Will the oceans evaporate someday

Answer 1

Yes - in around a billion years from now.

From a session at the annual meeting of the American Association for the Advancement of Science on 20 Feb 2000:

The Earth's oceans will disappear in about one billion years due to increased temperatures from a maturing sun, but Earth's problems may begin in half that time because of falling levels of carbon dioxide in the atmosphere, according to a Penn State researcher.

"The sun, like all main sequence stars, is getting brighter with time and that affects the Earth's climate," says Dr. James F. Kasting, professor of meteorology and geosciences. "Eventually temperatures will become high enough so that the oceans evaporate."

At 140 degrees Fahrenheit, water becomes a major constituent of the atmosphere. Much of this water migrates to the stratosphere where it is lost to the vacuum. Eventually, the oceans will evaporate into space.

"Astronomers always knew that the oceans would evaporate, but they typically thought it would occur only when the sun left the main sequence," Kasting told attendees today (Feb. 20) at the annual meeting of the American Association for the Advancement of Science. "That will be in 5 billion years."

Stars leave the main sequence when they stop burning hydrogen. The sun, a yellow, G-2 star, will then become a red giant encompassing the orbit of Mercury. Mercury will disappear and Venus will lose its atmosphere and become a burnt out planet. The Earth will suffer the same fate, even though it is outside the red giant's immediate reach.

"However, the oceans may evaporate much earlier," says Kasting, a faculty member with the College of Earth and Mineral Sciences. "My calculations are somewhat pessimistic and present a worst case scenario that does not include the effects of clouds, but they say a billion years."

Source:

• 'Earth's Oceans Destined to Leave in Billion Years'

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