It’s a grim and well-established fact that humanity is pretty good when it comes to trashing the planet. From plastic pollution to climate change, from species destruction to habitat destruction, there’s no question about it: we’re number one.
A new study in Nature has highlighted yet another way in which humanity has drastically and negatively altered the planet. According to a team led by the Institute of Social Ecology in Vienna, we’re responsible for cutting the amount of plant biomass stocks on Earth in half.
This research highlights that vegetation is a major store of carbon. Although it’s not quite as good as our oceans – which are arguably the most effective carbon sink the planet has to offer – trees and plants do soak up a fair amount of our carbon dioxide, and without them, the world would be far warmer.
According to the paper’s estimates, the planet’s vegetation currently stores 450 petagrams of carbon, which is equivalent to almost 0.5 trillion tons. That’s over 12 times the total carbon footprint of humanity in 2016, according to the Global Carbon Atlas – which strongly suggests that the world would be prohibitively warm if it wasn’t for this viridian carbon sink.
Using cutting-edge biomass datasets, however, the team suggest that 916 petagrams, or just over 1 trillion tons of carbon would be locked up in vegetation today if humanity hadn’t been around to interfere with it. That’s more than double the real figure, which means that we have been annihilating a key carbon sink that would otherwise have strongly mitigated anthropogenic climate change.
“Humans have halved the biomass carbon storage,” Professor Karlheinz Erb, of the Institute of Social Ecology in Vienna and lead author of the paper, told IFLScience.
It’ll probably come as no surprise that deforestation has literally eaten away at the planet’s stocks of biomass. It's important to note, though, that it's not just cutting down trees that's having an effect here, and that's what Elb et al. have zeroed in on.
Anywhere between 53 and 58 percent of the difference between today’s biomass stocks and their potential stocks can be blamed on deforestation and other plant removal factors, like urbanization. However, land management changes, like the spread of farming and grazing cattle, are responsible for the rest of the reduction.
Elb explained that the way the land is used was thought to have a small impact in this sense, but “here we show it is massive, similar in magnitude to the deforestation signal.”
Other research has shown that we're not only neutering this all-important carbon sink; we're perverting it. Another study recently revealed that our misuse of tropical forests has even turned them from a carbon sink into net producers of carbon. This is a huge shame, considering that tropical forests represent the greatest potential when it comes to the unenviable task of regenerating the planet's biomass stocks.
A recent, separate analysis looking into effective ways to solve climate change also highlights how important this carbon sink actually is. In its top 20 – ranked by how much atmospheric carbon is drawn down – forest preservation and eco-friendly land use schemes appear more than any other type of solution except for food-based options.
“In the short term, carbon sinks in vegetation are very effective, because ecosystems usually regrow naturally, without a lot of management or care,” Erb added.
Although it can hypothetically be saturated at a point, “conservation and reforestation are very strong mitigation options” for climate change in the near future.
So even though the paper explains that avoiding deforestation is “necessary”, it’s nowhere near enough to prevent dangerous climate change. The way we use our land needs to change as well.