Agricultural lands occupy about 40–50% of the Earth's land surface. Agricultural practices can make a significant contribution at low cost to increasing soil carbon sinks, reducing greenhouse gas (GHG) emissions and contributing biomass feedstocks for energy use. Considering all gases, the global technical mitigation potential from agriculture (excluding fossil fuel offsets from biomass) by 2030 is estimated to be ca. 5500–6000 Mt CO2-eq. yr−1. Economic potentials are estimated to be 1500–1600, 2500–2700 and 4000–4300 Mt CO2-eq. yr−1 at carbon prices of up to $US20, 50 and 100 t CO2-eq.−1, respectively. The value of the global agricultural GHG mitigation at the same three carbon prices is $US32 000, 130 000 and 420 000 million yr−1, respectively. At the European level, early estimates of soil carbon sequestration potential in croplands were ca. 200 Mt CO2 yr−1, but this is a technical potential and is for geographical Europe as far east as the Urals. The economic potential is much smaller, with more recent estimates for the EU27 suggesting a maximum potential of ca. 20 Mt CO2-eq. yr−1. The UK is small in global terms, but a large part of its land area (11 Mha) is used for agriculture. Agriculture accounts for about 7% of total UK GHG emissions. The mitigation potential of UK agriculture is estimated to be ca. 1–2 Mt CO2-eq. yr−1, accounting for less than 1% of UK total GHG emissions.