Abstract
The Holocene temperature history of Iceland is not well known, despite Iceland's climatically strategic location at the intersection of major surface currents in the high-latitude North Atlantic. Existing terrestrial records reveal spatially heterogeneous changes in Iceland's glacier extent, vegetation cover, and climate over the Holocene, but these records are temporally discontinuous and mostly qualitative. This paper presents the first quantitative estimates of temperatures throughout the entire Holocene on Iceland. Mean July temperatures are inferred based upon subfossil midge (Chironomidae) assemblages from three coastal lakes in northern Iceland. Midge data from each of the three lakes indicate broadly similar temperature trends, and suggest that the North Icelandic coast experienced relatively cool early Holocene summers and gradual warming throughout the Holocene until after 3 ka. This contrasts with many sites on Iceland and around the high-latitude Northern Hemisphere that experienced an early to mid-Holocene "thermal maximum" in response to enhanced summer insolation forcing. Our results suggest a heightened temperature gradient across Iceland in the early Holocene, with suppressed terrestrial temperatures along the northern coastal fringe, possibly as a result of sea surface conditions on the North Iceland shelf.
Original language | English (US) |
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Pages (from-to) | 3344-3358 |
Number of pages | 15 |
Journal | Quaternary Science Reviews |
Volume | 26 |
Issue number | 25-28 |
DOIs | |
State | Published - Dec 2007 |
Funding
J. Briner, D. Francis, A. Haag, Þ. Jónsson, E. McNie, H. Rosner, S. Ólafsdóttir, S. Steinþórsson, Y. Wang and M. Wooller helped in the field. Warm thanks to G. Gunnarsdóttir and family, and the farmers at Torfadalsvatn, for their hospitality and repeated access to the study sites. E. Thomas and E. Farris assisted with midge sample preparation. S. Ólafsdóttir and K.B. Ólafsdóttir at the University of Iceland measured TC. G.E. Jóhannsdóttir confirmed the identity of the Saksunarvatn tephra. A. Myrbo at the Lacustrine Research Center split cores and measured MS. L. Roschen at the University of Illinois measured BiSiO 2 . Y. Wang helped with preparing and submitting 14 C samples. J. Turnbull and C. Wolak (INSTAAR) and M. deMartino (University of Arizona) offered advice regarding 14 C dating. Funding and logistical support were provided by the National Science Foundation (NSF ATM-0318479 to G. Miller, NSF ATM-0317766 to M. Wooller, and DGE-9987607 to J. White), RANNIS (Icelandic Centre for Research) Grant 060236021 to Á. Geirsdóttir, the Science Institute of the University of Iceland, VECO Polar Resources, and the Geological Society of America. This manuscript benefited from discussions with J. Briner, C. Caseldine, D. Francis, N. Holmes, and M. Wooller, and from thoughtful comments by two anonymous reviewers.
ASJC Scopus subject areas
- Global and Planetary Change
- Ecology, Evolution, Behavior and Systematics
- Archaeology
- Archaeology
- Geology