Keywords

Clear and undoubted, as the sixth IPCC report of August 2021 confirms, it has to be noted that we humans are causing rapid climate change. Our emissions and destruction of our environment are leading us into a drastic change of life on a global scale. Our treatment of forests transforms them, too, into major sources of emissions. Man-made emissions from the economy, including agriculture and forestry, must be reduced immediately!

Reliable goals and ways of achieving climate neutrality as quickly as possible are the political order of the day. No more delaying, no more wait-and see, no more blame-shifting, no more beating around the bush—we need ambitious action in the right direction. Compliance with the Paris Climate Agreement is the narrow pathway into a future that might resemble the present. We need much stronger commitments and efforts toward keeping the climate roughly as we know it.

Forests at the Center of Multiple Crises

To protect the climate, as well as our health, much greater efforts are needed to preserve the biodiversity and biosphere integrity of our planet. Biodiversity is the backbone of our life (Díaz et al., 2006; Cardinale et al., 2012; Kadykalo et al., 2019). Its loss, which is dangerous for us, has progressed much farther than the climate crisis (Fig. 1), which is a burden on us and is now finally being perceived politically (Rockström et al., 2009; Steffen et al., 2015; Richardson et al., 2023). The biodiversity and biosphere integrity crisis is caused by the unchecked heavy encroachment on, and elimination of habitats that are permanently necessary for the diversity of species. Already 75% of the world’s land surface is severely degraded (IPBES, 2019). The damage amounts to an estimated $6.3 trillion per year (that’s 6.3 times a thousand billion!) and the livelihoods of about half a billion people are increasingly at high risk (Ding et al., 2017). Faced with the threat posed by the damage to nature, with the need to safeguard the Earth’s habitats, politics is not sufficiently attentive nor doing enough (Mazor et al., 2018). Political measures are inadequate. Moreover, most people today are completely unfamiliar with the things that must be protected, the still nearly untouched primary forests for instance. Most people live in an environment that has been almost completely degraded and excessively transformed. The loss of biodiversity, manifested in the decline of species and populations, continues unchecked around the world and especially in the tropics (e.g. Barley et al., 2016; Giam, 2017).

Fig. 1
A planetary boundaries chart presents the triple crisis consisting of biosphere integrity, nitrogen, and climate. The legends of boundary transgressed are self-operating space, zone of increasing risk, and high-risk zone. Genetic in biosphere integrity has the high-risk zone.

Triple crisis: biosphere integrity, nitrogen, and climate. Crises that reinforce each other in both the short and long term (Richardson et al., 2023)

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We Europeans have reached a level of consumption that entails not merely a very large ecological footprint in our continent, but also burdens for the whole world. In regard to forest destruction caused by international trade, the European Union (EU) plays a leading role, second only to the People’s Republic of China (WWF, 2021a). Yet the losses and the comprehensive need for action are still not sufficiently perceived as politically urgent. The opportunity for the EU to become a role model is still there—and hopefully will be seized as soon as possible.

Accounting for over 90% of forest loss, agriculture and forestry are its primary drivers, especially in tropical regions. Political regulations are needed that constrain responsible producers, companies, and traders through rules and obligations that prevent deforestation in their supply chains. In this way, climate change and the downward trend in vertebrate species (as a proxy for all biodiversity) could be slowed and vital biodiversity be rebuilt.

Forest as a Health Precaution

On average, a first transmission of pathogens from animals to humans occurs every four months. This transition is described for Ebola, malaria, avian influenza, Lassa fever and the Niphavirus, among others (Ellwanger et al., 2020; Wolfe et al., 2005; for Ebola: Olivero et al., 2017; for malaria: Brock et al., 2019; for avian influenza: Sehgal, 2010; for Lassa fever: Adetola & Adebisi, 2019; for Niphavirus: Shanko et al., 2015), and is an essential source for developing pandemics. With ongoing decimation, fragmentation, and overexploitation of forests, such spillovers occur ever more frequently as people are getting more often too close to forest animals, so that infections can take place more easily (WWF, 2020b). But it is not only our physical health that is protected by resilient biodiversity and threatened by habitat change (WWF, 2020b; Kilpatrick & Randolph, 2012). Our psyche, our mental balance, is also better nourished when we humans live in a diverse environment and can be in contact with biological diversity (Lovell et al., 2014; Harvey et al., 2020).

The One Health approach (Rabinowitz et al., 2013; Jorwal et al., 2020) shows our dependence on natural ecosystems. Only the preservation and restoration of natural and near-natural ecosystems will maintain our health in the long term. Conservation of—especially natural—forests is a form of protective health care in a context of continued population growth.

