On a grey morning in the European quarter, the building that does more than any other to shape how Europe’s cities will report on their own warming looks like nothing at all. It is an office. There are lanyards, a coffee machine, a meeting room named after a river. Somewhere inside, a civil servant is reading the eighth draft of a template — a spreadsheet, really — that a mid-sized city in Portugal or Poland will one day fill in to prove it is adapting to heat it cannot stop. The drama of the European urban climate decade is not in the heatwave. It is in the column headings.

This is the part of the story that gets lost. The public imagination of climate action in cities is asphalt being torn up, trees being planted, a mayor in a hard hat. The machinery that decides which of those acts counts, how they are measured, and whether a city can call itself a success — that machinery sits in Brussels, in a cluster of directorates, agencies and secretariats most Europeans could not name. It does not pour concrete. It writes the rules for everyone who does.

The Mission that put a number on the future

The most ambitious of these instruments has a deliberately blunt name: the EU Mission for 100 Climate-Neutral and Smart Cities by 2030. Launched in 2021 as one of five “missions” under the Horizon Europe research programme, it set a target that sounds almost naive in its roundness — one hundred cities, climate-neutral, by the end of the decade — and then went looking for volunteers. The response was telling. Three hundred and seventy-seven cities applied for a hundred places. The Commission, faced with that surplus of ambition, widened the door: in April 2022 it named 112 cities, the original hundred from all twenty-seven member states plus twelve from countries associated with Horizon Europe.

The number matters less than what joining costs. Each Mission city has to produce a Climate City Contract — not a building permit but a document, co-written with local residents, businesses and utilities, that lays out the city’s route to neutrality across energy, buildings, transport and waste, with an investment plan attached. The contract is, by the Commission’s own description, not legally binding. It is something stranger and arguably more demanding: a public, reviewable promise.

Who reads the homework

A promise needs a reader, and here the Brussels machinery shows its hand. When a city submits its Climate City Contract, it is assessed by the Commission with help from experts at the European Investment Bank and the Joint Research Centre — the EU’s in-house science service, which spends much of its time turning political aspiration into measurable indicators. A contract that passes review earns the city an EU Mission Label, a stamp that is meant, in turn, to unlock access to European, national and private finance.

The labels have been arriving in waves: ten cities in October 2023, twenty-three in March 2024, another twenty in the autumn, thirty-nine in May 2025. By October 2025 the Commission could announce that it had passed its own headline target — more than a hundred labelled cities, with 103 of the 112 participants over the line. The day-to-day support runs through a platform called NetZeroCities, delivered by a consortium led by the climate-innovation body Climate-KIC. The structure is layered, occasionally baffling, and entirely deliberate: the Commission sets the destination, an agency holds the purse, a science service writes the metrics, and a platform coaches the cities through the paperwork.

The contract itself would be a non-legally binding but carefully co-created delivery tool based on the realities and needs of each city.

Cities Mission implementation plan, European Commission

The older, larger machine

The Mission is the headline, but it is not the workhorse. That distinction belongs to a quieter institution whose secretariat also sits in Brussels: the Covenant of Mayors for Climate and Energy. Where the Mission has its hundred-odd cities, the Covenant has roughly ten thousand signatories — towns, cities and regions said to represent more than half the EU’s population. Its bargain is simpler and older. Sign up, and within two years you submit a Sustainable Energy and Climate Action Plan, the SECAP, which since the framework’s 2015 overhaul has had to fold climate adaptation in alongside emissions cuts.

This is where the column headings come in. The Covenant runs an online reporting platform, MyCovenant, and a set of standardised templates — the Excel sheet that mirrors them is, in its unglamorous way, one of the most consequential documents in European climate policy. It decides what a city must count: baseline emissions, risk assessments, the adaptation actions taken and the ones merely planned. A template is a theory of what matters, made mandatory. When a small municipality reports that it has greened a schoolyard or mapped its heat-vulnerable streets, it is translating a local act into a category that Brussels has pre-defined and can aggregate across a continent.

The law underneath

None of this floats free. Beneath the missions and the covenants sits the harder architecture of law. The European Climate Law, adopted in 2021, wrote the goal of climate neutrality by 2050 into binding legislation and, crucially, obliged both the Union and its member states to make continuous progress on adaptation — not just on cutting emissions, but on preparing for the warming already locked in. In the same month, the Commission published its EU Adaptation Strategy, with a phrase that has since become a kind of motto inside the directorates: adaptation must become “smarter, faster and more systemic”.

The strategy is candid about where the real work happens. It calls the local level “the bedrock of adaptation” and names the Covenant of Mayors as the main channel through which the EU reaches cities on the subject. It also concedes how uneven the ground still is. By the European Environment Agency’s reckoning, only about half of large European cities — 51 percent in 2022 — had a dedicated adaptation plan at all. For the other half, the templates exist before the policies they are meant to measure.

A separate instrument has grown up to close that gap: the EU Mission on Adaptation to Climate Change, a sibling of the Cities Mission, which has gathered more than three hundred regional and local signatories and aims to walk at least 150 regions and communities towards climate resilience by 2030. It runs its own portal, its own coaching, its own slowly hardening definitions of what resilience looks like on a spreadsheet.

The host city, on the same hook

There is an irony the Brussels machinery rarely advertises: the region that hosts it is bound by the same instruments as everyone else. The Brussels-Capital Region adopted its own Plan Air-Climat-Énergie in April 2023, committing to cut greenhouse-gas emissions by 47 percent against 2005 levels by 2030 and to reach carbon neutrality by 2050. The plan’s adaptation chapter reads like the Covenant template made local: better soil permeability, integrated rainwater management, more vegetation in the densest districts, and the creation of cooling zones to break up the urban heat island.

Those are the same categories a Portuguese or Polish city will report against, because they are the categories the templates contain. The directorate that drafts the column headings sits a few tram stops from neighbourhoods that will, in the coming summers, have to live inside them. The reporting framework is not an abstraction imposed from above on someone else’s city. It is also a description of the writers’ own.

What a template can and cannot do

It is fashionable to be cynical about all this — the labels, the non-binding contracts, the ten thousand signatories who may or may not deliver. The cynicism is not entirely wrong. A Mission Label is not a cooled street, and a SECAP submitted is not a SECAP enacted. The distance between a plan and its execution is exactly the distance Vienna or Paris spend years and political capital crossing. Brussels can require the report; it cannot pour the permeable pavement.

But the unglamorous truth is that comparability is itself a form of power. When ten thousand cities measure the same things in the same way, a councillor in one town can point to another and ask why their own adaptation lags. A funding body can rank applicants on like-for-like terms. A continent can, for the first time, see its own urban warming as a single dataset rather than ten thousand anecdotes. The lead author of the next reporting template will never be famous. The cities that fill it in will decide whether the European urban decade was measured honestly — and, eventually, whether it was real.

Sources: European Commission, EU Mission “100 Climate-Neutral and Smart Cities by 2030” (Cities Mission) implementation plan and announcements (2021–2025); NetZeroCities / Climate-KIC; European Climate, Infrastructure and Environment Executive Agency (CINEA); Joint Research Centre (JRC); European Investment Bank; EU Covenant of Mayors for Climate and Energy Secretariat, SECAP reporting guidelines and MyCovenant; European Climate Law (Regulation (EU) 2021/1119); EU Adaptation Strategy, COM(2021) 82 final; EU Mission on Adaptation to Climate Change; European Environment Agency, urban adaptation reporting; Bruxelles Environnement / Leefmilieu Brussel, Plan Régional Air-Climat-Énergie (PACE, 2023).