The ‘Little Ice Age’ of the 16th and 17th centuries was triggered by the genocide of indigenous people in the Americas by European settlers, new research claims.
Scientists have long wondered what caused the drop in temperatures so severe it sometimes caused the River Thames to freeze over.
Now, new analysis by University College London (UCL) argues that so many people were slaughtered or died of disease that the amount of agricultural land dramatically reduced, in turn sucking carbon dioxide (CO²) from the atmosphere.
Known as the ‘Great Dying’, the upheaval following the first contact with Europeans in 1492 is thought to have slashed the population of 60 million living across the Americas down to five or six million within just 100 years.
Published in ‘Quaternary Science Reviews’, the study found that much of the land previously cultivated by indigenous civilisations fell into disuse, becoming swallowed up by forest and grassland. It estimates that an area of 56 million hectares – roughly the size of France – was re-wilded in this way.
The scale of the change is believed to have drawn an amount of CO² from the atmosphere equivalent to two years’ fossil fuel emissions at the present rate.
Professor Mark Maslin, from UCL’s school of Geography, said: “There is a marked cooling around that time which is called the Little Ice Age, and what’s interesting is that we can see natural processes giving a bit of cooling, but to actually get the full cooling – double the natural processes – you have to have this genocide-generated drop in CO².”
The research team examined historical population data, using it to model the reduction of land devoted to agriculture.
They combined this with evidence of a cold period found in ice core records from Antarctica which contained trapped air bubbles. This was supported by records of charcoal and pollen deposits in the Americas.