A new study published on 14 August 2026 in Nature Climate Change finds that 103 European cities (including 22 capitals) targeting climate neutrality by 2030 plan to use carbon dioxide removal (CDR) to offset roughly one-fifth of their residual emissions—about 61 million tonnes of CO₂, comparable to Austria’s annual emissions.

The analysis was led by the European Commission’s Joint Research Centre (JRC), with contributions from the Potsdam Institute for Climate Impact Research (PIK) and others.

Key findings include:

Residual emissions are concentrated in sectors often viewed as relatively easy to abate: energy (median ~50%) and transport (median ~31%). This raises questions about whether cities are fully exploring deeper cuts before relying on removals, potentially prioritising cost and speed over more transformative changes.

Cities use vague criteria for defining residual emissions and have limited quantification of available CDR capacity (current estimates cover only ~18% of total residual emissions).

The study introduces the RESRI index to assess the robustness of residual-emission strategies. It highlights weaknesses in monitoring, quantification, timing, and planning for removals.

Plans overwhelmingly favour land-based (nature-based) approaches such as tree planting. These face challenges of permanence, limited urban land availability (competing with housing, health, and energy needs), and a lack of detailed land-availability assessments in current plans.

Permanent CDR methods appear far less often: only 32% of plans mention them (bioenergy with carbon capture and storage/BECCS in 27%, biochar in 13%, direct air carbon capture and storage/DACCS in 7%). Carbon credits feature in ~40% of plans but are often vaguely specified, treated as a last resort, and viewed with distrust by the cities themselves.

Co-author Quirina Rodriguez Mendez (PIK) noted that the ambitious targets are commendable and could inspire others, but cities risk under-considering options that eliminate emissions at source.

Transparent accounting is essential so that planned removals do not become “mere hot air.”

Researchers advise prioritising and front-loading deep emissions reductions so that residuals are limited to genuinely hard-to-abate sources. Demand-side measures could cut emissions by 40–80% depending on context. Over time, temporary land-based removals would need to be complemented by more permanent options, which requires clearer regulation, infrastructure, and support at national and international levels.

This work builds on earlier JRC guidance for cities in the EU Mission for 100 Climate-Neutral and Smart Cities, which stresses that residual emissions should be identified iteratively after maximising feasible reductions, and that only high-integrity carbon-removal credits (not avoidance credits) should be used for compensation, with strict rules against double-counting.

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This is the official press release from the Potsdam Institute for Climate Impact Research (PIK), published 14 August 2026.

An analysis of the 2030 climate-neutral plans of 103 European cities (including 22 capital cities) shows that municipalities plan to rely on carbon removal to compensate for about a fifth of their emissions. This equates to removing roughly 61 million tonnes of emissions—close to Austria’s annual emissions.

The study, published the same day in Nature Climate Change, was led by the Joint Research Centre of the European Commission with contributions from PIK scientists.

Main findings highlighted:

• Residual emissions are concentrated in the energy and transport sectors (medians of 50% and 31% respectively), even though both are generally considered relatively easy to abate. This raises concerns about strategy effectiveness, urban constraints, and tight timelines, with a risk that cost and speed may be prioritised over deeper transformative change.
• Cities often use vague criteria to define residual emissions and may not have fully explored options to eliminate them at source.
• The authors developed the RESRI index to measure the robustness of residual-emission strategies. It highlights weaknesses in monitoring and quantifying available carbon dioxide removal capacity and its timing. Current estimates cover only 18% of total residual emissions.
• Cities overwhelmingly rely on land-based (temporary) carbon removals such as tree planting. This raises issues of permanence and limited land availability in dense urban settings (competing demands for housing, health, energy, etc.). Plans generally lack detailed land-availability assessments.
• Permanent carbon removal is mentioned in only 32% of plans: bioenergy with carbon capture and storage (BECCS) in 27%, biochar in 13%, and direct air carbon capture and storage (DACCS) in 7%. Carbon credits appear in 40% of plans but are often poorly specified, treated as a last resort, and viewed with distrust by the cities themselves.

Quotes from co-author Quirina Rodriguez Mendez (PIK):

• The ambitious targets are to be applauded and can inspire others, but vague residual-emission criteria and insufficient focus on eliminating emissions first are concerns.
• Removals must actually occur and be transparently accounted for so they do not become “mere hot air.”

Recommendations offered:

• Front-load emissions reductions so residuals are limited to truly hard-to-abate sectors.
• Implement demand-side measures (potential reductions of 40–80% depending on context).
• Gradually complement temporary removals with more permanent options, which will require regulatory clarity, infrastructure, and predictable support involving national and international governance.

