Geoscience Reference
In-Depth Information
pearance (e.g., insects) along their routes
and at their destinations, and changes in
environmental indicators that tell them
when to start and when to end migration.
change. The forests of central Mexico
where the butterfly winters are expected
to become wetter and possibly cooler in the
next fifty years. The eastern United States
and Canada may become warmer and drier
and move the optimum habitats further
north, extending the required migration
distances.
One impact of warming can be measured
by the body size of animals. For example,
arctic foxes are becoming significantly
smaller, according to a study by Yoram Yom-
Tov of Tel Aviv University. Smaller bodies
allow mammals to endure warmer weather
more successfully. Another impact related
to sea level rise is the distribution of fresh-
water fish at the heads of estuaries. In a
number of locations reports from fisher-
men indicate that the range of the fish is
decreasing as intruding seawater pushes
them upstream.
It is a long and fascinating story with a
largely unpredictable ending. Some of the
wildlife species which seem to be strongly af-
fected so far by global warming include cari-
bou, polar bears, arctic foxes, gray wolves,
tree swallows, painted turtles, toads, and
salmon. Which organisms will ultimately
adjust to change and which will fall victim
to it remains a question to be answered in
the coming decades.
other animals
The Sundarbans mangrove forest, the larg-
est in the world, will be largely wiped out
by a two-foot sea level rise. Owned by both
India and Bangladesh, this is the home of
the only Bengal Tiger adapted for life in a
mangrove forest. It is boxed in by extensive
development around its upland edges, mak-
ing inland migration of the forest apace
with the sea level rise unlikely. The tiger
is of course an iconic animal like the polar
bear, but the Sundarbans also has 50 reptile
species, 300 bird species, 45 types of mam-
mals, and 120 edible fish species. These too
will disappear with the rising sea, and some
are found only in the Sundarbans.
As with birds and plants, the impact of
global change on other animals including
mammals, amphibians, insects, and fish
is a complex mixture of prey and preda-
tors, invasive species, food supplies, tim-
ing of food supplies, changing ecosystems,
changing habitats, rising temperatures,
and changing rainfall patterns, all mixed
in with the impact of human activities.
The Monarch butterfly, known for its awe-
inspiring migration pattern from central
Mexico to the eastern United States and
Canada, is particularly vulnerable to global