Nature’s intrinsic value should be an imperative for its preservation in our social and political conduct. But we civilized humans seem to have evolved with a blind spot, a missing development. So long as population density was low, nature seemed an inexhaustible resource for humans. But this is no longer true. We have already trimmed nature to such an extent that its necessary contributions to our lives (from soil fertility to water supply to pastoral care for stressed people) are ever more insecure. Moreover, increasing destruction of nature makes transmission of infectious diseases to humans more likely, thus magnifying the danger of pandemics. We cannot afford to expose what nature remains to further human-technical penetration. However, this is not fully felt nor accepted by the humans.

To avoid inflicting further large-scale damage on ourselves and the planet, we must avert the greatest current crises (Fig. 1), the biodiversity, biochemical,Footnote 1 land system change and climate crisis. Forests play a role in these crises in four ways, namely as

  • shrinking and degraded ecosystems with immense biodiversity and functional losses;

  • endangered utilization systems that, among other things, provide groundwater and drinking water, supply raw materials, and keep us healthy;

  • large-scale carbon sources as a result of degradation and loss;

  • objects of climate policy insofar as forests, storing carbon and regulating the climate, offer important nature-based solutions to the climate crisis.

While the transformative power of climate policy (away from fossil fuels) and the growing world population are steadily raising the demands on forests, the decline of forests and their quality is increasingly reducing their sustainable usability and thus the security of their services. The passage into the future has become very narrow and will become even narrower with every tenth of a degree of additional global warming due to human-induced emissions, with further deforestation, and with intensified land use. Animal, plant, and fungal species of the forest no longer have a future, and people thereby lose their livelihoods.

Main Message

With the loss of primary forests, global biodiversity, our health, and climate protection are in free fall as well. Without preserving the remaining natural forests, a climate that protects our (human) lives is not possible.

Forest Loss and Degradation in the Tropics

Some 30% of Germany’s land area is covered by forest. During the last decade, we have globally lost natural forest areas of this size every year (FAO, 2020)! More than 80% of this deforestation is due to the spread of agriculture (Kissinger et al., 2012; WWF, 2018a). The three main destroyers are soy cultivation for animal feed, the creation of palm oil plantations and cattle pastures (Fig. 2). Regionally, however, other factors are also strongly involved in deforestation, such as mining and infrastructure projects (dams and roads) in South America (WWF, 2015). Furthermore, the conversion of natural forests into timber plantations is another important factor: forests rich in biodiversity and carbon thus become degraded timber plantations that resemble agricultural land more than real forests. Such plantations are the fourth largest global driver of the destruction of valuable natural forests (WWF, 2021a).

Fig. 2
An illustration of six commodities causing tropical forest destruction. It presents 30% soy, 24% palm oil, 10% beef, 8% timber, 6% cocoa, and 5% coffee.

Between 2005 and 2017, more than 80% of tropical forest destruction was caused by just six commodities: soy, palm oil, beef, wood products, cocoa, and coffee (WWF, 2022)

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The effects are not adequately captured by adding up lost areas. Thus, the shrinking of the Amazon Forest, for example, leads to drying out with supra-regional effects (Leite-Filho et al., 2021; Zemp et al., 2017). Without forests, precipitation may cease in a worst-case scenario, leaving millions of people without sufficient drinking water for extended periods. In São Paulo, the supply of fresh water had to be cut off for months (Le Monde diplomatique, 2015) because fewer clouds formed over the Amazon rainforest. It is expected that such water shortages due to deforestation will become more frequent, especially at the end of the already noticeably lengthened dry seasons (Lima et al. 2014; WWF, 2020c). In Southeast Asia, palm oil production and industry are causing the loss of extremely climate-relevant peat swamp forests (WWF, 2018a). In Africa, where palm oil plantations are also expanding, population pressures on forests are already especially intense, as some 90% of wood production there is used for firewood and charcoal. The overexploited forests can no longer recover and are disintegrating on a large scale (Allen & Barnes, 1985).

Forests are lost through practices that are legal or illegal in the countries in which they occur. Political actors are only rarely committed to the conservation of natural forests. Illegal forest use and destruction are often even legitimized retroactively through the granting of property titles—amounting to governmental promotion of forest loss. Examples are known not only from Brazil, but from many other countries, including the European region—and such action is typically linked to corruption. Illegal logging, the largest sector of global environmental crime, ranks third in organized crime worldwide after drug trafficking and product counterfeiting (Nellemann et al., 2018). Its rise is only possible through “looking the other way” or “tolerating” at government level, German ministries included (WWF, 2021b). Illegally felled timber and timber products from overexploitation reach us on a large scale via China, for example; even barbecue charcoal, which seems harmless, represents the destruction of nature and misdeclaration (Haag et al., 2020; WWF, 2020d). Analyses by the WWF have uncovered serious consumer deception. Barbecue charcoal suppliers have advertised with the claim “no tropical wood,” but in fact exclusively used charcoal that could be traced back to tropical wood (WWF, 2018b).

