The boreal forest stores more carbon than all tropical forests combined

Introduction: the northern hemisphere's overlooked green giant

A biome far bigger than most people imagine

Stretching unbroken across Russia, Canada, and Scandinavia, the boreal forest, also known as the taiga, is the largest terrestrial biome on the planet, far ahead of the tropical forests that nonetheless occupy a much bigger place in the public imagination whenever the conversation turns to carbon and global climate.

There is something quite striking about the fact that it is a cold forest, often seen as austere and unremarkable, that holds the record for carbon storage, rather than the lush tropical forests we instinctively associate with biodiversity and global ecological richness.

Twice as much carbon per hectare as the tropics

According to several specialized studies, the boreal forest stores roughly twice as much carbon per hectare as tropical forests, a ratio that often surprises members of the public used to thinking of the Amazon or Central African forests as the planet's main carbon reservoirs. This difference is largely explained by the nature of the soil beneath this immense northern forest.

Unlike tropical forests, where carbon is mainly stored in the living biomass of the trees themselves, the taiga stores most of its carbon in its peaty soils, often frozen at depth, which have been accumulating organic matter for thousands of years without ever fully decomposing, thanks to cold temperatures that considerably slow down the microbial activity responsible for that decomposition. Scientists sometimes describe this underground reserve as an enormous, slow-motion savings account, one that has been quietly accruing interest since long before recorded human history.

Why taiga soils are so rich in carbon

The key role of permafrost and peaty soils

Permafrost, that permanently frozen ground beneath the surface, plays a central role in the boreal forest's carbon-storage capacity. By keeping temperatures consistently low, it considerably slows the decomposition of organic matter accumulated over millennia, allowing enormous quantities of carbon to stay trapped in the soil instead of being released into the atmosphere as carbon dioxide or methane.

These peaty soils form slowly, year after year, through the accumulation of partially decomposed plant matter under cold and often waterlogged conditions. This process, extremely slow on a human timescale, has allowed considerable carbon reserves to build up over periods measured in thousands of years rather than decades. In some areas, researchers have measured peat layers several meters deep, each centimeter representing years, sometimes decades, of accumulated growth.

An accumulation that took place over millennia

This enormous carbon reserve did not form overnight, but is the result of a continuous process spanning millennia, dating back to the last ice age in certain regions. Every year, a thin additional layer of organic matter is added to the soil, gradually contributing to the colossal reserve that the taiga represents today on a global scale.

This slow accumulation contrasts sharply with the potential speed of its release should climate conditions change significantly, a timing mismatch that particularly worries scientists specializing in the carbon cycle and high-latitude climatology. Building something over ten thousand years only to see it unravel within a single century is precisely the kind of asymmetry that keeps this field of research so urgent.

A fragile reserve in the face of climate change

Thawing permafrost, a very real threat

This considerable carbon reserve is now threatened by the accelerated warming of high latitudes, a region of the globe where temperatures are rising faster than the global average, a phenomenon scientists call Arctic amplification. This warming is causing a gradual thaw of permafrost that has remained stable for millennia until now, risking the release of some of the accumulated carbon.

This potential tipping point strikes me as particularly worrying: we are talking about a carbon reservoir built up over thousands of years, which could be released into the atmosphere in just a few decades if the thaw continues at a sustained pace.

From carbon sink to source of emissions

The most worrying risk identified by researchers is that the boreal forest, which has served for millennia as a long-standing carbon sink, could turn into a net source of emissions of greenhouse gases if permafrost thaw accelerates enough. Should this shift be confirmed on a large scale, it would have major consequences for global efforts to fight climate change.

This phenomenon is being closely watched by scientists, since it illustrates an example of positive climate feedback: warming causes thawing, which releases carbon, which in turn intensifies warming, potentially creating a self-reinforcing loop if no mitigation measures are put in place in time. Feedback loops of this kind are notoriously difficult to reverse once they gain momentum, which is exactly why researchers are so eager to catch the earliest possible warning signs.

The boreal forest's importance for global climate balance

An underestimated role in climate discussions

Despite its considerable importance, the boreal forest tends to feature less in public climate discussions than tropical forests, which receive wider media coverage due to their spectacular biodiversity and their exposure to direct, visible deforestation. Yet when it comes to carbon storage, the taiga plays a role at least as decisive for global climate balance.

Forest ecology researchers regularly call for greater scientific and political attention to this biome, particularly regarding the protection of peaty soils and rigorous monitoring of permafrost evolution in the regions affected by this accelerated thaw.

International research efforts underway

Several research institutions, notably linked to the FAO and NASA, run monitoring programs tracking the evolution of the boreal forest and its permafrost, combining satellite observations with field measurements to better understand the speed and scale of this thaw across different regions of the taiga, from Siberia to Canada and Scandinavia.

