Developed countries and emerging economies face two major challenges,
climate change and chronic diseases related to unhealthy diets. These two
major challenges are linked since changes in diets impact public health, but
also climate change through global greenhouse gas (GHG) emissions. The aim
of this paper is to analyze in a global public good game the link between
nutritional and climate mitigation policies at the national and
international level. Changes in diets induced by a nutritional policy lead
to health benefits at the national level. They can also increase or decrease
the GHG emissions of the country, with related externalities to other
countries. Our modelling framework thus highlights a novel indirect leakage
effect through the nutritional policy, which complicates the public good
problem. In this context, we ask whether countries should negotiate an
agreement on climate policies only (climate agreement), or an agreement on
both climate and nutritional policies (full agreement). In terms of global
emissions, our theoretical results show that it is better to cooperate both
on climate mitigation and nutritional policies when healthy changes in diets
have a large impact on emissions, whatever the direction of this impact. We
investigate whether it is necessarily bad for the environment that countries
are not informed about the impacts of nutritional policy on GHG emissions.
Our theoretical results on the role of information highlight again the
importance of the magnitude of emission changes induced by the nutritional
policy. When this magnitude is very low and the nutritional policy decreases
GHG emissions, then it is better to negotiate over the climate policy only,
without providing information to countries about the environmental impacts
of their nutritional policies.