Hurricane Dorian: Why are more extreme storms stalling?

The Category 5 hurricane was moving at speeds of about 1 mph over the Bahamas on Sunday and Monday.

Image of hurricane Dorian.
Image: NASA
  • Hurricane Dorian is one of the strongest Atlantic hurricanes on record, with wind speeds of more than 200 mph.
  • The storm was moving slowly over the Bahamas as a result of clashing high- and low-pressure systems.
  • It's unclear whether climate change is causing shifts in large-scale wind patterns, but scientists generally agree that warmer temperatures are causing storms to become stronger.


Hurricane Dorian became on Sunday the strongest hurricane to ever hit the Bahamas, pummelling islands with 200-mph winds and more than 20 feet of coastal flooding. At its strongest point, the Category 5 storm — the most severe ranking — floated nearly motionless over the islands, inching along at about 1 mph as it dropped more than 2 feet of rain. At least five people in the Bahamas were killed by the storm.

By Monday, Dorian was a Category 4 storm. On Tuesday, the slow-moving hurricane had lost much of its steam and was downranked to Category 2. But Dorian has grown in size if not force, and it's expected to move northerly over the Atlantic, parallel with the coast of Florida and, later, Georgia and the Carolinas. Violent winds have already struck parts of Florida, and officials in multiple states have already ordered thousands of residents to evacuate.

"I can't decide for you, but I'm asking you, as the mayor of Savannah: Please attempt to get out of town as best you can, and come back in a few days and begin your life over and move forward," Eddie DeLoach, mayor of Savannah, Georgia, said in a public appearance Monday night, according to The Savannah Morning News.

For now, the main focus of residents and officials in the storm's path is safety, rescue and, eventually, reconstruction. But for scientists who study storms and climate change, Dorian's intensity and brutal sluggishness highlight how warming temperatures are changing the nature of extreme storms around the globe.

​A pattern of stalling hurricanes

In recent years, scientists have identified a pattern: Severe hurricanes are not only becoming stronger and more common, but many are also moving more slowly and even stalling, as Hurricane Harvey did over Houston for days in 2017, dumping 60 inches of rain in the process. A study published in June by NASA and NOAA scientists showed that the average forward speed of North Atlantic hurricanes has slowed from 11.5 mph in 1944 to 9.6 mph in 2017.

So, is climate change making hurricanes slower? It's too early to say for sure, and the issue is still an area of debate among climate scientists. In the case of Dorian, the violent storm stalled above the Bahamas because, somewhat ironically, the atmosphere was too calm; a clash between high- and low-pressure systems caused the weather pattern to come to a standstill.

But scientists generally believe that warmer temperatures in the Arctic are likely playing a part in slowing down wind patterns, as NOAA hurricane expert Jim Kossin, co-author of the June study, told InsideClimate News:

"...in the broadest sense, global warming makes the global atmospheric circulation slow down," he said. "There is a lot of evidence to suggest this is more than just natural variability."

How exactly warmer temperatures affect wind patterns is a complicated issue that needs further research. But there's little debate among climate scientists as to whether climate change is making storms worse and more common.

"The environment for all such storms has changed because of climate change," Kevin Trenberth, a climate scientist with the National Center for Atmospheric Research, told Inside ClimateNews. "The oceans are warmer, especially in the upper 100 meters, which is most important for such storms," Trenberth said. "This makes available more energy via water vapor for the storms and makes for more activity: more intensity, bigger and longer lasting storms, with heavier rainfalls."

Study: Unattractive people far overestimate their looks

The finding is remarkably similar to the Dunning-Kruger effect, which describes how incompetent people tend to overestimate their own competency.

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  • Recent studies asked participants to rate the attractiveness of themselves and other participants, who were strangers.
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Astronomers find more than 100,000 "stellar nurseries"

Every star we can see, including our sun, was born in one of these violent clouds.

Credit: NASA / ESA via Getty Images
Surprising Science

This article was originally published on our sister site, Freethink.

An international team of astronomers has conducted the biggest survey of stellar nurseries to date, charting more than 100,000 star-birthing regions across our corner of the universe.

Stellar nurseries: Outer space is filled with clouds of dust and gas called nebulae. In some of these nebulae, gravity will pull the dust and gas into clumps that eventually get so big, they collapse on themselves — and a star is born.

These star-birthing nebulae are known as stellar nurseries.

The challenge: Stars are a key part of the universe — they lead to the formation of planets and produce the elements needed to create life as we know it. A better understanding of stars, then, means a better understanding of the universe — but there's still a lot we don't know about star formation.

This is partly because it's hard to see what's going on in stellar nurseries — the clouds of dust obscure optical telescopes' view — and also because there are just so many of them that it's hard to know what the average nursery is like.

The survey: The astronomers conducted their survey of stellar nurseries using the massive ALMA telescope array in Chile. Because ALMA is a radio telescope, it captures the radio waves emanating from celestial objects, rather than the light.

"The new thing ... is that we can use ALMA to take pictures of many galaxies, and these pictures are as sharp and detailed as those taken by optical telescopes," Jiayi Sun, an Ohio State University (OSU) researcher, said in a press release.

"This just hasn't been possible before."

Over the course of the five-year survey, the group was able to chart more than 100,000 stellar nurseries across more than 90 nearby galaxies, expanding the amount of available data on the celestial objects tenfold, according to OSU researcher Adam Leroy.

New insights: The survey is already yielding new insights into stellar nurseries, including the fact that they appear to be more diverse than previously thought.

"For a long time, conventional wisdom among astronomers was that all stellar nurseries looked more or less the same," Sun said. "But with this survey we can see that this is really not the case."

"While there are some similarities, the nature and appearance of these nurseries change within and among galaxies," he continued, "just like cities or trees may vary in important ways as you go from place to place across the world."

Astronomers have also learned from the survey that stellar nurseries aren't particularly efficient at producing stars and tend to live for only 10 to 30 million years, which isn't very long on a universal scale.

Looking ahead: Data from the survey is now publicly available, so expect to see other researchers using it to make their own observations about stellar nurseries in the future.

"We have an incredible dataset here that will continue to be useful," Leroy said. "This is really a new view of galaxies and we expect to be learning from it for years to come."

Protecting space stations from deadly space debris

Tiny specks of space debris can move faster than bullets and cause way more damage. Cleaning it up is imperative.

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  • NASA estimates that more than 500,000 pieces of space trash larger than a marble are currently in orbit. Estimates exceed 128 million pieces when factoring in smaller pieces from collisions. At 17,500 MPH, even a paint chip can cause serious damage.
  • To prevent this untrackable space debris from taking out satellites and putting astronauts in danger, scientists have been working on ways to retrieve large objects before they collide and create more problems.
  • The team at Clearspace, in collaboration with the European Space Agency, is on a mission to capture one such object using an autonomous spacecraft with claw-like arms. It's an expensive and very tricky mission, but one that could have a major impact on the future of space exploration.

This is the first episode of Just Might Work, an original series by Freethink, focused on surprising solutions to our biggest problems.

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