A few decades ago, it was found that the most remote corners of our planet store carbon for many years in frozen permafrost. But recent research conducted by NASA experts shows that permafrost in the Arctic is approaching its tipping point. As permafrost melts, greenhouse gases such as carbon dioxide and methane are released, both of which accelerate global warming.
Frozen arctic permafrost
Permafrost is soil that remains permanently frozen for long periods of time (often decades, centuries, or even millennia), usually throughout the year. Permafrost, found mostly in northern regions of the world such as the Arctic and parts of Alaska, Canada and Siberia, serves as a natural carbon store. This frozen ground contains organic matter such as dead plants and animal remains that have not fully decomposed due to cold weather.
Underground carbon is safe
Over time, these materials accumulate large amounts of carbon, effectively locking it underground in what has long been considered “carbon security.” But as the Arctic warms at a faster rate (up to four times faster than other regions), the permafrost is beginning to melt. This melting process releases previously accumulated greenhouse gases, including carbon dioxide and methane, into the atmosphere.
These heat-trapping gases contribute to global warming by transforming permafrost from a carbon sink to a source of emissions.
Greenhouse gases released from permafrost
A recent study by NASA and Stockholm University scientists provides an intriguing insight into this vast permafrost region. The study carefully analyzed where and how greenhouse gases are escaping as the Arctic warms.
Researchers found that between 2000 and 2020, emissions from land nearly dwarfed the amount of carbon dioxide absorbed.
Thus, the permafrost region makes an increasing contribution to global warming. This phenomenon is also associated with methane, another greenhouse gas. While methane isn’t as long-lived as carbon dioxide, it can make a pretty big dent in its short lifespan by trapping heat much more efficiently.
Permafrost disrupts balance
Abhishek Chatterjee is a scientist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California and co-author of the study.
“We know that the permafrost region has been capturing and storing carbon for tens of thousands of years,” says Chatterjee. “But now we see that climate-driven change is tipping the balance towards permafrost becoming a net source of greenhouse gas emissions.”
Perhaps the concept of permafrost needs to be expanded a little more. A section of the permafrost core reveals layers of icy soil. These lands are full of dead plant and animal remains that can be dated by various methods. This is the organic carbon that microbes feed on when permafrost melts and decomposes, releasing some of it as a greenhouse gas.
Monitoring permafrost emissions
Scientists use a variety of methods to track emissions, from ground-based instruments to airplanes and satellites. NASA’s Arctic and Northern Vulnerability Experiment (ABoVE) focuses on Alaska and Western Canada. However, measuring in large areas in the north is not easy.
The new study, part of the Global Carbon Project’s RECCAP-2 project, tracked three greenhouse gases – carbon dioxide, methane and nitrous oxide – in 7 million square miles of permafrost from 2000 to 2020.
Carbon emissions in Arctic ecosystems
Experts found that forests absorb slightly more carbon dioxide than they emit. But this was largely offset by carbon dioxide emissions from lakes and rivers, as well as forest and tundra fires.
The data shows that greenhouse gases contribute to global warming over a 20-year period. But over a 100-year period, emissions and absorption will largely offset each other. Thus, the region oscillates between being a carbon source and a weak carbon sink.
A complex picture emerged
To reach these conclusions about permafrost melting and associated greenhouse gas emissions, scientists had to use a number of methods. “Top-down” methods estimate emissions using ground and airborne measurements as well as ecosystem models, while “bottom-up” methods are used by NASA’s Orbital Carbon Observatory-2 (OCO-2) and Greenhouse Gas Monitoring Satellite JAXA (Japan Aerospace). Research Agency).
“This study is one of the first where we have been able to integrate different methods and datasets to bring together this very comprehensive greenhouse gas budget in a single report,” Chatterjee said. he said. “It reveals a very complex picture.”
Source: Port Altele
