Earth Becomes a Snowball...AGAIN?

Harvard ^ | 1999 | Hoffman

[Huebolt]

Could the Earth become a "snowball" in future? For the last million years, the Earth has been in its coldest state since the Neoproterozoic. We are now living in a relatively warm episode, some 80,000 years from the next glacial maximum, but some evidence suggests that each successive glaciation over the last several cycles has been getting stronger and stronger. During the most recent glacial event, 20,000 years ago, the deep ocean cooled to near its freezing point, and sea ice reached latitudes as low as 40 to 45 degrees north and south, still far from the critical threshold needed to plunge the Earth into a snowball state. But could such a state be in our future? Certainly over time scales of hundreds to thousands of years, we are more concerned with anthropogenic effects on climate, as the Earth heats up in response to emissions of carbon dioxide. But only time will tell where the Earth’s climate will drift over millions of years. If the trend of the last million years of Earth history is continued and if the polar continental "safety switch" were to fail, we may once again experience a global ice catastrophe which would inevitably jolt life in some new direction. Perhaps Robert Frost foresaw this in his poem, "Fire and Ice":

[Ann de IL]

bump

[SunkenCiv]

In a word, no. :')

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[SunkenCiv]

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[21twelve]

“Certainly over time scales of hundreds to thousands of years, we are more concerned with anthropogenic effects on climate, as the Earth heats up in response to emissions of carbon dioxide. But only time will tell where the Earth’s climate will drift over millions of years.”

1) Temps. seem to rise about 800 years BEFORE the CO2 levels rise.

2) Regardless, manmade CO2 only accounts for about 0.118% of the greenhouse effect.

3) The last interglacial warm period lasted about 13,000 to 15,000 years. We are on about year 12,000 for our current warm period. (Note: Past results are no guarantees of future events.)

[colorado tanker]

If this looks like it really would happen we could try terraforming - open a sea lane through the Isthmus of Panama. Some people think it's closure is what caused the Quaternary.

[BenLurkin]

Maybe the sun is dying.

[djf]

Excellent vid.
Here's the graph:

[SunkenCiv]

Look at the bright side, uh, oh, never mind... ;’)

[Oztrich Boy]

• Higher solar activity
• Higher solar radiation to sea surface
• Sea gets hotter
• Carbon dioxide outgasses from ocean
• ...
• Cap and trade.
• Profit!

[Huebolt]

I used to think all the catastophe theory hysteria was due to the illusion of central position wherein each generation has that certainty that times are different because WE ARE HERE and that the world will surely end before we do.

There were maniacal cults about armageddon, end-of-millenium, etc. Global cooling looks like the real thing.

I remember standing on a hill in west Texas and looking in disbelief at GLACIAL STRIATION MARKS left there during the last ice age. That's way, way south...