XIX
the no-policy scenario (table ES.1). This is in line with the 2017 assessment, implying that studies have not identified significant and unambiguous progress in the implementation of policies that would enable the NDCs to be achieved by 2030.
target is to be attained with about 66 percent chance. To keep global warming to 1.8°C with about 66 percent chance, global GHG emissions in 2030 should not exceed 34 (range 30–40) GtCO2
e. For a 66 percent
chance of keeping temperature increase below 1.5°C in 2100 (associated with no or a low overshoot), global GHG emissions in 2030 should not exceed 24 (range 22–30) GtCO2
e.
and 1.5°C pathways is about 32 GtCO2 This is about 13 GtCO2
report because the most recent 2°C scenarios indicate a lower benchmark. If, in addition, the conditional NDCs are fully implemented, the gap is reduced by about 2 GtCO2
in 2030 compared with the 2°C scenario. This is about 2 GtCO2
The full implementation of the unconditional NDCs is estimated to result in a gap of 15 GtCO2
e higher than the assessment
in the 2017 report, due to the much larger number of available scenario studies that rely less on large volumes of carbon dioxide removal and thus show lower 2030 benchmark values. Considering the full implementation of both unconditional and conditional NDCs would reduce this gap by about 3 GtCO2
e.
Implementing unconditional NDCs, and assuming that climate action continues consistently throughout the 21st
Century, would lead to a global mean temperature rise of about 3.2°C (with a range of 2.9–3.4°C) by 2100 relative to pre-industrial levels, and continuing thereafter. Implementation of the conditional NDCs would reduce these estimates by 0.2°C in 2100. These projections are similar to the 2017 estimates.
4. Countries need to strengthen the ambition of NDCs and scale up and increase effectiveness of domestic policy to achieve the temperature goals of the Paris Agreement. To bridge the 2030 emissions gap and ensure long-term decarbonization consistent with the Paris Agreement goals, countries must enhance their mitigation ambition. Enhanced ambition in the NDCs sends an important signal regarding mitigation commitment, both internationally and domestically. However, domestic policies are crucial to translate mitigation ambition into action.
Ambition can, in this context, be viewed as a combination of target-setting, preparedness to implement and a capacity to sustain further reductions over time.
There are various ways in which a country could reflect enhanced mitigation ambition in its NDCs (figure ES.4). These options are not mutually exclusive, and whether
e (range 12–17) e higher than the gap assessed in the previous
e. The emissions gap between unconditional NDCs e (range 28–34).
The updates to this year’s assessment result in changes of the GHG emission levels in 2030, compared with the 2017 Emissions Gap Report, consistent with limiting global warming to 2°C and lower. According to the new scenario estimates, emissions of all GHGs should not exceed 40 (range 38–45) GtCO2
e in 2030, if the 2°C
an NDC revision results in enhanced ambition depends on the scale of the revision rather than its form. It is important for countries to consider a wide range of options to identify those that are most meaningful and practical in their unique circumstances, and to bring about the deep emission reductions required to bridge the gap.
Major gaps in coverage and stringency of domestic policies remain, including among G20 members, in, for example, fossil fuel subsidy reduction, material efficiency measures in industry, oil and gas, methane, support schemes for renewables heating and cooling, emission standards for heavy-duty vehicles, and e-mobility programmes. Even in areas where policy coverage is high, stringency can be improved. For example, while all G20 countries have policies to support renewables in the electricity sector, stringency of these policies can still be enhanced.
The technical potential for reducing GHG emissions is significant and could be sufficient to bridge the emissions gap in 2030. A substantial part of this potential can be realized through scaling up and replicating existing, well-proven policies that simultaneously contribute to key sustainable development goals.
The 2017 Emissions Gap Report provided an updated assessment of the sectoral emission reduction potentials that are technically and economically feasible in 2030, considering prices up to US$100/tCO2
addition, a number of newer and less certain mitigation options were included, the mitigation potential would increase to 38 (range 35–41) GtCO2
policy scenario of 59 GtCO2 e. The emissions
reduction potential is thus sufficient to bridge the gap in 2030. As the 2017 Emissions Gap Report showed, a large part of the technical potential lies in three broad areas: renewable energy from wind and solar, energy-efficient appliances and cars, and afforestation and stopping deforestation.
In these and many other areas – and across all countries – there is significant potential to realize a substantive part of the technical mitigation potential through the replication of proven good-practice policies that can simultaneously contribute to key sustainable development goals. Realizing this potential would significantly narrow the gap by 2030, beyond current NDCs.
5. Non-state and subnational action plays an important role in delivering national pledges. Emission reduction potential from non-state and subnational action could ultimately be significant, allowing countries to raise ambition, but the current impacts are extremely limited and poorly documented.
NSAs provide important contributions to climate action beyond their quantified emission reductions. They build confidence in governments concerning climate policy and push for more ambitious national goals. They provide space for experimentation or act as
that global emissions could be reduced by 33 (range 30–36) GtCO2
e/year in 2030, compared with the current e/year (Chapter 3). If, in
e. It found
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