Depopulation of the Americas by European colonization may have initiated the Little Ice Age

Land use change in the Americas
Land use change in the Americas ca 1600

Times series for global atmospheric CO2 concentration and carbon isotope ratio time series derived from Antarctic ice cores reveal a decline in global atmospheric CO2 concentration of 7–10 ppm in the late 1500s and early 1600s. This corresponds to the Little Ice Age conventionally dated to the 16th to the 19th centuries during which global surface air temperatures dropped by 0.15°C. In a new study the removal by 1600 due to European introduced epidemics of 90% of the estimated pre-1492 population of 60.5 million in the Americas resulted in 55.8 million hectares of abandoned land. In the study it is calculated that the resulting uptake of carbon from this land use change may account for 47–67% of the atmospheric CO2 decline that initiated the Little Ice Age.