RealClimate: A Book Review — Did you know that in 1965 the U.S. Department of Agriculture planted
a particular variety of lilac in more than seventy locations around the
U.S. Northeast, to detect the onset of spring — in turn to be used to
determine the appropriate timing of corn planting and the like? The
records the USDA have kept show that those same lilacs are blooming as
much as two weeks earlier than they did in 1965. April has, in a very
real sense, become May. This is one of the interesting facts that
you’ll read about in Amy Seidl’s book, Early Spring,
a hot-off-the-press essay about the impacts of climate change on the
world immediately around us – the forest, the birds, the butterflies in
our backyards.
The brilliant title of Seidl’s book was one of the reasons that it
caught my attention. The other was that I have realized I need to
better educate myself about the impact of climate change on everyday
life. I’ve been dismissive of the idea that the average person can
really detect the impacts of recent warming on, for example, the timing
of the apple-blossom season, but I’ve been taken to task by several of
RealClimate’s readers for this. If you are paying attention, they have
argued, the changes are actually rather obvious.
Of course, Amy Seidl is not the average person. Rather, she’s a
trained ecologist with a Ph.D. (as well as an avid gardener) and she’s
clearly paying extremely close attention. Her book is the first one I
have read that effectively brings home the tangible impacts that global
warming will have – is having – on our everyday lives. “We are
increasingly familiar,” she writes, of images of melting glaciers, “but
how do we give them relevance in our lives? From my window I see no
glaciers.” She answers her own question with a series of vignettes,
some from her own experiences, many more from her extensive research
(well referenced throughout the book).
Cardinals, robins and cowbirds are all arriving earlier in Vermont
than they did a century ago. Kingfishes, fox sparrows and towhees are
not. Why the difference? The answer, as Seidl explains, is that the
former group has the ability to respond ecologically to the changes,
because these birds cue their arrival to temperature. The latter, it
appears, respond more directly to temporal cues, that won’t change even
as climate does. It’s obvious from this example that the make up of
bird life in Vermont – the species distribution – will change over
time. This may not necessarily be a bad thing of course. On the other
hand, it turns out that the robins are the most important host for West
Nile virus; the early bird gets the worm, so to speak, and passes it
along to humans.
Maple seedlings need about 100 days of below-freezing weather. As
this becomes rarer, fewer maples will populate the forests. This, Seidl
explains, is why species-range models predict the decline and eventual
loss of sugar maple (at least in New England) in the future. But, she
notes, the models don’t take into account the full complexity of the
system, such as the impact of competition among different species. So
we don’t really know what will happen, or how fast. What we do know is
that maple-sugar farmers have noticed – and documented – an earlier
maple sugaring season over the last few decades.
There are many other examples in Early Spring both of clear
climate-related changes (such as the early arrival of robins), and of
less clear-cut changes (the maple sugaring season). Seidl doesn’t make
the common mistake of assuming that the more ambiguous examples are
necessarily due to climate change. For example, she quotes a
maple-sugarer who points out that technological changes have allowed
them to tap maples earlier, and hence that the timing of sugaring is a
weak measure of climate change. The point though, is that even rather
minor changes are, after all, being noticed. And if much larger changes
do occur, as predicted, they will most certainly have impacts we can’t
ignore, even if we don’t live in the Arctic or in Bangladesh. In other
words, Seidl tells us, listen to the farmers and gardeners, and the
observations of regular people: they are meaningful. (04/19/09)
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