image: Head capsule of a midge larva found in Holocene lake sediments from northwest Greenland. view more
Credit: PNAS
A study estimates Greenland temperatures during past interglacial periods. Predicting mass loss from the Greenland Ice Sheet (GrIS) in response to future climate warming requires understanding GrIS behavior during past warm periods, such as the orbitally driven warming of the Early Holocene and the Last Interglacial Period (LIG). However, Greenland climate records during these periods are sparse, particularly near the ice sheet margin. Jamie McFarlin and colleagues report a lake sediment record near the northwest GrIS margin that preserves sediments from both the Early Holocene, 8,000-11,000 years ago, and the LIG, 116,000-129,000 years ago. The authors estimated past July air temperatures based on midge remains in the sediments, since different midges have different temperature tolerances. July temperatures during the Early Holocene were estimated to be 4-7°C warmer than modern temperatures (1952-2014). Midges preserved from the LIG suggest July temperatures 5.5-8.5°C warmer than modern temperatures. The results, combined with prior datasets, provide evidence of strong summer warming over northern Greenland during the Early Holocene and LIG. According to the authors, such warming is consistent with estimated local Early Holocene ice sheet thinning, but not with the inferred ice sheet extent during the LIG, and may portend strong warming of Greenland.
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Article #17-20420: "Pronounced summer warming in northwest Greenland during the Holocene and Last Interglacial," by Jamie M. McFarlin et al.
MEDIA CONTACT: Yarrow Axford, Northwestern University, Evanston, IL; tel: 847-467-2268; e-mail: <axford@northwestern.edu>
Journal
Proceedings of the National Academy of Sciences