(CN) — An international coalition of scientists published first-of-its-kind research Wednesday mapping how world governments can most efficiently spend their resources to promote biodiversity and stabilize the climate. Their findings could help accomplish goals set by lagging multilateral climate accords.
Ecological restoration projects are not created equal, as it turns out: some conservation programs yield greater benefits than others.
“The opportunities for restoration are not uniformly distributed, spatially, or among countries. It is a global problem and it requires a global solution,” said ecologist and study co-author Robin Chazdon, whose paper with lead author Bernardo Strassburg and 26 other scientists was published in the journal Nature on Wednesday.
The scientists developed and ran an algorithm, which they dubbed PLANGEA, to find the most efficient places where restoration can usefully balance climate-change mitigation, species preservation and cost reduction.
Prioritizing areas for restoration can help maximize the value of the effort, funds and time put toward environmental causes. That should come as good news to the 196 states party to the Convention on Biological Diversity, a multilateral treaty formed in 1992 to promote sustainable development and global biodiversity. Those countries agreed 10 years ago to restore at least 15% of “degraded ecosystems” by 2020. The U.S. did not sign on.
The world is not on track to meet the 15% goal. And steps that will help avert the extinctions of millions of species across the planet aren’t in perfect alignment with another looming ecological crisis: pulling the globe from the brink of runaway warming.
Ecosystem restoration is an expensive investment, and its payouts don’t arrive for decades or longer down the line. Plus, restoration efforts often run up against interests including the agriculture industry and private property owners for the use of the same, scarce resource: land.
“This kind of model shows us where the low-hanging fruits are, so to speak, where we can get the most benefits for multiple factors and for the lowest investment required,” Chazdon said.
PLANGEA compares the anticipated economic value derived from the land as it’s currently used and adds the expected cost of habitat restoration, then compares these expenses with the amount of carbon sequestration and habitat rescue that could be accomplished if lands that have been developed for residential, commercial or agricultural uses were reverted back to the forests, grasslands, or other biomes they’d foster if humans hadn’t converted the land for our purposes.
“You first have to have information on what is the existing land cover, then you have to have information on what is the actual ecosystem that, without human activity, would be occupying that land,” Chazdon said. “Then you could say ‘OK, I want to restore 15% of all ecosystems according to carbon [sequestration], biodiversity or — oh, let’s do both, and also let’s minimize costs!’ So then the model would run and predict those priority areas for the country.”
By measuring the push and pull of those three factors — biodiversity promotion, stabilizing the climate and reducing costs — the researchers compared the efficiency of different approaches.
Though most world governments have agreed to restore 15% of their converted lands back into natural areas, the costs and benefits of restoration vary depending on what particular lands are restored — different species depend on different biomes, and some types of wilderness do a better job of sequestering carbon than others.
Forests, for instance, are often called carbon sinks because they capture so much carbon dioxide as they produce food for themselves — trees then store the greenhouse gas in their trunks and roots, and in the soil. But widespread reforestation would do little to help, say, threatened reptiles and birds that thrive only in the arid shrublands of south Texas and Mexico.
Aiming solely to reduce atmospheric greenhouse gas concentrations, for instance, would achieve just 65% of potential biodiversity gains, while a biodiversity-oriented optimization would deliver 73% of the climate stabilization potential, the scientists found.
Compromise is key. The researchers found a combination of land restoration solutions that delivered 95% of the biodiversity benefits and 89% of the climate-change mitigation potential, though this optimization ignored the critical third criterion: cost-saving.
The good news is that even with cost effectiveness in the balance, a nearly-as-good solution emerges, one that could achieve 91% of possible biodiversity gains and 82% of the potential for mitigating climate change. On the other end of the spectrum, a plan that engaged in just the cheapest of restoration efforts would leave 76% of the possible biodiversity benefits and 61% of the possible climate-change mitigation on the table.
The law of diminishing marginal utility is at work here. The uber-ecological optimization path would cost about $5,835, give or take $870, per hectare restored. Meanwhile, the plan that balances the environmental goals and factors in cost-minimization comes at a 27% savings.
Chazdon said that if the productivity gap between global farmlands were closed, 55% of land now used for agricultural purposes around the world could be restored without disrupting yields.
“That gap can also be improved by reducing land used for beef, by reducing food waste and other methods that increase the sustainability of land for agriculture,” Chazdon added. “There’s a lot of agricultural land in the world that is producing very little, and if we can convert that land back into ecosystems and improve productivity in remaining lands, we’re much better off.”
The researchers identified portions of Central America, the Amazon, coastal West Africa and much of Southeast Asia as some of the world’s highest-priority regions. Protecting 30% of these areas could sequester carbon equivalent to nearly half of the emissions produced since the Industrial Revolution.
But there’s no world governing body with the authority to implement an optimally efficient plan to save the environment at low costs. The scientists found that individualist approaches, which would see each nation restoring some percentage of its own forests, are significantly more expensive and far less efficient at achieving climate goals.
“We’re all part of a common planet, and some countries … such as Brazil, have a much greater burden, so to speak, and opportunity for restoration than others. So how do we make that possible? We can’t expect other countries to pay for that all on their own,” Chazdon said. “Just in 2017, global fossil fuel subsidies were estimated to be $5.2 trillion. That was only for 2017. There’s a lot of money being invested in continuing to spew fossil fuels into the air. If priorities were changed, there’s plenty of money around.”
It’s hard not to get cynical.
“It’s about the flow of money, and if money could be flowing into these countries to support these activities, instead of to support destructive activities, it would make all the difference. So I think it’s pretty clear that countries are responding to their need for foreign investment,” Chazdon said. “And that speaks much louder than what a paper in Nature says.”
Not all hope is lost, however. Chazdon said that the Convention on Biological Diversity is going to use PLANGEA to hone its parties’ conservation commitments, for instance.
“Biodiversity loss and climate change are global problems that require a global solution,” Chazdon said. “We haven’t been looking at it that way enough.”
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