The Paris Agreement and NDCs: are the national mitigation targets sufficient to stay below the 1.5-2°C limit?

Short introduction on Switzerland’s emissions

Although CO₂ is the driving force behind the temperature changes, other gases such as methane (CH₄) also contribute their share to global warming, for example through the exploitation of gas fields, and emissions by livestock. While methane is emitted much less than CO₂ on a global scale, it is a much stronger greenhouse gas (GHG). Scientists estimated the relative strength of the important Kyoto greenhouse gases so that we can convert all emissions to an equivalent of CO₂ emissions. For example, the emission of one ton of methane has approximately the warming effect of 25 tons of CO₂. The factor of 25 reflects the climate forcing on a 100-year time horizon, following the Global Warming Potential presented in the IPCC Fourth Assessment Report (AR4).

With greenhouse gas emissions of approximately the equivalent of 47.2 mega tonnes of CO₂ (Mt CO₂eq), Switzerland contributed 0.098% to the global greenhouse gas emissions of 2017 (rank 88 - incl. EU27 on rank 3). All emissions estimates exclude emissions and absorption from land, which result from activities such as cutting down or planting of forests (Land Use, Land-Use Change and Forestry: LULUCF). Emissions from bunker fuels (international aviation and shipping) were also excluded, as they are not accounted for in national totals.

For 2030, Switzerland’s global contribution to greenhouse gas emissions is projected to stay at a similar level of approximately 0.11% (64.4 mega tonnes of CO₂ equivalent / rank 82 - incl. EU27 on rank 4). The emissions projections for Switzerland were derived by downscaling the Shared Socio-Economic Pathways’ (SSPs) “Middle-of-the-Road” baseline marker scenario SSP2. These pathways describe certain narratives of socio-economic developments and were, i.a., used to derive greenhouse gas emissions scenarios that correspond to these developments. SSP2 is a narrative with little shifts in socio-economic patterns compared to historical ones, and is connected to medium socio-economic challenges for both climate mitigation and adaptation. While different models were used for each storyline, per SSP (SSPs1-5) one model was chosen as representative “marker scenario”. As the emissions projections are not readily available on country-level, but national estimates are important, the pathways were downscaled in the aftermath. In 2017, Switzerland represented 0.11% of the global population. Its Gross Domestic Product (GDP) in 2017 were 0.46% of the global GDP.

Looking at the highest contributing emissions sectors and gases separately, we find that in 2017 the highest contributing emissions sectors were Energy and Agriculture (77.3% and 12.9%). Amongst the greenhouse gases that are considered in the Kyoto Protocol, the strongest contributor with 80.9% was CO₂. This was followed by CH₄ emissions, with a significantly lower share of 10.3%. When not considering the sectors and gases independently, but the sector-gas combinations instead, Energy CO₂ and Agriculture CH₄ (76.3% and 8.6%) represented the largest emissions in 2017.

Greenhouse gas mitigation and Nationally Determined Contribution (NDC)

In 2015, the majority of countries agreed to the Paris Agreement (PA), with the goal of “Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change” (Article 2.1.a). Countries stated their pledges and targets towards achieving the PA’s goals in their Nationally Determined Contributions (NDCs). With Article 4.4 of the Paris Agreement, Parties decided that “Developed country Parties should continue taking the lead by undertaking economy-wide absolute emission reduction targets. Developing country Parties should continue enhancing their mitigation efforts, and are encouraged to move over time towards economy-wide emission reduction or limitation targets in the light of different national circumstances.”

In its 2020 NDC, Switzerland communicates that “The updated and enhanced NDC represents a progression in several areas: a progression of the NDC from minus 50 percent by 2030 to at least minus 50 percent by 2030 compared to 1990 levels; an increase of the indicative goal to reduce greenhouse gas emissions to net zero emissions by 2050 (compared to the previous objective of minus 70 to 85 percent by 2050 compared to 1990); a 25 percent increase of the domestic share of emission reductions, from 60 percent to at least 75 percent; compensation of imported”grey” emissions through additional emission reductions abroad, not counted towards Switzerland’s emission reductions objectives.” (NDC, p. 1). Even though not stated in the NDC, we expect Switzerland’s contribution to be unconditional on, e.g., international financial support or technology transfer.

Switzerland includes quantitative information in its NDC, as the “Provisional value for base year emissions, subject to change due to recalculations of the greenhouse gas inventory, is 54158.92 kt CO₂eq.” (about 54.159 Mt CO₂eq), while the “Emissions in base year (1990) comprise emissions from all sectors, except LULUCF. Indirect CO₂ is also included.” (NDC, p. 3). It is assumed that the GWPs used when aggregating emissions from different gases follows the IPCC AR5, as the country mentions the “Global Warming Potential Values used: 100-yr GWP values from 5th IPCC assessment report, or from a subsequent IPCC assessment report as agreed upon by the CMA, as per UNFCCC decision 18/CMA.1 paragraph 37.” (NDC, p. 9). Derived from the given base year emissions, a reduction of at least 50% would result in a 27.080 MtCO₂eq AR5 emissions level or lower. The availability of national estimates of emissions mitigation targets and pathways in line with countries’ NDCs is of great importance when, e.g., aggregating to global emissions to then derive, i.a., the resulting end-of-century warming levels.

