Since the Paris Climate Conference wrapped up last December, 50 cities and companies have posted new climate initiatives in a United Nations-sanctioned registry called the Non-State Actor Zone for Climate Action (NAZCA). By spotlighting some 11,000 commitments cities, companies, regions, and investors have made since 2014, the U.N. hopes NAZCA becomes an essential tool in motivating more entries in the future.

But not everyone is so jazzed about it.

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Angel Hsu, director of Yale’s Data-Driven Environmental Solutions Group, spends a lot of time thinking about how to use data transparency to ease the troubles of fighting climate change. And as the registry currently stands, it’s more laundry hamper than database.

In April, Hsu and her colleagues published an article in Nature laying out the risks of “unevenly or idiosyncratically” reporting climate action data. The gist: If there aren’t clear reporting requirements for cities and companies, we have no way of knowing what’s working, what isn’t, and who’s pulling their fair share.

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Take carbon prices, for example. The authors write that less than one-sixth of the carbon-pricing initiatives registered with NAZCA actually cite a specific carbon price. When companies do name a price, it can range from $0.01 to $357.37 per metric ton of carbon dioxide.

The inconsistency matters because it implies a lack of accountability. Without a sense of what’s reasonable, freeloading becomes that much easier. NAZCA does not require companies or cities to report or track implementation data, so there’s no easy way of knowing whether or not they are actually following through on their commitments. Clear reporting standards can foster this kind of accountability, argue the researchers.

Hsu also cites consumer pressures in developed countries as motivating companies like Shell and BP to take action. But for cities, there’s no analogue of corporate social responsibility. City officials — and voters — just have to buy into climate action.

Selling that climate action can be easier said than done. In an analysis released last Thursday, C40 Cities — a coalition targeting urban climate action — details the barriers cities face when attempting to combat a changing climate. The group cites a lack of city-country coordination, a failure to make a convincing case for climate action, and, importantly, an inability to secure funding for green projects as among the hurdles facing efficient and effective climate action. For instance, write the authors, “only 1 in 5 C40 cities are able to borrow from the state, and only 1 in 4 to issue municipal bonds.”

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Cracking this nut is important because cities are well-positioned to do things that national governments can’t. “Sub-national governments have more flexibility to experiment with potentially risky policy tools,” write Hsu and colleagues.

Cities are a “living laboratory for sustainable prosperity,” Samuel Adams, director of the U.S. climate initiative at the World Resources Institute, told press last week. The lab could just use a bit more rigor.