Out of the frying pan of deforestation…into the fire of climate change?

Forests are like Boxer the horse from George Orwell’s Animal farm. The more ravenous and rapacious our appetites, the more work we ask the forests to do for an ever-shrinking share of the land: absorb our pollution; prevent floods; keep us healthy; preserve their huge variety of bugs, beasties, and plants. Now, with news of an international agreement to save the Amazon rainforest, it seems we might finally be sparing the horses a little. Good news as that undoubtedly is, it should not deflect us from a steely-eyed focus on decarbonising our energy needs. Without cutting carbon emissions through decarbonisation, we are sparing our forests only for them to wilt and decline under the double whammy of climate change and globalised plant pathogens.

So, powerfully meaningful as is the simple measure of forest persistence discussed this week, more meaningful are measures of forest quality and health. There are a plethora of forest quality and health measures, but the general rule is that diversity — of species and genetics within species, of tree age, of gaps and edges — is best. Diversity here encompasses both the number and the identity of species in a place: community characteristics matter. Losing species to extinction due to either deforestation or climate change causes irreversible losses for ecosystems and humans that cannot be offset.

Halting deforestation is a task requiring strong, inclusive, governance, backed up by measurement from satellite at ever-improving spatial and wavelength (i.e., colour) resolution. The recent South American agreement gives real hope that forest loss can be halted there. Reversing deforestation is also imperative for a nature positive and net zero strategies but it is not a solution to climate change. No amount of forest replaces the hard work of decarbonisation we need to undertake as a society.

Beyond ensuring forest persistence and reforestation, here are the next three things to do to secure our forests for the future.

Establish a truly global network of long-term forest monitoring plots. Existing forest inventories vary widely and unhelpfully in what and how they measure. Consistency is essential, returning again and again to individual trees to follow their life course as has been done so successfully in longitudinal studies of human health and well-being. This way we can build unprecedented understanding of carbon flows into and out of forests and of which kinds of trees are adapting, which succumbing. Monitoring all life forms in those forest plots is also essential, as the loss of fauna and flora components may also affects carbon storge and forest resilience, which has been largely overlooked.

Plant and manage forests to withstand the globalisation of pests and diseases. In a world in which humans, animals, and plants move rapidly around the world, international coordination is needed to ensure biosecurity. We all know now how frightening human pandemics can be, but plant pandemics also pose risks to our health and wealth. For all those forests lacking the space (or time) to maintain complete biotic interaction networks including facilitator plants, pollinators, seed dispersers, large herbivores and their predators, human action is required. Management choices that spread our bets will deliver forests resilient to climate change and globalised pathogens.

Look into the future. This means running computer models, but we must also carry out the manipulation experiments that benchmark our models against observable fact. The largest of these manipulation studies requires changing the amount of CO₂ around patches of intact forest. There are only three such Free-Air Carbon Enrichment (FACE) facilities in the world’s forests: AmazonFACE in the Brazilian rainforest, BIFoR FACE in the temperate UK, and EucFACE in seasonally hot and dry eucalyptus forest outside Sydney, Australia. More forest FACE facilities are needed if our climate models are not to be as poorly trained as some facial recognition software. Sustained measurement at existing facilities is also essential; at BIFoR FACE, for example, up to a third more carbon goes into the forest under elevated CO₂, but whether this translates into increased healthy growth of the forest remains to be seen.

Each of the next steps need money but not silly money; an eight-figure price tag would see us through the 2030s and help ensure a nature positive target. A moonshot scientifically but hardly beyond the reach of even a small consortium of funders with the will to show leadership. Without these steps, our carbon accounting amounts to no more than a flutter on the Grand National on horse that, like Orwell’s Boxer, is being driven to exhaustion.