Towards a Workable and Effective Climate Regime

2 Implications of climate science
for negotiators
Thomas F. Stocker
Physics Institute, University of Bern
The scientific assessments carried out by the Intergovernmental Panel on Climate
Change have delivered robust and rigorous scientific information for the complex
negotiations that should produce a binding agreement to limit climate change and its
impacts and risks. Understanding climate change as a threat to key resources for the
livelihood of humans and the functioning of ecosystems provides a more appropriate
perspective on the scale of the problem. Model simulations suggest that many options
exist today to limit climate change. However, these options are rapidly vanishing under
continued carbon emissions: Temperature targets must be revised upwards by about
0.4°C per decade for constant mitigation ambitions. Mitigating climate change has the
important benefit of creating favourable conditions to reach many of the Sustainable
Development Goals; business-as-usual and consequent unchecked climate change will
make these important universal goals unreachable.
1 Introduction
“Climate change is one of the greatest challenges of our time” – this is the assertion of
the parties to the United Nations Framework Convention on Climate Change (UNFCCC
2009). The Fifth Assessment Report of the IPCC (AR5), which was completed in
November 2014 with the publication of the Synthesis Report (IPCC 2014c), gives a
comprehensive snapshot of the knowledge science has to offer to quantify, understand,
and confront this problem. The four key messages from the “Summary for Policymakers”
of the Synthesis Report are:
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