Permafrost is frozen ground that contains large amounts of greenhouse gases. When permafrost melts, microbes in the soil release methane and carbon dioxide. Woo

Permafrost is frozen ground that contains large amounts of greenhouse gases. When permafrost melts, microbes in the soil release methane and carbon dioxide. Woolly mammoths may have helped keep permafrost frozen by trampling shrubs and moss, and packing down snow. Grass absorbs less sunlight than trees, which keeps the ground cooler.