The biosphere is a source and sink of gases and particles to the atmosphere. Thus, the biosphere sets the natural or
“preindustrial” chemical composition of the atmosphere. Human activity and climate change can perturb the
emissions to, deposition from, and chemistry within, the troposphere. At the same time, air pollution can impact
global ecosystem health, with implications for climate and food security. In this seminar, I will illustrate these ideas
with some recent studies from my group, highlighting in particular: (1) fire as a source of ozone and aerosols, (2) preindustrial
to future evolution of biogenic organic aerosol, and (3) the impact of ozone and air pollution on natural and
managed ecosystem health.