This 2024 Assessment Update by the Environmental Effects Assessment Panel (EEAP) of
the United Nations Environment Programme (UNEP) addresses the interacting effects of
changes in stratospheric ozone, solar ultraviolet (UV) radiation, and climate on the
environment and human health. These include new modelling studies that confirm the
benefits of the Montreal Protocol in protecting the stratospheric ozone layer and its role
in maintaining a stable climate, both at low and high latitudes. We also provide an update
on projected levels of solar UV radiation during the 21st century. Potential environmental
consequences of climate intervention scenarios are also briefly discussed, illustrating the
large uncertainties of, for example, Stratospheric Aerosol Injection (SAI). Modelling
studies predict that, although SAI would cool the Earth’s surface, other climate factors
would be affected, including stratospheric ozone depletion and precipitation patterns
