100,000 years ago
Homo Sapiens enters the forests of Europe
A group of Homo sapiens migrates out of Africa, following earlier forays and other human species, although they do not establish a permanent presence. The climate is slowly growing colder on a descent into the most recent glacial freeze, which covers northern latitudes in ice and takes sea levels down to an extreme of 140 meters below present level. (more)
Migration paths of Homo sapiens, maximum glacial extent and land exposed by low sea level during the most recent ice age
Human Migration Timeline
200 – 130,000 years ago
130 – 90,000
90 – 55,000
55 – 30,000
30 – 10,000
10 – 1,000
7.8 billion in 2021
415 parts per million in 2021
15° C in 2021
in hundreds of meters from datum in 1900
Note: Lighter yellow lines show oscillation between northern and southern hemispheres during ice ages
Sea level in hundreds of meters (note change of scale)
Slow descent into ice age following Eemian interglacial period
Toba volcano eruption
Humans close to extinction
Ice sheet maximum extent
Extinction of large mammals
Thousands of years
Sea level low -130 ± meters
Average temp low point ~ 9°C
CO2 low ~ 190 ppm
Timescale of 100,000 years
Venturing outside the tropical zone, bands of hunter/gatherers learn how to live in new landscapes with harsh winters, using fire for warmth as well as cooking. Whenever the cold relented even slightly, they and others that follow, encounter, fight with, and mate with Neanderthal people who are better adapted to winter and already skillful hunters. In the depths of the glacial period, Homo sapiens nearly go extinct even in Africa, when a large volcanic eruption throws ash across the skies and chills the tropics as well as northern lands. The cold world is also dry, turning forest into grassy savannah or steppe, even as fire becomes more crucial to survival.
The last ice age is not uniformly cold. The tropics remain steadily warm, although sometimes wetter and sometimes dryer, but the higher latitudes both north and south swing dramatically in temperature. Sudden spikes in temperature can
happen in a matter of decades, lasting 1000 years or less, then descending back into the freezer. First the southern hemisphere warms, then global ocean currents carry the heat north. The south cools, the north warms, particularly the oceans around Greenland. Averaging across the globe, temperatures seem less volatile, but change near the poles can be dramatic. A particularly sharp spike in temperatures recorded in Greenland 11,600 years ago took less than a century to raise average temperatures over 10°C, bringing the global climate into its currently stable range.
Animals in the higher latitudes move to follow their habitats. They suffer when changing conditions squeeze their food supply and thrive when new areas open up that suit them. Neanderthal and other human species travel through Europe and Asia, leaving evidence in charcoal, bones, tools, weapons, and art.
Image: Composite of Adobe Stock Images
Wikipedia. (2014). "Human_migrations_and_mitochondrial_haplogroups." Retrieved 22 September 2018, 2018, from https://en.wikipedia.org/wiki/Early_human_migrations#/media/File:Human_migrations_and_mitochondrial_haplogroups.PNG
CO2: Petit, J. R., et al. (1999). "Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica." Nature 399: 429–436. https://doi.org/10.1038/20859 Data also available at: https://commons.wikimedia.org/wiki/File:Vostok_Petit_data.svg
Temperature: Petit (1999) as above.
Buizert, C., B. Adrian, J. Ahn, M. Albert, R. B. Alley, D. Baggenstos and T. E. Woodruff (2015). "Precise interpolar phasing of abrupt climate change during the last ice age." Nature 520(7549): 661-665. doi.org/10.1038/nature14401
Manley, R. (2018). "Ice Cores." Climate Data Information, 2019, from http://www.climatedata.info/proxies/ice-cores/.
Population: Wikipedia. (2018). "World Population Estimates." Retrieved 20 September, 2018, from https://en.wikipedia.org/wiki/World_population_estimates.