End of a glaciation

(Image credited to Trevor Chinn)

During the glacial–interglacial cycles of the past half million years, it took well over 50,000 years for continental ice sheets to grow to their maximum extent. In contrast, the transitions from glacial maximum to interglacial conditions generally occurred over about 10,000 years. In this web focus, we present a collection of overview, primary research and opinion pieces that explore the links between solar radiation, ice-sheet melting, ocean circulation and climate that govern the transition from glacial maximum to interglacial warmth.



Stop-and-go deglaciation p585


Past transitions from glacial to interglacial climates have not been smooth. It would be wise to prepare for similarly sudden episodes of ice loss in future climate changes.


News and Views

Palaeoceanography: Pacific and Atlantic synchronized pp594-596

Samuel L. Jaccard


Deep convection does not normally occur in the modern North Pacific Ocean, but that may have changed during the last deglaciation. Sea ice and surface temperature reconstructions show that if so, it was not associated with significant northward heat transport.

Anthropology: Ice-free emigration p596

Alicia Newton



Progress Article

Links between early Holocene ice-sheet decay, sea-level rise and abrupt climate change pp601-606

Torbjörn E. Törnqvist & Marc P. Hijma


The beginning of the Holocene interglacial was marked by ice-sheet melting and sea-level rise. A review of sea level and climate records identifies two sea-level jumps associated with the final drainage of glacial Lake Agassiz, and links them to an abrupt cooling event.



Northern Hemisphere ice-sheet responses to past climate warming pp607-613

Anders E. Carlson & Kelsey Winsor


During periods of glaciation, the Northern Hemisphere was swathed by large ice sheets. A review of ice-sheet retreat during the last two deglaciations shows that land-based ice sheets responded rapidly to rising summer insolation, whereas marine-based ice sheets underwent a delayed, but more abrupt, response.



Regional climate control of glaciers in New Zealand and Europe during the pre-industrial Holocene pp627-630

Aaron E. Putnam, Joerg M. Schaefer, George H. Denton, David J. A. Barrell, Robert C. Finkel, Bjørn G. Andersen, Roseanne Schwartz, Trevor J. H. Chinn & Alice M. Doughty


Glacier snowlines in both the European Alps and the Southern Alps of New Zealand have retreated over the past century. An analysis of glacier fluctuations in New Zealand over the past 11,000 years suggests that this synchronous behaviour is unique to the past few hundred years.

Deep Arctic Ocean warming during the last glacial cycle pp631-634

T. M. Cronin, G. S. Dwyer, J. Farmer, H. A. Bauch, R. F. Spielhagen, M. Jakobsson, J. Nilsson, W. M. Briggs Jr & A. Stepanova


In the Arctic Ocean, a salinity gradient separates a shallow layer of cold, relatively fresh water from the warmer, saltier Atlantic water below. A reconstruction of intermediate water temperatures in the Arctic during the last glacial period shows the presence of relatively warm water that may reflect a deepening of the halocline.


From the archives


News and Views

Palaeoclimate: Southern westerlies and CO2

Dominic A. Hodgson & Louise C. Sime


The Southern Hemisphere westerly winds affect the exchange of carbon dioxide between the ocean and atmosphere. Climate reconstructions from the southern mid-latitudes may reveal variability in the strength and position of the wind belt since the Last Glacial Maximum.

Palaeoclimate: Analogue complexity

Dorothy Pak


The last deglaciation was punctuated by several millennial-scale climate changes. In the Gulf of California, the cold stages were marked by decreased upwelling, opposite to the changes expected if these shifts were analogous to modern seasonal variability.



Rapid oceanic and atmospheric changes during the Younger Dryas cold period

Jostein Bakke, Øyvind Lie, Einar Heegaard, Trond Dokken, Gerald H. Haug, Hilary H. Birks, Peter Dulski & Trygve Nilsen


The Younger Dryas event was a brief return to cold conditions before the onset of interglacial warmth. An analysis of sediment records from Lake Kråkenes in Norway and the Nordic Seas shows that during the late Younger Dryas, Northern Europe underwent rapidly oscillating climate conditions, possibly related to the break-up of Nordic sea-ice.

