One of the great challenges in the fight against climate change is how to effectively support the economic progress of developing countries without undermining their natural resource conservation and climate objectives. Even as the U.S. and other wealthy countries take action to cut pollution at home, their efforts to keep the planet’s temperature from rising 2 degrees C will be overwhelmed if developing countries are unable to transition quickly to a low-carbon economy.
A critical part of this challenge is slowing and reversing forest loss. The world is losing more than 25 million acres of forest every year, equivalent to the area of the state of Virginia. Forests are one of our planet’s most effective options for fighting climate change: keeping forests standing instead of clearing them for other land uses yields a double climate benefit – both avoiding the large-scale release of carbon currently stored in the trees, and maintaining forests ability to suck carbon out of the atmosphere long into the future. And this is on top of all the other benefits forests provide to people. So while deforestation and land use change make up only about 10% of annual greenhouse gas emissions, tropical forests represent 24-30% of emissions reduction opportunity.
One of the tools the United States has used in the last decade and a half to effectively support both economic development AND forest protection has been “debt-for-nature swaps” that reduce debt obligation of developing countries while simultaneously providing funding for conservation programs. Under the Tropical Forest Conservation Act (TFCA), a 1998 law passed with bipartisan support, about $223 million in congressionally appropriated funds have been used to conclude 19 debt treatment agreements with 14 countries that support programs to conserve tropical forests within the partner country. In total, since its inception, the TCFA has been involved in the protection of approximately 69 million acres of forest worldwide—an area larger than the state of Colorado.(1)
While funding for the TFCA has fallen off in recent years, a renewed effort in Congress to reauthorize and refund the bill is underway. Given the Administration’s intense focus on reducing climate emissions, it is worth applying an emissions lens to this program. We estimate that forest conservation supported by the TFCA has avoided climate emissions of about 70 million tons of carbon (or 250 million tons of CO2) per year. This is roughly equivalent to a year’s worth of emissions from 61 coal-fired power plants.
How do we get this number? Attempting to assess the carbon benefits of forest conservation is challenging, but also critically important for understanding the efficacy of our past and future efforts to safeguard the climate. Ultimately, our calculations must account for the fact that protecting forests not only keeps the carbon they currently store out of the atmosphere, but also preserves their ability to absorb future emissions.
It’s important to address three questions on our way to estimating the climate impact of this forest conservation program, which we will do as we walk through three different ways of coming up with a number.
First, how much carbon is actually stored in these forests? This 69 million acres of tropical forest lands store something on the order of 12 to 16 Gt of CO2 in both above and below-ground biomass (or 3.3 to 4.4 Gt of carbon). We get this answer from a bottom-up analysis, multiplying the total area affected by TFCA in each partner country by a range of published average carbon densities specific to each country (Saatchi et al 2011). This is a huge carbon stock – about twice as much as all U.S. emissions for an entire year; more than 1/4 of annual emissions globally.(2)
If we start with this carbon stock estimate, you can make a few assumptions and calculate an emissions impact. For example, assume that the entire area would have been mostly deforested by some future year, say 2040, with 75% of the total carbon currently stored in these forests being emitted to the atmosphere very quickly. That would be equivalent to 9-12 Gt CO2 of total emissions between 2001 when the program started and 2040. This is equivalent to 230 to 300 million tons CO2 avoided emissions per year (or 62 to 82 million tons carbon per year), just from the avoided deforestation.
Second, how much carbon does this area of forest sequester every year? Healthy forests continue to absorb carbon from the air year after year as they mature, even after hundreds of years. If you clear those forests, they no longer act like a sponge that cleans up some of the carbon we release to the atmosphere by generating electricity, moving goods and people around, and manufacturing stuff. The average amount of CO2 absorbed by secondary tropical forests is somewhere around 7.5 to 15 tons CO2 per hectare per year, or 0.83 to 1.7 tons C per acre per year (e.g. Bonner et al 2013, figure 5, noting the need to convert from biomass to C or CO2).
Starting with this sequestration potential of the TFCA forest area, you could imagine that without conservation actions all this forest would have remained forest, but a slowly degrading forest that no longer accumulates carbon over future years. Compared to the “with-TFCA” scenario of healthy forests that continue to absorb carbon, this is a difference of about 210 to 420 million tons CO2 per year (or 60 to 115 million tons of C) – but in this case it is forest sequestration that happens with TFCA conservation that might not have happened otherwise.
Third, and most importantly, what is a realistic scenario for what would have happened to these areas with versus without the TFCA conservation programs? The best estimate would be to calculate the carbon difference between these two possible futures. While much more digging into each individual program would be necessary to truly answer this question, we can come up with some reasonable guesses (and even see how different our estimate would be with different assumptions). We apply a reasonable rate of deforestation and include both deforestation emissions and lost sequestration, using the following assumptions:
- The area protected by TFCA increases slowly and steadily from 2001 to 2020, starting at zero and reaching 69 million acres in 2020;
- 2% of the TFCA-protected area would have been deforested each year if it were not protected by the program;
- Deforestation emits 75% of the carbon in forests;
- Deforested land no longer sequesters substantial amounts of carbon in future years after deforestation;
- Non-deforested areas remain healthy and continue their average sequestration; and
- Lost sequestration from deforested areas is accounted for through 2050.
In this third scenario, by 2020 when all TFCA conservation actions have been taken and the full 69 million acres is protected, the program is generating carbon benefits at the rate of about 225 to 370 million tons of CO2 per year (or 60 to 100 million tons C). This is a combination of avoided deforestation emissions (a little over one million acres would have been lost in 2020 without TFCA), and increased sequestration (that million hectares would absorb a lot of carbon through 2050).
In conclusion, this analysis draws attention to a few key points:
- Assessing the carbon benefits of forest conservation is challenging but doable.
- Calculations should account for both ways forest conservation contributes to a safe climate: by avoiding a big pulse of emissions when forests are lost; and by maintaining into the future the ability of the land to absorb more carbon, year after year.
- TFCA has been an amazingly powerful tool for generating climate benefits, reducing upwards of 250 million tons of CO2 emissions per year, or 70 million tons C per year – at a budgetary cost of less than 20 million dollars per year.
(1) It is important to note that this area estimate can be considered conservative (an underestimate), as it only considers the debt swap TFCA deals but not the debt reduction deals which don’t typically quantify the area of impact as clearly. At the same time, it can also be considered liberal (an overestimate) because these totals are not based on a grant-by-grant assessment of acreage directly financed by TFCA, but rather on the total acreage of forest lands conserved through programs that TFCA agreements have helped make possible.
(2) A top-down analysis yields a similar estimate: the world has about 4 billion hectares of forests, which store about 638 gigatons of carbon (FAO 2005). 69 million acres (or 27m hectares) is about 0.7% of global forests. 0.7% of 638 Gt C is 4.4 Gt C.