I don't think much of that article. It appears to be from a climate heating-denialist book and has a number of errors.

If you look at the Wikipedia page on the subject: https://en.wikipedia.org/wiki/Medieval_Warm_Period ...it shows that the medieval warm period was not a global phenomenon.

It also contains comical unchecked claims such as "During the Medieval Warm Period, wine grapes were grown as far north as England, where growing grapes is now not feasible". This is blatantly false, as there is a wine industry in England. With summers getting increasingly warm, recent decades have even seen the development of Welsh wines.

Edit: actually it seems to be a selection of articles from different sources, but prominence is given to "Evidence-Based Climate Science", an obscure book, for some reason.