By Donella Meadows
–February 7, 1991–
“Don’t write any more about the greenhouse effect,” some of my editors are saying. “It’s an old, boring story.”
Sorry, but I think there’s no story more new or exciting. We’re living through climate events of tantalizing uncertainty, which could challenge our ingenuity far more than any war. There are political angles: will George Bush maintain his isolation as the only industrial leader who doesn’t believe there’s a problem? There are scientific angles: why are the experts fighting about this, and why only American experts? And the planet is dropping clues as regularly and confusingly as any mystery thriller.
For example, a clue near at hand: since 1972 the first killing frost has come to my farm the third week of September — except in four of the past five years. In those years it came on October 8 (twice), October 11, and in 1990 October 20. A whole extra month of tomatoes! That sure looks like a warming to me.
Direct experience is convincing to those who experience it, but in fact those late frosts don’t mean a darn thing. Nor do this year’s freezes in the California orange groves. The momentary weather in any one place on this huge planet is as relevant to the whole climate as one tiny dot on your TV screen is to the entire shifting picture. Insignificant. But put enough dots together, and you get the big picture.
To back off for a wider view: winter snow cover in the northern hemisphere has been shrinking since 1978. The snow line is advancing south in the fall a little slower and north in the spring a little faster. This observation is worrying, because snow reflects away the sun’s energy. Less snow allows more warming, which means even less snow and even more warming. That’s a vicious circle, a possible planetary instability the scientists are watching with care.
Then there is the news that globally 1990 was the hottest year in recorded history, hotter even than the infamous 1988 that brought Midwest drought and Yellowstone fires. The heat wasn’t concentrated in the grainbelt this year, nor in New York or Washington, so there were no headlines. The warming was widespread and was particularly strong in the month of March and in Central Asia.
Is that proof that the greenhouse effect is here? No. A single year proves nothing. But there may be significance in the fact that the seven warmest years out of the last 120 were, in order of increasing temperature: 1980, 1989, 1981, 1983, 1987, 1988, 1990.
More clues from nature: since 1987 corals in tropical reefs throughout the Caribbean have been bleaching a ghostly white and dying. Researchers looking back over satellite data say that the locations and the times of bleaching correlate with unusually warm sea temperatures.
The Freshwater Institute in Winnipeg, Canada reports that Canadian lake temperatures have gone up over the last 20 years by three degrees Fahrenheit. The ice-free season has increased by three weeks. Because there is less rain and more evaporation, water flow through the lakes has gone down and therefore concentrations of dissolved chemicals have gone up. Small floating organisms and attached algae are changing in numbers and distribution — and these organisms are the base of the food chain that feeds all the larger creatures. The living community in the water is shifting at its foundation.
Don’t all these pieces of evidence together prove that global warming is happening? They add up to a lot more proof than anyone has ever given us that Star Wars will work or that sanctions on Iraq won’t work. But scientifically greenhouse warming is not proved, because in science you can’t prove a theory. You can only fail to disprove it. The most we can say is that the evidence is consistent with the theory of global warming. The greenhouse hypothesis is by no means disproved.
Except in the White House, of course, where there is a strong desire not to believe it.
This week U.N. negotiators are seeking to set up agreements by which the world’s nations will reduce their greenhouse gas emissions. Going into that meeting Germany, Denmark, the Netherlands, and Norway have already pledged to cut their carbon dioxide emissions. Japan, Britain, Sweden, and Canada have agreed to hold theirs stable. The U.S. has agreed to nothing.
That is our position, though our EPA has calculated that we could reduce our contributions to global warming by 25 percent at NEGATIVE COST — which is to say, we’d make money doing it. We could reduce another 25 percent at ZERO NET COST. These figures are conservative. They include only savings from available technologies in energy efficiency, CFC reductions, and forestry; they do not include possible gains from sustainable agriculture, materials recycling, lifestyle changes, or technical improvements. A more thorough calculation by the National Academy of Sciences says we could reduce U.S. contributions to global warming by 71 percent at no cost.
When the planetary news is breaking fast, when its possible consequences are far greater than the Gulf War, and when our government is being obdurate for no good reason, that’s not a boring story. It’s a story about a problem over which we of this generation have tremendous power, to postpone, prevent, endure, or regret. It seems to me the press should be planning to write about the greenhouse effect — or about our wise actions to prevent it — for another 100 years.
Copyright Sustainability Institute 1992