Written by David Steele

It’s getting scary. The global warming crisis is looking more serious than we thought even just a few years ago. Worse, it appears that it may be about to accelerate. Ominously, a big part of the reason for that is that the Earth’s terrestrial carbon sink – the net absorption of carbon dioxide from the atmosphere by the world’s plants – is shrinking.

In a normal year, the trees and grasses and other plants on the Earth absorb billions of tons of carbon dioxide from the atmosphere. They take in that CO2 and exhale oxygen in the process of photosynthesis, using it to grow leaves, branches, and roots. In an average year, it all amounts to the removal of about 30% of the CO2 we emit by burning fossil fuels. But for the last couple of years, the process, on net, has pretty much come to a halt.

2024 was the second year in a row in which the terrestrial carbon sink shrank to less than ¼ of its usual magnitude. Ecosystems on the planet emitted nearly as much CO2 into the air as they removed. In effect, almost none of the excess carbon we humans emitted was absorbed.

In 2023, massive wildfires across Russia, Canada and South America were the proximal causes of this failure, alongside lost plant productivity due to heat and drought. When scientists saw that the 2024’s wildfires were far less extensive, they thought that the terrestrial carbon sink would rebound to something like its earlier self.

But that didn’t happen. Instead, it stayed almost as weak as in 2023. How could that be?

It turns out that 2024 was the hottest and wettest year on record – and the heat and humidity fueled a massive increase in ecosystem respiration. Respiration is the opposite of photosynthesis, taking in oxygen and exhaling CO2. Satellite analysis indicates that the heat and dampness of 2024 intensified the respiration of not only world’s plants but also that of bacteria and fungi to the highest levels ever recorded.

Add in the fact that warming peatlands and the like are now spewing methane at record levels – a much more powerful global warming gas than carbon dioxide – and things look dire indeed.

We can’t just sit on our hands and let this continue.

Fortunately, we don’t have to. We can do something very powerful to turn this around – and quickly!

Rapid dietary change could radically reverse the trend

The dominant cause of CO2 release from terrestrial ecosystems is land clearing for farming. This is especially true in the tropical rainforests of South America and south-east Asia. The vast majority of this clearing has been in support of animal agriculture. If we, as a society, were to decide to dramatically curtail our consumption of animal products, we could stem this crisis and begin to return our planet to a stable climatic state.

If we were to collectively make that dietary change, not only could we put an end to the bulk of the deforestation that contributes so massively to carbon sink decline, we could end that decline – and very quickly and dramatically increase the magnitude of that sink.

The people of this world get only 18% of our calories from animal products, yet we use 78% of our of our agricultural lands to raise and feed farm animals. Were we to substantially phase out animal agriculture, we could return the great majority of those lands to the wild. Forests and grasslands could regrow, taking in carbon, countering global warming.

Recent research has found that returning just 30% of currently farmed land to the wild could remove fully half the carbon we’ve poured into the atmosphere since the dawn of the industrial revolution. Indeed, were we to somehow completely abandon animal agriculture, we could rewild a whopping three-quarters of the land we currently use to feed us. Plant-based diets are that much more efficient!

Once we made that change, forests and grasslands would rapidly regrow, carbon uptake would rapidly increase. For the ensuing several decades, the terrestrial carbon sink would be huge.

The likelihood of record warm and wet years that led last year to such a catastrophic rise in ecosystem respiration would decline alongside those of planet-warming CO2. We’d very definitely still need to phase out our use of fossil fuels – all of the gains would be ephemeral otherwise – but we’d buy ourselves time and a more comfortable world as we make that change.