Question 28

Permafrost, the permanently frozen ground covering vast stretches of the Northern Hemisphere, serves as one of the Earth's largest terrestrial carbon sinks. For thousands of years, this frozen soil has locked away the remains of ancient plants and animals, effectively halting the decomposition process. However, as global temperatures rise, this permafrost is beginning to thaw at an unprecedented rate. When the ice melts, the organic matter within the soil becomes accessible to microbes, which break it down and release the by-products into the atmosphere. Depending on oxygen availability, this process emits either carbon dioxide or methane. The release of methane is particularly concerning because it is significantly more efficient at trapping heat than carbon dioxide over shorter timeframes. This creates a dangerous feedback loop: as the planet warms, more permafrost thaws, releasing more greenhouse gases, which in turn causes further warming. Consequently, what was once a stable storage system for carbon is threatening to become a major contributor to global climate instability. What is the main conclusion drawn by the writer regarding permafrost?