Much criminal energy is devoted to extracting short-term benefits from forests. Some 15% to 30% of timber is harvested illegally (Nellemann & Nellemann, 2012). This can be curbed only through decisive action by state and society. Long-term protection of forests will be achieved only when we no longer treat environmental crime as a trivial offence and structure global supply chains in a thoroughly sustainable way. Appropriate action requires that we recognize such blind spots and take responsibility for forest loss and degradation. For this we need politicians, companies, and consumers who tackle forest protection and prioritize it on their long-term agendas.

Main Message

We know about forest loss and degradation in the tropics and the vital importance of forests—so why don’t we stop the loss of forests? Our civilization’s evolutionary blind spot, which makes us regard nature as inexhaustible, consistently leads to large and small myopic economic and utilization decisions that downgrade forests to mere resources. There is a danger that the importance of forest protection as a necessary basis of the economy will be recognized only once decisive tipping points will have been passed.

Forests as Centers of Life

Forests are the most important creators and preservers of biological wealth. Around 80% of all species living on land depend on forests as a form of vegetation, even though many of these species do not spend their entire lives there. As natural forests shrink, so does global diversity. The WWF report “Below-the-canopy” (WWF, 2019) uses data from 1970 to 2010 to show that the distribution of wild vertebrates has shrunk by more than half (53%). On average, there are only 47 individuals left for every 100. Imagine a village whose population has shrunk from 100 to 47 in just 40 years. The monitoring of 455 populations of 268 forest vertebrate species carried out since 1970 shows that the loss has so far continued unabated. The decline of forest species is disproportionately steep compared to the overall dataset (including non-forest species) (WWF, 2016a). Data updated to 2016 already show losses of 68% for all vertebrate species (WWF, 2020a). At this rate, we must fear that the forest-dependent vertebrate population today is only 20–30% of what it was in 1970.

We should also recognize that this negative trend goes back to well before 1970. Whereas humans and their farm animals accounted for only a few percent of the biomass of land-based vertebrates a few centuries ago, this share has now grown to around 95% (Bar-On et al., 2018; Harari, 2015). This increase is as good an illustration as any of the transformation process: away from nature, into the new age of the Anthropocene. Less than 5% of the biomass of land-based vertebrates (including here the excessive wild stocks in our forests!) are now “living free” (Fig. 3). Our entire biodiversity of eagles, antelopes, macaws, capercaillies, and monkeys to cheetahs, wildebeests, and giraffes to lions, orangutans, tigers, bison, and zebras hardly registers today in terms of biomass. Of all land-based vertebrates, 90% are born only to provide food for us humans.

Fig. 3
An illustration of the terrestrial vertebrate biomass. It presents 60% livestock, 35% humans, and 5% wildlife.

Humans and their livestock now make up over 95% of the terrestrial vertebrate biomass. (Data from Bar-On et al., 2018)

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The international environmental agreements adopted so far are far from sufficient to turn this around. What we need now is a transformation of our thinking, decision-making, conduct, and way of life. The UN Decade from 2021 to 2030 has therefore been proclaimed as the time of the necessary restoration of natural habitats. Only if we loosen the massive land-use pressure and give wild animals more space will they have a chance to survive the climate change that is already underway.

For “civilized” societies, forests are primarily an economic sector. Timber extraction is the dominant use, which in no way does justice to the importance of the forest for human life. Because the two great human tasks of protecting the climate and preserving biodiversity have so far barely been considered in macro- and micro-economic decisions concerning forests, current economic and forest-policy goals are exacerbating the “twin crises.”

Only an understanding of forests and nature as a value system for health, nutrient circulation, climate, and biodiversity (Kadykalo et al., 2019) can lead to the urgently needed sound forest-policy and nature-conservation decisions and to measures that protect and restore natural forests.

Main Message

Is it really so bad that forests lose their biological wealth? Yes, because 80% of biodiversity depends on protecting the forests. Some two-thirds of wildlife populations have already disappeared.

Biodiversity Protection: Not a Conduct-Relevant Concern

Countries with stagnating populations and without hunger theoretically offer the best prerequisites for enabling the preservation of biodiversity in an exemplary manner, especially on publicly owned land. Given this fact, how can it be that in the state of Brandenburg (Germany) today 581 animal species are on the brink of extinction and around 6,000 of 15,000 species are endangered (MOZ, 2021)? The main reasons cited for the threat to biodiversity are (1) intensive agriculture, (2) drying up of streams, lakes, and wetlands, and (3) urban sprawl and fragmentation of the countryside.

This shows that German politics (Brandenburg can serve as an example because the situation is similar in Germany’s other extended states) is not achieving its tasks. The needed continuous safeguarding of necessary habitats for animal, plant, and fungal species is evidently not a sufficient concern for politicians (and hence also for us citizens).

Germany is representative for the other 195 countries of this world. Societies, though they know better, show little willingness seriously to pursue the preservation of biological diversity (Ding et al., 2017). Companies as well as business and political lobbyists succeed again and again at preventing such pursuit. Moreover, the laboriously negotiated agreements, directives, conventions, laws, and regulations for the protection of nature are not sufficiently implemented. Even a country like Germany, with wealth, a (social) market economy, and democracy, fails to protect biodiversity. Instead, we leave an additional immense footprint outside our national borders.

