This article,

Earth's temperature in the past 18,000 years

seems to show Earth temperature during 5000-3000 years ago was approximately a degree hotter than today. Is this true, were there times during human inhabited Earth were Earth average temperature was hotter than today? If so, were there other moments not listed in that graphic from former times?

  • $\begingroup$ Note todays temp matters a lot less than what the temprature is predicted to reach in the next few decades. $\endgroup$
    – John
    Sep 14 '19 at 1:04

Answers would be "no" and "no."

That graphic isn't sourced, but it appears to refer to the Mid-Holocene Warm Period, roughly 7,000 to 5,000 years ago.

According to NOAA and other sources, the warming of the Mid-Holocene Warm Period was limited to part of the Northern Hemisphere; some regions would have been warmer than today, but not the globe:

It appears clear that changes in Earth's orbit have operated slowly over thousands and millions of years to change the amount of solar radiation reaching each latitudinal band of Earth during each month. These orbital changes can be easily calculated and predict that the Northern Hemisphere should have been warmer than today during the mid-Holocene in the summer and colder in the winter.

This graphic from the NOAA page cited above shows the estimated mid-Holocene temperature anomalies (variation from mean). Model-data comparison of surface temperature anomalies for the mid-Holocene (average of 5,500 to 6,500 years ago). Though humans had migrated widely the period, relatively few would have been living outside that cooler blue band.

Were there earlier warmer periods for modern-ish humanity before that? No, since earth was emerging from a glacial period starting about 11,500 years ago, and global average temperatures were gradually rebounding from about 6 degree Celsius cooler than today.

The next previous warm era would have been the Eemian interglacial period about 130,000 years ago, which again was associated with orbital variations.

You could quibble about the era of "human-inhabited" earth; homo sapiens arose about 300,000 years ago, but remained limited to Africa until about 70,000-50,000 years ago.

  • $\begingroup$ It doesnt really matter that they were limited to Africa, otherwise we would have to consider they werent in America until 13,000 years ago, in Antarticta until 100 years ago, etc. $\endgroup$
    – Pablo
    Sep 9 '19 at 19:23
  • $\begingroup$ *Antarctica. I voted you up since you gave me information I dont know, yet, looking for the Eemian period you mentioned I found this " It is estimated that the Eemian temperatures were 1–2° higher than the current ones (Kaspar, 2005)" sciencedirect.com/topics/earth-and-planetary-sciences/eemian $\endgroup$
    – Pablo
    Sep 9 '19 at 19:28
  • $\begingroup$ Added a graphic from the NOAA page. @Pablo Mentioning where humans lived during the era in question goes to the "human-inhabited Earth" part of the question; most humans were living in an anomalously cool part of the globe during the Mid-Holocene. $\endgroup$ Sep 9 '19 at 20:29

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