Deforestation is a primary contributor to climate change, [1] [2] and climate change affects the health of forests. [3] Land use change, especially in the form of deforestation, is the second largest source of carbon dioxide emissions from human activities, after the burning of fossil fuels. [4] [5] Greenhouse gases are emitted from deforestation during the burning of forest biomass and decomposition of remaining plant material and soil carbon. Global models and national greenhouse gas inventories give similar results for deforestation emissions. [5] As of 2019 [update] , deforestation is responsible for about 11% of global greenhouse gas emissions. [6] Carbon emissions from tropical deforestation are accelerating. [7] [8]
When forests grow they are a carbon sink and therefore have potential to mitigate the effects of climate change. Some of the effects of climate change, such as more wildfires, [9] invasive species, and more extreme weather events can lead to more forest loss. [10] [11] The relationship between deforestation and climate change is one of a positive (amplifying) climate feedback. [12] The more trees that are removed equals larger effects of climate change which, in turn, results in the loss of more trees. [13]
Forests cover 31% of the land area on Earth. Every year, 75,700 square kilometers (18.7 million acres) of the forest is lost. [14] There was a 12% increase in the loss of primary tropical forests from 2019 to 2020. [15]
Deforestation has many causes and drivers. Examples include agricultural clearcutting, livestock grazing, logging for timber, and wildfires.
Another cause of deforestation is due to the effects of climate change: More wildfires, [17] insect outbreaks, invasive species, and more frequent extreme weather events (such as storms) are factors that increase deforestation. [18]
A study suggests that "tropical, arid and temperate forests are experiencing a significant decline in resilience, probably related to increased water limitations and climate variability" which may shift ecosystems towards critical transitions and ecosystem collapses. [19] By contrast, "boreal forests show divergent local patterns with an average increasing trend in resilience, probably benefiting from warming and CO2 fertilization, which may outweigh the adverse effects of climate change". [19] It has been proposed that a loss of resilience in forests "can be detected from the increased temporal autocorrelation (TAC) in the state of the system, reflecting a decline in recovery rates due to the critical slowing down (CSD) of system processes that occur at thresholds". [19]
23% of tree cover losses result from wildfires and climate change increase their frequency and power. [20] The rising temperatures cause massive wildfires especially in the Boreal forests. One possible effect is the change of the forest composition. [21] Deforestation can also cause forests to become more fire prone through mechanisms such as logging. [22]Irreversible deforestation would result in a permanent rise in the global surface temperature. [23] Moreover, it suggests that standing tropical forests help cool the average global temperature by more than 1 °C or 1.8 °F. [24] [25] Deforestation of tropical forests may risk triggering tipping points in the climate system and of forest ecosystem collapse which would also have effects on climate change. [26] [27] [28] [29]
Several studies since the early 1990s [30] have shown that large-scale deforestation north of 50°N leads to overall net global cooling [31] while tropical deforestation produces substantial warming. Carbon-centric metrics are inadequate because biophysical mechanisms other than CO2 impacts are important, especially the much higher albedo of bare high-latitude ground vis-à-vis intact forest. [30] [24]
Deforestation, particularly in large swaths of the Amazon, where nearly 20% of the rainforest has been clear cut, has climactic effects and effects on water sources as well as on the soil. [32] [33] Moreover, the type of land usage after deforestation also produces varied results. When deforested land is converted to pasture land for livestock grazing it has a greater effect on the ecosystem than forest to cropland conversions. [34] Other effect of deforestation in the Amazon rainforest is seen through the greater amount of carbon dioxide emission. The Amazon rainforest absorbs one-fourth of the carbon dioxide emissions on Earth, however, the amount of CO2 absorbed today decreases by 30% than it was in the 1990s due to deforestation. [35]
Modeling studies have concluded that there are two crucial moments that can lead to devastating effects in the Amazon rainforest which are increase in temperature by 4 °C or 7.2 °F and deforestation reaching a level of 40%. [36]
Statistics have shown that there is a direct correlation between forest fires and deforestation. Statistics regarding the Brazilian Amazon area during the early 2000s have shown that fires and the air pollution that accompanies these fires mirror the patterns of deforestation and "high deforestation rates led to frequent fires". [37]
The Amazon rainforest has recently experienced fires that occurred inside the forest when wildfires tend to occur on the outer edges of the forest. [15] Wetlands have faced an increase in forest fires as well. [15] Due to the change in temperature, the climate around forests have become warm and dry, conditions that allow forest fires to occur. [15]
Under unmitigated climate change, by the end of the century, 21% of the Amazon would be vulnerable to post‐fire grass invasion. In 3% of the Amazon, fire return intervals are already shorter than the time required for grass exclusion by canopy recovery, implying a high risk of irreversible shifts to a fire‐maintained degraded forest grassy state. The south‐eastern region of the Amazon is currently at highest risk of irreversible degradation. [38]
According to a study in tropical peatland forest of Borneo, deforestation also contributes to the increase in fire risk. [39]
Forests are an important part of the global carbon cycle because trees and plants absorb carbon dioxide through photosynthesis. Therefore, they play an important role in climate change mitigation. [40] : 37 By removing the greenhouse gas carbon dioxide from the air, forests function as terrestrial carbon sinks, meaning they store large amounts of carbon in the form of biomass, encompassing roots, stems, branches, and leaves. Throughout their lifespan, trees continue to sequester carbon, storing atmospheric CO2 long-term. [41] Sustainable forest management, afforestation, reforestation are therefore important contributions to climate change mitigation.
