|The Week That Was
March 8-14, 1999
It’s been a busy week, with ice dominating the news -- not just in the Midwest and in Europe, where avalanches have taken their toll. Antarctic ice cores made the news in Science [March 12] and in Nature [March 11]. Swiss and American researchers analyzed cores, some dating back to 400,000 years. The scientific results were fascinating, but just as interesting was the diversity in the press coverage.
The Science paper came up with a blockbuster result. Every one of the three deglaciations [the transition from the ice age to a warm interglacial period] was associated with a sharp increase in carbon dioxide [CO2]. Only the Washington Post (March 15), however, managed to get the real story: “Contrary to what many believe, the team concluded the temperature rise comes first, followed by a carbon dioxide boost 400 to 1,000 years later. That’s what the researchers found at glacial-interglacial transitions from 240,000, 140,000, and 13,000 years ago. That sequence of events appears to contradict the fundamental logic of simple greenhouse warming theories, which argue that increases in heat-trapping gases will be followed by higher surface temperatures.”
It is clear that many scientists and others, who have glibly talked about the historic “association” of increases in temperature and CO2 have not really addressed the “chicken-and-egg” question of which came first.
The AP story reported the bare result without comment. The Washington Post, on the other hand, printed several pertinent comments, including one from the director of the US Geological Survey’s National Ice Core Laboratory. She has become somewhat skeptical about using analogs from past behavior for predicting what’s going to happen in the future. Commenting on the new results, she concluded: “That’s a sobering thought.” A government climate modeler expressed a different concern, worrying that “greenhouse skeptics will probably jump on this paper as ‘proof’” that there is no necessary causal connection between carbon dioxide levels and temperatures.”
The Nature paper, involving some of the same ice cores and also some of the same authors, found that atmospheric CO2 varied considerably in the last 11,000 years -- without any human intervention. In fact, there was not even a strong association between temperature and CO2 levels. The temperature history showed the well-known Climate “Optimum” (very hot and wet) of 6,000 years ago, after which the climate cooled and became drier. The AP story tries to link the drying and drought to warming. The Washington Post story explains why CO2 levels never stabilize and how the large swings in concentration were controlled both by absorption and release from the ocean and by growth and disappearance of vegetation. As the ice cover melted and glaciers receded 11,000 years ago, vegetation spread rapidly and in the process absorbed much of the atmosphere’s CO2. The level reached a minimum about 8,000 years ago and then grew steadily and slowly up to the beginning of the industrial age.
The moral to the story is that mathematical models that try to predict the fate of CO2 in the atmosphere are still imperfect. While they try to take account of the ocean, albeit crudely, they have not yet figured out how to factor in the biosphere. Only a few weeks ago, we learned of the surprising finding that North America absorbs more CO2 (probably by forests and soils) than it emits by fossil-fuel burning.
More ice stories -- The March 5 issue of Science carried an article with the headline “Rapid Thinning of Parts of the Southern Greenland Ice Sheet.” Well, bully! The authors don’t quite admit this, but their survey, conducted with airplanes and laser altimeters, may have covered less than 10 % of the Greenland ice sheet. They had to admit, however, that areas at higher elevation experienced a substantial thickening; but that information is buried in the text and not revealed in the title or the abstract. So what do we to make of this breathless and incomplete announcement? Does the reported thinning cut any ice [pun intended] with sea level rise? The authors don’t say and with good reason; the Greenland ice sheet is rather unimportant compared to Antarctica. Why write a paper? Perhaps they had to publish in order to get more money for research.
The Reuters story though is heart breaking. “Large tracts of the Greenland ice sheet … are disappearing faster than scientists expected in a sign that global warming is having dramatic effects, researchers said Thursday.” We guess that reporters don’t know how to ask the right questions when it comes to science -- probably because they study journalism. Only much later does the story hazard the sheer guess that less snowfall is “probably” not the culprit. How do they know? For good measure, the reporter throws in the fact that the Earth’s mean surface temperature has risen in the last hundred years. Not exactly a relevant fact, since Greenland temperatures have not been rising.
And now for something completely different! The San Francisco Giants have a problem in removing a mountain of dirt from behind second base of their new ballpark, because it has been declared a “hazardous waste.” Turns out, it contains less than 3 milligrams of lead per liter. The national standard (and California standard) requiring a tightly regulated and very expensive Class-1 landfill is 5 mg. But the California Department of Toxic Substances Control decided to use an informal “guideline” of 1.5 mg per liter apparently under the impression that young children would assemble at ballgames and have huge dirt-eating feasts.
As revealed in the San Francisco Chronicle, the Giants [or their contractor] had started to move some of the dirt to a Class 2 landfill when environmental groups, who have fought the new ballpark, raised a ruckus. The deputy director of the department denied that he was under pressure from the environmentalists, but failed to explain why his guideline was set without any scientific basis. He said he was not aware that his staff had given the Giants permission to start moving the dirt, because he had taken the day off. It was his birthday.
More on hazardous waste (and radioactivity) next week.