First impressions: Looking at the map of locations, it says there are 18 series, but I only count 15. There are likely more than one series from a couple of locations. Based on what I can see, 7 out of the 15 are extra-tropical in either North America, the North Atlantic, or Europe. So this area is over-represented and the Northern Hemisphere is over-represented.
Why is this important? Because previous work on the Medieval Warm Period has indicated that it was primarily a Northern Hemisphere event strongest in North America and Europe. (The LIA was more global.) So seeing it (a warming event occurring over about 400 years) in this data is not surprising.
2. Got this from Climate Audit, actually (which is instructive, 320 comments in the "Loehle Correction" thread). His last actual data point is 1935 (which is where his corrected Figure 2 ends). If you read the last paragraph of the correction, the difference between MWP and "end of 20th century values" is not significant. He calculated end-of-20th-century using a GISTEMP addendum, it appears.
3. What is significant? The warming rate. Reading Figure 1 roughly, the temperature increase is about 0.6 C in 400 years (I put the peak at about 900 AD). The warming rate in the 20th century was 0.6 C in 100 years, and the rate in the past 25 years was 0.4 C, which is 1.6 C in 100 years. So while comparing peak temperatures is a fun exercise, the rate of warming observed since 1900 is much faster than the rate of warming to the peak of the MWP.
Intriguing pattern: there is a big up and down temperature excursion right after 900 AD. I'd really like to see if that has a global signature or if it was regional.
Comments on "Loehle Correction" (Climate Audit)
Skimming, I note posts 16, 69 (Loehle is skeptical of rates, so I should be too), 95, 199, 203, and 301.
“Why is this important? Because previous work on the Medieval Warm Period has indicated that it was primarily a Northern Hemisphere event strongest in North America and Europe. (The LIA was more global.) So seeing it (a warming event occurring over about 400 years) in this data is not surprising.”
Current temperature models are primarily based on North American readings (most pervasive and “accurate”). Then there is the apples to oranges aspect to your retort - that being modern sampling techniques versus historical climate reconstruction. Consequently, the only possible comparisons are the peaks and valleys.
I’m calling BcoughULLcoughcoughSHcoughIcoughT.
I think we’re kind of stuck with mostly northern hemisphere data since there aren’t many good sampling locations down under.
The rate of increases are notable just because of their lack of periodicity yet the graphs show that each period of cooling began nearly precipitously which might make one question what shut off the cause of warming so suddenly.
Is not the current warming trend also more pronounced in the Northern Hemisphere?
Now that the temperature record is being politically rehabilitated, what do you think of the “Hockey Stick”? Do you think it was simply bad science or was there a more insidious motive?
Not unprecedented though. The 100 years before the Little Ice Age had a temperature plunge about the same.