Sunday, June 21, 2015

Current Warming 30 Times Faster Than After Warming From Last Ice Age

I recently told someone that our current rate of warming is 30 times faster than when the Earth left its last ice age (viz. the last glacial period), and they didn't believe me. So here are the numbers.

Here is the temperature reconstruction over the last 22,000 years from Shaken et al Nature (2012). Global temperature is in blue, relative to the Holocene:

The time periods along the x-axis are the Last Glacial Maximum (LGM), Oldest Dryas (OD), Bølling–Allerød (B–A), and Younger Dryas (YD).

From the chart:
  • global temperature anomaly in year -18,000 before present is -3.4°C
  • global temperature anomaly in year -11,000 before present is 0.0°C
so the average temperature change is 3.4°C in 7,000 years, or ~ 0.005°C/decade, compared to GISTEMP's current global 30-year trend of 0.16°C/decade

So that's a factor of 32 now compared to then -- rounds to 30 with uncertainties.

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