What the plans actually book
Giulia Ulpiani and colleagues had 61 trained readers work through the climate-neutrality action plans of 103 European cities that have committed to net zero by 2030, coding each one against a common protocol. The residual emissions those plans leave behind total 61.4 million tonnes of carbon dioxide equivalent, a median of 20 per cent of each city's baseline and 0.8 tonnes per resident. As a decarbonisation figure that is genuinely fast. As an accounting entry it is a promise to take back out of the atmosphere roughly what Austria emits in a year.[1]
Where that residual sits is the part worth reading twice. The median city leaves 50 per cent of it in stationary energy — buildings, essentially — and 31 per cent in transport. Neither belongs to the hard-to-abate category the term was invented for; nobody files heating and cars alongside cement clinker or long-haul aviation. In those sectors the binding constraint is time and money inside a 2030 deadline rather than a missing technology, and the authors read the pattern the same way: cost and speed took priority over the deeper change.[1]
Against 61.4 million tonnes of booked compensation, the study finds quantified removal for 11.3 million tonnes — 18 per cent. Only 8 per cent of cities scored top marks for quantifying their residual emissions at all, and 11 per cent for estimating how much removal they could actually obtain. The robustness index the authors build for these strategies comes out at a median of 0.5, which they place midway between fragile and promising.[1]
Land the city does not have
Every one of the 103 plans leans on temporary, land-based removal — tree planting and its relatives. That is a real carbon sink with two properties a net-zero target has to survive: it can be reversed, and it needs ground. Cities are where ground competes hardest with housing, health facilities and energy infrastructure, and the study finds the plans carry no detailed assessment of how much land is actually available for the job.[1]
Permanent removal appears in 32 per cent of the plans: bioenergy with carbon capture and storage at 27 per cent, biochar at 13 per cent, direct air capture and storage at 7 per cent. Carbon credits appear in 40 per cent, usually thinly specified, held back as a last resort and — the study notes — widely distrusted by the cities themselves. So the compensation instrument every city holds is the one a fire, a drought or a change of land use can undo, while the options that hold carbon for centuries sit in a minority of plans and depend on regulation, infrastructure and predictable support that no municipality here controls.[1]
The lever the authors point to is on the demand side: front-load the reductions, concentrate what is left in sectors that genuinely resist abatement, and use demand-side measures they estimate could cut emissions by 40 per cent to 80 per cent depending on context. That is the same place the lever sat when this column examined where farmland carbon and biodiversity losses concentrate, and the reason is structural: a demand reduction removes the emission before any accounting has to be done about it, so it needs no permanence, no land and no monitoring regime. An alternative reading is that cities booked removal because demand-side measures reach into transport pricing, building standards and diets that municipalities cannot legislate alone, which would make the gap a governance limit rather than an oversight.[1], [2]
What the next revision will show
There is a clean test coming. These plans are living documents inside a 2030 mission, and each revision either moves residual emissions out of buildings and transport into sectors that genuinely resist abatement, or it does not. If by the end of 2027 the median city's residual has stopped sitting mostly in stationary energy and transport, the front-loading advice landed. If the sectoral shares hold near 50 per cent and 31 per cent while the compensation column stays 18 per cent quantified, then 61.4 million tonnes is a placeholder carrying a target it was never sized to carry.[1]
The measurable part is smaller and nearer. The authors' index rewards quantifying the residual, naming compensation options, estimating available removal capacity, and putting monitoring and governance behind both. A city raises its score by writing down numbers it does not currently have: how many hectares, held by whom, for how long, verified how. That is a cheap thing to demand and an uncomfortable thing to produce, which is roughly the definition of a useful disclosure requirement.[1]