We introduce a novel game where a decaying atmospheric quality, modeled as a stock variable
determining the payoff externality, can be counteracted through individual mitigation efforts.
It encompasses three characteristics of climate change as a social dilemma: (a) the continuous
nature of climate degradation, (b) the constant influx of emissions resulting from human
economic activities, and (c) the greater efficacy of early mitigation actions. We report findings
from an experiment where, across four treatments, we manipulate the starting atmospheric
quality and introduce inequality in the endowments employed to mitigate. Results indicate
that subjects fail to mitigate in early periods, an individually rational strategy. We do not
find differences between treatments at the aggregate level. However, participants treat their
groupmates’ past mitigation as a strategic substitute for their own mitigation (i.e., if others’
mitigation increase, participants reduce their mitigation). This substitution is less intense if the
initial atmospheric quality is negative.
