Increasing productivity is one of the main mitigation strategies for the livestock sector, as it reduces emission intensities while delivering benefits for livelihoods and food security. However, reducing emission intensities does not necessarily result in net emissions reductions. Analyzing the evolution of the cattle sector over 15 years, we describe the relationship between increased productivity and GHG emissions, as mediated by animal numbers. Globally, productivity per animal and total production have increased and emission intensity has decreased. Without this reduction in emission intensities, emissions in 2020 would have been 24 % higher for dairy and 10 % for beef. However, global progress on net GHG mitigation from these sectors has not materialized, as animal numbers and total emissions have increased. These results hide significant heterogeneity, as the dairy sector of upper-middle countries, and both the dairy and beef sectors of high-income countries, have achieved net greenhouse gas mitigation while increasing total production by increasing productivity and reducing animal numbers. These cases demonstrate that it is possible to achieve net reductions in GHG emissions without reducing the production of animal source foods. However, in low-income countries, production growth is still driven by increases in animal numbers. International trade can play a role in reducing emissions: 95 % of dairy and 59 % of beef exports come from geographies that reduced their emissions intensities, but only 41 % of dairy and 9 % of beef exports come from countries that reduced their absolute emissions. Facilitating the transitions of the livestock sector towards reduced herd sizes and increased productivity is required for reducing the sector's emissions in line with ambitious climate stabilization targets like the ones set in the Paris Agreement.