By Donella Meadows
–October 13, 1994–
The first skim of frost came to my garden ten days late this year, on October 2. The squash leaves shriveled, the tomato vines turned black — but only on top. Underneath the plants stayed green and alive. Up by the house the marigolds and petunias were untouched. We had another week of grace before the definitive white killer arrived, silently, on October 11.
The killing frost is a time of grief, but this year I can’t complain. I had ten extra days of squash, three extra weeks of bouquets. I’ll have them again next year too, I predict. The Pinatubo cooling is gone, the greenhouse warming is back.
I’ve recorded first and last frost dates on this farm for 22 years. Until the mid-1980s I could count on a light touch at the end of August and a killer in the third week of September. Like clockwork. Then the first-frost date started creeping into October. The last frost in spring retreated backward by a good two weeks. I had an extra month of frost-free growing! That’s enough to make any gardener believe in global warming.
Then in June, 1991, the volcano Pinatubo in the Philippines spewed a mountainload of dust into the air. A month later the weather here snapped back to the crispness I knew from the 1970s. Long, hot, muggy spells disappeared. From plant growth to pest behavior, the garden shifted back to old familiar patterns. That fall the frost came on September 23rd.
We had September frosts in 1992 and 1993 too. I returned to my old planting routines, until this July, when I could tell by a hundred small signs that whatever snapped three years ago had snapped back. This late frost didn’t surprise me.
All of which proves nothing. A few data points from one tiny spot on this vast globe are statistically insignificant. Twenty-two years of weather variation do not add up to a clear change in the long-term pattern called climate.
But, as with the economy, the climate has leading and lagging indicators. The leading indicators are the sensitive reactions of nature — pests, frosts, soil moisture, plant growth. Folks who work in nature will detect change sooner than those who monitor climate through instruments, sooner than city people who write the nightly news, and much sooner than those who have such strong reasons for not wanting to think about climate change that they screen out all signals.
A lot of observations from nature are consistent not just with the happenings in my garden, but with the expectation of scientists that Pinatubo’s dust screen merely covered over for a few years the long-term warming of the planet. Eighty years of records from a biological field station in Michigan show that the once-common deer mouse is disappearing, moving north into Canada. So are the wild Calypso orchid and the grayling, a sport fish related to trout. Southern varieties of sunfish and ferns are moving north at a rate of about 10 miles a year, as are opossums, cardinals, mockingbirds, and several varieties of rats and mice.
Snowmelt in Alaska occurred two weeks earlier in the 1980s than it did in the 1940s. Glaciers are retreating. In the southern hemisphere, tree rings from 700-year-old mountain pines in Tasmania have been getting thicker since the 1960s.
Again, not one of these observations, nor all of them taken together, proves a climate change. But add to them the following scientific certainties: Human fossil fuel burning is emitting increasing amounts of carbon dioxide. This gas is building up measurably in the atmosphere. It is known to trap and hold heat. Volcanoes emit particles that screen out sunlight and cool the planet, but the particles settle out after a few years. No scientists, not even the ones paid by coal companies, challenge any of those statements.
For the moment politicians and journalists have lost sight of the greenhouse effect. That’s partly because of the Pinatubo cooling and partly because of the normal attention cycle of the media. First they discover a problem and exaggerate it. Headlines, magazine covers, and broadcasters tell us the planet is about to die. Then comes the revision. A few scientists and a host of economists are found who say the whole issue is a hoax. Then there is silence (“we’ve done that story”), until a hot summer dries up the Midwest, and the cycle starts again.
Those of us who work outdoors have a steadier view of things. We see all kinds of ups and downs, plus an undertow of increasing strangeness that has us worried. Things are changing, but too slowly to make news. An extra frost-free month may be a blessing, but when I watch nature’s response — the disappearance of old pests but the arrival of new ones, the confusion of prey and predators out of balance with each other, plants struggling with new rain and wind patterns — I get nervous about messing with the workings of the planet.
So I’m doing what I can to reduce my fossil fuel use. I’m opting out of the high-consumption society that never much attracted me in the first place. And I’m planting early next year, preparing for a hot summer, and waiting for the next media discovery of the heating of the planet — unless another volcano pops off.
Copyright Sustainability Institute 1994