This contribution is meant to be an “Absolute economy-wide emission reduction target compared with a base year” (NDC, p. 4). The covered sectors are listed as “energy; industrial processes and product use; agriculture; land-use, land-use change and forestry; waste and other (consistent with 2006 IPCC guidelines). All categories and pools in Switzerland’s inventory are covered.” (NDC, p. 4). Additionally, the country states that “Switzerland has included all categories of anthropogenic emissions or removals in its NDC.” (NDC, p. 5). All seven Kyoto GHGs are covered, with CO₂ including indirect CO₂ (NDC, p. 4).

Switzerland notes the “Base year for gases covered [to be] 1990 (not relevant where a reference level/period approach is applied)” (NDC, p. 4). Regarding reference levels, the country clarifies to use “For forest land: reference level; For non-forest land (cropland, grassland, wetlands, settlements, other land): reference period” (NDC, p. 3). Furthermore, “Emissions/removals from LULUCF will be reported and accounted for on a land-based approach. Forest land and non-forest land are not included in base year emissions, since only the net change in emissions compared with the reference level/period is accounted for in the land use sector (see 5f below).” (NDC, p. 3). Additional information on LULUCF, including accounting approaches, are given in Switzerland’s NDC (NDC, p. 8-11).

Regarding Article 6 of the PA (cooperation and markets), the country indicates that “In the interest of timely climate action and as an addition to domestic actions, Switzerland intends to use Article 6 activities, contributing to the overall emission reduction target of at least minus 50 percent by 2030 compared with 1990 levels.” (NDC, p. 14), and as long-term vision, “Switzerland aims to reduce its greenhouse gas emissions to net zero by 2050. This target lays the foundations for Switzerland’s 2050 climate strategy, which is to be transmitted to the UNFCCC Secretariat within a few weeks of this submission.” (NDC, p. 2).

The NDC-assessment is based on Switzerland’s NDC submitted to the UNFCCC in February 2020.

The Figure below provides additional information, regarding both the baseline emissions used in our assessment and the quantified mitigated pathways for Switzerland.

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Baseline emissions and mitigated emissions pathways based on the country’s Nationally Determined Contribution. In terms of national emissions, we look at the SSP2 baseline marker scenario, and the emissions of all IPCC sectors. Contributions from LULUCF are excluded (exclLU), and the emissions are based on GWPs from AR4. The left panel (a) shows the baseline emissions, indicating the contributions of the Kyoto Greenhouse Gases CO₂, CH₄, N₂O, and the basket of F-gases to the national emissions. If we could extract baseline data exclLU from the NDC, you can see their values as black squares (converted from GWP SAR to AR4 if needed). In the right panel (b), the quantified mitigated emissions pathways are shown, based on information from the country’s NDC and also on non-NDC emissions baselines, per target conditionality and range (marked un-/conditional best/worst). Even though not all countries have targets with different conditionalities or ranges, we need assumptions for all four cases to build one global pathway per conditionality plus range combination and to derive corresponding temperature estimates. Therefore, we indicate these four pathways here. Per combination, we performed several quantifications with differing assumptions and show the median and the minimal and maximal pathways here. Additionally, if we could quantify the targets based on data extracted purely from the NDC - or if the targets were directly given in absolute emissions, these targets are shown as squares (in the GWP originally given in the NDC).

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FIG 1

Data sources and further information

• Historical emissions: PRIMAP-hist v2.1 (Guetschow et al., 2016, 2019).
• Historical socio-economic data: PRIMAP-hist Socio-Eco v2.1 (Guetschow et al., 2019).
• Projected emissions and socio-economic data: downscaled SSPs (Guetschow et al., 2020, 2020).
• NDC quantifications: NDCmitiQ (Guenther et al., 2020, 2021).
• GDP is given in purchasing power parity (PPP).
• Main emissions sectors (Intergovernmental Panel on Climate Change, IPCC): Energy, Industrial Processes and Product Use (IPPU), Agriculture and LULUCF (Land Use, Land-Use Change and Forestry), also named AFOLU (Agriculture, Forestry and Other Land Use), and Waste.
• Kyoto GHG: basket of several GHGs, namely carbon dioxide (CO₂), Methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF₆), and since the second Kyoto Protocol period (2013-20) additionally nitrogen fluoride (NF₃).
• Global Warming Potentials (GWPs): GHGs have very different warming potentials. To make them comparable and for aggregation purposes, GWPs are used (how much energy will 1 ton of a certain gas absorb over a defined period of time, relative to the same mass of CO₂?).