New Research Opportunities in the Earth Sciences - New Research Opportunities in the Earth Sciences - page 61

How has the Global Climate System Operated
under States Different from Today?
Studies of our current glacial state provide an important baseline against
which future climate change can be assessed. This understanding of a world
characterized by ice sheets at both poles and atmospheric p CO 2 minimally 25 percent
less than present-day levels, however, captures only a fraction of the known range of
climate phenomena. Under the current rate of carbon emissions to the atmosphere,
greenhouse gas contents and associated radiative forcing will, by the end of this
century, reach levels that fall within the probable range of the last greenhouse period
of the Paleogene and Cretaceous (see Box 2.6). Critical insights into how Earth's
systems have functioned in such a high carbon dioxide environment are archived in
the records of past warm periods and major climate transitions. For example, deep-
time studies reveal past periods of anomalous tropical and polar warmth that were
associated with major changes in ocean and atmospheric circulation, including at
times marine anoxia and acidification, intensified hydrological cycling and regional
drought, and consequent substantial impact on marine and terrestrial ecosystems. For
many of these periods, the lack of thermostatic regulation reflects the absence of
those negative feedbacks that have stabilized surface temperatures during the current
icehouse climate system. These reconstructions further reveal how certain processes
and positive feedbacks that typically operate on longer timescales—or not at all in
glacial climates—can be accelerated under warmer conditions. Furthermore, intervals
of abrupt climate change documented by the deep-time geological record—most
notably, past hyperthermals of the early Cenozoic and the last greenhouse-icehouse
transition of the Late Paleozoic—reveal the nonlinear dynamics associated with
pushing the climate system through critical thresholds.
How does the Study of Interaction and Co-evolution of Life, Environment, and
Climate Benefit Society in General?
According to a 2009 Gallup Poll, only 39 percent of the American public view
evolution as the most reasonable explanation for the pattern of life on Earth, and there
is a strong positive correspondence between acceptance of evolution and level of
education (Newport, 2009). The United States ranks 33rd out of 34 developed
countries in acceptance that species, including humans, evolved. According to the
Pew Research Center (Kohut et al., 2009), only 57 percent of Americans accept the
scientific evidence for atmospheric warming, down from 77 percent only two years
earlier, and only 36 percent attribute global warming to the actions of humans. Many
attribute contemporary change to natural cycles, such as sunspot activity, without any
knowledge of the natural drivers, rates, patterns, possibilities, or consequences
illuminated robustly by the short- and long-term records of Earth history.
The increasingly robust record of the co-evolution of life and the environment
can be used to educate scientific and general populations about where Earth has been
and where it might be heading. It is fair to conclude that NSF-EAR shoulders the
responsibility of being the custodians of Earth history studies and the bridge to its