The study looked at how coal in China's Ordos Basin has changed in its ability to absorb methane over time. By conducting experiments on coal samples from different depths, researchers found that the coal's ability to absorb methane depends on factors like pressure, temperature, and the coal's composition. They created a model to predict how this absorption capacity has changed over millions of years. The results showed that there were three main stages in the coal's history of methane absorption: a period of low absorption, a period of increasing absorption, and a period of high absorption.