Composite of Sea Level – for last 600 k years. Note that SL was not always extremely low during glacial periods. From Rabineau et al, EPSL, 2006.

Encrusted speleothems at various levels in caves. (A) Geologic map of Mallorca (B) Schematic cross-section through a coastal cave in Mallorca showing multiple carbonate encrustation levels. (C and D) Present-day and paleo levels of encrusted speleothems related to higher (E) and lower (F) sea-level stands. (G) Typical morphology for tidal range–related carbonate encrustation (size of speleothem, 20 cm). (H) Bathymetric map of the western Mediterranean region and the predicted present-day rate of sea-level change due to GIA.

Sea Level was not always low during the last glacial period. New data from Mallorca (Spanish Island in Mediterranean). Stalagtites from caves. Dorale et al, Science, Feb 2010.

Comparison between Mallorca and other sea-level estimates. (A) Elevation of MIS 5a encrusted speleothems from Mallorca and (B) other deposits from the Bahamas, the Atlantic Coastal Plain, Bermuda, Grand Cayman, and Mallorca. (C) Sea-level reconstruction for Mallorca. Elevations and U/Th ages of encrusted speleothems throughout MIS 5 and at the onset of MIS 4. (D) The reconstructed ocean water 18O, scaled as sea level. (E) 60°N June insolation (27). Vertical yellow bar denotes the timing of peak MIS 5a sea level recorded at Mallorca and shows a good correlation with 60°N June insolation and the reconstructed ocean water 18O scaled as sea level.

Dates are U-Th at 81, 116 and 121 Kyrs.

Sea Level at 81 kyrs was 1 meter above present SL!

Meltwater Pulse 1a – glacial melt from the Mississippi River at end of Last Glacial Maximum.

Changes in Sea Level during the Holocene, the time following the end of the most recent glacial period,

data from Fleming et al. 1998, Fleming 2000, & Milne et al. 2005

Data from Tide Gauges: 18.5 cm Sea Level Rise in 100 years (1900 to 2000). Current SL rise rate 1 to 2 mm/year.

Younger Dryas – classic case of Rapid and Dramatic Climate Change

A deluge of fresh water from glacial Lake Agassiz, flowing into the North Atlantic via the Great Lakes and the St. Lawrence Seaway probably triggered the Younger Dryas event.

Rapid Oceanic and atmospheric changes during the Younger Dryas cold period.

Bakke, et al.,Nature Geoscience 2, 202 - 205 (2009). Data from Scandanavian lake and North Sea cores.

A new paper in Nature,, showing HOW RAPIDLY the climate changes of the Younger Dryas took place.

Ti content is influx of river sediments. DBD is dry bulk density of sediments, a measure of glacial activity.

The sea surface temperature (SST) is from the planktonic forams in cores.

Na and Ca data from Greenland ice core.

Diagram illustrating the atmospheric and oceanic conditions during the Younger Dryas.

The last 400 years of the YD were characterized by a regime that repeatedly ‘flickered’ towards interstadial conditions, controlled by a highly dynamic sea-ice cover in the North Atlantic as the halocline was periodically absent.

At the END of the YD period, North Atlantic sea ice was breaking up and re-forming, causing ‘flickering’ of temperature. Final End of YD occurred in less than 50 years.

Permafrost evidence for severe winter cooling during the Younger Dryas in northern Alaska

How wide-spread was the climate change of the YD?

ICE WEDGES in permafrost in Northern Alaska.

Ice wedges are cracks in the permafrost that open, fill and re-freeze on annual basis.

Stable isotope record (18O) of the Barrow ice‐wedge system (BIWS, red dots) in comparison with the N‐GRIP ice core for the time interval between 10 and 15 kyr cal BP.

Green circles indicate directly AMS 14C dated samples (mean calibrated ages).