more temperate regions.
Darwin’s account has since been confirmed by all sorts of physical
traces. Researchers studying ancient beetle casings, for example, have
found that during the ice ages, even tiny insects migrated thousands of
miles to track the climate. (To name just one of these, Tachinus caelatus is a
small, dullish brown beetle that today lives in the mountains west of Ulan
Bator, in Mongolia. During the last glacial period, it was common in
England.)
In its magnitude, the temperature change projected for the coming
century is roughly the same as the temperature swings of the ice ages. (If
current emissions trends continue, the Andes are expected to warm by as
much as nine degrees.) But if the magnitude of the change is similar, the
rate is not, and, once again, rate is key. Warming today is taking place at
least ten times faster than it did at the end of the last glaciation, and at the
end of all those glaciations that preceded it. To keep up, organisms will
have to migrate, or otherwise adapt, at least ten times more quickly. In
Silman’s plots, only the most fleet-footed (or rooted) trees, like the
hyperactive genus Schefflera, are keeping pace with rising temperatures.
How many species overall will be capable of moving fast enough remains
an open question, though, as Silman pointed out to me, in the coming
decades we are probably going to learn the answer, whether we want to or
not.
MANÚ National Park, where Silman’s plots are laid out, sits in the
southeastern corner of Peru, near the country’s borders with Bolivia and
Brazil, and it stretches over nearly six thousand square miles. According
to the United Nations Environment Programme, Manú is “possibly the
most biologically diverse protected area in the world.” Many species can
be found only in the park and its immediate environs; these include the
tree fern Cyathea multisegmenta, a bird known as the white-cheeked tody
flycatcher, a rodent called Barbara Brown’s brush-tailed rat, and a small,
black toad known only by its Latin name, Rhinella manu.