A recent report from the United States Department of Agriculture (I link it here) revealed worrying data about the future of US forests. According to forecasts, by 2070 these forests, which for centuries have acted as carbon sinks, could reverse their role, releasing more carbon into the atmosphere than they store.
This turnaround poses not only a threat to the ecological balance, but also a significant challenge to global climate change mitigation efforts.
The delicate balance of carbon
Forests have always played a crucial role in maintaining the carbon balance on Earth. They function as "taps" that absorb excess carbon and as "reservoirs" that store it. However, this balance is changing.
Excluding those in Alaska, US forests may no longer be absorbing 150 million metric tons of carbon annually within a few decades. To put that into perspective, that would be the equivalent of opening 40 new coal-fired plants, but it's actually much worse than that in many ways.
US forests, an interrupted cycle
To understand how a forest can go from carbon sink to carbon emitter, we need to look at the life cycle of a healthy forest. In a balanced forest, new trees grow, mature and eventually give way to new shoots. But in North America, not enough young trees are being planted. 'Mature' forests are outnumbering young ones, which are also more vulnerable to the effects of climate change such as fires, droughts or storms.
Young trees absorb carbon rapidly to grow, while older trees, while containing more carbon, see their growth slow down after reaching a certain size. With this trend, US forests will absorb less carbon each year.
Forests USA, the solution is not so simple
Planting new forests might seem like the obvious solution, but in the modern world everything becomes complicated: space is limited and often fought over by industrial interests.
And then proposals also arrive, perhaps out of "desperation" perhaps not, which have something surreal: some scientists have suggested removing the old forests to make room for the young ones. An idea that leaves you amazed, obsolete and harmful, fortunately stigmatized by the experts themselves United States Department of Agriculture (USDA). Old forests may continue to sequester carbon at rates that far exceed those of younger forests.
The priceless value of mature forests
Mature forests are not just carbon sinks. They provide essential ecosystem services, such as global nutrient cycling, erosion prevention, increased water and air quality, stabilization of local weather conditions, and provide habitat for wildlife.
And let's not forget the pollinators, on which our crops are based. The mere fact of being able to think about cutting them gives the measure of how sclerotic the debate is in the USA. It's the equivalent of proposing guns to teachers to combat school shootings.
If the United States is truly to achieve its goal of net-zero emissions by 2050, it will need to remove as much carbon from the atmosphere as it emits. Doing so without the help of their forests will be a challenge, especially if they become an obstacle rather than an ally.