This international research is essential for refining global climate models, which need to accurately account for this immense carbon reserve's potential contribution to future greenhouse gas emissions, a parameter still surrounded by significant uncertainty depending on the scenarios researchers consider. Getting that number even roughly right matters enormously, since it directly shapes how aggressively governments plan to cut emissions elsewhere in the system.

What this carbon reserve teaches us about ecosystems

A lesson in humility about natural balances

The boreal forest example shows just how much ecosystems can play essential climate roles without this being immediately visible or spectacular. Unlike a dense tropical forest, instantly recognizable as a biodiversity reservoir, the taiga hides most of its climate contribution beneath the surface, in soils we don't naturally associate with such a decisive role in the global carbon balance.

This story reminds me that we should sometimes be wary of preconceived notions about what really matters for the climate: it isn't always the most spectacular landscapes that play the most decisive role in the planet's great balances.

An invitation to rethink our conservation priorities

This discovery invites us to rethink global priorities in forest conservation, paying greater attention to ecosystems sometimes overlooked in favor of more widely publicized forests. Protecting the boreal forest and its peaty soils could prove just as crucial for global climate balance as preserving tropical forests, a message scientists are trying to get across to international policymakers.

This awareness is growing, but remains insufficient given the scale of the climate role played by this biome, which is why many researchers continue to push for significantly stronger scientific monitoring and protection of these northern territories.

Comparing the taiga and the Amazon without pitting them against each other

Two carbon reservoirs with different logics

I think these two forests are too often compared as though we had to choose which one to protect first, when in fact they serve complementary rather than competing climate functions. Protecting one while ignoring the other would mean neglecting an entire part of the global climate equation, which would be especially damaging for the whole planet in the long run.

The Amazon rainforest stores most of its carbon in living biomass, its towering trees and dense vegetation, which makes it particularly vulnerable to direct deforestation, since every felled tree immediately releases part of its stored carbon. The boreal forest, on the other hand, stores most of its carbon in the soil, which makes it less vulnerable to conventional logging but far more sensitive to temperature shifts that affect permafrost at depth.

This difference in mechanism explains why protection strategies must be tailored to each biome: curbing deforestation for the Amazon, and limiting warming at high latitudes to preserve the stability of the taiga's permafrost, two complementary approaches rather than interchangeable ones. International policymakers would do well to build this distinction more thoroughly into their respective climate strategies, rather than applying a single template to fundamentally different ecosystems, whether the humid tropics or the frozen expanses of the far north.

Less spectacular biodiversity, but just as essential

While the boreal forest hosts less spectacular biodiversity than the tropics, it is nonetheless home to species perfectly adapted to its extreme conditions, such as certain large mammals, migratory birds, and cold-resistant plant species, which depend directly on the stability of this ecosystem for their long-term survival, from one season to the next and one decade to the next.

This taiga-specific biodiversity remains under-studied compared to that of tropical forests, a research imbalance that several scientific institutions are now trying to correct by strengthening study programs devoted specifically to high-latitude ecosystems, from northern Canada to eastern Siberia. Funding for this kind of long-term, cold-climate fieldwork has historically lagged behind tropical research budgets, even though the stakes are arguably just as high.

What to take away about the boreal forest

A colossal and fragile carbon reservoir

In short, the boreal forest, which spans Russia, Canada, and Scandinavia, is the largest terrestrial biome on the planet and stores roughly twice as much carbon per hectare as tropical forests, mainly within its deeply frozen peaty soils. This considerable reserve, built up over millennia, is now threatened by accelerated warming at high latitudes.

The gradual thaw of permafrost could turn this centuries-old carbon sink into a net source of greenhouse gas emissions, a scenario scientists are closely monitoring through international research programs that combine satellite observations with field measurements.

A reserve that urgently needs protecting

This story is a reminder that the world's major climate balances do not play out solely in the most widely publicized tropical forests, but also in colder, less spectacular territories, whose role nonetheless remains absolutely decisive for the climate future of the entire planet.

Giving greater scientific and political attention to the boreal forest and its peaty soils now looks like an issue just as urgent as fighting tropical deforestation, two priorities that should ideally move forward together in global climate strategies over the coming decades. This point, still too rarely highlighted at major international climate conferences, deserves a far more central place in future global negotiations on ecosystem protection. Until that shift in attention happens, one of the planet's largest carbon reserves will keep operating largely out of the public eye, several degrees below freezing and several steps removed from the evening news.

By Maxime Marquette, columnist

Sources

Primary sources

FAO — Foresterie, ressources sur les forêts mondiales — 2026

Nature — Carbon cycle, ressources de recherche — 2026

NASA — Observations satellitaires des écosystèmes terrestres — 2026

Secondary sources

National Geographic France — Rubrique Environnement — 2026

Futura-Sciences — Rubrique Planète — 2026

Sciences et Avenir — Actualités scientifiques — 2026