High-resolution 10,000-year temperature reconstructions from Lake Fog2, northern Alaska
Abstract
Lacustrine organic geochemical proxies provide unprecedented opportunities to reveal the regional histories of climate change in Arctic environments. North of the Brooks Range in Alaska, glacial kettle lakes support haptophyte algae that produce long chain alkenones (LCAs) and bacteria that produce branched glycerol dialkyl glycerol tetraether lipids (brGDGTs). Lake-bottom sediments preserve ancient lipids that resist environmental degradation, which may be used in turn to reconstruct ancient climates. Using a 3.6m piston core from Lake Fog2, we reconstructed a Holocene climate record that tracks seasonally distinct temperatures in the spring (LCAs) and summer (brGDGTs). Our LCA-based lake surface temperature reconstruction suggests long-term warming beginning near 5.3 Kyr BP and terminating approximately 1.6 Kyr BP, tracking long-term winter insolation trends for the region, while our brGDGT-based air temperature reconstruction suggests a warm period between 10.3 to 9.0 Kyr BP aligned with the summer insolation maximum. In tandem, the reconstructions suggest northern Alaska experienced an early Holocene summer thermal maximum and spring warmth in the mid-Holocene. In this presentation, we will compare our Holocene spring and summer temperature records with potential drivers including seasonal solar insolation, sea ice coverage in the Beaufort and Chukchi Seas, and greenhouse gas concentrations to identify the primary forcing mechanisms involved.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP31E1703H
- Keywords:
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- 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 1041 Stable isotope geochemistry;
- GEOCHEMISTRYDE: 1055 Organic and biogenic geochemistry;
- GEOCHEMISTRY