Interannual to decadal scale North Pacific climate dynamics during the last millennium from Eclipse Icefield (St. Elias Mountains) ice core stable isotope records
Abstract
A 345 meter ice core recovered from the St. Elias Mountains, Yukon Territory, Canada during 2002 has been continuously analyzed for stable hydrogen isotopes (deltaD), and is used to interpret changes in the North Pacfic hydrologic cycle and climate variability over the past 1000 years. Given the high annual snow accumulation rate at the site (1.5 meters/year), the record is high resolution (subannual) and annually dated to 1450 AD, and dated with ice flow models prior to 1450 AD. Five-year averaged isotope data over the past millennium display a classic Little Ice Age (LIA)/Medieval Climate Anomaly (MCA) pattern; that is, lower isotope ratios during the LIA, and higher isotope ratios during the MCA. Using the simple isotope/temperature relationship typically applied to ice core data, the Eclipse record may indicate lower regional temperatures and enhanced temperature variability during the period 1250 to 1700 AD. However, isotope data from an ice core recovered near the summit of Mt. Logan is clearly related to different hydrologic regimes. Regardless of the scaling used on the Eclipse isotope data, a distinct drop in isotope ratio occurs just prior to 1200AD, and may correspond with changes observed in tropical coral records. We suggest that fundamental changes in teleconnection and/or ENSO/PDO dynamics between the high and low latitudes in the Pacific may be responsible for the 13th century event. Based on the 1000-year record at 5-year resolution, as well as annual isotope data for the past 550 years, the 20th century is not anomalous with respect to previous time periods.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.U43B0848K
- Keywords:
-
- 0720 Glaciers;
- 1605 Abrupt/rapid climate change (4901;
- 8408);
- 1616 Climate variability (1635;
- 3305;
- 3309;
- 4215;
- 4513);
- 1620 Climate dynamics (0429;
- 3309);
- 4932 Ice cores (0724)