I'm always wary about weasel words like "As Much As", especially with no direct reference to see how the original data was presented. I always just assume that

I'm always wary about weasel words like "As Much As", especially with no direct reference to see how the original data was presented. I always just assume that means "By the most optimistic possible reading of the data that furthers the goal of this article" - so it may be that the value from the most extreme single data point of minimum->maximum is 3.6f. The wikipedia graph even states in the description that "Little Ice Age was not a distinct planet-wide period but a regional phenomenon" - though that again in turn doesn't seem to be directly stated in the referenced citation and editorialization too....