In Bruno-land we have been unusually warm in late March and unusually cold for the past ten days of April. It is not yet clear whether this year’s weather in the Perigord will continue the trend of the wine harvest coming earlier each year. Last year some growers began picking in late August, which is very early indeed. My neighbours’ journals suggest that 60 years ago, late September was the usual time to start picking and back before 1914 many growers began in the first week of October.
This chimes in perfectly with evidence from across the Atlantic, where the 19th century writer and naturalist (and anti-war campaigner) Henry Thoreau kept careful records of when plants around his home at Walden pond near Concord in Massachusetts would begin to flower in the 1850s. The highbush blueberry always flowed in early to mid-May. These days it flowers in mid-April, according to a group of naturalist scholars writing in the New York Times. And this year they began to flower on April 1; that is quite a shift. Even allowing for annual variations, the trend seems evident.
Richard B. Primack, professor of biology at Boston University, and Abraham J. Miller-Rushing of the Acadia National Park. write:
“Over the last 160 years, April temperatures at the nearby Blue Hill Meteorological Observatory have warmed by around five degrees, because of a combination of global warming and warming associated with the expansion of paved surfaces and buildings in metropolitan Boston. Plants on average flower two days earlier for each degree increase in Concord — thus, the town’s plants are generally flowering about 10 days earlier than when Thoreau made his observations. With temperatures predicted to rise by four to eight additional degrees this century, plants could flower 8 to 16 days earlier than they do now.
Of the species that Thoreau noted in the mid-19th century, a quarter seem to be missing. A further third are now rare, with only a few plants remaining in the area. Some of the most charismatic wildflowers, like many species of orchids and lilies, have disappeared from the area entirely….We discovered that the plants whose flowering times were most responsive to temperature — the ones more likely to bloom early in warm weather — were the very ones most likely to survive the changes in climate. They maintained healthy population sizes or even increased in abundance. In contrast, plant species that were unable to “track” changes in temperature in this way tended to decline or disappear, and have been replaced by non-native invasive species.”
As Thoreau wrote, “The question is not what you look at, but what you see.”