Article citation
Ulpiani, G., Rodriguez Mendez, Q., Todeschi, V., Hernandez Moral, G., Vetters, N., Pittalis, M., Fuss, S., Gevers Deynoot, C., Creutzig, F. (2026). Empirical insights into residual emissions in urban net-zero targets. Nature Climate Change. DOI: 10.1038/s41558-026-02691-0

Contact
PIK press office: +49 331 288 2507 | press@pik-potsdam.de The page also includes a photo caption noting that cities plan to offset a fifth of emissions through carbon removal despite major reduction potential in energy and transport.

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Empirical insights into residual emissions in urban net-zero targets

Empirical insights into residual emissions in urban net-zero targets is a peer-reviewed analysis published on 14 August 2026 in Nature Climate Change.

Published:  Nature Climate Change

DOI: 10.1038/s41558-026-02691-0

Provided: Potsdam Institute for Climate Impact Research

Authors (partial list from available sources): Giulia Ulpiani and others (led by the European Commission’s Joint Research Centre), with contributions including Quirina Rodriguez Mendez, Sabine Fuss, and Felix Creutzig (Potsdam Institute for Climate Impact Research / related institutions). Full author list includes Todeschi, Hernandez Moral, Vetters, Pittalis, Gevers Deynoot, and others.

Cities increasingly pledge net-zero emissions targets, but the robustness of their residual emissions strategies remains uncertain. The study examines the approaches of 103 European cities aiming at net zero by 2030 (participants in the EU’s 100 Climate-Neutral and Smart Cities Mission).

Total residual emissions amount to 61.4 MtCO₂e, originating mostly from buildings and transport, with a median of 0.8 tCO₂e per capita (indicating rapid planned decarbonization). All municipal strategies rely on temporary, land-based CO₂ removal; carbon credits appear in 40% of plans and permanent CO₂ removal in 32%.

The authors develop the Residual Emissions Strategy Robustness Index (RESRI) to assess compensation strategies. Current maturity is medium-low, with notable geographical disparities. Cities invest in options mapping and governance, but pay little attention to land availability, the potential of the urban fabric as a distributed carbon sink, provisions against carbon reversals, monitoring, timing, and quantification (estimates cover only 18% of total residual emissions). The paper distils recommendations and best practices.

Key empirical findings

• Magnitude: Median residual emissions ~20% of baseline (IQR often 18–21% or higher when using more recent inventories). Many cities set residual percentages via targets rather than detailed abatement analysis. Scope is mainly Scope 1 and 2; limited Scope 3 (mainly waste); frequent exclusions of fluorinated gases, industry, ports/airports, etc.
• Sectoral origins: Stationary energy (buildings/facilities; median ~50%, wide IQR) and transport (median ~31%) dominate residuals. Other sectors contribute ≤4%. Presence of ports/airports correlates with higher residuals even when those facilities are formally excluded.
• Compensation approaches:
  • All 103 cities plan temporary land-based sinks (urban revegetation/greening ~98%, soil carbon ~84%, forestation/improved management ~80%; combinations common). Wetlands/blue carbon less frequent.
  • Permanent options mentioned by only 32% (BECCS 27%, biochar 13%, DACCS 7%).
  • Carbon credits in ~40% of plans (often vague, last-resort, and met with distrust).
• Robustness gaps (via RESRI): Weaknesses in land-availability assessments, permanence safeguards, monitoring/quantification/timing, and treating the urban built environment as a potential carbon sink. Best practices exist (e.g., species selection for resilience, monitoring equipment, carbon buffers, land-protection provisions) but are not widespread.

The work builds on earlier JRC guidance and analyses of Mission Cities’ Climate-Neutrality Action Plans. It stresses prioritising deep emissions reductions (including demand-side measures) so residuals concentrate in truly hard-to-abate sources, improving quantification and monitoring, assessing land constraints rigorously, and gradually shifting toward more permanent CDR where needed—supported by clearer multi-level governance and infrastructure.

The paper is open access. Full text, figures (including residual distributions and compensation options), methods, and Supplementary Information (with best-practice examples) are available via Nature:

Empirical insights into residual emissions in urban net-zero targets | Nature Climate Change

Abstract

Cities increasingly pledge net-zero emissions targets, but the robustness of their residual emissions strategies remains uncertain. We examine the approaches of 103 European cities aiming at net zero by 2030. Total residual emissions are 61.4 MtCO₂e originating mostly from buildings and transport, with the median at 0.8 tCO₂e per capita, indicating a rapid decarbonization process. All municipal strategies rely on temporary, land-based CO₂ removal, then carbon credits (40%) and permanent CO₂ removal (32%). We develop the residual emissions strategy robustness index to assess the robustness of compensation strategies, indicating that the current maturity is medium-low with notable geographical disparities. Although cities invest in options mapping and governance, little attention is paid to land availability, the potential of the urban fabric to become a distributed carbon sink, provisions against carbon reversals, monitoring, timing and quantification (estimates cover only 18% of total residual emissions). We also distil recommendations and best practices to address residual emissions.

