Some things worth noting about the "centuries of data"... There wasn't even a "thermometer" until sometime around 1650 or so (give or take), and back then it was inaccurate, inconsistent, and really only good for telling you if it was getting hotter or cooler but no measure of how much so. Not until the early 1700s when Fahrenheit made the first mercury-thermometer and standardized a scale did we even have an ability to take measures of temperature and have an "international" standard to compare. At this time in the world, there were still places we had not been and certainly no one was going around recording lots of weather/temperature data all over the world. Simply put, there is no "centuries of data" to speak of. Modern weather forecasting really happened during my lifetime (and I'm not 40 yet)... so once you get back around 100 years or so, such data is not entirely reliable nor widespread as it was not being taken for the purpose of projecting global anything.