HR: 1330h
AN: PP42A-0865    [PDF]
TI: Timing and Spatial Extent of Mid-Holocene Abrupt Climate Change
AU: * Morrill, C
EM: morrill@ucar.edu
AF: National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 United States
AB: A number of recently-published paleoclimate records suggest that the mid-Holocene (about 6000 to 4000 calendar years ago) was a period of particularly widespread abrupt climate change. These changes mark the shift between the Holocene climatic optimum (generally warm and wet conditions) and the "neoglacial" (generally cool and dry conditions). This shift could be a rapid response of the climate system to decreasing insolation. Detecting abrupt climate changes in individual records is difficult, however, because the time-series also reflect thresholds and non-linearities that are inherent to the proxies. In this research, I have compiled more than a hundred previously-published proxy records from around the globe in order to assess the evidence for abrupt climate change during the mid-Holocene. The records include all types of proxies (i.e., pollen, ice cores, lake sediments, marine sediments, loess, peat, speleothems, charcoal). All records have a resolution of 150 years or better, well-defined age models, and clear proxy interpretations. Abrupt climate changes are identified objectively through the use of a moving t-test. The scarcity of records outside of North America and Europe makes it difficult to describe regional patterns with any reasonable degree of certainty. There is not a single preferred time of abrupt change; these changes appear to occur at several times during the mid-Holocene. These results will be used to discuss hypotheses for the causes of mid-Holocene abrupt climate change.
DE: 1620 Climate dynamics (3309)
DE: 3344 Paleoclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting