Human activity involving fossil fuels has been a much bigger contributor to climate change than previously thought, a new study from the University of Rochester has found. Methane is a greenhouse gas that, compared to carbon dioxide, doesn’t last very long in the atmosphere. However, and as with other greenhouse gases, it does trap heat, contributing to the harmful warming of our planet.
Greenhouse gases result from both natural processes and human activity; in the latter category, carbon dioxide is the number one greenhouse gas followed by methane. Whereas carbon dioxide stays in the atmosphere for around 100 years, methane stays in the atmosphere for around a decade, making it a key target in emissions reduction efforts. However, it is possible that scientists have underestimated the amount of methane resulting from human activity.
Wildlife and plants naturally produce methane referred to as biological methane, which can be detected by the presence of an isotope called carbon-14. In comparison, fossil methane, which has spent millions of years trapped in ancient hydrocarbon deposits, doesn’t contain the same isotope. Fossil methane can be released due to some natural processes, but also from human activity — namely, the coal, oil, and gas industries.
Teasing apart the source of fossil versus biological methane in the atmosphere is tricky. The new study involved a different method: drilling ice from Greenland that features small bubbles of trapped ancient air. By melting the ice, the researchers extracted the air and were able to peer into its chemical composition.
The results were surprising — before the Industrial Revolution, the amount of naturally released fossil methane was around 10 times lower than previously thought. This means that human activities may be more responsible for methane emissions to a tune of 25- to 40-percent.
There’s a glimmer of good news, however, and it’s that curbing human activities that result in methane emissions may have a greater impact on reducing climate change than anticipated. Benjamin Hmiel, one of the researchers behind the study, explained:
I don’t want to get too hopeless on this because my data does have a positive implication: most of the methane emissions are anthropogenic, so we have more control. If we can reduce our emissions, it’s going to have more of an impact.