Deep in the compacted snow of Greenland, scientists have pulled out pockets of air that are up to 40 years old — and what they found inside is changing how we understand climate change.
An international team from Utrecht University and the University of Maryland has developed a new way to study methane, a powerful greenhouse gas responsible for roughly 30% of the warming our planet has experienced so far. The researchers drilled into a dense layer of snow called firn at the EastGRIP research station in Greenland and collected air samples that were as much as four decades old. By analyzing the chemical makeup of this trapped air, they created the first-ever record of how methane has behaved in our atmosphere over time.
Methane is the second-most important greenhouse gas after carbon dioxide. It comes from natural sources like wetlands and rice paddies, and from human activities like farming and burning fossil fuels. The atmosphere naturally removes methane through chemical reactions, but scientists have struggled to understand whether this cleanup process is changing.
The breakthrough came when researchers noticed something unexpected in their measurements: certain rare methane molecules, called clumped isotopes, were present in much higher amounts than they should be based on known methane sources. After running computer models spanning 1,000 years of atmospheric history, the team determined these molecules form during the methane removal process itself — and their abundance tells us how efficiently the atmosphere is cleaning itself.
"Since the start of industrialization, humans have disrupted the balance between methane emissions and breakdown so profoundly that it's visible in our measurements," said Malavika Sivan, the study's lead author.
Getting those measurements required serious effort. Analyzing clumped methane isotopes demanded about 1,000 liters (264 gallons) of air — more than a typical bathtub can hold. The team collected 500 to 700 liters (130 to 185 gallons) of 40-year-old air by essentially pumping it out from deep within the snow. Each sample revealed what the atmosphere was like decades ago.
The findings matter because methane reduction offers one of the quickest ways to slow warming in the near term. The study gives scientists a new tool to track whether cleanup efforts are actually working. Professor Thomas Röckmann of Utrecht University noted that international agreements like the Global Methane Pledge, which aims to cut methane emissions 30% by 2030, could help reverse the trend — if nations follow through.