Thing is with the Medieval Warming Period, ice core samples & botanical records indicate that globally (as opposed to locally in Europe), overall temperatures decreased slightly.
I don't believe there is any consistent, overall change to climate that applies over the entire globe simultaneously. At the time the Vikings were leaving Greenland because it was getting too cold to grow crops and raise cattle, the people of the greatest civilization of the times in South East Asia, the Khmers of Cambodia who built the amazing temples and irrigation system at Angkor Wat, who dominated the entire region, including the Vietnamese who were later so troublesome to the Americans, suffered a different type of climate change.
For at least a couple of seasons, the monsoons did not arrive and the snows of the Himalayas did not melt, which normally flow down the Mekong and fill the lakes and irrigation systems around Angkor Wat.
The agricultural system of the Khmer civilization was devastated. The neighbouring Thais took that opportunity to invade, and ransaked the capital in 1431.
It was always a mystery why the local population fled, never to return, leaving the temples and city to become a lost city, gradually becoming overgrown by jungle until the French colonialist discovered it in the 19th century.
The jigsaw is now making sense, thanks to some Australian scientists examining tree rings of ancient forests in the area.
The upsurge in overall global temperatures is the fastest & most pronounced we've seen so far
I think you are referring to what has been measured
so far. What has been measured during the past 100 years is far, far greater than what has been measured during the past 20 million years. Statements like your above quote have to be interpreted.
I'll give you the correct interpretation, as follows:
"The great paucity of information on global temperatures during the past 20 million years years provides no firm evidence as to whether or not current warming trends are faster than what has occurred during any similar period in the past. The resolution
of our data is not sufficient. (See, we're still on the topic of photography. Resolution
is very important
Of course, when climate scientists occasionally make such statements in line with your quote above, they are probably advised by the media experts in charge, not to tell the truth, or it may cause people to think for themselves and undermine the cause of climate-change-alarmism.