Division of Information Technology, Engineering and the Environment
Institute for Sustainable Systems and Technologies
Institute for Sustainable Systems and Technologies
Melvin and Joan Lane Professor for Interdisciplinary
Environmental Studies;
Professor, Department of Biological Sciences;
Co-Director, Centre for Environmental Science and Policy at the Stanford
Institute for International Studies,
Stanford University U.S.A.
http://stephenschneider.stanford.edu
Abstract
Successful compliance with Article 2 of the United Nations Framework
Convention on Climate Change, prevention of “dangerous anthropogenic
interference with the climate system” (DAI), is dependent in part on the
climate policy decisions driving future greenhouse gas mitigation
efforts and stabilization levels. The likelihood of avoiding a given
threshold for DAI is in part dependent upon the range of uncertainty for
climate sensitivity. We combine a set of probabilistic global average
temperature metrics for DAI with probability distributions of future
climate change produced from published climate sensitivity distributions
and a range of proposed emissions stabilization pathways differing in
both stabilization level and approach trajectory—including overshoot
scenarios.
These analyses present a “likelihood framework” to
differentiate future emissions pathways with regard to their potential
for preventing DAI. Our analysis of overshoot scenarios in comparison
with non-overshoot scenarios demonstrates that overshoot of a given
stabilization target can significantly increase the likelihood of
exceeding “dangerous” climate impact thresholds, even though equilibrium
warming is identical to non-overshoot stabilization at the same
concentration target.
