Mitigation Pathways Discussion in: UN IPCC Releases AR5 Synthesis Report on Climate Change, Risks, Adaptation and Mitigation

Delaying additional mitigation to 2030 will substantially increase the challenges associated with limiting warming over the 21st century to below 2 °C relative to pre-industrial levels, the report said.  It will require substantially higher rates of emissions reductions from 2030 to 2050; a much more rapid scale-up of low-carbon energy over this period; a larger reliance on CDR (carbon dioxide removal) in the long term; and higher transitional and long-term economic impacts.  Estimated global emissions levels in 2020 based on the Cancún Pledges are not consistent with cost-effective mitigation trajectories that are at least about as likely as not to limit warming to below 2°C relative to pre-industrial levels, but they do not preclude the option to meet this goal.

Many adaptation and mitigation options can help address climate change, but no single option is sufficient by itself.  Effective implementation depends on policies and cooperation at all scales, and can be enhanced through integrated responses that link adaptation and mitigation with other societal objectives.

—IPCC Fifth Assessment Synthesis Report

The Synthesis Report finds that mitigation cost estimates vary, but suggests that global economic growth would not be strongly affected.  In business-as-usual scenarios, consumption—a proxy for economic growth—grows by 1.6 to 3% per year over the 21st century.  Ambitious mitigation would reduce this by about 0.06 percentage points. “Compared to the imminent risk of irreversible climate change impacts, the risks of mitigation are manageable,” said Youba Sokona, Co-Chair of IPCC Working Group III.

These economic estimates of mitigation costs do not account for the benefits of reduced climate change, nor do they account for the numerous co-benefits associated with human health, livelihoods, and development.

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