You hear the phrase “we’re number one!” from Americans fairly often, usually in relation to sports or politics. Now new research from the Union of Concerned Scientists shows that there’s another domain where it applies. It’s not as an assertion of superiority, and probably never will lead to a chant at the Olympics, the World Cup or even the UN climate negotiations. Rather, it’s in terms of our potential to use our land sector – that is, agriculture and forests – to reduce our global warming pollution and avoid the worst consequences of climate change.
The new research, summarized and with details on the methods and underlying database at www.ucsusa.org/halfwaythere, shows that the United States’ potential for climate mitigation from AFOLU (agriculture, forestry and other land use) is about 2 billion tons of CO2 equivalent (CO2eq) in 2020 and 3 Gt in 2030 – more than any other country. We’re followed by Indonesia, China and India, with large potential also from Brazil and the European Union also.
How big are gigatons of CO2? Well, for comparison, the UN Environment Program’s most recent annual Emissions Gap Report estimates the “emissions gap” at 8-10 Gt CO2eq in 2020 and 14-17 Gt CO2eq. This is the gap between what countries have already said they’d do to reduce emissions by 2020, and what would be need to keep global temperatures below 2 degrees C, which the IPCC has identified as the level leading to dangerous climate change.
This means that the 7 GtCO2eq of AFOLU potential corresponding to the world’s major emitters that our report looked at, gets us over halfway to closing the emissions gap in 2020, and nearly halfway there for the gap in 2030. This is why the report is titled Halfway There? In other words, we’re talking about substantial amounts of mitigation.
These numbers come from a review of mitigation potential estimates in the published literature, and one important caveat is that the number of studies we used is very low (n=13). There are actually more estimates of global AFOLU potential, and the recent IPCC report reviewed them and showed that they range from less than 1 to more than 13 Gt CO2eq. But often they just give an overall total, and/or relate to only part of AFOLU – e.g. emissions from deforestation. This study looked at country-specific estimates – an important change now that the UN climate negotiations are moving towards each country putting forward its “Intended National Determined Contributions” (INDCs) next spring. INDCs state countries’ intentions in terms of climate actions after 2020, when the new agreement to be negotiated in Paris next December will come into effect.
What makes us number one – yes, I’m speaking now as an American – is a combination of potentials identified by different published studies. We over-use fertilizer, resulting in nitrogen runoff that leads to emissions of nitrous oxide (N2O), a global warming pollutant that is 300 times as strong as CO2. We are the world’s largest consumer of beef, a food with a very high emissions footprint, so we could reduce our agriculture-related emissions by shifting our diet towards lower-emissions alternatives such as chicken, dairy and of course plant sources. We have high levels of food waste, particularly at the consumer and restaurant parts of the food chain, which increases the climate impacts of our agriculture. And we have a lot of land that could be reforested, or restored to other kinds of natural ecosystems such as prairies. This would result in carbon sequestration, that is, taking CO2 out of the atmosphere. Finally, although our forests are currently a large sink – that is, their growth sequesters about a gigaton annually – this is threatened by climate change and consequences of it like fires and insect outbreaks. So taking action to keep the sink intact effectively contributes to reducing our overall net emissions.
What does it mean to be Number One? Well, it says that we can do a lot, and contribute a lot to the fight against climate change. It also means that we have an obligation to do what we can. When the U.S. presents its INDC next March, we’ll see how our government plans to fulfill it.