Earth's Great CO2 Experiment

"Climate change is a national security issue. It's a national and international economic issue. It happens to be an environmental issue, but unfortunately it's only been defined as an environmental issue and that's a big mistake," began Harvard professor Daniel Schrag in his presentation to the 2006 Association for the Study of Peak Oil USA last October in Boston, Massachusetts.

Schrag is a geologist by training who studies climate over the course of millions and billions of years. He pointed out that the earth hasn't seen CO2 concentrations comparable to today since the Eocene age some 30 million years ago, and given current trends, is likely to "be off the top of this page."

"Now Cameron (Wake) talked a lot about what we know and that's true, we know a lot about climate change. What I want to do is talk about what we don't know, because to me the uncertainty in this problem, which is often used as an excuse for inaction, is actually at the heart of this problem. It's what we don't know that actually should worry us."

Schrag pointed out that because of the brightness of Venus' atmosphere, it that atmosphere had the same density as Earth's, it would actually be colder than earth despite being close to the use. The reason the surface temperature of our sister planet is warmer than 460 degrees F is because of the "greenhouse effect"; its atmosphere is 100 times thicker than earths and composed almost entirely of carbon dioxide.

On Earth the problem of modeling our climate is complicated by the presence of water in the atmosphere, he said. Using 100 years of ocean and land observations, "we have assembled that information and created the best possible models we have of the future. And now we're taking the planet to someplace it hasn't been for 30 million years, and the question is, how good do you expect those models to be based on a hundred years of observation? That's the experiment we're doing with the planet."

Schrag observed that the last time we think the planet's atmosphere held 500 ppm of CO2 was in the distant Eocene epoch 30-50 million years ago, but because there were no ice caps in Greenland or the Antarctic, we simply can't be sure. There were crocodiles living above the Arctic circle, the deep ocean was 12 degrees C rather than 1 degree C as today, the Antarctic was covered in a pine forest and sea level was at least 100 meters higher than it is today.

While all this doesn't sound all that bad, he said, getting there in a mere 100 years time is problematic. He asked how many people in the audience live within 100 meters of sea level.

The world as it might have appeared during the Eocene epoch more than 30 million years ago when carbon dioxide levels were thought to be in the range of 500 parts per million

Turning back to the climate models, he said the 'dirty little secret' is that when we try to account for influence of rising CO2 levels, "we can't get it right", noting that we don't understand the role of winter in these ancient climates. Palm trees in Wyoming would die in winter, so there's some part of our understanding -- probably the feedback loops -- of those distant times that we can't fully account for.

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