To Tree, or Not to Tree. That is Not the Question

June 27, 2020

Jeff Goodell’s new Rolling Stone piece examines the “Trillion Tree” initiative that we’re hearing from, among others, our climate science denying President.

Tree planting has become a low-risk non-answer that some climate deniers have been proposing for the climate crisis, sometimes without actually mentioning the climate crisis.

Trees, after all, are like Mom and Apple pie. Who’s against trees?

Goodell’s point is that Trees, that is, preserving and expanding intact forests of trees – which can sequester large amounts of carbon, are a good adjunct to our efforts on climate IF we are concurrently closing down the CO2 spigot.

But planting more industrial tree farms does not equate to a major carbon drawdown, in fact it might be the opposite. And without a halt to human emissions, dying forests could become a carbon source, not a sink.

Jeff Goodell in Rolling Stone:

On one hand, this near-universal support for tree-planting as a solution to the climate crisis is not surprising. Who doesn’t love trees? They are our ancient partners on this planet, and they may be far more intelligent than we know (Read Richard Powers’ magnificent novel The Overstory). And yes, the 3 trillion or so trees that already grow on the planet suck up about a third of the CO2 we dump into the atmosphere by burning fossil fuels. But the idea that we’re going to solve the climate crisis by planting a trillion trees is a particular kind of lunacy, and a great example of what happens when bad science hooks up with do-gooderism and they sleep together in a bed of political expediency.

A pair of new studies out this week show just how misplaced hopes for tree-planting have been. One study, published in Nature Sustainability, looks at how 25 years of forest subsidies in Chile have decreased biodiversity without increasing total carbon stored in above-ground biomass. A second study, in Science, raises big questions about the long-term security of carbon stored in forests, especially as those forests become increasingly vulnerable to drought, wildfires, and disease in our rapidly warming world.

The idea of planting trees as a solution to the climate crisis is nothing new. It was an important part of the 1992 Kyoto Protocol and the 2015 Paris Agreement. Many nations around the world — GermanyCanadaKenya — have launched ambitious tree-planting projects in recent decades. Last August, volunteers in India planted 220 million trees in a single day.

Tree planting is also a key part of cap-and-trade schemes, which allow polluters to continue emitting CO2 if that CO2 can be offset (or absorbed) in other ways. In California, the cap-and-trade program has recognized 133 million tons of CO2 in benefits from forest carbon offset projects between 2013 and 2019. Skepticism, however, abounds, especially on questions about permanence: What happens to all of that carbon stored in trees if, say, a forest burns down?

Tree-planting mania began in earnest last July with a high profile paper in Scienceauthored by Timothy Crowther, a 33-year-old assistant professor at ETH Zurich in Switzerland. Crowther and his team built models that used variables such as soil quality and other factors to suggest there was plenty of room for a trillion new trees on the planet. According to Crowther, those trees could absorb two-thirds of the CO2 that humans have added to the atmosphere in the industrial era. Tree planting, Crowther argued, is “our most effective climate change solution.”

The paper was a sensation, picked up by 700 media outlets. Crowther was profiled in Nature and Science and celebrated for his simple, elegant analysis of the world’s most urgent problem.

But the report was deeply flawed. One scientist called the paper “shockingly bad.” Science published six submissions from critics who cited substantial errors. In addition to slamming the paper for miscalculating the amount of carbon storage that can be stored in forests by a factor of 10, critics argued it favored converting grasslands and wetlands to forests and ignored how trees might affect water supplies and temperatures. “The claim that global tree restoration is our most effective climate change solution is simply incorrect scientifically and dangerously misleading,” one group wrote.

In a published response to the criticism, Crowther’s team made clear they saw tree planting as just “one of the most effective carbon drawdown solutions” and emphasized that reducing carbon emissions is critical. But they challenged other objections, arguing that disagreements about carbon storage calculations were not the result of errors but different definitions of “forest” and confusion about their methods.

