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