Wait no longer (
https://www.financialexpress.com/archive/our-world-was-hotter-1000-years-ago/572665/ )
Further back in history
Its clear that the world was warmer during medieval times. By mapping the data published (all peer-reviewed) by 752 individual scientists from 442 separate research institutions across 41 different countries, and correlating their comparisons of temperatures changes since medieval times, after factoring in the fact that these studies use a range of ice cores, stalagmites, sediments and isotopes, we find that temperatures were about 0.5C warmer worldwide.
Prior to IPCCs third assessment report of 2001, the accepted depiction of the prior millenniums warmth was that published in the panels 1990 maiden assessment global temperatures had fluctuated drastically over the period. And data derived from sources including tree-rings, lake sediments, ice cores and historical documents bear out that position. Indeed, its abundantly evident that since the last glacial period ended, over 14,000 years ago, the Earths climate has undergone multi-century swings from warming to cooling that occur often and with remarkable rapidity. And not one but three such radical shifts occurred within the past millennium.
The years 900-1300 AD have been labelled the Medieval Warming Period, as global temperatures rose precipitously from the bitter cold of the previous epochthe Dark Agesto levels several degrees warmer than today. A sudden period of cooling then followed and lasted until the year 1850. This Little Ice Age brought on extremely cold temperatures, corresponding with three periods of protracted solar inactivity, the lowest temperatures coinciding with the quietest of the three (The Maunder Minimum 1645-1710). And then began the modern warming period, which, by the way, many scientists believe ended with the millennium itself.
Given these natural shifts over the past 1,000 years, its certainly not surprising that after a period of cooling, which followed a period of warming, wed again enter a period of warming. And that, of course, presented quite the quandary to opportunists hell-bent on blaming warming on industrial revolution-triggered atmospheric CO2 increases. Something had to be done to convince the world that modern warming was unprecedented and could therefore only be explained by something unnatural, specifically the greenhouse effect. And something was indeed done.
Thats just the medieval warming - same goes for the earlier warmings refered to.