Glacial terminations as southern warmings without northern control

E. W. Wolff, H. Fischer & R. Röthlisberger


The mechanisms for localization of black-smoker systems at mid-ocean ridges remain to be fully understood. Seismic data for a segment of the Juan de Fuca ridge with long-lived black-smoker vents reveal ongoing magma recharge into the crustal magma chamber, thereby providing an explanation for the localization.

Expression of the bipolar see-saw in Antarctic climate records during the last deglaciation

B. Stenni, D. Buiron, M. Frezzotti, S. Albani, C. Barbante, E. Bard, J. M. Barnola, M. Baroni, M. Baumgartner, M. Bonazza, E. Capron, E. Castellano, J. Chappellaz, B. Delmonte, S. Falourd, L. Genoni, P. Iacumin, J. Jouzel, S. Kipfstuhl, A. Landais, B. Lemieux-Dudon, V. Maggi, V. Masson-Delmotte, C. Mazzola, B. Minster, M. Montagnat, R. Mulvaney, B. Narcisi, H. Oerter, F. Parrenin, J. R. Petit, C. Ritz, C. Scarchilli, A. Schilt, S. Schüpbach, J. Schwander, E. Selmo, M. Severi, T. F. Stocker & R. Udisti


During the last deglaciation, climate changes over Greenland and Antarctica on millennial timescales were asynchronous. A temperature record from the Talos Dome in Antarctica confirms this asynchrony and shows clear regional differences in deglacial warming between the Indo-Pacific and Atlantic sectors of Antarctica.

Moisture variability in the southwestern United States linked to abrupt glacial climate change

J. D. M. Wagner, J. E. Cole, J. W. Beck, P. J. Patchett, G. M. Henderson & H. R. Barnett


The atmospheric response to millennial-scale circulation changes in the North Atlantic Ocean during the last glacial period has been difficult to constrain. Cave deposits from southwestern North America reveal that atmospheric moisture in this region increased in response to slowdowns of the Atlantic meridional overturning circulation.

Increased ventilation age of the deep northeast Pacific Ocean during the last deglaciation

David C. Lund, Alan C. Mix & John Southon


The amount of radiocarbon-depleted carbon dioxide in the atmosphere rose dramatically during the last deglaciation. Estimates of the radiocarbon content of water at 2.7 km depth in the northeast Pacific Ocean over the past 24,000 years suggest that this water mass was not a significant source of this carbon.



Retreat of the East Antarctic ice sheet during the last glacial termination

Andrew Mackintosh, Nicholas Golledge, Eugene Domack, Robert Dunbar, Amy Leventer, Duanne White, David Pollard, Robert DeConto, David Fink, Dan Zwartz, Damian Gore & Caroline Lavoie


The East Antarctic ice sheet retreated at the end of the last glacial period. Terrestrial and marine data suggest that the retreat began 14,000 years ago, indicating that the East Antarctic ice sheet probably did not contribute to meltwater pulse 1a 14,700 years ago.

Large climate-driven changes of oceanic oxygen concentrations during the last deglaciation

Samuel L. Jaccard & Eric D. Galbraith


Ocean warming during the last deglaciation decreased the solubility of oxygen. A global compilation of marine sediment records shows that the deglacial trend of deoxygenation was overprinted by changes in ocean circulation and marine productivity.

Extreme deepening of the Atlantic overturning circulation during deglaciation

Stephen Barker, Gregor Knorr, Maryline J. Vautravers, Paula Diz & Luke C. Skinner


The termination of the last glacial period was punctuated by the collapse and resumption of Atlantic meridional overturning circulation. Sedimentary records from the South Atlantic Ocean indicate that an unusually deep limb of North Atlantic Deep Water formed after the resumption of overturning circulation during the Bølling–Allerød warm event.

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