Denmark map. There’s been a lot of ambitious talk lately about carbon neutrality. It’s exciting stuff, but it’s worth pausing to consider just how huge that challenge is. And what, precisely, does it mean? Zero emissions, or lots of offsets? 

I thought it was interesting to take a look at the climate action plan from the city of Copenhagen. It’s certainly a contender for the title of the greenest and most progressive city on earth, and it’s a city that has pledged to become carbon neutral by 2025. But what you find is that even for the Danes, carbon neutrality is more aspirational than actionable:

By implementing the climate plan’s contributions — and assisted by the expected developments — we expect to reduce Copenhagen’s CO2 emissions from 2,500,000 tonnes CO2 today to about 1,150,000 tonnes in 2025.

To become completely neutral we must also remove just as much CO2 as we produce. We will need to compensate for the 1,150,000 tonnes of CO2 in 2025 by for example investing in still more windmills, use new technologies or plant forests which absorb CO2.

In other words, even Copenhagen doesn’t have a plan to achieve zero emissions. They’ll rely on what amounts to offsets for over a million tons of CO2, roughly half of their current carbon footprint.

Still, their goals are astonishing: Copenhagen has an action plan to cut their already-low emissions in half over the next 15 years. Wow. That will be a signal achievement, and one that will no doubt provide valuable lessons for us in the Northwest, both in terms of strategies to reduce our emissions as well some clearer notion of what it means to be “carbon neutral.”

Applying Copenhagen’s achievement here in the Northwest makes for an interesting comparison because, as it happens, the city of Copenhagen is roughly the same size as the three big cities in the Northwest. Seattle emitted around 6.7 million tons of CO2 in 2008; Multnomah County, home to Portland, emitted about 8.5 million tons that year; while Vancouver claimed just over 2.5 million tons. (It’s important to keep in mind that these inventories measure different things in different ways, so comparisons between the numbers are not informative. For example, Vancouver’s number refers to a much narrower scope.) If each city followed Copenhagen’s lead and reduced its emissions by half — a phenomenal achievement — Seattle would need to offset more than 3 million tons of CO2, Multnomah-Portland more than 4 million tons, and Vancouver well over 1 million tons.

If Seattle, Portland, and Vancouver do as Copenhagen does, and succeed in cutting their emissions in half over the next 20 years, that will be worth shouting from the green rooftops. But even so, to reach carbon neutrality we’d be talking about somewhere in the range of $160 million dollars of investment annually by the cities for various carbon offset projects (assuming a price of $20 a ton for offsets). That’s a lot of money. And it’s an open question, at least to my mind, whether achieving “carbon neutrality” for a specific city for a specific point in time would really the best use of that money.

Now, in fairness, for all the hand-wringing they induce from people like me, offsets are not necessarily a bad idea. At their best, they can foster important advancements for developing countries, low-cost emissions saving in farm country, or ecological restoration. On the other hand, $160 million might be better spent making investments in strategies to further reduce emissions locally, even if those advancements wouldn’t result in carbon neutrality. Yet on the third hand, it’s not exactly clear how to achieve those further reductions; even Copenhagen doesn’t yet have a plan. I’d say we’re in a pickle.

Now before everyone accuses me of being a giant kill-joy, I should add that there are at least two reasons that a community may want to aim to be “carbon neutral,” even if what that really means is big offset purchases to supplement local carbon reductions.

Reason #1: “80 percent below 1990 levels by 2050″ doesn’t exactly roll off the tongue. So even if we don’t know what “carbon neutral” looks like, it seems somehow easier for people to get their heads around conceptually. People are inspired by the idea of carbon neutrality in a way that they clearly aren’t by “the terms of the Kyoto Protocol” or “80 percent.”

Reason #2: We need something to push us — our elected officials, our businesses, and individuals — to think big. Really big. If, as a planet, we’re going to achieve climate stability, the time for incremental change has passed. As Knute Berger put it yesterday when he proposed removing a major bridge in the Seattle area: “Why, in the 21st Century, aren’t we repairing and restoring the environmental damage of the past instead of doubling down on it?”

That could be the kind of question people ask under the “carbon neutral” banner.

Yet I’m wary. The really game-changing climate policies are simply not at a neighborhood or city scale. They’re at the national and global scale — comprehensive and enforceable carbon limits or pricing.

While local areas can incubate ideas and build supportive constituencies, our climate action won’t ultimately add up to much unless it is comprehensive and much, much larger. So city-level aspiration should not be allowed to redirect our attention from national policy — it should be leveraged to reinforce the big stuff. 

This post originally appeared at Sightline’s Daily Score blog.