Question 38

For millennia, the frozen soils of the Arctic, known as permafrost, have acted as a vast repository for organic carbon, effectively locking away the remains of ancient plants and animals. However, as global temperatures rise, these permanently frozen grounds are beginning to thaw at an unprecedented rate. This thawing process reactivates dormant microbes in the soil, which then begin to decompose the newly accessible organic matter. A significant byproduct of this microbial activity is the release of methane, a greenhouse gas that is far more effective at trapping heat in the atmosphere than carbon dioxide over the short term. The release of this gas accelerates atmospheric warming, which in turn causes even more permafrost to melt. This self-perpetuating cycle, often referred to as a positive feedback loop, poses a critical challenge to climate scientists. Because the scale of potential emissions from these northern reservoirs remains difficult to quantify precisely, what was once a stable carbon sink threatens to become a volatile source of emissions, potentially undermining international efforts to stabilize global climate patterns. What is the main concern regarding permafrost thawing expressed in the passage?