Over on Isaac Arthur’s Youtube channel he presented some theories on terraforming. One thought that came to mind was if society could place shades and/or mirrors in solar geosynchronous orbit to match Earth’s orbit (to block or enhance light falling on the planet), why not shade the poles – and over time refreeze the waters there.
If we could return to glacial periods, induce an artificial ice-age, but only at the poles, how much land would we lose to the ice — but how much land would we gain as the sea drops?
Here’s a chart with which to start:
Let’s say we target 100 meters of sea level drop refrozen as icecap ice. How much land would that expose to farming? Realize that during the last glacial maximum humans wandered across millions of additional square kilometers of land. If you examine most coast lines you’ll find that the continental shelves are not that deep and extend for tens of kilometers from current coasts.
But how much would there be?
Well, search as I might I couldn’t come up with accurate estimates. I think between 10% and 20% might be reasonable. Some areas would expand considerably, like low flat countries and states (like Florida or Bangladesh). But would it be economically viable? Maybe, if the land exposed was rich and arable and not take too much reparation to get to a production state.
Some haphazard evidence I found…
“We address this issue by calculating an estimation of habitable land area during the Last Glacial Maximum (between 22 and 19 kya) when sea level was 120 m lower than today using the polygon creation function in Google Earth. We then subtract areas of land that were likely uninhabitable during the LGM – either due to glacier cover, extreme aridity, elevation, or areas at high latitudes. From this, the combined habitable land areas of Eurasia, Africa and the Australian landmass are estimated as 76,959,712.4 km2”
“The maximum amount of water trapped in glacial ice occurred roughly 26,000 years ago. This point in time is referred to as the Last Glacial Maximum (LGM). At the time of the LGM, the Earth’s ocean levels were at their lowest point and extensive reaches of dry land were exposed along the continents’ coasts. As the glaciers began to melt, sea level rose worldwide, resulting in nearly a 10% reduction of the Earth’s entire landmass. In the Northeastern Gulf of Mexico, this translates to the inundation (covering with water) of more than 350,000 km2 of what had been dry land, which in turn forced the relocation of plants, animals, and — what is of primary interest to our research — people.
Compared to today, LGM Florida encompassed twice its present land area and was probably slightly cooler and dryer. Furthermore, Florida’s Pleistocene landscape was not as extensively traversed by rivers as it is today. Instead, groundwater was much deeper in the rock and closer to the coasts, as it ran to its lowest level. Typically the greatest amount of surficial fresh water is within 10km of the ocean coastline.”
“In the last major glacial period some 20,000 years ago, New Zealand’s land area was much larger, as the sea was 120–30 metres lower than its present level. The three main islands were joined together as a single island. During this period, rivers such as the Clutha, Rakaia and Waimakariri carried huge loads of sediment all the way to the edge of the continental shelf. The Waikato River (dashed line) originally flowed north and entered the sea on the eastern side of the North Island. About 20,000 years ago it changed to its present course.”