A new study reports that during Pleistocene cold stages, when CO2 concentrations dipped below 200 ppm, Arctic Siberia had much more fertile soil and productive vegetation than exists today. Extensive grassland ecosystems could sustain year-round grazers: horses, mammoths, bison. Today this region’s large herbivores must be fed by humans to secure survival due to extremely … Continue reading Large Herbivores Grazed On Grass Year-Round In The Arctic When CO2 Was 180 ppm. Now They Cannot.