Historical impacts of grazing on carbon stocks and climate mitigation opportunities

Grazing has been associated with contrasting effects on soil carbon stocks at local scales, but accurate global assessments of its net impact are lacking. Here we conducted a meta-analysis of 1,473 soil carbon observations from grazing studies to quantify global changes in soil carbon stocks due to grazing practices. Our analysis shows that grazing has reduced soil carbon stocks at 1-m depth by 46 ± 13 PgC over the past 60 years. The interplay between grazing intensity and environmental factors explains global variations in soil carbon changes. Maps of optimal grazing intensity indicate that implementing grazing management on 21 million km 2 of grazing lands, mainly through decreasing grazing intensity on 75% of lands and increasing it on the rest could result in a potential uptake of 63 ± 18 PgC in vegetation and soils. These results highlight the potential of employing grazing as a climate mitigation strategy.