Holocene mean temperatures derived from studies in the Abisko area, N Sweden

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This lecture

• respons to climate change • Mutual Climatic Range method (MCR) • Holocene MCR data from Lake Tibetanus, Abisko, N Sweden • Other climate records from the same area

Green ( campestris)

• Larvae and adults are exclusively carnivorous generalists • Cold-blooded • Habitat: sandy ground with sparse vegetation • Open, warm, sun exposed environments

Insects and climate

• Climate often limits insects geographical distribution • Arctic to temperate areas – Temperatures sets the limits • Stenothermic species – Species adapted to a narrow temperature span

Where are remains found?

Ca 5000 year old insect remains in peat from a bog in Småland

• Preserve well in wet/moist environments • Natural deposits • lake and fluvial sediments • Carr and bog peat

Beetles (Coleoptera)

• Robust exoskeleton – Body parts of adults – Identification to species level • Diverse adaption to both terrestrial and aquatic habitats • Many stenothermic species – Predators, scavengers genaralists

Climate reconstructions

• Mean temperature reconstructions – Mutual Climatic Range method (MCR) • Mean temperature of the warmest month (TMAX) • Mean temperature of the coldest month (TMIN) • Difference summer/winter temperatures (TRANGE) • Changes in humidity

Geographical distribution → Climatic range

• Atkinson et al. 1987. Nature 352:587-592 • Data from metereological stations • Geographical space is translated to temperature range • Climate envelopes for each species • Data base of climate envelopes Elias 2007

Climate envelopes

Elias 2007 • Stenothermic beetle species recorded in a sample • Envelopes stacked • Overlapping range represent the temperature reconstruction • This is the climate range were all species may coexist

MCR results

• Tests on modern beetle assemblages adjacent to weather stations – Acceptable accuracy of reconstructed temperatures • Slight underestimation of Tmax and Tmin of the coldest temperatures • Regression equations – Calibration of mean values • Jack knife method

Abisko Lake Tibetanus 560 m a.s.l. Lake Njulla 999 m a.s.l.

Barnekow 1999

MCR results from Lake Tibetanus

Macroscopic plant remains from L Tibetanus

Barnekow, L. 1999. The Holocene 9:253-265

Barnekow 1999

Lake Njulla 999 m a.s.l. • Diatom assemblages (July temp) • Chironomid assemblages July temp

Bigler et al. 2003. J of Paleolimnology 23:13-29.