Weil-Accardo provide a new set of paleo sea level constraints from the Last Interglacial from Madgascar, collected using modern field techniques and measurements. They find that relative sea level in this location was relatively stable at about 3.4 m above present between 129 and 115 thousand years ago. There is no evidence of fluctuations or higher relative sea level at this location. #PaleoClimate #SeaLevel #ClimateChange #IceSheets https://www.sciencedirect.com/science/article/pii/S0277379123002457

Shackleton et al reconstruct the Earth's energy balance for the past 150 thousand years from δ¹⁸O in benthic foraminifera by utilizing the fact that the amount of energy required to heat/cool the ocean and melt/freeze glacial ice is roughly the same. Their technique does not require a separation of the ice sheet and ocean temperature components of δ¹⁸O. #paleoclimate #IceSheets #ClimateChange https://www.nature.com/articles/s41561-023-01250-y

Toucanne et al investigate the history of the Marine Isotope Stage (MIS) 4 glaciation in Europe with proxy records from the Bay of Biscay. The nature of the sediments in this core indicates that it is unlikely that British Irish and Fennocandian ice sheets merged in the MIS 4 glaciation, and that the North Sea remained ice free. This is in contrast to what is shown in my ice sheet reconstruction, PaleoMIST, and therefore revision is necessary. #IceSheets #Paleoclimate https://www.sciencedirect.com/science/article/pii/S0921818123001947

Halsted et al review the glacial history of the northeastern United States. They could not precisely determine the timing of the Last Glacial Maximum extent, or the timing of the beginning of sustained retreat. They assume that the initial recession began between 24-20 ka, but this is based on proxy records. This problem is related to the lack of suitable material from that time to radiocarbon date, and inheritance of ¹⁰Be in boulders. #Paleoclimate #IceSheets https://onlinelibrary.wiley.com/doi/full/10.1002/jqs.3563

Hodder et al do a deep dive into the stratigraphy of the southern Hudson Bay Lowlands to investigate the claims of Marine Isotope Stage 3 (MIS 3 - 55-27 ka) nonglacial sediments. They find that it is unlikely that the lowlands were ice free during MIS 3, and that instead all pre-Last Glacial Maximum (>20 ka) nonglacial sediments are MIS 5e or older. They conclude that Hudson Bay remained ice covered throughout MIS 3. #PaleoClimate #ClimateChange #IceSheets https://www.cambridge.org/core/journals/quaternary-research/article/was-there-a-nonglacial-episode-in-the-western-hudson-bay-lowland-during-marine-isotope-stage-3/0DB7680C057CD02CBC721CCD7E6100A6

Robel et al create a model of water exfiltration from sediments underneath glaciers as a glacier thins. As the ice thins, the overburden pressue decreases, allowing the water to escape the sediments. This causes a positive feedback loop, where the water will allow the ice to slide easier, promoting more thinning. #ClimateChange #IceSheets #Glaciers #Hydrology https://www.science.org/doi/full/10.1126/sciadv.adh3693

My paper on the impacts of subglacial conditions on ice sheet evolution at glacial time scales is now published in the August issue of the Journal of Glaciology. #IceSheets #Paleoclimate #ClimateChange https://www.cambridge.org/core/journals/journal-of-glaciology/article/impact-of-spatially-varying-ice-sheet-basal-conditions-on-sliding-at-glacial-time-scales/16E8307D3768782F71186B66F1946553

The East GRIP coring has hit the base of the NEGIS ice stream of the Greenland Ice Sheet, finding the glacier is underlain by mud, thus confirming the role of sediment deformation in its dynamics. Undoubtedly this was challenging to pull off, considering the glacier is flowing several centimeters per day. #Greenland #Glacier #IceSheets https://news.ku.dk/all_news/2023/07/pay-dirt-for-ice-core-scientists-in-east-greenland-as-they-reach-bedrock/

Hobart et al present a new Atlantic Ocean benthic δ¹⁸O stack, with a chronology tied to the Chinese speleothem record and associated ice rafted debris events that are correlated to the speleothem record. This new stack does not vary that much from the commonly used LR04 stack, which had a chronology tuned to orbital parameters. They conclude that glacial cycles are paced by precession. #PaleoClimate #IceSheets #ClimateChange https://www.nature.com/articles/s41561-023-01235-x

