ProblemA Hurricanes and Global Warming
Every year, coastal regions brace themselves for violent windstorms
known as hurricanes. But how do these storms form and grow?
Hurricanes (which also include storms known as ”typhoons” in the
Northwest Pacific and”severe tropical cyclones” in the Indian Ocean and
Southwest Pacific) areextremely destructive and often responsible for
the deaths of hundreds andoccasionally thousands of people.
Many meteorologists agree that global warming has occurred (around
half degree C) inthe last several decades at the earth’s surface, and
the trend is likely tocontinue. The problem is, what does global warming
imply for hurricaneactivity? Please structure an reasonable model,
measuring the extent of globalwarming and the strength of global
hurricane activities, and estimating therelationship between them.
The oversimplified answer: Warm ocean water plus the Earth’s eastward
“They’re heat engines,” said meteorologist Jeff Masters of the
websiteWeather Undergroundin aprevious interview. “They take heat from
the oceans and convert it to the energy of their winds. They’re taking
thermal energy and making mechanical energy out of it.”
The natural engine that is a hurricane is fueled by warm, moist air.
The storms move heat from the ocean surface high into Earth’s
atmosphere. They can travel thousands of miles from the tropics toward
the Earth’s poles.
According toNOAA’s National Hurricane Center, the average hurricane
eye—the still center where pressure is lowest and air temperature is
highest—stretches 20 to 30 miles across, with some even growing as
large as 120 miles wide.
The strongest storms, equivalent to Category 5 on the Saffir-Simpson
scale, have sustained winds that exceed 155 miles an hour.
Why Are Hurricanes Dangerous?
While hurricanes are categorized based on their wind speeds, wind
isn’t typically the most dangerous part of such storms. “It’s the
storm surge,” said Kerry Emanuel, an atmospheric scientist at MIT, in
an earlier interview. The storm surge is the bulge of water built up
in front of a cyclone or hurricane courtesy of its winds.
It’s the number one killer in hurricanes, Emanuel explained. “That’s
what killed people in Katrina, it’s what killed people in Sandy and in
Emanuel likened a storm surge to a tsunami. One just happens to be
caused by earthquakes (tsunamis), while the other is generated by
Flash flooding caused by intense rains is also a major killer, Emanuel
said. “Hurricane Mitch [in 1998] killed 12,000 people and it was all
from flash flooding.”
Then comes wind that blows around debris. Hurricane Andrew in 1992 is
an example of this. “It didn’t really cause too much of a storm
surge,” the atmospheric scientist said, “but boy did it blow a lot of
Climate change will likely increase the frequency of “the high-end
hurricanes,” Emanuel said.
And those powerful storms have the potential to produce a lot of rain,
flooding, and strong storm surges.
Is That a Hurricane or a Cyclone?
What’s the difference between hurricanes, cyclones, and typhoons?
Actually, they’re all the same weather phenomenon. Scientists just
call these storms different things depending on where they occur.
In the Atlantic and northern Pacific, the storms are called
hurricanes, after the Caribbean god of evil, named Hurrican.
In the northwestern Pacific, the same powerful storms are called
typhoons. In the southeastern Indian Ocean and southwestern Pacific,
they are called severe tropical cyclones.
In the northern Indian Ocean, they’re called severe cyclonic storms.
In the southwestern Indian Ocean, they’re just called tropical
To be classified as a hurricane, typhoon, or cyclone, a storm must
reach wind speeds of at least 74 miles an hour.
If a hurricane’s winds reach speeds of 111 miles an hour, it is
upgraded to an “intense hurricane.”
If a typhoon hits 150 miles an hour—as Usagi did in 2013—then it
becomes a “supertyphoon.”
While the Atlantic hurricane season runs from June 1 through November
30, the typhoon and cyclone seasons follow slightly different
In the northeastern Pacific, the official season runs from May 15 to
November 30. In the northwestern Pacific, typhoons are most common
from late June through December. And the northern Indian Ocean sees
cyclones from April to December.