So they ended up an Iron Age European society, virtually unable to make their own iron. A second item on my checklist is climate change. Climate can get warmer or colder or dryer or wetter. In the case of the Vikings -- in Greenland, the climate got colder in the late 1300s, and especially in the 1400s. But a cold climate isn't necessarily fatal, because the Inuit -- the Eskimos inhabiting
因此虽然他们是铁器时代的欧洲社会，但当他们崩溃时， 他们已经不能冶炼铁器了。在清单上的第二点是： 气候变化：或变暖、或变冷、或变干、或变湿。 在这个案例中，14世纪晚期，尤其是15世纪， 气候变冷。但寒冷的气候并不是决定性的因素，