Today our major greenhouse gas is CO2 but in the past, it was lead. Which isn’t a greenhouse gas but thanks to mining during the 1100s, a lot of it was in the air and man, that could not have been a good time for people breathing it. New ice cores prove that lead pollution was just as bad then as air pollution during the Industrial Revolution which goes to show, we’ve always been pretty bad at this.
Ice cores taken from a glacier in the Swiss-Italian Alps track the rise and fall of lead pollution. The substance was used heavily in the building of churches as well as more practical things like water pipes. Which we know now is not a great idea.
The ice core also showed how historical events were linked to lead mining in that the deaths and coronations of kings were often tied to rise and falls in production and at least one very famous murder was tracked through lead found in the ice.