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Chipping away at Switzerland’s forests

Lucie Wuethrich

Swiss forests are growing but that growth is uneven. They are thinning and even retreating on the Central Plateau region. Lucie Wuethrich challenges the wisdom of Switzerland’s approach to meet its carbon zero target by, in part, increasing its reliance on burning wood. 

“2021 is a make-or-break year to confront the global climate emergency,” according to UN Secretary General, António Guterres. His words come on the heels of a recently released report by 17 top scientists warning of a “ghastly future of mass extinction, declining health and climate-disruption upheavals”. 

The biomass industry insists it is environmentally friendly and clean. ‘Wood’ that it were so simple.

It remains to be seen whether the world will take heed. We are fascinated by fictional apocalypse but seem unable or unwilling to accept the real one facing us. More emissions have been spewed into the atmosphere in the 20 years since the Kyoto Protocol than in the 20 years preceding it, not one of the industrial nations is on track to meet its Paris Agreement obligations and none of the 20 Aichi Biodiversity Targets have been met.

The latest catchphrase—or rather hashtag—is carbon neutrality. Governments are competing to be the first to wean themselves off fossil fuels and adopt clean forms of renewable energy. Switzerland has pledged to reduce its net carbon emissions to zero by 2050. One way it proposes to do this is by increasing the country’s reliance on forest biomass. 

Woody biomass consists of wood sourced from forests and landscape maintenance as well as from industry offcuts and waste, which can be used to produce heat and/or electricity by combustion and gasification. In Switzerland, woody biomass generates mostly heat, accounting for 11% of the country’s heating demands, making it the second most important renewable after hydropower. This figure is set to increase under the government’s Energy Strategy 2050, with forest-derived wood playing an oversized role.

And why not? Forests cover almost a third of Switzerland and boast some of the highest growing stocks and natural regeneration rates in Europe. Moreover, the country has a long tradition of sustainable, “near natural” silviculture which, for the past century, has helped preserve the health and indeed beauty of its woodlands and hedgerows despite a high level of forest resource intensity. Burning local wood also reduces fossil fuel imports and use, boosts energy self-reliance and is carbon neutral and sustainable, according to the Swiss Federal Office of Energy (SFOE). The biomass industry goes two steps further and insists it is environmentally friendly and clean.

Wood that it were so simple.


The most obvious problem is that forests are multifunctional and that these functions overlap. Cutting down trees benefits wood production, but can seriously affect other forest functions, particularly when carried out intensively. 

Timber production is by far the most important role demanded of Swiss forests, but half are also expected to protect people and assets from mass movement hazards such as avalanches and landslides, and some 40% filter drinking water and protect watersheds. They also help mitigate erosion; supply soil and food; act as carbon sinks; and provide havens for biodiversity and wildlife, as well as spaces for human relaxation and recreation, to say nothing of their aesthetic appeal.

Forests must somehow provide all these services while simultaneously contending with more diseases, wood boring insects, extreme weather events and forest fires linked to climate change. They have already weathered several extreme droughts and average annual temperatures that are increasing at twice the global mean. Both beech (Fagus sylvatica) and Norwegian spruce (Picea abies), vital to the forestry sector, are maladapted and vulnerable to warming temperatures. Many are already showing signs of stress.

To all these pressures must now be added another: the surging demand for energy wood and biomass in particular. 

Just 14% of all Swiss timber was used for fuel in 1990. By 2019 this figure had jumped to 42%. Over the same period, sales of energy wood increased by 64% despite the total number of wood-fired systems decreasing by 21%. Domestic wood chip production leapt 214.3% from 2004 to 2019 while pellet production, which has been growing at a steady 5% per year, reached a record 257,000 tons in 2019. Home fireplaces and outdated ovens fed with traditional logs are being replaced with larger, hungrier semi- and fully-automated biomass-fired systems that burn day and night to heat entire buildings and neighbourhoods. The number of medium-sized installations (50-500 kW) has quadrupled since 1990, while installations over 500kW have increased from a total of 227 in 1990 to 1,112 in 2019. By comparison, a 50 kW installation can heat 5-10 apartments of 100 m2 each.