I am super excited, because I just received the preliminary version of DATED-2, an updated reconstruction of the ice sheet margins for the Eurasian Ice Sheets between 41-10 thousand years ago. I will be working through these to produce ice volume estimates during the next two days. If you are going to #INQUA2023 in Rome, these results will be presented there next week on Monday! #PaleoClimate #IceSheets https://inquaroma2023.exordo.com/programme/presentation/966

Off to #IUGG this morning to talk #IceSheets #CMIP6 #CMIP7 and #ISMIP7, but stopping by @rahmstorf 's talk on #AMOC #TippingPoints first.

Give me a shout if you're at #IUGG23 this week and want to meet up!

An underappreciated point is that while we intuitively think clear blue skies and sun = melt, clouds can also mean (even more) melt. Depending on their composition - ice, water vapour or a mix of the two, they can emit a lot of long wave energy that also helps to drive melt at the surface, especially if warm moist air also moves over the surface. Clouds are still one of our biggest uncertainties in how fast the #IceSheets will melt under #ClimateChange @CopernicusEU @polarportal

Martin Ekman gave the first #GIAschool2023 lecture on The History of Land Uplift Research, drawing from his book The Changing Level of the Baltic Sea during 300 Years: A Clue to Understanding the Earth. This and other Historical Geophysics books here: https://historicalgeophysics.ax

#sciencehistory #GIA #icesheets #sealevel #geophysics #iceage

For those who love glacial #geomorphology (who doesn't?), the Geological Survey of Canada recently published a volume summarizing some of the work they have done to deduce the history of the Laurentide Ice Sheet in northern Canada during the past 15 years. One of the main conclusions they make is that ice flow sets that were previously interpreted as being pre-Last Glacial Maximum (LGM) are now interpreted as being from the LGM. #GlacialGeology #IceSheets #ClimateChange https://doi.org/10.4095/331426

I just submitted a manuscript on deglacial Greenland sea level. I am crossing my fingers the peer review goes smoothly! As a preview, I uploaded the paleo sea level data I compiled to Zenodo. https://zenodo.org/record/8036552 #Greenland #PaleoSeaLevel #SeaLevel #IceSheets #SeaLevelChange #ClimateChange

Almost completed my paper on Greenland sea level changes and my ice sheet reconstruction. It has 177 references, I hope they are not upset by that! I am really hoping to submit tomorrow. #Greenland #SeaLevel #IceSheets #ClimateChange

Shaw et al present a review of sea level changes in southeastern Asia since the Last Glacial Maximum (~20,000 years ago), and provide a perspective on the risks of sea level rise in Singapore. #SeaLevel #PaleoClimate #IceSheets #ClimateChange https://www.nature.com/articles/s43247-023-00868-5

In their model, when the ice sheet retreats, water that ponds at the ice margin is routed into the Atlantic Ocean, which weakens the AMOC. The weaker AMOC causes Northern Hemisphere cooling, which eventually allows the Laurentide Ice Sheet to build up and advance again and stops the routing of water to the ocean. This causes the AMOC strength to return, and therefore warm up the world again at the time when the ice sheet was in an advanced position. 2/2 #PaleoClimate #ClimateChange #IceSheets

Wickert et al propose a southern Laurentide Ice Sheet control on variations in the strength of Atlantic Meridional Overturning Circulation (AMOC) during the last deglaciation. The strength of the AMOC is one of the big controls on global climate, as it brings warm water from the tropics northwards. Their proposed mechanism explains the paradox of having more a more extensive ice sheet during globally warm periods. 1/2 #PaleoClimate #ClimateChange #IceSheets https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL100391

With the 4th day of 12%+ area melting in #Greenland but still no net ice loss, it's probably time to re-up this very old post on the @polarportal on the difference between #melt + ablation or #SMB over #glaciers + #IceSheets

http://polarportal.dk/en/news/news/what-is-the-difference-between-surface-mass-balance-and-melting/