If you look at the study I posted on this in the climategate thread which takes a more global look at MCA period studies https://www.researchgate.net/publication/225228973_Was_There_a_'Medieval_Warm_Period'_and_if_so_Where_and_When
you can see that there isn't global warming during the MCA. What warming there is differs in timing by centuries for different locations and other areas show no warming.
That's a very localised study you are posting - for Kamchutka only, and for July temps only. Which also acknowledges further research is needed to understand the 'spatially complex' pattern of climate change in the area. Here's the full abstract here. https://www.sciencedirect.com/science/article/abs/pii/S0277379113000279