Fragmented patchwork

Switzerland’s Central Plateau region, known as Mittelland, which sweeps in an arc from Geneva in the west to St Gallen in the east, is bearing the brunt of this silvicultural onslaught. Roads, towns and agriculture have long nibbled timidly but steadily into its mixed forests, but radical thinning and clearcutting are now carving them into a tattered, fragmented patchwork dotted with growing piles of neat roundwood and hirsute stacks of whole trees. This least forested region supplies the most timber, with just 4 cantons—Bern, Zurich, Aargau and Vaud—all with substantial Plateau forests, regularly providing half the 5 million m³ or so of wood harvested annually Swiss-wide. 

Mittelland forests have lost 5.6% of their overall surface area since 1990 and decreased in stock by 10.3%, from 426 to 382 m³/hectare (ha). Bernese forests, which produce the bear’s share at around one fifth of all domestic timber, have shrunk by 13.5% in the Plateau region.

Over a century of Swiss “close-to-nature” silviculture is being quite literally uprooted in favour of a Forest Policy 2020 that calls for “the sustainably harvestable wood harvest potential” to “be exhausted” while simultaneously respecting all other forest functions.

Greenwashing is popular these days, especially where wood is concerned.


It remains to be seen just how “sustainable” biomass harvesting can be, but research warns that increasing worldwide primary energy sourced from wood by just 2% would require current global commercial wood harvests to double. Timber production and tree mortality in Central Plateau forests already outstrip their increment (3,283,000 m³/year vs 2,973,000 m³/year), a sure sign of overexploitation and clearcutting—that hallmark of biomass harvesting—is starting in the Jura and the pre-Alps too. Yet domestic wood energy production is projected to increase by as much as 50% to offset fossil fuel use. Something will have to give.

The law already has. While clearcutting and deforestation are prohibited under the Federal Act on Forest (ForA) and the Forest Ordinance (ForO), both regard “forest roads and other forest structures and installations” as forest, not deforestation, and the ForO states that “clearcutting does not arise, if the old stand is cleared following sufficient and secured regeneration”, a specious but failsafe argument when 90% of Swiss forests regenerate naturally.

Another pervasive smokescreen is that biomass comes from “offcuts” and “wood waste” via the grandly-named “optimised cascade use”, which should see wood passing through a number of phases or products before being burnt. But the first two terms are used loosely and demand is so great that whole trees are being chipped directly. Swiss sawmills specialise in softwoods and unless the country develops the capacity to produce the high-performance, glued hardwood timber used in construction, the Central Plateau’s quality hardwoods, particularly beech, will continue to be deemed “low value” and exported at low prices or burnt. Until recently there was little incentive to log these broadleaf forests commercially, but profitable biomass has tipped the scales and mobile chippers do not distinguish between soft and hardwood trees and make short shrift of both. 

Woody biomass is portrayed as a natural, clean, environmentally friendly alternative to coal, oil and gas, but burning it emits similar asthma, cancer and lung disease-causing particulate matter, noxious chemicals and the same carbon dioxide (CO2) as the fossil fuels it seeks to replace. Residential biomass is especially problematic because emissions occur closer to the ground and aren’t always filtered. Spiralling demand means that trees are being chipped and burned with up to 50% moisture content. Damp wood burns less hotly and cleanly, and produces more ash, which must also be disposed of. Unlike other countries, Switzerland does not yet allow such residues to be spread on fields, so they are thrown out with the country’s municipal solid waste, already one of world’s highest per capita. Clean biomass is an oxymoron.

The biggest delusion of all however is that biomass is carbon neutral. 

Freshly cut timber is piled on the side of a forestry road
The author claims that biomass doesn’t usually come from “waste wood” but whole trees as pictured here on the Belpberg, outside the capital, Bern. Lucie Wuethrich

Answer to the climate crisis?

