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Frontiers
Were Dinosaurs Blown Away?
June 1996
According to the latest extinction theory, dinosaurs
and their cohorts weren't done in by asteroids alone, but were blown out
of existence by gigantic hurricanes called hypercanes.
The theory, developed by Kerry Emanuel of the Massachusetts Institute of Technology
(MIT) and four colleagues, argues that neither an asteroid nor volcanic eruptions
by themselves could have kicked up enough dust to cause worldwide extinctions
245 million and 65 million years ago.
But, according to the Fort Worth, Texas, Star-Telegram, these natural
disasters may still have been partly responsible.
Using a computer model created by Richard Rotunno at the NSF-funded National
Center for Atmospheric Research, the research team demonstrated that the asteroid
and/or volcanos may have caused hypercanes--"runaway hurricanes that are capable
of injecting massive amounts of water and aerosols into the middle and upper
atmosphere where they may have profound effects on atmospheric chemistry and
radiative transfer."
Either an asteroid or a series of volcanos could have heated patches of ocean
to as much as 50°C (122°F), the scientists write in the Journal of
Geophysical Research. When tested in the model, these conditions generated
tropical cyclones with wind speeds as high as 675 mph, which is close to the
speed of sound.
Unlike an asteroid, a hypercane would send into the atmosphere not dust, but
large quantities of water. The model shows that the water would create sheets
of new clouds, which would block out the sun, disrupt radiation patterns, and
perhaps trigger ozone depletion.
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