Since I am both a gardener and allergy sufferer I was of two minds when I saw white patches on neighborhood roofs yesterday morning; I don’t like to see our gardening season end, but I’m all for a good freeze wiping out the annual ragweed infestation. By the afternoon however, when I saw bumblebees buzzing among the still blooming impatiens, I knew the frost I had seen earlier was light and scattered at best.
Gardeners and allergy sufferers who might have been thinking that the gardening and pollen seasons here in Southwestern New Hampshire seemed to be getting longer weren’t imagining it. Our average first frost date is September 15th and the chance of a hard freeze on October 7th stands at about 50%, but here it is October 8th and we haven’t even had a real frost yet. Temperatures this weekend are supposed to soar into the 80s and remain above average for most of the week. So what is going on?
Twenty researchers at the National Academy of Sciences, documenting pollen data and daily temperatures in Canada and the U.S. over the last 20 years, found an increase in the number of frost free days and a shift in the timing of fall frosts, which means that spring now begins earlier and fall later. In some areas the span between the last frost in spring and first frost in fall has lengthened by as many as 27 days.
A report whose lead authors include Lewis Ziska of the U.S. Department of Agriculture and Christine Rogers of the University of Massachusetts, Amherst says “There was a highly significant correlation between latitude and increase in the length (days) of the ragweed pollen season over the period from 1995 to 2009.” Since ragweed is an annual plant that is killed by frost, this means that annual vegetables and flowers also have a longer growing season.
The aerobiology committee for the American Academy of Allergy, Asthma and Immunology says: “As we’re seeing warmer and warmer weather, fall gets warmer and longer and the effect is that there’s no frost to kill the ragweed and end the allergy season. Rising temperatures have produced a similar lengthening of the spring allergy season, which is now starting about a month earlier than it did decades ago.”
I can’t speak for allergy sufferers, but gardeners have known for a long time now that something was afoot-we didn’t really need scientists and politicians telling us that. But what is there to do about it? As I see it, all we can do is plant our gardens earlier and then take our allergy pills and harvest later, but a more long term solution might include voting for those who don’t deny the reality that surrounds them.
Photo of the Earth and Sun is by NASA