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This article quantifies the aggregate potential of greenhouse gas (GHG) emissions reductions in 2030 from the assumed full implementation of major international cooperative initiatives (ICIs). To this end, a methodology is proposed to aggregate emission reduction goals of the most significant and potentially impactful global initiatives. We identified the extent to which reductions are additional to national policies, assuming these actions do not displace climate actions elsewhere, and accounted for overlap ranges between the ICIs. The analysis was conducted for 17 initiatives, selected from an original list of over 300 with a series of testing criteria, across eight sectors and ten major emitting economies. These initiatives include cities, regions, businesses, and other subnational and non-state actors, cooperating with each other and sometimes working in partnership with national governments or other international organizations. Our analysis shows that the combined achievement of initiatives' reduction goals could reduce global emissions in 2030 by 18-21 GtCO 2 e/year in addition to current national policies (total of 60-63 GtCO 2 e/year), down to 39-44 GtCO 2 e/year. If delivered fully, reductions from these 17 initiatives would help move the global emissions trajectory within the range of a 2°C-consistent emission pathway by 2030, although a significant gap would remain to reduce emissions to a 1.5°C-consistent pathway. Key policy insights. We propose a transparent and robust methodology to aggregate GHG mitigation potential of ICIs, accounting for overlaps between ICIs.. If major initiatives meet their goals and do not change the course of other existing climate actions, they could make large contributions by 2030 towards global efforts to stay within the range of a below 2°C-consistent emission pathway by 2030. The full suite of existing initiatives beyond those in this analysis could further increase ambition towards achieving the Paris Agreement's temperature goals.. Cities and regions, businesses and forestry initiatives account for significantly more than half of all possible emission reductions from ICIs; implementation of their goals should be a key policy focus.

By January 2022, 156 countries had submitted new or updated nationally determined contributions (NDCs) under the Paris Agreement. This study analyses the greenhouse gas (GHG) emissions and macroeconomic impacts of the new NDCs. The total impact of the updated unconditional and conditional NDCs of these countries on global emission levels by 2030 is an additional reduction of about 3.8 and 3.9 GtCO2eq, respectively, compared to the previously submitted NDCs as of October 2020. However, this total reduction must be about three times greater to be consistent with keeping global temperature increase to well below 2 °C, and even seven times greater for 1.5 °C. Nine G20 economies have pledged stronger emission reduction targets for 2030 in their updated NDCs, leading to additional aggregated GHG emission reductions of about 3.3 GtCO2eq, compared to those in the previous NDCs. The socio-economic impacts of the updated NDCs are limited in major economies and largely depend on the emission reduction effort included in the NDCs. However, two G20 economies have submitted new targets that will lead to an increase in emissions of about 0.3 GtCO2eq, compared to their previous NDCs. The updated NDCs of non-G20 economies contain further net reductions. We conclude that countries should strongly increase the ambition levels of their updated NDC submissions to keep the climate goals of the Paris Agreement within reach.