This autumn’s devastating torrential rains in Spain, hurricanes in the Caribbean Sea and typhoons in Southeast Asia are a warning of the apocalyptic future that looms unless the world can quickly halt global warming. The devastation is a direct consequence of 2023 and 2024 being the hottest years on record, with global temperatures peaking at 1.5°C above pre-industrial levels and the Paris Agreement targets evaporating as fast as carbon dioxide emissions have increased. The record warmth has been fuelled by the rapidly worsening crisis in the carbon sequestration capacity of forests, plants and oceans.
Adding to concerns that global warming may soon pass irreversible tipping points are signs that the Earth’s natural carbon sinks, which have long captured more than half of the carbon dioxide emitted, are showing serious signs of failure in forests, oceans, grasslands and wetlands. For every tonne of human-made carbon dioxide emissions, oceans have, over time and relatively consistently, captured more than a quarter of a tonne and terrestrial ecosystems almost a third.
Now, the results of a high-profile study, led by ecologist Piyu Ke at Tsinghua University, suggest that the world’s land-based forests, plants and soils almost completely stopped capturing carbon dioxide during the El Niño year of 2023, contributing to record high emissions to the atmosphere.
While between 2010 and 2022, land-based carbon sinks captured an average of two gigatonnes of carbon from the atmosphere each year, in 2023 they only removed between about a quarter and two-thirds of a gigaton of carbon. This is, according to the researchers’ preliminary results, between three and eight times lower than the average over recent decades.
Even if many of today’s climate models have not taken into account that nature’s carbon sinks can collapse, thus explaining some of the increased emissions in the atmosphere, the connections are basically quite simple.
“Imagine your plants at home: if you don’t water them, they’re not very productive, they don’t grow, they don’t take up carbon” and “put that on a big scale like the Amazon forest”, Stephen Sitch, a co-author of the study is quoted as saying by Reuters.
That land-based carbon sinks almost completely collapsed may be a temporary effect of a moderately strong variant of the natural phenomenon El Niño having fuelled warming. But it is inevitable that the underlying warming will make the carbon sinks increasingly ineffective.
“We’re seeing massive cracks on land — terrestrial ecosystems are losing their carbon store and carbon uptake capacity, but the oceans are also showing signs of instability” commented Johan Rockström, director of the Potsdam Institute for Climate Impact Research, on the findings at New York Climate Week in September.
In some cases, traditional carbon sinks are instead becoming a source of emissions. “Expansion of agriculture has turned tropical rainforests in Southeast Asia into a net source of emissions in recent years”, writes The Guardian. ”Emissions from soil — which is the second-largest active carbon store after the oceans — are expected to increase by as much as 40% by the end of the century if they continue at the current rate.”
It will also take between several decades and 100 years for Canada’s coniferous forests to rebuild the carbon stocks that went up in smoke during the huge fires of 2023 over an area twice the size of Denmark, six times larger than normal and three times larger than ever before. Although wet tropical forests recover faster, they have proved vulnerable to extreme drought.
“Nature has so far balanced our abuse. This is coming to an end”, summarises Johan Rockström.
“What happens to the world if forests stop absorbing carbon? Ask Finland” as the title of a major story run by The Guardian on 15 October about the collapsing carbon sink in Finland’s vast forests, asks.
Finland’s two-year-old climate law aims to achieve net zero emissions by 2035, fifteen years ahead of the Paris Agreement’s global target for 2050. This ambition has been shattered by the realization that between 2009 and 2022, Finnish forests have lost 80–90% of their capacity to absorb carbon, while net emissions from soils and wetlands have increased. This has turned the land-based carbon sink into its opposite, a source of net emissions.
“We cannot achieve carbon neutrality if the land sector is a source of emissions. They have to be sinks because all emissions can’t be decreased to zero in other sectors”, says Juha Mikola, a researcher at the Natural Resources Institute Finland (Luke), which is responsible for producing the government’s official figures. This is also true for Sweden and at least 118 countries that rely heavily on their forests to meet their climate targets.
One main reason for the collapse of the Finnish land sector is undoubtedly that commercial forestry — including logging in rare primeval forests — has increased from an already relentless pace. But there are also signs that the climate crisis has become a driver of the decline. Rising temperatures, most rapidly in the Arctic part of the country, are increasing the rate at which peatlands are degrading and releasing greenhouse gases into the air. The number of dying trees has also multiplied in south-eastern Finland in recent years as forests are stressed by drought and high temperatures.
