IIRC glacial periods during the Ice Age could come pretty fast. WI the glaciers came down to northern Europe and the northeastern US (have yall seen the maps?) and caused sea levels to drop. What happens if this glaciation is completed over a seventy year period from 1865 to 1935? Japan, Britain, Taiwan, Indonesia and the Philippines are connected to Eurasia. North America and Eurasia are all connected by land bridges by 1935. Most of the UK is under ice. One question is how soon can the "reclaimed" land be put to any productive use? Is the soil too salty from being undersea to be much more than a desert?