MODERN TIMES

Art Hobson

ahobson@uark.edu

NWA Times 21 July 2007

"Planet Earth today: imminent peril"

I put today's title in quotes because it's the title of the final section of a scientific paper in the peer-reviewed Philosophical Transactions of the Royal Society by six eminent scientists headed by James Hansen, NASA's chief climate scientist. The paper can be found on the net by searching on its title "Climate change and trace gases."

Since the 1980s, when he was the first scientist to warn the U.S. Congress about climate change, no scientist has been more right about global warming than Jim Hansen. I heard him lecture at a recent meeting, and talked with him afterward. Shaking his head, he said he didn't know what America could be thinking of as we spew carbon dioxide (CO2) from cars and electric plants, and as corporations plan a new generation of coal plants. There is a disconnect, he said, between our business policies and physical reality.

Hansen's paper is typical of a number of recent alarming scientific analyses. Hansen argues that data from the past few million years show Earth's climate to be remarkably sensitive to external changes, changes in . "Positive feedbacks"—commonly known as "viscious circles"—predominate, causing the planet to be whipsawed between climate states. Two such feedbacks are especially dangerous today. "Albedo (reflectivity) flip" occurs when a large expanse of highly reflective ice melts, exposing non-reflective water or soil, leading to a viscious circle of warming and melting. "Greenhouse gas feedback" occurs when atmospheric warming caused by the tendency of CO2 and other gases to capture infrared radiation causes, for example, permafrost melting, which releases further greenhouse gases, leading again to a viscious circle.

During the past half-century, the Arctic Ocean, which is normally covered by an ice sheet a few yards thick, has already half melted and is nearing an albedo flip. Greenland's ice is vanishing, and the sub-continent is nearing an albedo flip. The melting is accelerating as great torrents of meltwater gush downward through crevices in the miles-thick ice sheets, reaching the base of the ice sheets, and lubricating the rock-ice interface, allowing the huge sheets to accelerate downhill toward the ocean. A similar process is occurring in the miles-thick West Antarctic ice sheet.

Hansen expects these processes to raise ocean levels by 15 feet by 2100, flooding global coastlines and cities. By 2200, Greenland or West Antarctica could completely melt, raising ocean levels by a catastrophic 25 to 50 feet and producing, according to Hansen, "a different planet."

Hansen and others give us 10 to 20 years to seriously reduce our greenhouse gas emissions, before reaching a "tipping point" beyond which the feedback effects described above take things completely out of human hands. If we continue to follow business as usual, we are going to be rudely awakened within 20 years to find that it's too late for action. Is this the world we want for our grandchildren?

As a convenient way of thinking about the solution, consider the "carbon pie." Before the industrial age, the CO2 concentration in the atmosphere was 280 CO2 molecules per million air molecules, or "280 ppm." Today, that concentration is over 380 ppm. Hansen and many others estimate that the dangerous level is about 450 ppm, 70 ppm beyond our present level. Every four billion tons of fossil carbon that we burn raises this concentration by another one ppm. Once CO2 gets into the atmosphere, it stays there for a few centuries. So we must not burn more than 70 x 4 = 280 billion tons of fossil carbon during the next few centuries.

This 280 billion tons is the "carbon pie." If we consume it all, we might be doomed. How shall we allocate it? It's pretty clear that the only fair apportionment is per capita: Each nation's slice of carbon should be proportional to that nation's population. The rich nations, having 20 percent of the world's population, would get 56 billion tons (20 percent of 280 billion tons), enough to last these nations only 10 years at present rates of use. Thus, rich nations will soon have to buy carbon rights from developing nations, which will surely come at a very high price, and which will provide income for the developing nations to find better ways to get their energy.

This will all sound like theoretical pie-in-the-sky to "practical" business people, but the ultimate impracticality is the melt-down of our planet. What seemed practical a century ago is, today, wildly impractical.

There's an easy but surprisingly important action you can take to help. The new Swepco coal plant planned near Texarkana will emit enormous amounts of CO2. Because of global warming risks, we must not allow new coal-fired power plants to emit their CO2 into the atmosphere. There are alternatives: efficiency measures can replace the need for this plant; renewable energy sources such as wind can replace this plant; if the plant is nevertheless built, it must capture and store its carbon—a technology that's under development. If carbon capture and storage technology is not fully developed by the time the plant is opened, the plant must be delayed until such technology can be installed. On the web, go to http://www.sustainablearkansas.info to send an automated message to the Arkansas Public Service Commission, which will soon rule on this plant. The PSC is happy to receive messages from everybody; you needn't be 18, you can reside outside of Arkansas or outside of the U.S., and many different people can send the message from a single email address.

We're all in this together. It's time, it's far past time, to get busy.
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