilometers) up.

That mismatch "pushes the storm over" or decapitates it, Kossin said. When the wind shear near Michael eased, the storm took off, he said.

"It's kind of like someone was holding on to it when it was trying to run and they let it go," Kossin said.

Another huge factor was the water temperature. Warm water is the energy that fuels hurricanes, and the Gulf water is 4 to 5 degrees warmer than normal.

Water temperatures in the Gulf of Mexico vary along with weather, but some scientists said the warm waters are signs of human-caused climate change.

"Have humans contributed to how dangerous Michael is?" Kossin said. "Now we can look at how warm the waters are and that certainly has contributed to how intense Michael is and its intensification."

The warm waters, Kossin said, are a "human fingerprint" of climate change.

Kossin and others have a study out this month in the Journal of Climate with computer simulations showing that human-caused global warming will increase rapid intensification of tropical weather across the globe in the future.

Other studies have shown rapid intensification has already increased over past decades. One study this year in Geophysical Research Letters found that since 1986, the rate of intensification of storms like Michael has increased by about 13 mph.

 

[etudiant]

Not sure that is sufficient to prove the point. We need to see actual increases in high intensity hurricanes, not just periods of rapid intensification.

Otherwise, one is preaching to the choir.

[Vice-Regent]

Seems self-evident with a couple of analogs in the pipeline and modeling evidence pointing to our new vulnerability. Both Joaquin and Irma were potential East Coast major hurricanes. It's all noise when they miss the mark. One must sense out the broad strokes of the situation and adapt accordingly although it's difficult to imagine one "adapting" to the storms of our grandchildren parents.