As faithful Daily Grist readers know, yesterday six western states (and two Canadian provinces) formally debuted the Western Climate Initiative, a cap-and-trade agreement aiming to lower GHG emissions by 15 percent below 2005 levels by 2020.

What of his future?

Carbon neutral in his lifetime.

Inevitably, announcements like this are met with heated debate over the target. Is it strong enough? Fast enough? Politically palatable? The 80%-by-2050 target seems to be gaining steam in political circles, though some bills propose a mere 70% or even 65%. Some enviros argue we need 90%.

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The intensity with which this numerical parsing is debated has always struck me a faintly silly. For one thing, if we’ve reduced GHGs by, say, 55% by 2040, will our subsequent course of action really be dictated in any substantial way by whether we chose 70% or 80% as our 2050 target? We have only the vaguest notion what that state of affairs would look like and what considerations would face us at that point.

Secondly, numerical targets are, by and large, politically inert. They aren’t inspiring. They aren’t sticky. "80% by 2050" isn’t a rallying cry, it’s a gauge readout, recorded on a ledger. It’s a slogan only a wonk could love.

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After thinking about this a while, here’s my proposed replacement:

Children born today should live to see a U.S. that produces no climate pollution.

In other words, U.S. carbon neutral by 2060 or so. Eliminate net carbon emissions.

Why no carbon emissions rather than an 80% or 90% reduction? For one thing, it’s better rhetoric. It’s easy to understand, easy to communicate. It’s not "less bad." It’s "solve the problem." It’s not, "like today, but less so." It’s "the future." It’s a goal as ambitious as winning WWII or landing on the moon. It can inspire.

But is it practical? Can it be done? Obviously that’s unknowable to some degree. Me, I believe it’s possible.

It depends on what you think the toughest carbon reductions will be — the first 20% or the last 20%. My impression is that the 80%-by-2050 target came about in part because people think there will be a hard nut of carbon-intensive activities that will be difficult to eliminate. That’s the last 20%.

My guess, however, is that the first 20% will be the toughest. We’re talking about changing some extremely ingrained habits, dislodging some powerful political players, and changing some long-standing rules and regulations. Once that initial work is done — and I expect it will involve some brutal battles — momentum will gather. Once we hit 50%, 60%, 70% reductions, the momentum will be unstoppable. All the big players will be on board. The public will have begun to view emitting GHGs as a weird, dirty relic of our past. The rest will be a mop-up operation.

We’ll never stop, once we’ve genuinely started.

So why not say so? Why not go big? Why not have some confidence in our creativity and commitment? Why not inspire?

I want my kids to live in a country that does not pollute the atmosphere with GHGs. You don’t need to know any math to understand that.