Short answers, pulled from the story.
Grasslands store about 20 percent of global soil carbon stocks. This underground biomass creates deep, fertile soils with high organic matter content, making soil carbon account for about 81 percent of the total ecosystem carbon in grasslands.
The first true grasslands emerged around 5 million years ago during the Late Miocene in the New World and the Pliocene in the Old World. These landscapes appeared as existing forest biomes declined and the climate shifted to become hotter and drier.
Almost 90 percent of the European semi-natural grasslands do not exist anymore, having disappeared during the 20th century due to political and economic reasons. The original wild-plant communities have been replaced by sown monocultures of cultivated varieties of grasses and clovers.
Global losses from grassland degradation are estimated to be over 7 billion dollars per year. The most significant threat to grasslands is human land use, especially agriculture and mining.
The United Nations General Assembly proclaimed the UN Decade on Restoration for the period 2021 to 2030, involving a joint resolution by over 70 countries. This initiative is led by the United Nations Environment Programme and the Food and Agriculture Organization.