Columbus' voyages sparked epidemics that killed so many people, it may have crashed carbon dioxide levels worldwide

Christopher Columbus's arrival in the Americas in 1492 is often viewed as a significant moment in history, signalling the start of a new era of exploration and colonisation. However, the impact went beyond human history, affecting the Earth's climate.

Columbus' expedition to the Americas brought not only conquest and exploitation but also diseases like smallpox and influenza, devastating indigenous populations who lacked immunity. It's estimated that 80% to 95% of the indigenous population perished within 150 years of European contact, from millions to less than 500.

This population decline had a profound effect on global atmospheric compositions, as revealed by ice cores. These cores, extracted from glaciers, preserve air bubbles that reflect the atmosphere's composition over time. Antarctic ice bubbles from the 16th and 17th centuries showed a notable drop in carbon dioxide levels, which the study's authors attributed to the decline of indigenous populations and subsequent reforestation absorbing carbon dioxide through photosynthesis.

The research also addressed a debate about ice cores' data reliability, comparing Law Dome and West Antarctic Ice Sheet (WAIS) cores. The analysis of a newly drilled Skytrain Ice Rise core confirmed the forest regrowth's gradual carbon dioxide absorption, supporting the idea of significant land use changes in the Americas after Columbus' arrival.

This study highlights the link between historical human actions and climate change, demonstrating a rare phenomenon of human-induced cooling. It underscores humanity's significant impact on Earth's climate balance.

The findings of this research has been published in Nature Communications.