The shells result from eons of dynamic processes that began as the Earth formed. These processes, taken together, constitute global change. Without global change, we humans and much of the rest of the biosphere would not exist, because global change generated an oxygen-containing atmosphere, our protective stratospheric ozone layer, and global temperatures that support life (due to the greenhouse effect) as we know it. Until the last few thousand years, global change has been dominantly a "natural" process.
Recent observations have led scientists to conclude that human activities contribute to global change, that our industrial and land-management practices increase the rate of change of several geophysical phenomena, and that some changes may be deleterious to the biosphere. Nations around the world have banded together in a wide range of scientific and policy-based activities to determine the nature of human contributions to global change and to determine the effect such changes can have on our lives. These are gathered under the umbrella known as the International Geosphere-Biosphere Program (IGBP), which is, in essence, a massive effort to understand and learn to manage the world's environments.
Can you think of any place (or condition) at the Earth's surface where life is not to be found?
Friday, July 17, 2009
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