of the most powerful storms on earth are getting stronger, according to new
research published this week. VOA's Art Chimes reports.
Elsner of Florida State University and his colleagues based their conclusion on
25 years of satellite data.
we look over the entire globe, we see that the strongest tropical cyclones are
actually getting stronger. And this increase is most notable over the North
Atlantic and also the northern Indian Oceans."
researchers found that the top wind speeds in the strongest tropical cyclones
have been increasing. And, the stronger the cyclone, the bigger the increase.
say these storms pick up energy from the warm water they pass over. Elsner says
that's really a simplified version of what's happening.
this thermodynamic theory of hurricane intensification says that, with all else
being equal, the warmer the ocean, the stronger the storms," he said in an
interview. "So it stands to reason that if the theory is correct we should
see increases in the intensity of the strongest storms with the warming
that's exactly what they saw. For their study, Elsner and his colleagues
examined the top wind speed in a range of storms, from weak to strong.
weaker storms showed little or no increase in their maximum wind speed over 25
years of observations. But in the same period, the top wind speed in the
strongest storms rose significantly.
the wind speed and how much power, destructive power, a hurricane has are very
well correlated," Elsner said.
the storm data comes from satellites, Elsner says satellite instruments don't
measure the wind speed directly.
what you can do is look at how the pattern of the satellite pictures [is]
changing over time. If you see how the clouds change from one picture to the
next, you can get some idea of motion. So if you look at where the clouds were
at one time, then later, you get some idea of speed."
effect the researchers observed was not evenly distributed around the world,
probably because of different conditions in the various areas where tropical
we speculate that has to do with the amount of warming we're seeing in the
different basins," Elsner explained. "So basins that are marginally
warm enough to support tropical cyclones on average and [where temperatures]
are increasing, then we expect to see the effect stronger in those basins, and
those include the North Atlantic and Indian Oceans."
this effect related to climate change? Elsner says his study looked at data
from the past quarter-century, so he says it can't necessarily predict what's
in the future. But warmer oceans could provide the energy to fuel stronger
storms, and he says the data is consistent with the idea that global warming
could affect sea temperatures.
gives us some confidence that if the seas continue to warm, we're likely to see
the stronger storms getting stronger."
Elsner of Florida State University. His paper appears this week in the journal Nature.