Large forest landscapes are transformed more (e.g., Russia and Canada) or less (many countries in the tropics) systematically. Important narrow corridors of life, such as those between the peat swamp forests of Sebangau and the “Heart of Borneo,” the central forests of the Indonesian island, are not being deliberately preserved. However, continuous habitats are needed by the over 2 million known species as well as by the species not concretely known today, which may number over 10 or 20 million.

Continuity in nature is not a rigid concept. Even a dynamic river landscape, with its floods, deposits, accumulations, and overlays of sediment, continuously provides a great variety of habitats that emerge anew again and again. The decomposition of dead trees and the regrowth of young ones is part of one continuity, so long as both are connected on a small scale within the forest’s life cycle and are not separated from each other on a large scale to the detriment of biodiversity. Even natural fires are part of this in boreal forests, whereas today’s frequent and very extensive fires, well over 90% of which are caused by humans, prevent continuity.

The preservation of biodiversity absolutely requires spatial and temporal continuity and can be facilitated today only through reliable political action. Only effectively managed protected areas and forest management that is close to nature and worthy of the name (DNR-Forest management guideline, 2021) can reliably achieve biodiversity preservation. Yet the biodiversity-and-climate crisis is fueled anew each day by unsustainable decisions and financial flows. Protestors of all kinds are insulted, threatened, persecuted, or even murdered. With political reason and a well-functioning executive, this could be changed immediately and in an exemplary manner.

Main Message

We are setting the wrong priorities and are thus recklessly putting biodiversity at risk at all levels—as if we did not need it! Diversity requires space and restraint in our politics and daily living.

Timber Use and Forest Loss—A Climate Problem

If the forests were a state, they would currently be the third largest carbon emitter after China and the United States of America. This is due to its man-made destruction, as forests would naturally be a carbon sink: around 50% of the carbon bound to land is bound in forests (WWF, 2020c). Overexploitation of forests, forestry that pays no attention to the carbon storage in forest landscapes, water drainage, slash-and-burn agriculture, out-of-control forest fires, conversion of forests to other uses (especially agricultural land), biologically degraded timber plantations, and the expansion of infrastructure and mining are continuously releasing sequestered carbon (WWF, 2015). A combination of local human activities and local to global political economic decisions are putting pressure on the forest system. This puts a massive strain on our climate. On average, 15% of annual global CO2 emissions are caused by deforestation and forest degradation (WWF, 2016b; Smith et al., 2014). At 8%, tropical forest degradation accounts for more than half of these losses.

Not only forest loss through slash-and-burn, but also the use of wood itself poses a problem. Any use of wood biomass for energy and heat or for short-lived wood products leads to a further burden on the climate through carbon release. Swedish forestry and wood use has been calculated to release more CO2 than all other sectors of Swedish society (Protect the Forest & Greenpeace Nordic, 2021).

The Forest Declaration signed at the Climate Change Conference in Glasgow (COP 26) will hardly stop the loss of forests by 2030. Instead, it may even fuel the conversion of carbon- and biodiversity-rich forests and their soils. German and EU policy must see the forest for what it is: one of the largest terrestrial CO2 reservoirs and guarantor of diverse life on earth—and also, for some time already, a main source of emissions and therefore cause of immense climate harms. This must be considered for the immediate initiation of appropriate preservation measures.

Main Message

Considered as a state, forests are the third-largest emitter of carbon after China and the United States. Wood use and forest loss constitute immense climate problems!

Forests as Carbon Reservoir—Urgently Needed

Forests store about 638 gigatonnes (Gt) of carbon, 283 Gt in living biomass above ground, 38 Gt in deadwood, and 317 Gt in the soil (top 30 cm; FAO, 2011), but with a decreasing trend due to global forest losses. Due to the growth of vegetation, the primary forests of the boreal and temperate zones alone can store around one Gt of carbon per year on average (1.3 ± 0.5 Gt per year). Primary forests that are over 200 years old store an additional 2.4 metric tons of carbon per hectare per year on average (Luyssaert et al., 2008), reason enough to preserve them at all costs. Tropical forests store around 200 to 300 Gt of carbon. About 60% of photosynthesis worldwide takes place in tropical forests—they absorb about 72 Gt of carbon each year and release normally a little less again through respiration (Pan et al., 2011). The world’s tropical forests have already been weak net emitters of carbon between 2000 and 2014. In the dry El Niño year of 2015, they were calculated to have released up to 2.7 Gt (Mitchard, 2018).

