Thursday, April 1, 2010

Earth Didn't Freeze Over - Why?

"Clouds May Hold Key to Why Early Earth Didn't Freeze Over"
Space.com (March 31, 2010)

"A paradox about the climate of the early Earth that has been plaguing scientists for nearly 50 years may have a new solution.

"The so-called 'young' sun paradox — first proposed by Carl Sagan and his colleague George Mullen in 1972 — refers to the fact that the Earth had liquid oceans for the first half of its more than 4-billion-year existence despite the fact that the sun was likely only 70 percent as bright in its youth as it is now.

"A lower solar luminosity should have left Earth's oceans frozen over, but there is ample evidence in the Earth's geological record that there was liquid water — and life — on the planet at the time.

"Over the past few decades, scientists have proposed several possible mechanisms that may have kept the Earth toasty enough to keep water from freezing during our planet's early history – a period of time called the Archaean. But just when scientists think they have the paradox solved, other researchers come up with alternate explanations or reasons why a previous proposal doesn't work...."

This idea may catch on - particularly since it involves greenhouse gasses that (all the 'right' people assume) are what's driving Global Warming: and that its humanity's fault. And maybe Earth's atmosphere trapped heat more effectively in the past than it does now because it had more carbon dioxide than it does now. Almost a third of Earth's atmosphere might have been carbon dioxide in 'the good old days.'

Or, not.

The article discusses that, and albedo - how much energy (specifically, light) gets bounced right back into space.

Various scientists have pretty good ideas to explain what happened. Several of them: some mutually contradictory. The only thing that's really certain is that Earth's oceans were liquid for a really, really long time. Aside from geological evidence, there's us: we're here, and that wouldn't be too likely if this planet's water had been frozen solid for much of its history.

None of this 'proves' that science is wrong. Collecting data, analyzing it, and working out mathematical models to explain the observations is how science works. I've written about this before. ("A Patron Saint of - Scientists?!" (October 25, 2009), "Faith and Reason, Religion and Science" (March 20, 2009), A Catholic Citizen in America, for starters)

And I'm not surprised that Earth hasn't always been just the way it has been for the last few centuries.

Related posts:More:An overview of the last 4,500,000,000 or so years on Earth: (from "The Ice is Falling! Runaway Melt Mode! And You Should See What's Happening to Minnesota Trees!" (September 23, 2009)

2 comments:

Brigid said...

Forgot an apostrophe: "this planets water"

The Friendly Neighborhood Proofreader

Brian, aka Aluwir, aka Norski said...

Brigid,

Oops. Got it, fixed it.

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