Spin the Earth as it was during the last ice age. Switch between seven moments from the Last Glacial Maximum 21,000 years ago to today, and watch the ice sheets grow and collapse while the coastlines move with a sea level more than 100 metres lower than now. Tap a city to see how thick the ice above it was.
An ice age map of the real world
The Ice Age Globe shows Earth as it actually was, not as a stylised diagram. Unlike a flat ice age map it shows the whole planet at once, with the coastlines of the time rather than today’s. Land that is now under the sea, such as Beringia between Siberia and Alaska, Doggerland under the North Sea, and the plain that joined New Zealand’s North and South Islands, appears as dry land in the eras when it really was dry.
What the map shows
Every era shows four things. White is grounded ice, shaded by thickness, so the domes of the great ice sheets stand out from their thin edges. Green and brown is land that exists today. Tan is land that only existed because the sea was lower. The thin orange line is today’s coastline, drawn for orientation, so you can always see how far the shore has moved.
Tap any of the seven marked cities to see what stood at that spot, with the ice drawn to the same scale as the city’s tallest buildings today. Chicago, Calgary and Stockholm disappear under ice. Auckland and Wellington were never iced over, but both sat far from a sea that had retreated toward the edge of the continental shelf, and Wellington had no strait to look across at all.
How we built it
The ice sheets and shifting coastlines come from ICE-6G_C (VM5a), the University of Toronto reconstruction of the last deglaciation by W.R. Peltier, D.F. Argus and R. Drummond, which is constrained by GPS measurements of the Earth’s crust still rebounding from the weight of the vanished ice. We took the model’s ice thickness and palaeotopography grids, worked out how much the bedrock itself has moved since the ice age, added that to the NOAA ETOPO 2022 bedrock relief model, and drew each era’s coastline at the zero metre line. Enclosed basins below sea level are shown as lakes rather than ocean.
What the model cannot show. ICE-6G_C is a global model on a one degree grid, roughly 110 km across. That is fine for the Laurentide and Fennoscandian ice sheets, which were continental in scale, but too coarse to draw small mountain ice fields. The glaciers of the Southern Alps and Fiordland were real and extensive, and the globe barely shows them. City ice thicknesses are the model value for the cell containing the city, so treat them as good estimates rather than survey measurements. Sea level fall was also not identical everywhere, because the Earth’s crust and the shape of the sea surface both changed. Near New Zealand the model puts the drop at a bit over 100 metres, against roughly 120 metres for the global average.
Questions people ask
How much of the world was covered in ice during the ice age
At the Last Glacial Maximum roughly a quarter of the world’s land area was under ice, about two and a half times as much ice as exists today. Most of it sat in two giant sheets over North America and northern Europe.
How low did the sea get during the last ice age
Global sea level was roughly 120 to 130 metres lower than today at the Last Glacial Maximum, because so much of the world’s water was stacked on land as ice. That exposed continental shelves everywhere, adding an area of dry land comparable to South America.
Was New Zealand covered in ice during the last ice age
Mostly no. Glaciers filled the Southern Alps and carved the fiords of Fiordland, and ice reached the lowlands of the southern South Island, but the rest of the country was ice free grassland and scrub. The bigger change was the coastline. With the sea about 100 metres lower here, the North and South Islands were joined into a single island by a broad plain west of today’s Cook Strait.
When did the ice age end
The great melt ran from about 19,000 to about 6,000 years ago, interrupted by the cold snap of the Younger Dryas about 12,900 years ago. Strictly speaking the ice age has not ended at all. We live in a warm interval of it, and Antarctica and Greenland still carry continental ice sheets.
Data. Ice thickness and palaeotopography from ICE-6G_C (VM5a), W.R. Peltier, D.F. Argus and R. Drummond, University of Toronto. Modern relief from NOAA ETOPO 2022. Read more in our feature on what New Zealand looked like during the last ice age.