In any case, the flaws in the study didn’t staunch its appeal. Marc Benioff, the billionaire CEO of Salesforce and well-known Bay Area philanthropist, latched onto it and began his own trillion-tree crusade. Thanks largely to Benioff’s enthusiasm, the World Economic Forum launched the Trillion Tree Initiative at its annual meeting in Davos earlier this year, with an endorsement by environmental rock star Jane Goodall. Big environmental and conservation groups like the World Wildlife Federation launched their own trillion-tree campaigns. Benioff also got the ear of White House advisor Jared Kushner, who passed the idea along to President Trump. Trump, who thinks climate change is a hoax perpetuated by the Chinese and has spent his entire presidency gutting protections of forests and parklands, even mentioned the virtues of tree-planting in his speech at Davos. On Earth Day, Trump planted a tree on the South Lawn (“I’ve always loved planting trees”).

Last February, Arkansas Rep. Bruce Westerman, a Republican, introduced the Trillion Tree Act, a pro-logging bill masquerading as a solution to climate change. It was a naked attempt to capitalize on some of the trillion tree mojo. “This deceptive bill is the worst kind of greenwashing and a complete distraction from urgently needed reductions in fossil fuel pollution,” Randi Spivak, public lands program director at the Center for Biological Diversity, said when the bill was introduced.

But trillion trees mania rolls on. It’s a climate crisis solution gone wild.

In Chile, as one of the new studies points out, the government subsidized the replacement of native forests with profitable tree plantations. The researchers measured the full impact of the afforestation subsidies and calculated their effects on net carbon and biodiversity changes across the entire country. They found that while afforestation payments expanded the area covered by trees, they decreased the area of native forests. Because Chile’s native forests are far more carbon dense and biodiverse than plantations (think rainforest vs. Christmas tree farm), the subsidies had the perverse effect of failing to increase carbon storage, while at the same time accelerating biodiversity losses.

The new paper published this week in Science further clarifies just how risky it is to bet on trees as a big solution for the climate crisis. Yes, forests can and do suck up huge amounts of carbon, but they are also vulnerable to the ravages of the climate crisis themselves. According to the report, the biomass dynamics of nearly half the forests on the planet are strongly sensitive to what the authors call “stand-replacing disturbances.” In other words, wildfires, drought, and disease – as well as logging by lumber-hungry humans.

“When it comes to storing carbon in forests, the issue no one has really looked at is permanence,” says lead author Bill Anderegg, an assistant professor of biology at the University of Utah. “How long will the carbon be locked away for? Fifty years? A hundred years?”

The paper cites numerous examples of the impact our rapidly changing climate is already having on forests: the severe 2011–2015 drought in California killed an estimated 140 million trees and turned the state’s ecosystems from a carbon sink into a carbon source — dead and dying trees in California contributed about 600 million tons of CO2 into the atmosphere, which is about equal to 10 percent of the state’s greenhouse gas emissions over that period. Similarly, infestations of bark beetles, a voracious tree-devouring insect amped up by rising temperatures, have killed billions of trees across millions of acres of land in the past two decades and have converted large regions of the Canadian boreal forest from a carbon sink to a carbon source.

And that may be a harbinger of things to come. As Anderegg’s paper points out, if we keep burning fossil fuels and heating up the planet, the impact on forests could be so great that instead of being a climate crisis solution, forests could become a climate crisis accelerant. Earth-system model projections over the 21st century indicate that terrestrial ecosystems (the vast majority of which are forests) could sequester as much as 36.7 billion tons of CO2 a year – or, in a high CO2 emissions scenario, release as much as 22 billion tons.

In other words, trillion-tree boosters might have it all wrong: Instead of being the engine of our salvation, forests could turn out to be the engine of our demise.

13 Responses to “To Tree, or Not to Tree. That is Not the Question”

  1. rhymeswithgoalie Says:

    There’s much more to trees than carbon storage. Tree removal has exacerbated flooding and topsoil loss.

    Decades of support for clearing land for agriculture in the England* aggravated the major flooding accompanying the increased rain events, and it is only recently they have reversed those ill-thought laws and policies.

    *I don’t know about Wales, and Scotland has only one tree, anyway.

