Is global warming unprecedented?
No. The earth’s average temperature has increased over the last 30 years, and many point to this as evidence of a dangerous human-induced warming. But temperatures have risen and fallen many times before that. The Medieval Warm Period (c. 1100-1450) and earlier periods were likely as warm or warmer than the present. The earth was cooling as recently as the period from the 1940s to the 1970s, giving rise to fears of a coming ice age, until temperatures began to increase in the mid-1970s up through the present day. While it is likely that mankind’s activities have made a contribution to warming, current temperatures are within the range of natural variability.
