The ongoing disturbances of the atmosphere that affect the biogeochemical
and physical processes that determine the climate may influence
human and natural systems in profound ways. We have attempted
to outline a few of the major ecosystem services that are associated
with climate and the atmosphere, as well as introduce the challenging
task of quantifying, and ultimately monetizing, these services.
Current monetized estimates of climate damage by the middle of
the 21st century from typical climate change scenarios range from
slight economic benefit to a trillion or more dollars lost annually,
with most macroeconomic assessments assuming a one to two percent
annual loss to GWP from climate change. Moreover, the interacting
processes and biogeochemical cycles occurring across a wide spectrum
of scales lead to synergistic effects that are not usually considered
and sometimes not even known (i.e. surprises) when we attempt
to disaggregate and value ecosystem services (e.g. Schneider and
Turner, 1995) . The deforestation of the Amazon basin is one example
of interacting scales where land use change affecting local and
regional climate may also produce a net global residual. Even
if the mosaic of regional effects average themselves out globally,
there could be residual effects arising from heterogeneous forcing
of the climate in areas outside of the tropics (i.e. regional
high concentrations of sulfate aerosols or tropospheric ozone).
Ecosystems both mediate and respond to the climate system through
a variety of physical, biological, and chemical feedback cycles.
The uncertainty of resulting synergisms and potential global effects,
as exemplified in the Amazon basin, points to the important challenge
of defining and understanding the processes that link species
and ecosystems with climate. With increasing knowledge, we can
better anticipate ecological responses under changing climate
scenarios. Meanwhile, humanity continues to perform this potentially
trillion dollar unnatural experiment on "Laboratory Earth".
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