If we could get a whole new continent—equal to twice the size of the continental United States—of vegetation by spending, say, $100 billion, would that be a good deal?
How would we go about answering that?
Well, we might start by noting that the total value of crops raised in the U.S. in 2016 was about $143.4 billion. That’s for one year. And it’s from just about 18 percent of all U.S. land.
But we’re talking about adding a continent of vegetation double the size of the United States, or 11 times as much land as we cultivated last year. At a one-time cost of $100 billion.
Sounds like a bargain to me.
But wait! The deal’s actually a whole lot better. We got that new continent’s worth of vegetation at a price of—nothing.
Economists refer to costs (like pollution) of economic activity that aren’t borne by producers as externalities, or, to be specific, negative externalities. Benefits that aren’t borne by producers are also externalities—positive externalities. We might call such a positive externality an “anti-pollutant.”
All that increased plant growth around the world is a positive externality from all our carbon dioxide emissions. And its value is simply enormous.
That makes CO2 an amazing anti-pollutant. Yes, it has a minor, perhaps immeasurably small upward effect on global average temperature (perhaps around 0.5–2.0 degrees C for every doubling of its concentration).
Viscount Matt Ridley, a scientist and member of the U.K. House of Lords Science and Technology Select Committee, commented on this to Julie Kelly of National Review:
This is a huge global phenomenon, which is bringing enormous financial benefits to agriculture. That means we have a genuine benefit to carbon dioxide that surely must be taken into account if you are calculating the social cost of carbon. Given that we are not seeing any clear impact on droughts, floods, or storms, it is very hard to argue that there have been net negatives to carbon from climate change so far. In fact, there have clearly been net benefits.
By the way, it’s not just “climate skeptics” who point to the greening of planet earth by CO2. Even NASA made a big deal of the story, reporting that after modeling the contributions of CO2, nitrogen fertilization, and various climate changes over the period, researchers concluded that 70 percent of the greening was attributable to CO2, with the next-biggest contributor, nitrogen, accounting for only 9 percent. It depicts the story in this brief video:
This isn’t a brand new recognition. The Center for the Study of Carbon Dioxide and Global Change produced videos in 1992, The Greening of Planet Earth, and 1998, The Greening of Planet Earth Continues, that explained how this works, but at the time there wasn’t a whole lot of data to demonstrate that what made sense in theory was actually happening. Now there is. It’s time for a sequel.