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Agricultural activities are a substantial contributor to global greenhouse gas (GHG) emissions, accounting for about 58% of the world's anthropogenic non‐carbon dioxide GHG emissions and 14% of all anthropogenic GHG emissions, and agriculture is often viewed as a potential source of relatively low‐cost emissions reductions. We estimate the costs of GHG mitigation for 36 world agricultural regions for the 2000–2020 period, taking into account net GHG reductions, yield effects, livestock productivity effects, commodity prices, labor requirements, and capital costs where appropriate. For croplands and rice cultivation, we use biophysical, process‐based models (DAYCENT and DNDC) to capture the net GHG and yield effects of baseline and mitigation scenarios for different world regions. For the livestock sector, we use information from the literature on key mitigation options and apply the mitigation options to emission baselines compiled by EPA.

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Climate smart agriculture has been emphasized for mitigating anthropogenic greenhouse gas (GHG) emissions, yet the mitigation potential of individual management practices remain largely unexplored in semi-arid cropping systems. This study evaluated the effects of different winter cover crop mixtures on CO2 and N2O emissions, net GHG balance (GHGnet), greenhouse gas intensity (GHGI), yield-scaled GHG emissions, and soil properties in irrigated forage corn (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) rotations. Four cover crop treatments: (1) grasses, brassicas, and legumes mixture (GBL), (2) grasses and brassicas mixture (GB), (3) grasses and legumes mixture (GL), and (4) a no-cover crop (NCC) control, each replicated four times under corn and sorghum phase of the rotations, were tested in the semi-arid Southern Great Plains of USA. Results showed 5–10 times higher soil respiration with cover crop mixtures than NCC during the cover crop phase and no difference during the cash crop phase. The average N2O-N emission in NCC was 44% lower than GL and 77% lower than GBL in corn and sorghum rotations. Cash crop yield was 13–30% greater in cover crop treatments than NCC, but treatment effects were not observed for GHGnet, yield-scaled emissions, and GHGI. Integrating cover crops could be a climate smart strategy for forage production in irrigated semi-arid agroecosystems.