Today we’re releasing an important report on what the world’s largest emitters of greenhouse gases could do to reduce the global warming pollution released by their land sectors—that is, their agriculture and forests. It’s called Halfway There? What the Land Sector Can Contribute to Closing the Emissions Gap.
The emissions gap is the difference between what the world’s countries have already pledged to do to cut their emissions, and what they need to do to avoid dangerous climate change. Our report shows that just the biggest emitters have the potential to close half of that gap by reducing land sector emissions in the 2020-2030 time frame.
The land sector—AFOLU, standing for “Agriculture, Forestry and Other Land Use”, in the IPCC’s terminology—accounts for a quarter of global emissions, according to the IPCC’s most recent estimate last year. Thus, it’s no surprise that it can contribute a lot—indeed, it has to—to closing the emissions gap. But our report shows that the potential is substantially larger than just the emissions level would suggest. There are a couple of reasons for this.
First of all, AFOLU includes one possibility that other parts of the economy lack. It can not only reduce its emissions, but also sequester carbon—that is, take global warming pollution out of the air. This neat trick, invented by algae a couple billion years ago, and substantially improved on by trees over the last 300 million or so, means that with reforestation and restoration of other kinds of ecosystems, the land sector actually has considerably higher mitigation potential than its total emissions would indicate. Indeed, it’s the only sector that can produce the “negative emissions” in the 2nd half of the twenty-first century that the IPCC report indicated as necessary to keep global warming below the dangerous 2 degrees C level.
Another distinctive characteristic of the AFOLU sector is that many of the changes that would reduce emissions—e.g. ending deforestation, improving water management in rice production, or shifting to more healthy diets—would also have large benefits for productivity, biodiversity and human health. So they’d be worth doing even apart from their climate benefits, and even more worthwhile since we can significantly reduce or slow the pace of the dangerous climate impacts that our children and grandchildren will face.
When we presented the initial results of this study at the climate change negotiations in Lima in December, I emphasized the finding that the country with the biggest potential is the United States—“we’re number one!” But several countries have large potentials, and one interesting finding is that they come from quite different subsectors of the land sector. This graphic shows in relative terms which kinds of approaches can mitigate the most emissions in different countries we studied (dark blue is highest, light blue is medium):
Many countries have a lot of potential to reduce their emissions from cattle production, and several to sequester carbon by regrowing forests (that taking-it-back-out-of-the-air trick). But others have quite distinctive profiles in terms of what they can do. Indonesia, for example, has large emissions from deforestation and the clearing of peat swamps. China can reduce the methane from their rice production by modifying how long paddies are flooded. The pattern is “common but differentiated”, in the official terminology used in the climate negotiations. Or, in more colloquial (and maybe dated) words: “different strokes for different folks.”
Here I have to clarify that we’re talking about the potential to close the emissions gap, not to provide the total mitigation that’ll be necessary. Part of the reason that the gap is already considerably less than it would be under business-as-usual projections, is that many countries have already pledged to reduce their fossil fuel emissions in different ways. Few have made commitments to mitigate from their land sectors, so there’s a lot left there that they can do. But the land sector won’t solve the whole problem.
It can, however, contribute a lot to closing the gap, especially if the big countries we examined step up and decide to act. Check out the details of our analysis (along with the complete dataset, a detailed description of our methods, and the presentation of the results that I gave in Lima) at www.ucsusa.org/halfwaythere, and let us know what you think!