Focus 2 - Theme: Last Glacial Cycle

Focus2 last-glacial-cyc-Fig2
One-to-one coupling of glacial climate variability in Greenland and Antarctica (EPICA Community Members, 2006).


Major advances have been made in reconstructing and understanding glacial-interglacial cycles. Knowledge of greenhouse gas forcing has been gained from ice core records, and climatic time series from both hemispheres (see figure) have been better synchronized into consistent age models (Shackleton et al. 2000; Roucoux et al. 2005; Brauer et al. 2008). Together with PMIP2 model experiments and the MARGO spatial time-slice reconstruction of the LGM surface ocean (Kucera at al. 2005), these efforts have advanced our understanding of the sensitivity and response of the climate system to natural forcings and feedbacks such as changes in insolation, greenhouse gases, ice cover, and ocean circulation.

However, we still lack comprehensive understanding of the causes of carbon cycle changes, the amplifiers of orbital forcing, and the inter-hemispheric coupling of millennial-scale abrupt climate change. High-to-low latitude comparisons (e.g. the Pole-Equator-Pole transects; Markgraf 2001; Battarbee et al. 2004) have shown, for example, that the millennial Dansgaard/Oeschger (DO) cycles recorded in Greenland ice cores, also occur at low latitudes (e.g., Cruz et al. 2005) but it is not yet clear what drives them and how they are transmitted globally, nor how ecosystems responded to the substantial and rapid climate fluctuations.

The primary emphasis of post-glacial studies has concerned rapid cooling events during deglaciation and the early Holocene, in particular the Younger Dryas (12.9-11.6 ka) and the 8.2-ka event, which provide opportunities to study regional the environmental dynamics associated with rapid climate change.

Working groups

There was no specific working group formally assigned to this Theme. However, many other PAGES WGs had aspects that encompassed the last glacial cycle. Related WGs included: 

> ADOM

> PIGS

> Global Paleofire

> PALSEA2

 

 

 

References

Battarbee, R.W., Gasse, F. and Stickley, C.E. 2004: Past Climate Variability Through Europe and Africa. In: J.P. Smol (Ed.) Developments in Paleoenvironmental Research, Springer, New York: 638.
Cruz, F.W.Jr, Burns, S.J., Karmann, I., Sharp, W.D., Vuille, M., Cardoso, A.O., Ferrari, J.A., Silva Dias, P.L. and Viana, O.Jr., 2005: Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil, Nature, 434: 63-66.
Kucera, M., Schneider, R. and Weinelt, M., 2005: MARGO-Multiproxy Approach for the Reconstruction of the Glacial Ocean surface, Quaternary Science Reviews, 24: 813-1107.
Markgraf, V., 2001: Interhemispheric Climate Linkages, Academic Press, San Diego: 454.Shackleton, N.J., Hall, M.A. and Vincent, E., 2000: Phase relationships between millennial-scale events 64,000-24,000 years ago, Paleoceanography, 15: 565-569.