“At two degrees, the melting of the Arctic ice sheets will pass a tipping point of collapse, flooding dozens of the world’s major cities this century — and threatening, over many centuries, to elevate sea level as much as 200 feet. At that amount of warming, it is estimated, global GDP, per capita, will be cut by 13 percent. Four hundred million more people will suffer from water scarcity, and even in the northern latitudes heat waves will kill thousands each summer. It will be worse in the planet’s equatorial band. In India, where many cities now numbering in the many millions would become unliveably hot, there would be 32 times as many extreme heat waves, each lasting five times as long and exposing, in total, 93 times more people. This is two degrees — practically speaking, our absolute best-case climate scenario.”
They have also, thankfully, offered a practical suggestion, proposing the imposition of a carbon tax many, many times higher than those currently in use or being considered — they propose raising the cost of a ton of carbon possibly as high $5,000 by 2030, a price they suggest may have to grow to $27,000 per ton by 2100. Today, the average price of carbon across 42 major economies is just $8 per ton. The new Nobel laureate in economics, William Nordhaus, made his name by almost inventing the economic study of climate change, and his preferred carbon tax is $40 per ton — which would probably land us at about 3.5 degrees of warming. He considers that grotesque level “optimal.”
But a carbon tax is only a spark to action, not action itself. And the action needed is at a scale and a speed almost unimaginable to most of us. The IPCC report called it unprecedented. Other activists often see one precedent, in all of human history, citing the model of how the United States prepared for World War II, and calling for a global mobilization of that kind — all of the world’s rivalrous societies and nationalistic governments and self-interested industries organized around the common pursuit of a stable and comfortable climate as though warming was an existential threat.
It is. And the World War II mobilization metaphor is not hyperbole. To avoid warming of the kind the IPCC now calls catastrophic requires a complete rebuilding of the entire energy infrastructure of the world, a thorough reworking of agricultural practices and diet to entirely eliminate carbon emissions from farming, and a battery of cultural changes to the way those of us in the wealthy West, at least, conduct our lives. And we need to do all of that in two, or possibly three, decades. As a comparison, simply the last phase of the recent three-stop extension of New York City’s Second Avenue subway line took 12 years. All told, from the first groundbreaking, the project took 45 years.
That is not to say it’s over or we’re doomed. Stalling warming below four degrees is better than surpassing it, keeping temperatures below three is better still, and the closer we get to two degrees the more miraculous. That is because climate change isn’t binary, and doesn’t just kick in, full force, at any particular temperature level; it’s a function that gets worse over time as long as we produce greenhouse gases. How long we continue to is, really, up to us, which is to say it will be determined in the province of politics, which is to say public panic like that produced by the IPCC report can be a very productive form of policy pressure.
There are also those far-fetched alternatives I mentioned — carbon capture and solar geoengineering — but each is far from workable at the moment and, even in theory, come with really scary drawbacks. But even if the technology becomes dramatically cheaper and more efficient over the next few years, you would need to build them out across the globe, as well — whole plantations sucking carbon almost everywhere on the planet. It will take quite a long time to build those, in other words, even if they worked, and we simply don’t have that many years left to act.
A few weeks ago, as the IPCC report loomed, I had lunch with a prominent climate scientist who’d been involved in earlier reports and has done considerable work on local preparedness as well. I asked if he thought New York would eventually build a sea wall or surge barrier to protect the city from sea-level rise and flooding. Yes, he said, Manhattan will be protected, at any cost. But major infrastructure projects like these take decades — typically about 30 years. Even if we began building today, he said, the barrier would not be finished in time to save Howard Beach and other parts of southern Queens and Brooklyn. Soon enough, he said, you’ll see the city adjust accordingly — halting new infrastructure projects there, eventually pulling back from even quotidian maintenance like sewer repairs and generally signaling to current residents that they will not be able to leave behind their homes, when they die, to their children. And of course a sea wall to protect New York only encloses the narrows of New York Harbor, leaving all of Long Island exposed.
This is just the threat from sea level, and just one (very rich) metropolitan area. The world is much bigger than that, but so is climate change. It is also very fast, with more than half the carbon humanity has ever emitted into the atmosphere having come in just the last 25 years, since Al Gore published his first book on climate change. Monday’s IPCC may seem like a dramatic departure, and it is. But there is going to be much more like it coming. So long as we continue to squander what little time we have, the news will only get worse from here.