An Inconvenient Explanation

Global warming points of view: Philadelphia Magazine

---------------
The new Al Gore, visibly more relaxed and likable than during his last campaign, basically says this:

Our world is habitable because some of the heat from the sun is held here by gases in the atmosphere that are descriptively labeled “greenhouse gases.” Carbon dioxide is one of the main components. Unfortunately, measurements over the past 30 years show a steep climb in carbon dioxide concentrations and happen to track closely a concurrent rise in the average temperature of the Earth. All that extra carbon dioxide, a.k.a. CO2, isn’t produced “naturally”; it’s mostly a result of mankind burning fossil fuels.

If the profligate use of fossil fuels continues and the carbon dioxide levels keep rising, the temperature of the Earth’s atmosphere and oceans will rise to calamitous heights, melting glaciers, disturbing water systems, and causing droughts, crop failures, and much stronger hurricanes and cyclones. Gore forecasts the worst-case scenario as “a nature walk through the Book of Revelation.”

But the real worst case that the once (and future?) politician presents is the breakup and melting of the two massive ice sheets that cover Greenland and Antarctica, an event that would raise global sea levels so much that many coastal areas would be under water. Using an animated seeping blue stain that’s reminiscent of how filmmakers once illustrated the progress of the Nazi regime, Gore shows large parts of San Francisco, Beijing, Shanghai and New York becoming submerged. The result, he says, will be tens of millions of “climate refugees.” It will make the upheaval caused by the flooding of New Orleans and its displaced persons seem like a walk in the park.

There’s no way to watch An Inconvenient Truth without getting worried - at least a little worried.

=============

Penn professor Bob Giegengack:

The Earth has been warming, he says, for about 20,000 years. We’ve only been collecting data on that trend for about 200 years. “For most of Earth history,” he says, “the globe has been warmer than it has been for the last 200 years. It has only rarely been cooler.” Those cooler periods have meant things like two miles of ice piled over much of what is now North America.

...
The Earth’s orbit around the sun is more or less circular, but when other planets align in certain ways and their gravitational forces tug at the Earth, the orbit stretches into a more elliptical shape. Combined with the tilt of the Earth on its axis as it spins, that greater or lesser distance from the sun, plus the consequent difference in solar radiation that reaches our planet, is responsible for long-term climate change.

...
Gieg clicks a button, and three charts come together. The peaks and valleys of the Milankovi´c cycles for planetary temperature align well with the ocean-floor estimates, and those match closely the records of carbon dioxide concentrations and temperature indications from ice cores. So, the professor maintains, these core samples from the polar ice and ocean floor help show that the Earth’s temperature and the levels of carbon dioxide in the atmosphere have been in lockstep for tens of thousands of years.

Of course, that was long before anybody was burning fossil fuels. So Giegengack tells his students they might want to consider that “natural” climatic temperature cycles control carbon dioxide levels, not the other way around. That’s the crux of his argument with Gore’s view of global warming

...
there was a three-decade period of unusually low temperatures that culminated in the popular consciousness with the awful winter of 1976-77. Back then, scientists started sounding the alarm about a new ice age.

...
“I don’t think we’re going to have a rational discussion of this question in the present environment,” he says. “The scientists are mad because they think nobody in Washington is listening to them. So it’s all either apocalyptic disaster or conflict of interest. If you suggest that we’re not going to hell in a handbasket because the rate of global warming is low compared to so many other environmental issues that we’re enduring, then you’re accused of being in the employ of the oil companies and you’re labeled a Republican.”

...
“Sea level is rising,” Giegengack agrees, switching off the sound. But, he explains, it’s been rising ever since warming set in 18,000 years ago. The rate of rise has been pretty slow - only about 400 feet so far. And recently - meaning in the thousands of years - the rate has slowed even more.