Integrated assessment of international climate mitigation commitments outside the UNFCCC

Abstract

In the Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC), for the first time, non-state actors were addressed in the international negotiations and were explicitly invited to act on climate change. Indeed, there are many transnational emission reduction initiatives (TERIs) outside the UNFCCC, driven by non-state actors or national governments, which aim at reducing greenhouse gas (GHG) emissions. Using an Integrated Assessment Model (IAM), this study assessed the potential impact of a selection of large TERIs that existed before the Paris Agreement on global greenhouse gas emissions. TERIs could lead to significant emission reductions: the eleven selected initiatives included in the analysis here couldif fully implementeddeliver annual GHG emission reductions of 2.5 GtCO 2 eq by 2020 and of 5.0 GtCO 2 eq by 2030 from a no-policy-baseline emission level of 53.7 GtCO 2 and 61.1 GtCO 2 eq, respectively. Although these reductions are of similar magnitude as those pledged by countries under the umbrella of the UNFCCC, these reductions may significantly overlap with those of pledges and Nationally Determined Contributions. The maximum estimate of overlap is around 70% by 2020 and 80% by 2030. This means that the combined impact on global GHG emissions of TERIs and NDCs, assuming a maximum overlap, would lead to emission levels between 53 and 55 GtCO 2 eq by 2030, compared to a level of 54 to 56 GtCO 2 eq resulting from NDCs alone.

The global expansion of climate mitigation policy interventions, the Talanoa Dialogue and the role of behavioural insights

“…Our study extends previous assessments about the development of climate and energy policy mixes [23,[24][25][26], including studies of measures and commitments by non-state actors [27,28]. 9 Notably, these efforts have focused on specific aspects of climate policy (e.g.…”

Beyond national climate action: the impact of region, city, and business commitments on global greenhouse gas emissions

“…On a global level, there are few studies that have aggregated the GHG mitigation potential of individual NSA commitments. Roelfsema et al (Roelfsema et al, 2018) projected that the commitments reported to CDP, C40 Cities and Covenant of Mayors (the present Global Covenant of Mayors) would together lead to a reduction of about 1.3 GtCO 2 e/year compared to a no-policy baseline by 2030. While Roelfsema et al (2018) and our analysis used different baselines, we find the calculated GHG mitigation potential values to be comparable to our results (1.2-2.0 GtCO 2 e/year by 2030).…”

“…Roelfsema et al (Roelfsema et al, 2018) projected that the commitments reported to CDP, C40 Cities and Covenant of Mayors (the present Global Covenant of Mayors) would together lead to a reduction of about 1.3 GtCO 2 e/year compared to a no-policy baseline by 2030. While Roelfsema et al (2018) and our analysis used different baselines, we find the calculated GHG mitigation potential values to be comparable to our results (1.2-2.0 GtCO 2 e/year by 2030). The Global Covenant of Mayors estimates a 1.4 GtCO 2 e/year emissions reduction by 2030, compared to a current policy baseline with a modelling start year of 2010 (GCoM, 2018a).…”

“…Höhne et al (2015), UNEP (2015) and Graichen et al (2017) aggregated the potential GHG impact of selected international cooperative initiatives; these applied a more systematic approach to quantifying overlaps by developing a sector-based overlap matrix across initiatives and considering different types of intra-and inter-sectoral overlaps. Roelfsema et al (Roelfsema et al, 2018) used an integrated assessment model and estimated that 11 selected transnational emission reduction initiatives could -if fully implemented-deliver annual GHG emission reductions of 5.0 GtCO 2 e/year by 2030; overlaps across initiatives were based on literature estimates. Hsu, Höhne, Kuramochi et al (2019b) presented a research roadmap for quantifying individual-scale nonstate and subnational climate mitigation action.…”

Promises and risks of nonstate action in climate and sustainability governance

“…Some doubt their effectiveness (e.g., Michaelowa & Michaelowa, ) or stress their dependency on state‐based forms of governance (e.g., Bulkeley et al, ; Hickmann, ), yet others assert that nonstate actions will contribute to complexity, fragmentation, and possibly undermine governance legitimacy and accountability (Kuyper, Linnér, & Schroeder, ). A growing number of studies, however, take an optimistic, if cautious, view that nonstate action could bridge governance gaps (e.g., Graichen et al, ; Hsu, Cheng, Weinfurter, Xu, & Yick, ; Hsu, Moffat, Weinfurter, & Schwartz, ; Roelfsema, Harmsen, Olivier, Hof, & Van Vuuren, ; Tosun & Schoenefeld, ). While there has been growing optimism, and emphasis on potential and positive signals, few studies look at whether, and under which circumstances, optimistic expectations can be realized.…”