Re #1: About 125,000 years ago[0] during the Pleistocene epoch. Wikipedia has a history of Earth's temperatures[1]. Somewhat related, XKCD[2] made a nice illus

Re #1: About 125,000 years ago[0] during the Pleistocene epoch. Wikipedia has a history of Earth's temperatures[1]. Somewhat related, XKCD[2] made a nice illustration to explain the temperature fluctuations of the last 22,000 years. [0]: http://science.sciencemag.org/content/355/6322/276 http://science.sciencemag.org/content/355/6322/276 [1]: https://en.wikipedia.org/wiki/Geologic_temperature_record#/media/File:All_palaeotemps.svg https://en.wikipedia.org/wiki/Geologic_temperature_record#/m... [2]: https://xkcd.com/1732/ https://xkcd.com/1732/