- WASHINGTON (AFP) - U.S. researchers put together the history of recent sudden
climate changes on Venus, which may provide clues to the future of Earth
in a few million years.
-
- "Our model shows that Venus has
changed dynamically in the recent past," said Mark Bullock of the
University of Colorado at Boulder.
-
- "Since Venus and Earth have a number
of similarities, there are implications here for our own future,"
Bullock said.
-
- He and other researchers try to explain
why in an article appearing in the March issue of Scientific American.
-
- Though Venus and Earth were virtual twins
early in their evolutionary histories, they took vastly different paths.
-
- Today Venus is hot enough -- 482 Celsius
(900 Fahrenheit) -- to make rocks glow, and has a noxious carbon dioxide
atmosphere encased by a dense cloud deck of sulfuric acid.
-
- But those clouds may have waxed and waned
over the eons, scientists say.
-
- Venus and the Earth are the only planets
in the solar system with complex, evolving climates.
-
- Computer modeling by Bullock and colleague
David Grinspoon indicates that volcanic activity some 800 million years
ago "repaved" Venus with lava, evidenced by a dearth of impact
craters on the planet's surface.
-
- The two estimate that enough lava erupted
to cover the surface with a layer up to 9.6 kilometers (six miles) thick.
-
- The volcanic activity would also have
contributed to the runaway greenhouse effect on Venus, according to the
researchers.
-
- Venus may have remained shrouded for
well over 100 million years, they said.
-
- "But we calculated that volcanism
must have been active within the past 30 million years to support the thick
clouds observed today," Grinspoon said. Those volcanos are still active.
-
- "The climates of Earth-like planets
can undergo abrupt transitions because of interactions among planetary-scale
processes," the two wrote in Scientific American.
-
- "In the long term Earth's fate is
sealed," they wrote. "As the sun ages, it brightens. In about
a billion years, the oceans will begin to evaporate rapidly and the climate
will succumb to a runaway greenhouse."
-
- "Earth and Venus, having started
as nearly identical twins and diverged, may one day look alike."
|
