Present-Day Environments and Climate Change - Mountains and Plains: The Ecology of Wyoming Landscapes - page 40

of unusually warm years and warm winters. this warm-
ing has occurred throughout the state. not surprisingly,
during this period some glaciers have disappeared and
wildland fires and bark beetle epidemics have become
more widespread. 23 Shuman confirmed that tempera-
ture trends were correlated with atmospheric green-
house gas concentrations. He could not find correlations
with solar irradiance, the Pacific Decadal oscillation, el
niño / La niña years, or changes in land use. essentially
the same results have been found for Montana using
comparable data. 24
could the temperature trends for Wyoming be
part of a cycle when viewed over a longer period? to
address this question, Shuman examined changes in
the 14,000-year-old pollen record preserved in lake
sediments to infer temperature changes for Yellowstone
national Park and the Bighorn Mountains (see chapter
2). these pollen records show the warming that caused
glacial melting about 10,000 years ago, and also the cool
and warm periods that have occurred since that time.
Shuman concluded that it is unlikely that warming dur-
ing the past 40 or 50 years is part of a long cycle. 25 He
also determined that “recent temperatures in Yellow-
stone national Park . . . have exceeded those recon-
structed for the past >6000 years and are now similar
to the highest temperatures of the Holocene record.” 26
though less pronounced, his analysis of data for the
Bighorn Mountains gave the same results.
in Wyoming, as elsewhere, changes in rain and
snowfall are more variable and uncertain than tem-
perature change. Shuman did find a decline in the
frequency of wet winters. Moreover, based on climate
data since 1895, he found there were no winters for the
8-year period from 1999 to 2007 that were wetter than
the 83-year average from prior to 1978. only 12 winters
in the past 57 years have been wetter. 27 Another study
reported that the snowpack in the Rocky Mountains has
been dropping more in the past 30 years than in the
past few centuries, a decline reflected in data on stream-
flow and reservoir levels. 28 According to the national
Weather Service, 2012 was the third-driest year in
118 years. 29 Still, the results are mixed. the national
climate Assessment program projected that, by 2090,
precipitation in Wyoming would be about the same or
possibly 10 percent higher. 30 When long-term precipi-
tation records are examined for the 10 major drainage

basins in Wyoming, there is no obvious trend in six of
the basins, though a downward trend is suggested in
four (see chapter 17). changes in future rain and snow-
fall are likely to be variable across the state, but with
warmer temperatures, evaporation will be greater. in a
warmer climate, it is probable there will be less snow,
less irrigation water, less forage production, more acres
burned in wildfires, and other related changes.
Although earth's climate has changed throughout
geologic time, the consensus of climate scientists is that
recent and ongoing climate change is occurring more
rapidly than before and that the best explanation for
these changes involves greenhouse gases produced by
human activities. 31 Also, even though most organisms
have adapted to previous episodes of climate change
during the long history of life on earth, through evolu-
tion or migrating to more favorable environments, biol-
ogists wonder whether the current rate of change is too
rapid for the evolution of many species to keep up. Local
extinctions of species will accelerate if migration to
areas having favorable climates is not possible. Almost
everywhere, habitat has already been fragmented to the
point where conservation biologists are concerned that
some species will not have a pathway along which they
can move when migration is necessary (see chapter 18).
Also, potential destinations may already be fully occu-
pied. Such issues are pertinent even if humans are not
the cause of the current episode of climate change.
Slowing the rate of climate change will require sig-
nificant and controversial changes in the way industry
is powered, the way homes and workplaces are heated
and cooled, and the modes of transportation that are
used. Progress has been made on using wind, solar
power, and biofuels, and on the capture and sequestra-
tion of carbon dioxide, but some observers are skeptical
about such alternatives. Proponents are convinced that
using energy more efficiently, combined with reducing
dependency on fossil fuels, is feasible and provides vari-
ous benefits. these include opportunities for the eco-
nomic growth associated with new industries that could
help supply worldwide markets.
current rates of climate change are likely to adversely
affect some aspects of the economies of western states.
For agriculture, the challenges will include finding
additional freshwater for more irrigation at a time when
water is even less available than it is now. this chal-