The transition to a carbon-neutral society is not only an urgent challenge but also an opportunity to build a safer future. The European Union has set itself, through the Paris Agreement and the European Green Deal, ambitious goal of achieving climate neutrality by 2050. European cities are at the forefront of this effort. Initiatives such as EU mission for 100 climate-neutral and smart cities (Cities Mission), supports selected cities to achieve so-called net-zero by 2030. However, a key and often misunderstood question remains: how to deal with emissions that cannot be completely eliminated at source?

Reducing emissions must always come first

The cornerstone of any legitimate climate strategy is Emissions Reduction First principle. Carbon removal, otherwise known as negative emissions, must never be a substitute for feasible emission reductions at source. Relying solely on offsets could slow the transition away from fossil fuels and delay a true transformation. Cities must maximize their efforts across all sectors and only move towards removals when all available technical and economic reduction options have been exhausted.

How to analytically define residual emissions?

Even after the most stringent measures are implemented, emissions will remain in some sectors (such as historic buildings, wastewater treatment, heavy industry or agriculture) that are technically unavoidable for the time being. These are called residual emissions.

A report by the Joint Research Centre (JRC) strongly advises European cities not to set their residual emissions targets simply by blind administrative targets, but through thorough analytical work. The city should clearly identify the sources of emissions, explore modern technological solutions, and understand the constraints (including legislative or financial) that prevent their elimination. Transparency in acknowledging the necessity of these emissions prevents suspicions of „greenwashing“ and legitimizes the goal of climate neutrality.

Compensation mechanisms: Disposal directly in and outside the city

To achieve net zero, cities must offset their demonstrable residual emissions by removing greenhouse gases from the atmosphere. This process can be achieved through two main approaches, ideally combined:

1. In-boundary carbon removals: These are targeted anthropogenic activities directly on the territory of the city. They can be Nature-based solutions, such as afforestation, urban greening, wetland restoration or soil carbon storage. On the other hand, there are permanent and technological solutions, such as the use of biochar on green roofs, DACCS (direct air capture) technologies, or carbon storage in embedded bio-materials such as structural wood in buildings, making the buildings themselves a CO2 sink.
2. Purchase of verified carbon credits (Out-of-boundary credits): To offset emissions, cities can purchase certified carbon credits from projects outside their territory. However, in the context of net zero goals, they are acceptable exclusively credits for real carbon removal (removal credits). Credits for merely „avoiding“ emissions (e.g. by building a solar power plant instead of a coal-fired one) are not eligible to offset residual emissions in a carbon neutrality strategy.

The „Like-for-like“ rule

When planning strategically, cities should pay attention to the principle of like-for-like. This accounting principle highlights differences in permanence. Fossil fuel emissions remain in the atmosphere for millennia and should therefore be primarily offset by methods permanent removal (e.g. geological storage using DACCS or BioCCS technologies). Short-term natural storage (such as trees) that are vulnerable to fires and pests should be used more to offset biogenic emissions or methane.

Pillars of high integrity and transparent reporting

The emissions removal plan must be based on clear and ethical principles:

• Transparency: Positive emissions (pollution produced) and negative emissions (carbon removed) must be reported in inventories separately. This avoids double counting and ensures the mathematical verifiability of climate targets. This is particularly difficult in the LULUCF sector (Land Use and Forestry), where the principle of completeness and exclusivity of land categories must be observed.
• Environmental and ethical integrity: Measures must not lead to damage to other aspects of the environment. A reckless effort to plant a huge number of trees could threaten native biodiversity (the problem of monocultures) or compete with food production.
• Co-benefits maximization and diversification: Ideal carbon removal methods also bring other social and environmental benefits. For example, urban forests mitigate the heat island effect, retain stormwater, and improve air quality. By diversifying approaches, a city spreads the financial and physical risks of a single project failing.

EU Certification Framework (CRCF)

The new EU Regulation on Carbon Certification and Carbon Farming (CRCF) provides guidance for cities in ensuring the high quality of carbon credits and domestic sequestration. This regulation introduces a European registry and strict assessment criteria. QUALITY, which includes Quantification (precise measurement of benefit), Complementarity (additionality – activity goes beyond common practice), Long-term storage a Sustainability. Cities should require full compliance with these standards when procuring credits or creating policies.

On the path to zero emissions, a city is not just a passive implementer. Managing complex CO2 capture technologies places it in the role of a key player. strategist, innovator, investor and convener Only through a transparent, diversified and analytical approach to ongoing emissions can cities turn the vision of climate neutrality into reality and guarantee a greener, more resilient and sustainable future for their residents. JRi&CO2AI