English: These two graphs show global temperatures for two different time periods (Hansen and Sato, 2011). The top graph shows global surface temperature for the past 5.3 million years as inferred from cores of ocean sediments taken all around the global ocean. The last 800,000 years are expanded in the bottom graph. From the cited public-domain source (Hansen and Sato, 2011): "Assumptions are required to estimate global surface temperature change from deep ocean changes, but we argue and present evidence that the ocean core record yields a better measure of global mean change than that provided by polar ice cores.

Civilization developed during the Holocene, the interglacial period of the past 10,000 years during which global temperature and sea level have been unusually stable. (This image) shows two prior interglacial periods that were warmer than the Holocene: the Eemian (about 130,000 years ago) and the Holsteinian (about 400,000 years ago). In both periods sea level reached heights at least 4-6 meters (13-20 feet) greater than today. In the early Pliocene (around 3 million years ago) global temperature was no more than 1-2°C warmer than today, yet sea level was 15-25 meters (50-80 feet) higher."