Climate Number: 24.2 Teragrams
Since the 1750′s, the amount of methane (CH4) in the atmosphere has increased by 250 percent. Much of this methane is emitted from lakes in northern regions. Glacial movement across the far North (north of 45 degrees) during the last ice age leveled the landscape, carved depressions in the bedrock and deposited ice that formed lakes as it melted. About 40 percent of Earth’s lakes are located north of 45 degrees North. Some of these northern regions have almost half of their surface area covered by lakes. On these lake bottoms, the decomposition of organic matter, much of which comes into lakes as the “active layer” of the surrounding permafrost thaws during the warm months, results in significant releases of methane into the atmosphere. In total, 24.2 teragrams (about 53,000,000,000 pounds) of methane is released from northern lakes each year. As temperatures have warmed over the past few decades, the permafrost “active layer” has become deeper in many areas and the total area covered by permafrost has shrunk. Thawing of Siberia’s Yedoma ice complex, where many of these high latitude lakes occur, could result in a total release of almost 50,000 teragrams of methane.
For Comparison: 24.2 teragrams weighs more than two million Boeing 757-200s.
Seasons: Winter, Spring, Summer, Fall
Source: Walter, KM et al. “Methane bubbling from northern lakes: present and future contributions to the global methane budget.” Philosophical Transactions of the Royal Society: A 365 (2007): 1657-1676.
