Henry David Thoreau was an exacting observer and prolific journal keeper. For 6 years, he tracked the life histories of more than 400 plant species in a 67-square-kilometer area around Concord, Massachusetts. Now, a group of plant ecologists at Boston and Harvard Universities have surveyed the same area, comparing notes -- abundances, habitats, and flowering times -- with Thoreau. They claim to have substantiated the stress on plant communities caused by global warming (Science, July 4, 2008).
I don't doubt the warming, but I wonder whether a study of plants in so highly developed an area can yield any meaningful data vis-a-vis climate change. My wife has been recording the flowering time of the montbretia on our hill for 17 years. It varies a week or more from the average, with no discernible secular trend. As for abundances of plants and animals, changes have been dramatic. The montbretia has prospered, running riot in the ditches. Some of the more delicate wildflowers of the hedgerows, such as herb robert, have become rarer. Slugs have faded from the scene (except the garden). Badgers are gone. Foxes rarer. Corncrakes and cuckoos kaput. Before I would attribute any of this to climate change I would consider the massive transformation in agriculture -- the use of heavily fertilized monocrops and grubbing out of hedgerows -- and the domestication of the landscape for holiday homes. Looking for the signal of a degree or two of global warming in the midst of so much human-inflicted trauma seems to me a bit of a stretch.
Mind you, I'm not knocking the ecologists. Here on the Dingle Peninsula they have come to the rescue of one of our rarest and most mysterious species, the Natterjack toad. This little animal inhabits one tiny patch of Ireland near the head of Dingle Bay. Whether this is the last remnant of a once wider population, or a relatively recent introduction has been a matter of considerable debate. Now the government is offering farmers subsidies to provide shallow ponds for the toads. A cooperating farmer can earn up to $6000 annually, no small inducement. Will it help the Natterjack survive?
I mentioned here the other day the fox on my window sill, the first fox I had seen on our property in several years. Two days later a friend saw a dead fox in the road nearby and I feared it was my visitor. But no, my wife saw our fox again yesterday, waltzing along the wall in front of the cottage. The threat of climate change is surely of less consequence to the foxes of our area than the huge increase in automotive traffic. On the main road below the house recently I saw what appeared to be a black mink scampering from ditch to ditch, dodging traffic, no doubt descended from escaped importees as minks are not indigenous to Ireland. Where in the midst of so much direct and local environmental disruption are we to spot the elusive signature of global warming?