A commenter here a couple of months ago posted a link to a truly great resource of paleoclimate proxy reconstructions covering various time periods all including the time of the Medieval Warm Period, or MWP.
The MWP was a time of generally warmer temperatures in the North Atlantic region lasting from roughly 950AD to 1250AD. It was once thought to have been global in extent and perhaps as warm as or warmer than today. Notably, the 1990 IPCC report contained a rough, manually drawn schematic of global temperatures over the last 1100 years that placed the MWP well above the current global anomaly:
But science progresses, and that crude educated guess has since been replaced with a multitude of scientific studies based on all kinds of climate proxies, from pollen in lake sediment to layers of calcium carbonate in limestone caves. These studies indicate that the medieval warm period was not globally synchronous and was not warmer than today. It remains one of the most common denialists talking points, even if it is of questionable relevance when it comes to what the future likely holds.
So it is with tremendous, unintended irony that, via CO2 [Psuedo] Science, a local denialist drops a truly great resource for illustrating the current state of the science around this issue at our feet.
This web resource can be found here and is a repository of graphics of temperature reconstructions, together with references to the studies they came from, all scattered across an image of our blue planet. So in one spot we have 43 paleoclimate studies visually associated with the area studied.
But what’s so ironic? Well, far from supportting the desired fiction of a globally synchronous MWP, it makes it completely clear that this was not the case. These studies surely do show warm periods, and most show warm periods in medieval times. But they are not synchronized at all.
A few examples will show what I mean. Now remember, this is supposed to show that all over the planet it was nice and warm between ~950AD and 1250AD.
- on the antarctic peninsula we have pronounced warmth 1100-1600AD
- in central Chile,1150-1350
- Yangtze River Delta, China we have warmth from anytime before 1000AD to 1450AD
- in New Zeland: 1200-1350AD
- The ocean near Florida was warmer 650AD to 850AD
- Lake Teletskoye, Altai Mountains, Southern Siberia, Russia, 1200-1450
I think you get the idea. Now, to be sure there are some studies showing a nice ~950AD to ~1250AD warming, notably in the North Atlantic area. But this is supposed to be evidence that the MWP was everywhere! According to their own citations, it was not.
What I did above may look like cherry picking, and technically it is, but in my defense I am just going through the bowlful they provided. These are their cherries, but when we actually look, they are mostly just pits.