Geological context of climate change as a basis for policy

Abstract

A vigorous public debate over possibly dangerous human-caused global warming exists. In reality, the great majority of scientists hold balanced and non-extreme views about the complex issue of climate change.

Scientists accept (i) that global climate has and will change; (ii) that human activities (not just carbon dioxide emissions) definitely affect local climate, and have the potential, summed, to measurably affect global climate; and (iii) that carbon dioxide is a mild greenhouse gas. The true scientific debate is about the sign and magnitude of any global human effect, and its likely significance when considered in the context of natural climate change.

Modern temperature measurements, from thermometers to satellite measurements, only go back 150 years. Geological datasets do not provide direct temperature measurements, least of all of Average Global Temperature. Instead, they comprise local or regional proxy records of climate change of varying quality. Nonetheless, numerous high quality palaeo-climate records, and especially those from ice cores and deep-sea mud cores, exist, and comprise the essential context within modern climate change must be studied.

Scientists agree that natural climate-related events and change are real, with real human and environmental costs. These hazards include storms, floods, droughts, bushfires, and temperature steps and longer term cooling or warming trends. Natural climate-related events and change will continue, and human and environmental damage will be wrought. In our present state of knowledge they can neither be predicted far ahead nor prevented once underway. The matter of dealing with future climate change, therefore, is primarily one of risk appraisal and minimization, as that for natural risks which vary from place to place around the globe.