In the global effort to combat climate change, soil has been recognized as the largest terrestrial carbon sink. Yet, most climate policies and carbon accounting systems focus only on the top 30 centimeters. A comprehensive new review, led by an international team of scientists from institutions including The University of Western Australia, Amity University, and Tsinghua University, explains why this surface-level view is dangerously incomplete and calls for a fundamental shift in how we manage the massive carbon reserves stored deep within the Earth.

This extensive work synthesizes global research to build a cohesive picture of deep soil carbon—the organic matter stored below the standard sampling depth. The analysis confirms that these subsoil layers contain a colossal amount of carbon, estimated at over 850 petagrams worldwide, which accounts for 50% to 60% of the total carbon stock in the top meter of soil. By examining the sources, distribution, and stability of this carbon, the review provides a critical framework for understanding its role in long-term climate mitigation and soil health.

The Himalayas, often called the “Water Tower of Asia,” supply water to rivers that support nearly 2 billion people. However, new findings show that climate warming is threatening these river systems. Using satellite images and field observations from 1980 to 2020, researchers found that melting glaciers and thawing frozen ground are causing Himalayan rivers to shift course much faster than before, increasing the risk of flooding, erosion, and damage to roads, bridges, and other infrastructure.