Abstract
Because of human population growth, global livestock, and associated
ammonia, emisions are projected to increase through the end of the
century, with possible impacts on atmospheric chemistry and climate. In
this study, we propose a methodology to project global gridded livestock
densities and NH3 emissions from agriculture until 2100. Based on future
regional livestock production and constrained by grassland distribution
evolution, future livestock distribution has been projected for three
Shared Socio-economic Pathways (SSP2-4.5, SSP4-3.4, and SSP5-8.5) and
used in the CAMEO process-based model to estimate the resulting NH3
emissions until 2100. Our global future emissions compare well with the
range estimated in Phase 6 of the Coupled Model Intercomparison Project
(CMIP6), but some significant differences arise within the SSPs. Our
global future ammonia emissions in 2100 range from 50 to 70 TgN.yr−1
depending on the SSPs, representing an increase of 30 to 50 % compared
to present day. Africa is identified as the region with the most
significant regional emission budget worldwide, ranging from 10 to 16
TgN.yr−1 in 2100. Through a set of simulations, we quantified the impact
of climate change on future NH3 emissions. Climate change is estimated
to contribute to the emission increase of up to 20%. The produced
datasets of future NH3 emissions is an alternative option to IAM-based
emissions for studies aiming at projecting the evolution of atmospheric
chemistry and its impact on climate.