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Dynamics of the Sun-Earth Climate System

Arthur R. Green, Geoscientist, Retired from Exxon-Mobil Exploration Company, Houston, TX

The climate of planet Earth is in a continuous state of either cooling or warming as the elegant sun-earth climate system equilibrates the surface temperature within a range of 16°C.

We are currently living in a not-yet-completed interglacial stage, and we are experiencing a minor warming trend. Glacial periods tend to have more rapid climate changes. In the last 15,000 years, there have been two types of climate change: (1) moderate and gradual, and (2) major and abrupt.

The last decade of climate research has taught us what we don't know and has revealed that we are only at the beginning of the learning curve. "We do not understand the fundamentals of abrupt climate change well enough to predict them" (NRC Abrupt Climate Change, 2002).

The models used to project future climate changes and their importance are at an early stage of development. Because forward modeling is so complex, geologic science has a unique role in understanding the processes of climate change. Geology is the only discipline that routinely works backward in time to unravel facts and interactions of natural processes. Paleoclimatic rock and ice records show that large climate changes have occurred on our planet throughout its history. These changes appear to be caused by the equilibrating interactions of a large number of drivers both internal to the planet as well as external solar forces.

The deep difficulty of conducting climate and global change research is that it requires the non-linear complex integration of a wide spectrum of the sciences: meteorology, physics, chemistry, geology, botany, biology, mathematics, and sophisticated computer modeling.

Climate is not weather - it is infinitely more complex, and mature scientific analysis may be non-intuitive.

The last 17,000 years of ice core records coupled with the events of ancient history chronicle a fascinating story of human progress and adaptability. During this period, the Earth's climate varied as ice at the poles waxed and waned and sea levels rose and fell. The flooding and retreat of the seas along coastal zones and the advance and retreat of glaciers created migration paths for animal populations and man. The migrating and mixing of peoples, the growth of agriculture, the domestication of animals, and the establishment of the world's ancient cities were all influenced by the rhythms of the planet's changing climate.

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