Natural stores of climate-warming carbon are crammed into a small percentage of Earth’s land, according to a new study that identifies the ecosystems humanity must protect to avoid climate catastrophe.
The study, published today in the journal Nature Sustainability, found that half of Earth’s ‘unrecoverable carbon’ – defined as carbon that, if emitted into the atmosphere, could not be returned to the atmosphere. ‘here 2050 – is in just 3.3% of the Earth’s land surface. The carbon in these reserves is equivalent to 15 times the global fossil fuel emissions released in 2020.
Most of that carbon is in peatlands, mangroves and old-growth forests on six continents, according to the study. If these ecosystems were degraded or destroyed due to human activity, their carbon would be emitted into the atmosphere, effectively preventing humanity from limiting global warming to less than 1.5 degrees Celsius (2.7 Fahrenheit), the benchmark for a “safe” climate set by the 2015 Paris Agreement.
Scientists used the latest data – including an analysis of more than 10,000 forest carbon samples – to understand how soil and biomass can scavenge greenhouse gases after changes in land use.
They found that unrecoverable carbon spans six of the seven continents, including vast reserves in the Amazon, the Congo Basin, the islands of Southeast Asia, Northwest America North, southern Chile, southeastern Australia and New Zealand.
The Amazon is home to 30 million people, including 350 indigenous and ethnic groups. This rainforest provides habitat for one in 10 known species on the planet and produces almost a quarter of the world’s fresh water.
It also stores over 20% of all unrecoverable carbon in its trees and soil, more than any other region on Earth.
“The ancient forests of the Amazon are extremely carbon-rich ecosystems because they have been able to sequester carbon for decades, even centuries – and they grow all year round,” said Juan Carlos Ledezma, technical specialist at Conservation International for the US Programs and co-author of the study.
Some of the largest unrecoverable carbon stores in the Amazon are found in Igapó, seasonally flooded forests along the banks of the Amazon River. For up to six months a year, these forests are submerged under several meters of water, which traps carbon in the ground, where it can accumulate over time.
The problem: An increase in deforestation in recent years is bringing the Amazon closer to a tipping point after which it will lose the ability to generate rainfall, gradually turning into a dry savannah.
About 15% of the Amazon has been deforested so far; the tipping point could occur if a quarter of the forest is lost. At current rates of deforestation, this could happen in 10 to 15 years, scientists predict.
“Increased deforestation will accelerate climate change, fueling higher temperatures and lower humidity in the Amazon. This could dry out this rainforest and release the carbon it contains,” Ledezma explained. dry forests are more likely to catch fire, which would release even more carbon.This is a dangerous feedback loop, which we must avoid.
The Niger Delta in Africa is home to the most contiguous expanse of mangroves in the world, rich in fauna and marine species. However, the real treasure is buried deep in the soil of these marshes.
“Much of the mud in the mangrove forests has not seen the light of day for decades, if not centuries. If left undisturbed, the carbon in soil sediments is locked away,” says Conservation International scientist Allie Goldstein, who co-authored the paper. “Mangroves cover only a fraction of the Earth’s surface, but what they lack in quantity they make up for in quality – holding the highest density of unrecoverable carbon of any other ecosystem.”
In the Niger Delta alone, 240 million tons of unrecoverable carbon resides in the dense tangle of trees and soils that make up this coastal forest. Along with these climate benefits, mangroves provide critical habitats for marine species and can act as a buffer for coastal communities, protecting them from storm surges and sea level rise.
Despite their importance, the Niger Delta mangroves face increasing pressure from the extractive industry, which exports 1.41 million barrels of oil from this region every day. In addition to the deforestation of rigs, camps, roads and other infrastructure related to extractive production, oil frequently spills into the mangrove forest, polluting coastlines and damaging trees.
PAPUA NEW GUINEA PEATLANDS
Located in the southwest Pacific, Papua New Guinea holds 3.9 billion metric tons of unrecoverable carbon, making it a “wall-to-wall carbon store,” according to Noon.
“Most of the country’s carbon is stored in its peatlands,” she says. “These wetland ecosystems are made up of decaying waterlogged plants that have accumulated carbon over centuries.”
Globally, peatlands contain more than 39 billion metric tons of unrecoverable carbon, which accumulates and locks into the soil. However, like the flooded forests of the Amazon, these wetlands are extremely vulnerable to changes in humidity.
“Peatlands are climate superstars, but they face a variety of threats that could release the carbon they have stored,” says Noon. “In most cases, peatlands are either drained to turn the land into a fertile agricultural area for palm oil production, or extracted as a source of fuel.”
How to protect unrecoverable carbon?
At least 4 billion metric tons of unrecoverable carbon have been lost to disturbances such as agriculture or wildfires over the past decade – and deforestation rates continue to rise around the world.
In addition to creating new protected areas, it is essential to recognize the land rights of indigenous peoples, says Noon.
“Globally, Indigenous peoples have proven to be some of the best stewards of nature; their lands show less species decline and pollution, and better managed resources,” she says. “Strengthening Indigenous land rights is a critical step towards protecting the world’s ecosystems and the carbon they store.
Currently, 47 billion metric tons of unrecoverable carbon – more than a third of the total – is on government-recognized lands of Indigenous Peoples and local communities. The authors say there is likely even more unrecoverable carbon located on indigenous and community lands without legal status.
However, being located on indigenous lands does not always guarantee that unrecoverable carbon is conserved, Ledezma says.
Map based on the lands of indigenous peoples and local communities officially recognized by national governments. Areas with missing data do not necessarily indicate the absence of indigenous peoples and local communities.
“In the Amazon alone, almost half of the intact forests are located on indigenous territories, making indigenous peoples essential partners in the effort to protect from unrecoverable carbon,” he says.
“However, many communities lack the resources and incentives they need to resist the pressure to turn forests into farms or mining areas. Governments must provide more support to indigenous communities, strengthen legal recognition of their lands and formally recognize the crucial role that indigenous peoples play in the fight against climate change.
And expanding protection for lands with high concentrations of unrecoverable carbon, as well as supporting indigenous and community-led conservation actions, are essential for countries to meet their climate and biodiversity goals, adds Goldstein.
“This is a rare scenario where we have time to prevent an environmental catastrophe before it happens,” she said.
“It’s our generation’s carbon to save, and how we choose to move forward as a global community will determine our climate fate.”
Cover image: The Amazon (© Johnny Lye)
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