The most recent major hurricane to hit the Houston area was
Hurricane Alicia in 1983. I know because I was there.
With top winds of 127 miles per hour spawning 23 tornadoes, this
Category 5 hurricane was a major disaster.
Since then, Houston has seen a number of tropical storms and
hurricanes, but not since Alicia has the city required extensive
evacuation.
Has anything really changed over the past century, or are we
just ignorant of our weather’s history?
On Aug. 29, Hurricane Katrina made landfall over New Orleans as
a Category 4 hurricane.
Like Houston, New Orleans has seen its share of heavy weather,
but Katrina quickly became the worst disaster to befall the United
States.
Hurricane Rita later made landfall over Texas, where my family
lives.
For the second year in a row, this hurricane season will top the
previous record as the worst.
The actual number of hurricanes this season is statistically
insignificant. What matters is their intensity.
Over time, the few hurricanes that develop have become stronger
as a direct effect of global warming.
Hurricanes begin in the tropics, where the warmest water in the
ocean evaporates into the air, rises high into the atmosphere, and
then condenses into clouds.
Over time, a circulation cell develops with a low-pressure
atmosphere over the ocean surface, sucking up warm water and
depositing it into the upper atmosphere.
When this circulation cell stabilizes and forms an
“eye,” a hurricane is born.
The engine that drives a hurricane is the warm ocean-surface
temperature, and global warming has caused this temperature to
increase by a few degrees.
The correlation between increased ocean-surface temperatures
(raised by global warming) and hurricane intensity can be seen in
the case of Hurricane Rita. During the storm’s movement
across the Gulf of Mexico, high sea-surface temperatures have
contributed to her gaining strength.
Jensen is a graduate student in earth and space
sciences.