Natural forest loss, degradation, and fires result in forest and savannah landscapes being net carbon emitters, despite their just outlined sequestration capacities. Savannah and forest fires annually release 1.7 to 4.1 Gt of carbon into the atmosphere worldwide—plus an estimated 39 million metric tons of methane (with a much higher global warming potential than CO2), 20.7 million metric tons of nitrous oxides (NOx), and 3.5 million metric tons of sulphur dioxide (SO2). The difference is over 3 billion metric tons of carbon equivalents, to the detriment of the—ever decreasing!—storage capacity (WWF, 2016b).

Ideally, this flow should be reversed. Since many commercial forests are now very young, their stored carbon stocks can be increased very quickly by a longer rotation period, that is, a higher tree age at felling. Carbon sequestered in the forest does not harm the climate. This insight could drive action, if it were not for the forestry and timber industry’s pronounced will to exploit the forest: “Only people outside the forestry world believe that the forest is about nature. It is about growth, felling and stock” (Fokken, 2021). Forestry worldwide primarily aims at felling and then using wood to benefit financially from forests and wood plantations. The narrative of carbon storage is summarily rewritten: forest storage becomes wood storage. It is claimed that what matters is not the carbon stored in the forest, but primarily the carbon stored in the harvested and processed (wood) products. Thinking in this way, one can harvest at will, because intensive use produces a large stock of wood and thus constitutes practical climate protection—but without attending equally to the degradation of carbon storage in live forests.

However, such carbon storage in wood works only if this wood is preserved. Yet, presently less than 20% of the wood processed in Germany ends up in long-lasting wood products such as furniture or parts of houses (based on Mantau, 2012). And even this figure is only of limited significance, because many processes for manufacturing wood products (pressboard, MDH panels, etc.) require much energy, whose generation is associated with carbon dioxide emissions. More than three quarters of the 135 million cubic meters of raw wood used thus lead to the release of over 10 million metric tons of carbon dioxide per year. In China, the wood products industry has already become a net contributor of carbon (Ji et al., 2013).

Main Message

Forests are urgently needed as a carbon sink. The one-sided narrative of carbon storage in wood products and of the uses of wood as a substitute material thus detracts from sound and necessary action for climate and biodiversity protection.

Using Wood for Energy—Globally Not Climate Neutral

The strategists of the forestry and timber industry have meanwhile recognized the problem and developed another narrative. According to them, short-term wood products (such as paper towels and cardboard boxes) and the energetic use of wood (burning for energy and heat) are also a gain for the climate: burning wood is climate-neutral and moreover can replace more energy-intensive fossil fuels. But both claims are wrong. The use of wood for energy is not climate-neutral just because new trees can grow in the forest. The forest’s carbon cycle has been massively altered and disturbed by humans; due to loss and degradation, the global forest area is in decline in extent as well as in ecological quality. So far, 2 billion hectares (about one-third) of the global forest area and most of its carbon storage capacity have been lost. Any additional energetic use of wood thus places an additional burden on the climate through the release of carbon. Forests cannot compensate for their own emissions because they are losing ground around the world and are becoming patchier and younger. Just between 2005 and 2017, the EU’s international trade was responsible for 3.5 million hectares of forest destruction in the tropics (WWF, 2021a).

The substitution effect of wood used for energy is not present, as the efficiency of using wood for energy is low. Compared to the combustion of coal or gas, wood combustion even releases more carbon (Fig. 4). Moreover, in view of the agreed decarbonization of the economy by 2050 at the latest, any substitution effects existing today (dpa, 2021) are rapidly declining; with the transformation of the economy and the achievement of climate neutrality in the land use sector, they may disappear completely.

Fig. 4
An illustration of carbon release during the combustion of wood. 403, 340, and 202 kilogram C O 2 per megawatt hour from timber, hard coal, and gas, respectively.

Carbon release during the combustion of wood, hard coal, and gas (Mwh: megawatt hour; based on IPCC, 2006 in Kuhlmann & Gerhardt, 2017)

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Main Message

The “regenerative” sustainable energy source forest is too small. The current use intensity is aggravating our acute climate crisis. The use of wood for energy is no more climate neutral than a forest fire.

Forestry—Not Climate Neutral

The most commonly used harvesting and silviculture methods worldwide are clear-cutting and clear-cut-like logging. Clear-cutting is economically most lucrative in the short term, as the wood biomass can be used in only one operation. This creates an area of open space. Clear-cut areas become significantly warmer than the original forest area due to unhindered solar radiation and have no forest interior climate. The higher temperatures cause soil carbon to be released through increased activity of soil organisms and accelerated chemical processes (Wieting & Leversee, 2019). The faster turnover of substances reduces the humus content and soil fertility. Clear-cut areas are destroyed forest ecosystems whose material cycle can only be closed again very slowly. Increased carbon release can often be detected in such areas even more than 10 years after clear-cutting (Wieting & Leversee, 2019). Clearcutting is not similar to a natural disturbance, neither windthrow nor fire, as biomass is removed to a much higher degree. The frequency, spatial structure and extent of clear-cutting are also not remotely comparable to natural disturbance dynamics.

