Scientists have long believed that the climate-altering gases began building up in the atmosphere about the year 1750 — the dawn of the Industrial Revolution.
But writing in the journal Nature, lead researcher Celia Sapart of Utrecht University in the Netherlands says that air bubbles stored deep in glaciers reveal that average global methane emissions per person during the Roman Empire and China’s Han Dynasty were much greater than had been believed.
While the total amount of methane produced today is about 70 times greater than in preindustrial times, clearing cropland, cooking and creating metals from the years 1 to 400 A.D. started the trend of manmade greenhouse gas increasing in the atmosphere.
Other spikes in methane emissions occurred during a period known as the Medieval Climate Anomaly, from about 800 to 1200 A.D., and during the Little Ice Age, between 1300 and 1600.
The researchers say they were able to determine what part of methane emissions during those times was due to wildfires and other natural causes as opposed to human activities.
“The results show that between 100 B.C. and A.D. 1600, human activity may have been responsible for roughly 20-30% of the total pyrogenic (created by burning or heat) methane emissions,” the authors wrote.
Art: Pietro da Cortona, The Forge of Vulcan