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

Short introduction on Viet Nam’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 363.1 mega tonnes of CO₂ (Mt CO₂eq), Viet Nam contributed 0.76% to the global greenhouse gas emissions of 2017 (rank 25 - 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, Viet Nam’s global contribution to greenhouse gas emissions is projected to stay at a similar level of approximately 0.76% (429.2 mega tonnes of CO₂ equivalent / rank 25 - incl. EU27 on rank 4). The emissions projections for Viet Nam 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, Viet Nam represented 1.25% of the global population. Its Gross Domestic Product (GDP) in 2017 were 0.53% 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 (57.4% and 24.2%). Amongst the greenhouse gases that are considered in the Kyoto Protocol, the strongest contributor with 61.6% was CO₂. This was followed by CH₄ emissions, with a significantly lower share of 29.7%. When not considering the sectors and gases independently, but the sector-gas combinations instead, Energy CO₂ and Agriculture CH₄ (49.6% and 16.2%) 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, the country states that “With domestic resources, by 2025 Viet Nam will have reduced total GHG emissions by about 7.3% compared to the BAU scenario (equivalent to 52.9 million tonnes of CO₂eq [AR4]), and by 2030 Viet Nam will have reduced total GHG emissions by about 9% compared to the BAU scenario (equivalent to 83.9 million tonnes of CO₂eq [AR4]).” (NDC, p. 14, GWP: p. 14). Furthermore, “The above-mentioned 9% contribution can be increased to 27% by 2030 (equivalent to 250.8 million tonnes of CO₂eq) with international support received through bilateral, multilateral cooperation as well as through the implementation of market and non-market mechanisms under Article 6 of the Paris Agreement, in line with the socio-economic conditions and international conventions to which Viet Nam is signatory.” (NDC, p. 14). For the year 2025, only the unconditional and no enhanced conditional target is given.

Viet Nam includes quantitative information in its NDC necessary to estimate the target values in absolute terms. 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. BAU emissions (including LULUCF) are estimated to be 726.2 MtCO₂eq AR4 in 2025, and 927.9 MtCO₂eq AR4 in 2030, with the projection starting in 2014, with LULUCF estimated as an increasing net sink of -37.9 MtCO₂eq AR4 in 2025, and -49.2 MtCO₂eq AR4 in 2030 (NDC, p. 12). Additionally, relative and absolute reductions for the unconditional and conditional plus total contribution per sector are listed (NDC, p. 15), enabling the quantification of target emissions. This results in estimated mitigated emissions of 844.0 or 677.1 MtCO₂eq AR4 for the unconditional or total contribution in 2030. The provided numerical data further enables us to estimate the target emissions when only focusing on emissions excluding LULUCF. These are quantified as 902.5 or 747.6 MtCO₂eq AR4 for 2030, in the unconditional and total case, respectively (6% or 23% reduction compared to BAU exclLU). The target is economy-wide (“covering the entire economy”: NDC, p. 13), and all main IPCC sectors (Energy, IPPU, Agriculture, LULUCF, and Waste) are explicitly presented as covered (NDC, p. 7), together with the corresponding sectoral reductions (NDC, p. 15). As for the Kyoto GHGs addressed by Viet Nam’s contribution, CO₂, CH₄, N₂O, and HFCs are listed as covered (NDC, p. 14). From PRIMAP-hist v2.1 HISTCR (exclLU, in AR4), no data are available for any of the F-gases, hence the coverage is assessed to be 100% of national emissions.

For LULUCF, the NDC presents various measures to achieve the planned emissions reductions or enhancement of sequestration potential. These include “Protecting, conserving and sustainably using forests and forest land to increase carbon sequestration and forest certification; Planting and developing forests, prioritising production forests, large timber forests and coastal forests; Restoring protection forests and special-use forests; Defining areas for restoring natural forests, promoting forest regeneration and enrichment planting in areas planned for forestry; Improving forest carbon stock quality and volume; and Developing agroforestry models to enhance carbon stocks and conserve land.” (NDC, p. 16). Furthermore, “In the LULUCF sector, mitigation measures that can bring synergy with socio-economic development at a high level include the protection of natural forests (3.5 million ha) and the protection and afforestation of special-use forest (50,000 ha).” (NDC, p. 27).

Compared to its previous submissions, the 2020 updated NDC is stated to be more ambitious, as “GHG reductions in the updated NDC in the case of unconditional contribution are increased in both amount as well as ratio compared to BAU by 2030. More specifically, the reductions are increased by 21.2 million tonnes of CO₂eq (from 62.7 million tonnes in the current NDC to 83.9 million tonnes [AR4] in the updated NDC), or by 1% in percentage terms (from 8% in the current NDC to 9% in the updated NDC). With international support, the contribution is increased from 25% to 27%, increasing the reduction amount by 52.6 million tonnes of CO₂eq (from 198.2 million tonnes in the current NDC to 250.8 million tonnes [AR4] in the updated NDC).” (NDC, p. 14). Additionally, Viet Nam’s previous NDC excluded the important sector Industrial Processes and Product Use (IPPU). “The IP sector has been included in GHG inventory, BAU scenario and mitigation measures. With total emissions of 38.6 million tonnes of CO₂eq, 12.0% of the country’s total emissions in 2014, the IP sector is expected to emit 140.3 million tonnes of CO₂eq, or 14.4% of the country’s total emissions, in 2030.” (NDC, p. 8).

The NDC-assessment is based on Viet Nam’s NDC submitted to the UNFCCC in September 2020.

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

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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?).