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Description

You've probably heard of Post-Glacial Rebound, the phenomenon where land previously depressed by Ice sheets rebounds once they melt, well turns out it's still happening pretty quickly in Canada and Finland, and land will continue to rise in the foreseeable future ... The implication is that coastlines were actually significantly different in historical times and should appear differently on maps from as recently as 1,000 years ago, and the changes get larger the further back one's go, the coastlines of the southern hudson bay advances by as quickly as 3 km a century , and the Puerto-Rico sized Akimiski island between Ontario and Quebec just did not exist 3,000 years ago! I was surprised to see it's never been taken into account in worldAs, so I decided to make a few patches...

North America:

I couldn't find definitive maps for recent dates (most recent complete one was for 3000 BC, and is almost 20 years old) , so I made a model mainly based on "Uncertainties of Glacial Isostatic Adjustment Model Predictions in North America Associated With 3D Structure ", 2020, which provides map of historical recent uplift, and extrapolated it using curves of uplift speed and altitude at various locations from "The Viscosity of the Top Third of the Lower Mantle Estimated Using GPS, GRACE, and Relative Sea Level Measurements of Glacial Isostatic Adjustment " , 2021, which reviews and compares some of the litterature around Canadian isostatic rebound, I checked if it was coherent with some maps of past and future uplift, then ploted it on QGIS with GEBCO elevation data.

There is some variation in the uplift rate of the Northern Hudson bay/Foxe Bassin in recent papers, so I took a conservative low one (which also fits some of the archeological studies better for this timespan) . It's probably worth noting that some of the lowest lying islands of Foxe Basin are very young (most of their area is <2k years old) despite size of over 1000 km²; if this model gives a good order of magnitude, then canada gains at least 4,000 km² (likely significantly more) of land per century from uplift, fun! By comparison Finland gains 1,000 km² (TIKKANEN & Oksanen , 2002)

For 2,000 BC, same methods as above, although it's sufficiently old I can more accurately compare with pre-made maps, (notably Dyke, Arthur S. (2004) , by comparison my model is somewhat conservative for the southern hudson bay and foxe basin)

Baltic Sea:

2,500 BC and 1 AD were quite straightforward and mostly based on the maps of Markku Poutanen & Holger Steffen, 2014 and Alex Nap, 2017 for 1 AD, 2400 BC and 3000 BC

The "far future" map is the coastline once the region reach isostatic equilibrium... so probably at least 10,000+ years away in some spots, this assume little anthropogenic effect of course... It's mostly based on the prediction of residual uplift from Holger Steffen, Georg Kaufmann, Patrick Wu, 2006 , the coastline of the "Bothnian Lake" is taken from the aforementioned Poutanen, Steffen, as for lakes it's a mix between some dedicated studies (such as Seppä, Tikkanen, Mäkiaho, 2012 for Lake Pielinen), others are rough estimates based on the general topography change and estimates of the first two papers I mentionned.

So far, I haven't found good sources for the long term, Isostatic Equilibrium state of Canada, unlike those for the Baltic sea, the most I could find were some quick calculation of order of magnitude of remaining uplifts (Eastern Quebec is expected to rise by another 100m), but nothing more, so I haven't tried mapping it, but from quick estimates, it should look like this , James Bay and Foxe Basin should be entirely emerged, Hudson bay should be smaller, and a whole bunch of Arctic islands should be linked. Fun fact, it's already expected in the litterature that the emergence of new land will cause sovereignty problems between Quebec, Ontario, Nunavut and Cree nations!

Description

You've probably heard of Post-Glacial Rebound, the phenomenon where land previously depressed by Ice sheets rebounds once they melt, well turns out it's still happening pretty quickly in Canada and Finland, and land will continue to rise in the foreseeable future ... The implication is that coastlines were actually significantly different in historical times and should appear differently on maps from as recently as 1,000 years ago, and the changes get larger the further back one's go, the coastlines of the southern hudson bay advances by as quickly as 3 km a century , and the Puerto-Rico sized Akimiski island between Ontario and Quebec just did not exist 3,000 years ago! I was surprised to see it's never been taken into account in worldAs, so I decided to make a few patches...

North America:

I couldn't find definitive maps for recent dates (most recent complete one was for 3000 BC, and is almost 20 years old) , so I made a model mainly based on "Uncertainties of Glacial Isostatic Adjustment Model Predictions in North America Associated With 3D Structure ", 2020, which provides map of historical recent uplift, and extrapolated it using curves of uplift speed and altitude at various locations from "The Viscosity of the Top Third of the Lower Mantle Estimated Using GPS, GRACE, and Relative Sea Level Measurements of Glacial Isostatic Adjustment " , 2021, which reviews and compares some of the litterature around Canadian isostatic rebound, I checked if it was coherent with some maps of past and future uplift, then ploted it on QGIS with GEBCO elevation data.

There is some variation in the uplift rate of the Northern Hudson bay/Foxe Bassin in recent papers, so I took a conservative low one (which also fits some of the archeological studies better for this timespan) . It's probably worth noting that some of the lowest lying islands of Foxe Basin are very young (most of their area is <2k years old) despite size of over 1000 km²; if this model gives a good order of magnitude, then canada gains at least 4,000 km² (likely significantly more) of land per century from uplift, fun! By comparison Finland gains 1,000 km² (TIKKANEN & Oksanen , 2002)

For 2,000 BC, same methods as above, although it's sufficiently old I can more accurately compare with pre-made maps, (notably Dyke, Arthur S. (2004) , by comparison my model is somewhat conservative for the southern hudson bay and foxe basin)

Baltic Sea:

2,500 BC and 1 AD were quite straightforward and mostly based on the maps of Markku Poutanen & Holger Steffen, 2014 and Alex Nap, 2017 for 1 AD, 2400 BC and 3000 BC

The "far future" map is the coastline once the region reach isostatic equilibrium... so probably at least 10,000+ years away in some spots, this assume little anthropogenic effect of course... It's mostly based on the prediction of residual uplift from Holger Steffen, Georg Kaufmann, Patrick Wu, 2006 , the coastline of the "Bothnian Lake" is taken from the aforementioned Poutanen, Steffen, as for lakes it's a mix between some dedicated studies (such as Seppä, Tikkanen, Mäkiaho, 2012 for Lake Pielinen), others are rough estimates based on the general topography change and estimates of the first two papers I mentionned.

So far, I haven't found good sources for the long term, Isostatic Equilibrium state of Canada, unlike those for the Baltic sea, the most I could find were some quick calculation of order of magnitude of remaining uplifts (Eastern Quebec is expected to rise by another 100m), but nothing more, so I haven't tried mapping it, but from quick estimates, it should look like this , James Bay and Foxe Basin should be entirely emerged, Hudson bay should be smaller, and a whole bunch of Arctic islands should be linked. Fun fact, it's already expected in the litterature that the emergence of new land will cause sovereignty problems between Quebec, Ontario, Nunavut and Cree nations!