To make forestry more climate-friendly, management must be adapted accordingly. Soil-conserving management methods that preserve the forest climate are just as imperative as adapted game densities. A move away from clear-cutting towards forest use that maintains the cooling effect of forests, the improved water balance (groundwater supply; Flade & Winter, 2021), and the carbon storage of vegetation and soil is most likely to compensate for the biomass losses caused by wood harvesting and can be described as climate- and biodiversity-friendly. The realization that—due to the necessary forest paths and aisles, the removal of wood, and the reduction of thermoregulation—wood harvesting always leads to an impairment of forest ecosystems should motivate politics to minimize these impairments. Plans—concerning the Central European beech forests for example—exist (Winter et al., 2015) and should serve as blueprints for forest management here.

Forest growing stock is the key to carbon storage, and this can sustainably take place only in a near-natural forest ecosystem. The circulation of carbon within the forest, that is, the decomposition of dead trees and the renewed carbon fixation in young trees, can thus represent an immanent balanced part of the storage medium and the growing storage capital. In a beech forest—the natural vegetation in over two thirds of Germany’s forest area—dead older trees need up to 30 years to become humus. Even dead trees thus bind carbon within the forest ecosystem over a longer term than the period straightway necessary to implement climate protection measures. Even in spruce forests that have died due to drought and bark beetle infestation, the carbon remains sequestered on the surface longer than when the damaged wood is used for energy. The clear-cutting-like clearing and soil cultivation of planted areas again releases (soil) carbon for years and in large quantities (for example Nõgu, 2014; Wieting & Leversee, 2019). Young forests, including young commercial forests, have an immense potential within the next decades to absorb carbon into the living tree population, which could remain stored for many decades—so long as people do not overuse, clear, burn, or degrade the forest.

Main Message

While local perspectives can be misleading, from a global perspective, clear-cutting and clear-cutting-like interventions are endangering the climate and biodiversity. Allowing trees to age, preserving deadwood, and allowing natural regeneration with adapted game populations would have a positive effect on the climate and help mitigate forest damage. This would be active climate and biodiversity protection and should be promoted politically.

What If We Reached a Global Increase by 3 Degrees?

For about two decades, the temperature increase in the Northern hemisphere has been exceeding that in the Southern. With an average global temperature increase of three degrees, the rise in the Northern latitudes would most likely be significantly larger (Feulner et al., 2013). The forest ecosystems of Europe’s boreal, cool temperate, and Mediterranean climate zones can neither adapt to this development nor migrate with it (Garamvölgyi & Hufnagel, 2013; Hufnagel & Garamvölgyi, 2014; on forest fragmentation: Bacles & Jump, 2011). Water shortages and droughts are already putting pressure on forests, and it can be assumed that this will intensify as temperatures rise. Extreme weather, such as storms, heavy rainfall and extreme temperatures, will increasingly destabilize forests. The boreal forest belt will shift Northwards, especially in Russia.

Tropical forests will suffer greatly due to increasing use intensity and higher temperatures. Their self-sustaining nutrient and water cycles will no longer be maintainable if further damage occurs. In addition to fires, the tropical forests are increasingly becoming a source of carbon due to desiccation processes. This has been proven for the first time in 2020 for parts of the Brazilian Amazon region (Houghton et al., 2000). These emissions further increase the approximately 20% share of anthropogenic carbon emissions from land use in the tropics (Le Quéré et al., 2016).

Dry years are already leading to increased carbon releases from the tropics (Liu et al., 2017). Further loss of forest area will accelerate the drying process (Baccini et al., 2017). A so far only slightly higher global mean temperature (Fig. 5) has already led to the dry season there lasting up to 6 weeks longer in some years and to a further significant increase in the risk of forest fires, especially at the end of the dry season (WWF, 2020c). It can be assumed that, with a 3-degree higher annual mean temperature, the tropical forests with their extensive services described above will become largely unavailable to us humans. Fifteen different climate models based on the two emission scenarios A2 and B1 (with, respectively, 550 and 860 ppm CO2 in the atmosphere in 2100) show that the tropical forests of South America could very quickly turn into savannas by the end of the century. The 20% loss of forest area in the Amazon basin by 2020 could increase by at least another 30% due to climate change. Here, we are not looking at the continued destruction by humans, but at the disintegration of tropical forests due to periods of drought, which cause the conversion of tropical forests into savannah (Salazar et al., 2007). The biological diversity of the South American tropics will accordingly also be lost (Senior et al., 2019). A study for Central America calculates in a scenario for the tropical forests there with up to 3.5 degrees more (RCP4.5 scenario) an average decrease in precipitation of up to 4 millimeters per day and a dry season that is around 40 days longer. As for South America, the scenario for the end of the twenty-first century shows a large-scale desertification of the tropical forests there (Lyra et al., 2017).

