Geoscience Reference
In-Depth Information
and some of them are likely to be perilous. But we have just entered the
Climate Casino, and there is time to turn around and walk back out.
This topic describes the science, economics, and politics involved—and
the steps necessary to undo what we are doing.
A ROAD MAP OF THE TERRAIN AHEAD
Global warming is one of the defi ning issues of our time. It ranks
along with violent confl icts and economic depressions as a force that
will shape the human and natural landscapes for the indefi nite fu-
ture. Global warming is also a complex subject. It spans disciplines
from basic climate science, ecology, and engineering to economics,
politics, and international relations, and the result is a topic with many
chapters. Before embarking on an extended journey, readers may fi nd it
useful to look at a map of what lies ahead. Here are the major themes
discussed in the fi ve parts that follow.
Part I surveys the science of global warming. Climate science is a
dynamic fi eld, but the essential elements have been developed by earth
scientists over the last century and are well established.
The ultimate source of global warming is the burning of fossil (or
carbon-based) fuels such as coal, oil, and natural gas, which leads to
emissions of carbon dioxide (CO
2
). Gases such as CO
2
are called green-
house gases (GHGs). They accumulate in the atmosphere and stay there
for a long time. Higher atmospheric concentrations of GHGs lead to
surface warming of the land and oceans. The initial warming effects
are amplifi ed through feedback effects in the atmosphere, oceans, ice
sheets, and biological systems. The resulting impacts include changes in
temperatures as well as impacts on temperature extremes, precipitation
patterns, storm location and frequency, snow packs, river runoff, water
availability, and ice sheets. Each of these will have profound impacts on
biological and human activities that are sensitive to the climate.
Past climates—varying from ice-free to snowball earth—were driven
by natural sources. Current climate change is increasingly caused by
human activities. The major driver of global warming is the emissions
of CO
2
from the burning of fossil fuels. CO
2
concentrations in the atmo-
sphere were 280 parts per million (ppm) in 1750 and have reached