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Here’s a skeptical reading of the claim and the underlying study.

1. The “one-fifth” figure is partly an artifact of the target design

The cities are participants in the EU’s 100 Climate-Neutral and Smart Cities Mission, which effectively steers them toward residual emissions of roughly ≤20 %.

Many simply set residual emissions near that indicative ceiling rather than deriving them bottom-up from a rigorous assessment of what is truly unavoidable.

The study itself notes that for about half the cities the residual percentage looks more like a target-setting outcome than the result of detailed abatement analysis.

So the “fifth” is not an independent discovery of hard-to-abate emissions; it is partly the number the framework encouraged them to adopt.

2. Calling energy and transport “easy-to-abate” is too glib in a 2030 urban context

The critique that residuals are concentrated in energy (buildings) and transport—sectors often labelled easy to abate—is technically true in long-term models.

In real European cities facing a 2030 deadline it is far less true.

Deep building renovations at the required scale face labour shortages, heritage constraints, split incentives between landlords and tenants, and financing gaps.

Rapid modal shift and fleet electrification run into grid capacity, charging infrastructure, public acceptance, and the sheer turnover rate of the existing vehicle stock. Treating these as “easy” under a six-year remaining horizon understates the practical, political, and capital constraints cities actually face.

Some residual in these sectors by 2030 is realistic, not just a failure of ambition.

3. Land-based removals are over-relied upon, but the alternative (permanent engineered removals) is not ready at city scale either

The study correctly flags heavy reliance on temporary land-based sinks (tree planting, soil carbon, etc.) and the absence of serious land-availability assessments. Urban land is contested; permanence is uncertain under climate stress; and monitoring is weak. That is a genuine problem.

However, the implication that cities should already be leaning harder on permanent options (BECCS, biochar, DACCS) is also questionable.

These technologies are still expensive, infrastructure-light, and in many cases require national or regional coordination (CO₂ transport and storage networks, sustainable biomass supply, energy for DAC).

Expecting 103 cities to have mature, quantified permanent-CDR strategies ready for 2030 is unrealistic given the current maturity and policy environment. The low mention rate (32 %) partly reflects technological and institutional readiness, not only municipal shortsightedness.

4. The RESRI index and “few have thought through how” framing can overstate the failure

The researchers created an index that scores plans low on quantification, timing, land assessment, reversal provisions, and monitoring. That is useful diagnostic work.

But climate-neutrality action plans submitted in the first iteration of a voluntary mission are planning documents, not fully engineered delivery programmes.

Many cities explicitly treat residual-emission strategies as something to refine in later iterations.

Judging the first-round plans against a high bar for robustness and then concluding that “few have thought through how” risks turning an early-stage governance gap into a stronger indictment than the evidence supports.

5. Incentives and political economy

Cities have strong political incentives to announce ambitious 2030 net-zero targets.

Once the target is set, the residual becomes a residual accounting problem that can be deferred or outsourced (credits, future land sinks, hoped-for technology).

National governments and the EU set the broader regulatory and infrastructure conditions for permanent removals and high-integrity credits.

Blaming municipal plans for under-developed CDR strategies while the enabling framework at higher levels remains incomplete is incomplete analysis.

There is also a risk that aggressive residual targets plus weak delivery simply produce creative accounting or delayed action rather than real atmospheric benefit.

6. Broader context the study under-emphasises

• Demand-side measures and deeper absolute reductions are rightly recommended, yet the political feasibility of large behavioural or lifestyle changes inside electoral cycles is limited.
• Scope coverage is incomplete (limited Scope 3, frequent exclusions of ports, airports, F-gases, industry). The residual that is being compensated is already a narrowed residual.
• Carbon credits are viewed with distrust by the cities themselves—an interesting data point that cuts against simple “offsetting is the easy way out” narratives.

Bottom line (skeptical version)

The headline is directionally accurate: many EU Mission Cities are banking on roughly 20 % residual emissions being balanced by carbon removal, and their concrete plans for delivering those removals are under-specified, especially on quantification, land constraints, permanence, and monitoring.

That is a real integrity risk.

However, the framing can overstate municipal failure while underplaying (a) the top-down pressure to hit a ~20 % residual band, (b) the genuine difficulty of fully eliminating building and transport emissions by 2030 in dense European cities, and (c) the still-immature state of permanent CDR options and supporting infrastructure.

The bigger problem is not that cities “haven’t thought about it,” but that the entire net-zero-by-2030 architecture for cities leans on residual compensation mechanisms that are not yet robust at the required scale and speed. The study usefully documents the gap; a fully skeptical reading asks whether the underlying target design itself is creating the conditions for that gap.