American colonisation triggered climate change

  I have seen suggestions of this sort of thing before.  That the 'Little Ice Age' was in part at least caused by the massacre of millions of people in China during the Mongol conquest or by the Black Death.  In both cases for the same reason as stated for the colonisation of the Americas, in terms of reduction of agriculture as populations plummeted leading to more carbon dioxide being absorbed.  Although in the case of China another factor was that since rich was important in the south especially a drop in use of paddy fields also meant less methane being produced and this is markedly stronger a greenhouse gas than CO2. 

  I suspect all three might be a factor in the Little Ice Age.  Either in initially starting it or prolonging and deepening it.