Hot or not? McKibben and the Bieb, together at last.

In North America this summer, drought, fire, and heat are putting climate back in the headlines — if not, yet, in the election-year political debate. At such moments, it’s tempting for anyone who’s been talking about the issue all along to pile on with the “see what we mean?”s and “we told you so”s. But it’s far more important to use the moment to catalyze understanding and action.

Two articles this weekend set the moment’s choices in deep relief. On the cover of Rolling Stone, sharing display space with Justin Bieber’s come-hither pout and Eraserhead ‘do, Bill McKibben sketches an arrestingly urgent map of our plight, using three numbers to explain why the fate of the planet comes down to fossil-fuel company finances. In the Sunday New York Times, David Leonhardt, the paper’s Washington bureau chief, finds a “ray of hope on climate change” in global clean-energy trends.

Let’s start with Leonhardt. He tells us, “The world’s largest economies may now be in the process of creating a climate-change response that does not depend on the politically painful process of raising the price of dirty energy.” Solar and wind investments are largely paying off; natural gas development, however controversial, has brought prices down for a fossil fuel that puts less carbon into the atmosphere than coal.

All this means we’re already a lot closer to clean-energy nirvana than most people think — and if government would keep funding research and deployment, we could get there.

“Carbon pricing is going to have an uphill climb in the U.S. for the foreseeable future,” says Robert N. Stavins, a Harvard economist who is a leading advocate for such pricing, “so it does make sense to think about other things.”

Those others things, in the simplest terms, are policies intended to help find a breakthrough technology that can power the economy without heating the planet. “Our best hope,” says Benjamin H. Strauss, a scientist who is the chief operating officer of Climate Central, a research group, “is some kind of disruptive technology that takes off on its own, the way the Internet and the fax took off.”

Leonhardt is a pragmatist who is smart enough to hedge his optimism with all the usual disclaimers. Even so, the reader’s takeaway is relief: We don’t have to wait for Congress to break its Beltway deadlock and put some sort of price tag on carbon. We don’t have to tighten our belts and lay off the gasoline. If we just sit back and let good old human ingenuity work its magic, we can dodge the climate bullet, and enjoy our barbecues this summer without that gnawing fear that we may be the barbecue. Whew!

Cue entrance music — Radiohead, impassioned, heartbreaking — for Bill McKibben. (He is, as we regularly disclose here, a longtime Grist board member and, also, a friend.) His Rolling Stone piece walks us through a sequence of numbers that will put you right back off your charcoal-grilled burger.

Figure No. 1 is 2 degrees C (3.6 degrees F), the level of warming that pretty much everyone agrees we can’t go beyond without some pretty awful consequences — “the bottomest of bottom lines.”

Figure No. 2 is 565 gigatons — the amount of additional carbon dioxide scientists estimate we can add to the atmosphere by midcentury and still have some reasonable hope of staying below the 2-degrees level.

The third and most important number is 2,795 gigatons — the amount of carbon “already contained in the proven coal and oil and gas reserves of the fossil-fuel companies, and the countries (think Venezuela or Kuwait) that act like fossil-fuel companies.”

That third number keeps McKibben awake at night, and should have us all on edge.

Think of two degrees Celsius as the legal drinking limit – equivalent to the 0.08 blood-alcohol level below which you might get away with driving home. The 565 gigatons is how many drinks you could have and still stay below that limit – the six beers, say, you might consume in an evening. And the 2,795 gigatons? That’s the three 12-packs the fossil-fuel industry has on the table, already opened and ready to pour.

We have five times as much oil and coal and gas on the books as climate scientists think is safe to burn. We’d have to keep 80 percent of those reserves locked away underground to avoid that fate …

Not burning that fuel would cost the fossil-fuel industry trillions of dollars.

If you paid attention to the scientists and kept 80 percent of it underground, you’d be writing off $20 trillion in assets. The numbers aren’t exact, of course, but that carbon bubble makes the housing bubble look small by comparison. It won’t necessarily burst — we might well burn all that carbon, in which case investors will do fine. But if we do, the planet will crater. You can have a healthy fossil-fuel balance sheet, or a relatively healthy planet — but now that we know the numbers, it looks like you can’t have both. Do the math: 2,795 is five times 565. That’s how the story ends.

These numbers frame our climate choices much more starkly than we’re accustomed to. They’re not about conservation or research; they’re about asset valuation and risk management. If we’re going to bend the climate-change curve, the fossil-fuel industry is going to take one hell of a multi-trillion-dollar haircut. So it will push back against this prospect for all it’s worth.

Now, to be sure, these companies are going to pay that price no matter what: Either they’ll pay it later, when the disastrous effects of irreversible climate change finally persuade the last denier ostriches that we’re in trouble, or they’ll pay it sooner, when we might have an opportunity to mitigate the worst impact of such change.

Since they’re corporations, and will always protect next quarter’s earnings ahead of longer-term concerns, they’ll do everything they can to postpone this reckoning. Our job, McKibben says, is to speed it up — to make the oil companies feel this pain now. The sooner the price on their fuel stockpiles reflects the actual cost to the planet and the human race of burning that fuel, the better our chances. While a global energy-market crash is no fun to contemplate, it’s also inevitable — and we might want to pay that price sooner, before the crash also engulfs the civilization we call home.

Alone among businesses, the fossil-fuel industry is allowed to dump its main waste, carbon dioxide, for free. Nobody else gets that break — if you own a restaurant, you have to pay someone to cart away your trash, since piling it in the street would breed rats. But the fossil-fuel industry is different, and for sound historical reasons: Until a quarter-century ago, almost no one knew that CO2 was dangerous. But now that we understand that carbon is heating the planet and acidifying the oceans, its price becomes the central issue …

The fight, in the end, is about whether the industry will succeed in its fight to keep its special pollution break alive past the point of climate catastrophe, or whether, in the economists’ parlance, we’ll make them internalize those externalities.

The only efforts that will fully engage the attention of these corporations are those that affect their stock prices. We can’t change the energy habits of the globe overnight, but markets are notoriously fickle and easily spooked, and if enough people make enough noise suggesting that the days of carbon’s free ride are numbered, energy companies might start feeling the market-price pain now. One prospect McKibben raises is a campus divestiture movement a la the anti-apartheid protests of the 1980s, using the consciences and pocketbooks of universities driven by the passion of their students.

So there you have it: a largely optimistic view from The New York Times‘ economics correspondent, suggesting we may already be on the road to an unfolding climate solution without facing a political or economic reckoning; and a tougher call to arms from McKibben, showing why that reckoning is inevitable, the quicker the better. It’s “You May Already Have Won!” vs. “We have only just begun to fight.”

Leonhardt’s stance is more comforting. McKibben’s is more credible — and more inspiring.