Only five mega-forests remain today of the vast and magnificent primordial woodlands—rich in biodiversity and characterised by towering, centuries-old trees—that once covered much of our planet. The smallest of these blankets the entirety of New Guinea, an island twice the size of California. It is exceeded in extent by the equatorial forest of the Congo Basin, followed by the tropical forest of the Amazon. The two largest mega-forests lie in the Northern Hemisphere: the expansive North American boreal forest, stretching from Alaska to Canada’s Atlantic coast, and the Taiga—the largest forest on Earth—located almost entirely in Russia and extending from the Pacific Ocean to the northernmost reaches of Europe.

Beyond the mega-forests, there exist the so-called Intact Forest Landscapes (IFLs). The term, coined in the late 1990s by a group of scientists and activists, refers to forested areas deemed urgently in need of protection from industrial logging. To qualify as an IFL, a forest must be free of roads, power lines, mines, towns, and industrial installations for at least 500 square kilometres. Within these intact forest landscapes, vital treeless areas such as rivers, lakes, and wetlands may also be found.

Mega-forests and IFLs are as essential to our planet as the air we breathe. The world will become increasingly uninhabitable if we fail to safeguard its biological integrity—particularly its forests. According to the Intergovernmental Panel on Climate Change (IPCC), limiting global warming is impossible without halting and reversing deforestation by 2030. Through photosynthesis, plants possess the extraordinary ability to convert carbon dioxide into biomass. Twice in Earth’s history, they have done so with such efficiency that they altered global environmental conditions. The first instance occurred around 400 million years ago, when plants and fungi spread across the planet, dramatically reducing atmospheric carbon dioxide. The second occurred approximately 225 million years ago, following massive volcanic eruptions in Siberia that increased atmospheric CO₂, warmed the planet, and led to the extinction of most terrestrial and marine species.

Over time, the Earth recovered, and new species emerged. Around 100 million years ago, angiosperms—plants that reproduce through flowers—appeared and rapidly displaced conifers as the dominant vegetation. The explosive spread of flowering plants captured atmospheric carbon to levels comparable to those of today, enabling the flourishing of complex life, including humans.

Now, in little more than the blink of an eye, human activities are saturating the atmosphere and oceans with carbon at an astonishing rate. What Permian volcanic eruptions accomplished over the course of roughly one million years, humanity is replicating in just over two centuries. By continuing to burn fossil fuels, we are releasing into the atmosphere the carbon that plants had stored over millennia.

Today, nearly fifteen billion trees are felled every year. Rainforests have been reduced by half. The boreal forests of the north fare little better: they suffer from the destructive impacts of explosives used in mining by oil companies, and during the brief summers, they burn due to increasingly frequent wildfires. Tropical forests face relentless logging and road construction, which grant hunters and industry access to previously unreachable areas.

The leading driver of global deforestation is cattle ranching. Brazil alone devotes 170 million hectares of land to livestock. Soybean cultivation follows, occupying 131 million hectares—primarily in South America—with 70 per cent of global production used as feed for beef cattle. In third place, with 21 million hectares, are Southeast Asia’s oil palm plantations. In just fifteen years, 10 per cent of the world’s IFLs have been lost; excluding Russia and northern Scandinavia, Europe is now entirely devoid of intact forest landscapes.

The European continent, once blanketed by forests, has lost roughly half of its woodland since antiquity, beginning with the expansion of the Roman Empire. In South America, after the arrival of the Portuguese, 130 million hectares of native forest were gradually cleared for sugar, cocoa, livestock, charcoal, and mineral extraction; today, only 8 per cent remains. North America fared little better: by the mid-nineteenth century, 70 per cent of its forests had been destroyed. In just fifty years, 500,000 square kilometres of forest—an area equivalent to Illinois, Michigan, Ohio, and Wisconsin combined—were cut.

Mega-forests, already vital for carbon storage and planetary cooling, also safeguard essential biodiversity that cannot simply be restored through reforestation. Within the apparent chaos of a primordial forest, plants and animals maintain complex, interdependent relationships, and even slight disturbances can disrupt the ecological balance. After twenty years, a newly planted forest still cannot replicate the biological conditions of a primaeval one; such woodlands remain impoverished and far less capable of absorbing carbon.

Mega-forests deserve comprehensive protection. Safeguarding them is far less costly than attempting to recreate them, and the first step is to prevent road construction. The American ecologist Aldo Leopold, soon after joining the U.S. Forest Service, realised that roads, grazing, and the eradication of wolves—followed by an explosion in deer populations—were degrading natural ecosystems. Entire hillsides collapsed, obstructing watercourses and driving native trout toward extinction; areas once covered in thriving pines were overtaken by shrubs, a consequence of logging. In 1924, he established the first American wilderness area in New Mexico, free of roads. Additional protected areas followed, and in 2001, the U.S. Forest Service designated 24 million hectares of roadless forest in southeast Alaska, prohibiting new road construction. It became clear that the most effective way to protect forests was to keep roads out. The more intact a forest, the greater its carbon-sequestration capacity.

Expanding protected areas is an essential tool for environmental conservation. In 1990, only 4 per cent of the planet was protected; thirty years later, the figure had risen to 17 per cent, and many nations are working to reach 30 per cent by 2030. Noteworthy measures have been adopted by governments in the Congo Basin and the Amazon, which have placed tens of millions of hectares of mega-forests under protection.

Supporting the Indigenous peoples who have inhabited these forests for millennia is another effective conservation strategy. Their cultures and spiritualities are deeply rooted in the forest, and no one knows these ecosystems better than they do. Brazil, Colombia, and, more recently, Canada have recognised Indigenous land rights; strengthening this movement is both a practical and ethical means of safeguarding forests, as these communities possess unparalleled knowledge of how to care for them.

Protected areas, Indigenous stewardship, the absence of roads, and forest restoration are all vital measures through which nations may still ensure that future generations inherit a world with forests. Public officials and governments bear the greatest responsibility, but individual actions also matter: reducing energy consumption, eating less beef, and choosing sustainably sourced products can all make a meaningful difference.

We can still change course and rediscover harmony with nature; what is required is the will to do so. The coming decades will be decisive for restoring the lost Eden of the only habitable planet we know—Earth, home to all living beings.

Bibliography

Reid, J., & Lovejoy, T. Ever Green. Einaudi.

Attenborough, D. A Life on Our Planet. Mondadori.