Fig. 5
A dual-line graph plots the fluctuating lines for the temperatures in the northern hemisphere and southern hemisphere from 1993 to 2023. A graph is over a world map. A thermometer in the Celcius is on the left.

Monthly values of the global temperature deviation on the land surface over the last 30 years (NCDC, 2022). Temperatures in the Northern hemisphere (orange) are rising more strongly than those in the Southern hemisphere (blue)

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A scientifically valid prediction or detailed description of a future climate, however, is hardly possible. Since the term climate always refers to a time span of 30 years, this term can in any case not be reliably used in the context of rapidly changing weather patterns. Forests have never been static and will continue to change in the future. However, since the climate and the associated weather patterns change faster than forests can react, they will be able to fulfill their functions only partially or not at all. Single short-term extreme weather events may be decisive for whether a forest is preserved or lost.

It is important to know that it is not possible to adapt a forest through silviculture to a predicted, later climate because (1) we do not know this climate, because (2) this climate will probably not achieve comparatively stable growth conditions for centuries due to the rapidly changing weather patterns triggered by humans, and because (3) active adaptation by business-oriented humans always takes account of only very small parts of ecosystem functionality. In view of the increasing changeability of weather patterns and the complex interactions in forest ecosystems, the probability of drawing erroneous conclusions is high. We can only try to strengthen the commercial forest for as long as possible by means of forest ecosystems that are as natural as possible with tree species native to the site and forest management that is close to nature.

By 2023, Germany has suffered extensive damage to (about 600,000 hectares of) its forest area for the first time—and this after merely 3 years of drought with a mean temperature increase of merely 1 °C. So far, this damage has mainly affected spruce (Picea abies), which is widely planted but not suited to locations below 600 meters above sea level. The profit-oriented spruce industry has deliberately accepted the associated greater economic risk under “normal” weather conditions. Since the loss incurred was and is largely compensated politically through subsidies, the risk is not borne by the forest owners, but by the taxpayer (and of course by the climate). This large-scale silvicultural mistake has been pointed out by nature conservation associations for decades but was not taken seriously by politicians and forest owners. The damage to native tree species is still minor, especially in near-natural forest management, but it is already noticeable there as well.

It is foreseeable that the climate factor, coming on top of the already existing stress factors (excessive nitrogen and pesticide inputs, excessive exploitation and thinning, excessive game or livestock densities, damage to soils, and impaired water management) will greatly harm forests. The heat threshold for plant cells lies between 35 and 46 °C. And every 10 degrees, a tree’s respiration and water loss doubles (Coder, 2011). In our temperate latitudes, conifers already reach their heat limit between 35 and 42 degrees, while for deciduous trees it only occurs between 40 and 45 °C (Profft, 2005). It should be borne in mind that the air’s increasing carbon dioxide content can be more problematic for some tree species than for others; for example, it has been shown that birch trees cope much worse with high CO2 concentrations than poplars (Darbah et al., 2010).

Various adaptation strategies can help during prolonged heat, but only temporarily. When heat is coupled with drought, the cooling possibilities through transpiration are lost (Coder, 2011). More water evaporates through the leaves than can be replaced—the transpiration flow breaks off and the cooling stops. The tree dies a quick death from combined heat and drought, something that has been observed in tropical forests as well (Allen et al., 2010). Storms can also harm forests, especially when preceded by heavy rainfall. Both combinations of factors would become more frequent in a 3-degree warmer world, so that forests will continually struggle for survival in many locations. Since we need forests for climate protection, we must not allow this and must act.

Main Message

With a warming by 3 degrees, many forests are ecologically finished. Forests will increasingly disintegrate. Even where they survive, they will no longer be able to provide their previous ecosystem services.

The Immediate Program for Forests

Climate and biodiversity protection must become central political goals and instruments—cross-sectoral and authoritative at all political levels. There must be no climate protection at the expense of biodiversity protection.

An immediate program to protect our forests should include or consider the following:

  • Deforestation and forest degradation has been stopped by law at the EU level since 2023 (EUDR, 2023). Raw materials and downstream products that are associated with forest destruction are no longer allowed to be imported into the EU, exported from the EU, or traded within the EU. This legislation needs strong implementation with high numbers of controls and deterrent penalties. To prevent leakage effects and the destruction of other nature worth protecting, such as grasslands, savannahs and other wooded lands, to complete the raw material list and to stop deforestation resulting from the finance sector all stakeholders, especially politicians, should support inclusion of other wooded land, maize and the finance sector into the EUDR by 2025 that the regulation can become effective without loopholes and trade-offs.

  • To enable deforestation-free sustainable supply chains for agricultural and wood raw materials and their products long-term, support programs are needed for the development of a sustainable agriculture that, in particular, would improve soil fertility and prevent further deforestation.

  • Reductions are required in climate-damaging emissions from agriculture and in the excessive use of pesticides and nitrogen fertilizers.

