2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 13
Presentation Time: 11:30 AM


EASTERBROOK, Don J., Dept. of Geology, Western Washington Univ, Bellingham, WA 98225, dbunny@cc.wwu.edu

The sensitive, global synchroniety of abrupt Younger Dryas climate oscillations, shown by double YD moraines in the Pacific NW, Rocky Mts., Swiss Alps, Canada, Scandinavia, and New Zealand, challenges the viability of changes in the North Atlantic deep current to explain such abrupt changes in both hemispheres with no time lag. New cosmogenic dates from twin YD moraines in the North Cascades and Sawtooth Mts. confirm that the western U.S. was sensitive to these abrupt climate changes, far removed from any oceanic connection to the North Atlantic.

These late Pleistocene, global, climate changes have implications for understanding present–day global warming. Climatic modelers have predicted that global temperatures will soar in the next several decades as a result of increased atmospheric CO2. However, evidence from glaciers and the oceans suggest that these predictions may be premature. Advance and retreat of glaciers in the Pacific NW and elsewhere show three distinct oscillations, each having a period of ~25–30 years. Glaciers advanced from about 1890 until the early 1920s (cool cycle), retreated rapidly from ~1930 to ~1950-55 (warm cycle), readvanced from ~1955 to ~1980 (cool cycle), then retreated rapidly from ~1980 to the present (warm cycle). Comparable, cyclical, oscillation patterns occurred in the North Pacific (PDO), the North Atlantic (NAO), Europe, and Greenland. Global temperature curves show a cool reversal from ~1950 to 1980) at a time when large amounts of CO2 were introduced into the atmosphere, inferring that global temperatures then were not driven by atmospheric CO2. During this cool cycle, solar irradiance curves almost exactly match the global temperature curve. Satellite data indicate intensifying solar radiation over the past 24 years, coinciding with the present 25–year warm cycle and suggesting a solar cause for the warming. If the cycles continue as in the past, the current warm cycle should end in the next few years, and global warming should abate, rather than increase, in the next 25–30 years, followed by renewed global warming in the following 25–30 years.