  2. jimbills Says:

    Trump can accept planting trees….:

    ….without accepting climate change. It doesn’t require ANY actual change in current consumption patterns and energy sources, it provides tax breaks for businesses, boosts the timber industry, and it provides political cover for Republicans to show they are doing something environmentally. Total win-win for him.

  3. redskylite Says:

    Trees can steer the onus away from the need to cut/eliminate the burning of fossil fuels, so deniers do not need to consider CO2 emissions from coal/oil/gas etc.

    While trees are part of balancing natural emissions, they can never cope with the additional burden we are placing on nature.

    “Investing in forests to fight climate change seems like a sure bet. Trees absorb carbon dioxide from the atmosphere, pump out oxygen, and live for decades. What could go wrong?

    The answer, according to a newly published paper in Science, is: a lot. Fires, rising temperatures, disease, pests and humans all pose threats to forests, and as climate change escalates, so too do these threats. While forest-based solutions need to play an important role in addressing climate change, the risks to forests from climate change must also be considered.”

  4. Sir Charles Says:

    Rather than benefiting, large-scale tree planting may do the opposite and isn’t a simple climate solution, 2 new studies warn.

    Planting trees can reduce biodiversity, little impact on carbon emissions.
    Amount of carbon new forests can absorb overestimated.

    • rhymeswithgoalie Says:

      While its easier and cheaper to plant a few varieties, activists can work to get a more diverse collection. Perhaps they can do Oaks Week then later intersperse with Fast-Growing Fruit Week, then a Pines Week, Trash-tree Week, Assorted Non-Oak Hardwoods, etc.

  5. Keith Omelvena Says:

    “dying forests could become a carbon source, not a sink.” Well that’s not quite true is it? Of course if current forests die and slowly decay without replacement, they will be a source of carbon, but as opposed to what? Bare Earth? We need to get planting! Anywhere and everywhere! Those trees won’t be holding significant carbon storage for decades anyhow, so why wait until the morons have all died off and even fundamentalist right wingers can see the planet turning into a lifeless hell hole?

  6. J4Zonian Says:

    “Trees can steer the onus away from the need to cut/eliminate the burning of fossil fuels, so deniers do not need to consider CO2 emissions from coal/oil/gas etc.”

    This part seems to be contradicted by the rest of the comment, but lack of quotes or explanation makes me wonder.

    To clarify: Though I’ve been pushing forestry as a crucial solution for many years, no, trees can’t “steer the onus away from the need to cut/eliminate the burning of fossil fuels” and we certainly do need to eliminate (not consider) coal/oil/gas, etc.. If done right, using the best wild forestry practices, diverse plantings of trees and other species, and permaculture principles, trees can help, as part of a much larger program of adapting society to the real world.

    We have to cut emissions by replacing fossil fuels with efficiency, wiser lives and clean safe renewable energy, (wasting far less energy and food) eliminating CFCs, pretty much stopping flying and long distance (and most other) private driving in favor of high speed rail, light rail and other rail and EV buses and jitneys, shifting to ecological production of concrete and steel by disregarding the desire of mbillionaires to continue profiting, and lots more. Forests are necessary for our physical and emotional well-being; so are lots of other things.

    The demonstrations have been great, and have gotten important but small concessions in some places so far. Time to expand the scope of demands that will stop unrest.

  7. Brent Jensen-Schmidt Says:

    The only real problem with planting a gazillion trees, building a billion mini hydro plants and putting wings on pigs, is that they are used as excuses for inaction. Too late, the concepts are already out there. All other problems are trivial and can be addressed. If CAGW hits, the term Biodiversity will only be used in the past tense.
    If trees burn they put back the CO2 they extracted minus the charcoal left. Regular burning is used to claim carbon credits after all. A misuse of a not too brilliant idea.
    The logic of the above post is unconvincing.

  8. dumboldguy Says:

    Planting trees is a “feel good” solution. What we need to do is STOP cutting trees and destroying forest habitat in the third world for such things as palm plantations, cattle ranching, and industrial agriculture.

  9. jimbills Says:

    Testing. I haven’t been able to comment here for several days.

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