Let's see 1300 A.D. That was the end of a "Global Warming" cycle that had begun in about 950 A.D., as well as the beginning of a new period of "Global Cooling".
and in less than 300 years, the Thames at London would freeze solid enough to hold ice pageants on. Climate waxes and wanes, never staying just so...
Maybe Robert was making a "countdown clock" for when all life would cease due to climate change....
I believe it was that cooling that drove the Vikings to extinction in Greenland.