Before unpacking the intricacies of the carbon cycle, ask yourself this: if raging Australian bushfires, Arctic wildfires and conflagrations in the Amazon are denounced as carbon and environmental catastrophes—even crimes in the case of the latter—how can cutting down trees and burning their derivatives in heaters and boilers be touted not just as carbon neutral but the answer to the climate crisis?

The short answer is because it isn’t. Logging long-established forests, especially hardwoods, and burning them as biomass on an industrial scale isn’t just bad for forests and human health, it is also detrimental to both climate and carbon sinks, and almost always results in greater net carbon emissions than if fossil fuels had been used, according to a growing number of scientists, articles and statements. Even the Federal Office for the Environment (FOEN) warns that “strategies that only increase the use of wood as biofuel are not efficient from a CO2 balance perspective”.

The carbon neutral artifice is rooted in the fact that forests are renewable. They can be felled and burned, the argument goes, because regrowing and remaining trees will go on absorbing and sequestering carbon. This is a false hypothesis however because even if felled forests do regrow, regrowth (carbon capture) is slow and measured in decades or centuries, as opposed to burning (carbon emission) which occurs within minutes. Half a tree’s dry mass can consist of carbon, which is released during combustion, and there’s even more carbon in the soil. Swiss woodland soils account for 60% of all sequestered forest carbon which is also released during logging and subsequently when sudden light and higher temperatures boost microbial breakdown.

To this billowing carbon bill should also be added the CO2 emitted by burning fossil fuels during biomass harvesting, processing and shipping. Except it isn’t. Thanks to an accounting sleight-of-hand, the CO2  emissions from tailpipes are conveniently omitted. As indeed are the millions of metric tons emanating from biomass burner smokestacks and flues. 

Wood is less energy-dense

And it gets worse. Energy wood in all its forms is less energy-dense than fossil fuels, particularly coal, so more must be burnt to produce the same unit of energy. A molecule of CO2 has the same effect regardless of whether it was produced from burning coal, oil, gas or wet woodchips; burning biomass, particularly wet wood chips, just produces more of them. Wood’s poor combustion and processing efficiencies therefore mean that burning forests for fuel in lieu of fossil fuels will likely result in more atmospheric CO2.

So, while clever accounting and creative PR wipe wood-derived CO2 from the climate ledgers and public view, it continues to accumulate in the atmosphere, driving climate change.

It was a Swiss pastor, Jean Senebier, who first postulated that plants somehow “decompose” CO2 from the air and incorporate the carbon. His discovery over two centuries ago forms the cornerstone of our combat against climate change. As do forests. Natural and naturalised forests represent the single most effective and cheapest means we currently have of removing CO2 from the atmosphere and sequestering carbon long-term, to say nothing of all the other vital roles they play. The ultimate irony is that during the 19th century’s Industrial Revolution it was the switch to coal that saved Europe’s forests. Today we eschew coal and once more burn trees, this time in the name of climate change mitigation.

Switzerland’s Plateau forests can still be exploited sustainably as they once were not so long ago, but the extracted timber should be prioritised for construction, as a low-carbon alternative to concrete and steel, not burnt as biomass on an industrial scale. The infinite renewables such as solar, wind, hydro and geothermal energies should be promoted and further subsidised instead. Forests regrow but they are finite, as is the time we have left to act.

In this “make or break year” it is up to every one of us to decide how we heat our homes, but every tree felled for pellets or woodchips means one less air-cleansing, carbon-capturing mechanism; one less home for wildlife; one less network of soil-retaining, water-filtering roots; one less patch of shade; one less tree to climb. 

And more CO2.

Once biomass gains traction it will become almost impossible to stop.

The views expressed in this article are solely those of the author, and do not necessarily reflect the views of SWI

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SWI - a branch of Swiss Broadcasting Corporation SRG SSR