“The reasons [for Finland’s shift] are not fully explored but it’s very likely a combination of unsustainable forest management and also dieback because of droughts and extreme weather conditions. We see similar trends in Canada, very much from disease outbreaks, but also in Sweden”, comments Johan Rockström.
“These are countries in the temperate north that have factored in their carbon sink as a very central part of their climate policy”, he adds. “It’s such a big risk for these governments.” France, Germany, the Czech Republic, Sweden and Estonia are among the countries in Europe that have seen significant declines in their land sinks, according to Rockström. Across the EU, the amount of carbon absorbed by its soils fell each year by about a third between 2010 and 2022.
According to the five-year averages reported in Sweden (but not reported separately year by year), the net uptake of carbon dioxide equivalents by forests has fallen by 25–30% in ten years, from just over 50 to just under 40 million tonnes.
My old high school friend, the natural geographer Anders Lindroth, now Professor Emeritus at Lund University, was one of those who challenged the forest lobby’s green-washing in the SVT series “Slaget om skogen” [The Fight over the Forest] on the Swedish popular science program, Vetenskapens värld [World of Science] and pointed out the key role of forestry in the insufficient transition.
“For Sweden to have a chance of achieving net zero emissions by 2045, today’s clear-felling with the cutting down of younger and younger trees must be stopped and replaced by continuous cover forestry and reduced felling rates”, he states.
“There is simply no alternative climate measure that combines cost-effectiveness with speed in the same way,” he wrote in an opinion piece together with Göran Englund, Professor of Ecology at Umeå University and Torbjörn Skytt, doctor of ecological engineering at Mid Sweden University, in the Swedish broadsheet, Svenska Dagbladet, on 22 October 2022.
The argument was backed up by calculations indicating that Sweden’s climate target of net zero by 2045 could be achieved by reducing today’s high deforestation of around 95% of growth to the average level of 70% of growth during the period 1980–2015. Reducing harvesting to 60% of growth could even achieve the target ten years earlier.
According to clear research results, it takes 10–15 years for emissions from clear-felling to cease through re-growth and for the forest to start acting as a carbon sink again. According to Anders Lindroth, emissions from Sweden’s two million hectares of clear-felling are very high and correspond to around 15 million tonnes of carbon dioxide, as much as the entire transport sector.
Reduced felling would also increase biodiversity and, for example, help older and coarser trees to be used to a greater extent for wooden beams to replace steel and concrete.
This necessary transition is opposed by the short-term profit interests of the forestry industry, its lobbyists and politicians in their wake. The misery is underlined by the fact that the Swedish Tidö government wants to simplify permits for logging even in primeval forests close to the mountains.
“It is so depressing to hear the parties describe our forestry as sustainable and beneficial to the climate”, writes Anders Lindroth in an email, “with few exceptions, it is the forestry industry’s image that they unashamedly buy into. The only way is to reduce felling in relation to growth. But the politicians (most of them) want to increase the rate of felling. A hole in the head is what it is.”
The fact that Donald “Drill, Baby, Drill” Trump won the US election and that 13 Swedish wind farms in the Baltic Sea are being sacrificed on the altar of the military arms race are new, unmistakable proofs that the world’s capitalist rulers are completely incapable of doing anything about it. Trump’s election victory is effectively a kiss of death to the willingness to fund climate action in poor countries, which is the main issue at this year’s UN-led climate circus, COP29, in the oil-rich country of Azerbaijan on 11–22 November.
The fact that at a time when emissions should be falling by at least 9% a year to meet climate targets, the world instead increased emissions by 1.3% last year means we are rushing towards tipping points that will dramatically accelerate the effects of climate change and threaten to make them irreversible.
“It is imperative to cut emissions drastically now”, UN chief, Antonio Guterres, said before COP29 in Azerbaijan. Unfortunately, warnings of a dystopian future fall on the deaf ears of world leaders, who are instead preoccupied with war, arms races and deadly superpower rivalries.
Hopefully all these provocations will eventually lead to other tipping points, of a social and political nature, where first and foremost the world’s workers and youth, poor and oppressed, realize the need to rise up on a massive and global scale in a common struggle to avert the wars, rampant class divisions and climate threats that are looming.