  • There must be peatland restoration and protection of peatland soils to achieve climate neutrality at the landscape level and to protect forest landscapes from drying out (see also chapter “Peatland Must Be Wet”).

  • The burning of wood and the production of short-lived wood products such as paper towels, cardboard boxes and disposable pallets must be drastically reduced in favor of reusable items and long-lasting wood products.

  • Protection of forest areas must be increased worldwide, and the management of protected areas (e.g., Natura2000 in the EU) must be significantly improved.

  • Rapid implementation of the EU Biodiversity Strategy will create large areas within the EU where biodiversity can be preserved through wilderness development or extensive use. The rapid and undiluted full implementation of the strategy should serve as a positive example that the needed ecological stabilization is finally given its due importance.

  • The global forest area should be expanded by up to one billion hectares, among other things because of its importance for thermoregulation and water storage as well as for soil fertility and averting soil erosion. In this effort, land rights for indigenous and local communities and benefit-sharing should play central roles.

  • We need extensive forest management that favors native tree species and eschews clear-cutting and pesticides.

  • Financial resources for the conservation of primary forests and the creation of tree-rich forest landscapes must be made available in large and sufficient amounts.

  • Estimates suggest that more than US$300 billion per year are needed for several years to restore forest landscapes (Ding et al., 2017). With somewhat lower investments of around US$200 billion per year, an additional annual storage of 9 Gt of CO2 could be facilitated (Felbermeier et al., 2016). This requires about US$150 billion per year for tree plantations outside the forest, $22 billion for the conservation of forest land, and another $20 billion for improved forest management (forest restoration). So, the cost of conserving still existing tropical forests sums up to around $40 to $50 billion per year.

  • In line with its responsibility for emissions and deforestation, Germany would have to contribute at least US$8 billion annually. The governments of countries with tropical forests could thus use large parts of the already deforested areas sustainably without converting further natural forests (including indigenous forests) into agricultural land by slash-and-burn. The money would have to compensate for the loss of income, since, on the one hand, fewer wood and agricultural raw materials can be sold and, on the other hand, agricultural land that has already been deforested is after a few years no longer as productive as newly created land that has been well supplied with nutrients through slash-and-burn. What is needed, therefore, is a gentle humus-building method of cultivation that produces somewhat higher costs but does not jeopardize the world’s food supply in the coming decades (Erb et al., 2016).

  • All legislation and binding guidelines, including those for the financial markets, must respect the purpose of forest conservation, that is, exclude further forest conversion. Exceptions must be reduced to a minimum or should be considered only if the overall quality of the forest improves and the forest carbon stock increases significantly to around 700 Gt.

  • Experiences from the efforts to implement REDD+, the concept for reducing emissions from forest loss and degradation (WWF, 2011), and the approach “Restoring Forest Landscapes” (NYDF, 2014) show that the reduction of the deforestation rate quickly ceases when the required funds are not made available. The United Nations are trying to provide the pathways and the necessary funding but needs significantly higher contributions from member states to achieve this goal.

Beyond direct forest protection, the following should be noted:

  • Politicians have a duty to achieve the climate targets and to impose clear obligations on enterprises.

  • The preservation of an approximately stable climate is non-negotiable. The scientific findings are available, which means that politicians, governments, and entrepreneurs have a duty to act.

  • Businesses, including the forestry and timber industry, are well-informed about the climate and biodiversity crises and must be held accountable for faulty conduct.

  • The containment of environmental crime immediately needs clear laws with effective enforcement. Short-sighted economic activities at the expense of future generations and beyond planetary capacities should be made illegal and punished.

  • The Paris Climate Agreement must be fulfilled in full. The nationally determined contributions (NDCs) must be effectively strengthened, as their formulation and implementation have thus far failed to achieve the limitation of warming to a maximum of 1.5 degrees.

  • Rich countries like Germany must become role models in climate and biodiversity protection lest we irresponsibly allow the damage we have already done to continue growing.

To close our evolutionary blind spot, we need irrevocable agreements that preserve the Earth with its habitats and diversity. The Glasgow Declaration on Forests, signed by leaders from 140 countries, should be followed up with further agreements. It should be considered whether the preservation of ecosystems requires that some natural areas be placed outside nation states and their decision-making powers to safeguard their continued flourishing and intergenerational justice against the vagaries of national election cycles. The common forest and climate policies of the community of states should make it possible for forests to be no longer the third largest carbon emitter, but part of the solution that would reduce our current emissions by around 15%.

Main Message

No more delaying, no more wait-and see, no more blame-shifting, no more beating around the bush—we need ambitious action in the right direction. Compliance with the Paris Climate Agreement is the narrow pathway into a future that might resemble the present. Will and efforts to preserve the climate and biodiversity roughly as we know them must be significantly strengthened. Reliable goals and ways of achieving climate neutrality as quickly as possible are the political order of the day. Forests should be no longer the third largest carbon emitter, but part of the solution that would reduce our current emission by around 15%.