An important consideration in such efforts is that forests can turn from sinks to carbon sources. [42] [43] [44] In 2019 forests took up a third less carbon than they did in the 1990s, due to higher temperatures, droughts [45] and deforestation. The typical tropical forest may become a carbon source by the 2060s. [46]
Researchers have found that, in terms of environmental services, it is better to avoid deforestation than to allow for deforestation to subsequently reforest, as the former leads to irreversible effects in terms of biodiversity loss and soil degradation. [47] Furthermore, the probability that legacy carbon will be released from soil is higher in younger boreal forest. [48] Global greenhouse gas emissions caused by damage to tropical rainforests may have been substantially underestimated until around 2019. [49] Additionally, the effects of afforestation and reforestation will be farther in the future than keeping existing forests intact. [50] It takes much longer − several decades − for the benefits for global warming to manifest to the same carbon sequestration benefits from mature trees in tropical forests and hence from limiting deforestation. [51] Therefore, scientists consider "the protection and recovery of carbon-rich and long-lived ecosystems, especially natural forests" to be "the major climate solution". [52]
The planting of trees on marginal crop and pasture lands helps to incorporate carbon from atmospheric CO
2 into biomass. [53] [54] For this carbon sequestration process to succeed the carbon must not return to the atmosphere from biomass burning or rotting when the trees die. [55] To this end, land allotted to the trees must not be converted to other uses. Alternatively, the wood from them must itself be sequestered, e.g., via biochar, bioenergy with carbon capture and storage, landfill or stored by use in construction.
Earth offers enough room to plant an additional 0.9 billion ha of tree canopy cover, although this estimate has been criticized, [56] [57] and the true area that has a net cooling effect on the climate when accounting for biophysical feedbacks like albedo is 20-80% lower. [58] [59] Planting and protecting these trees would sequester 205 billion tons of carbon if the trees survive future climate stress to reach maturity. [60] [59] To put this number into perspective, this is about 20 years of current global carbon emissions (as of 2019) . [61] This level of sequestration would represent about 25% of the atmosphere's carbon pool in 2019. [59]
Life expectancy of forests varies throughout the world, influenced by tree species, site conditions, and natural disturbance patterns. In some forests, carbon may be stored for centuries, while in other forests, carbon is released with frequent stand replacing fires. Forests that are harvested prior to stand replacing events allow for the retention of carbon in manufactured forest products such as lumber. [62] However, only a portion of the carbon removed from logged forests ends up as durable goods and buildings. The remainder ends up as sawmill by-products such as pulp, paper, and pallets. [63] If all new construction globally utilized 90% wood products, largely via adoption of mass timber in low rise construction, this could sequester 700 million net tons of carbon per year. [64] [65] This is in addition to the elimination of carbon emissions from the displaced construction material such as steel or concrete, which are carbon-intense to produce.
A meta-analysis found that mixed species plantations would increase carbon storage alongside other benefits of diversifying planted forests. [66]
Although a bamboo forest stores less total carbon than a mature forest of trees, a bamboo plantation sequesters carbon at a much faster rate than a mature forest or a tree plantation. Therefore, the farming of bamboo timber may have significant carbon sequestration potential. [67]
The Food and Agriculture Organization (FAO) reported that: "The total carbon stock in forests decreased from 668 gigatonnes in 1990 to 662 gigatonnes in 2020". [68] : 11 In Canada's boreal forests as much as 80% of the total carbon is stored in the soils as dead organic matter. [69]
The IPCC Sixth Assessment Report says: "Secondary forest regrowth and restoration of degraded forests and non-forest ecosystems can play a large role in carbon sequestration (high confidence) with high resilience to disturbances and additional benefits such as enhanced biodiversity." [70] [71]
Impacts on temperature are affected by the location of the forest. For example, reforestation in boreal or subarctic regions has less impact on climate. This is because it substitutes a high-albedo, snow-dominated region with a lower-albedo forest canopy. By contrast, tropical reforestation projects lead to a positive change such as the formation of clouds. These clouds then reflect the sunlight, lowering temperatures. [72] : 1457
Planting trees in tropical climates with wet seasons has another advantage. In such a setting, trees grow more quickly (fixing more carbon) because they can grow year-round. Trees in tropical climates have, on average, larger, brighter, and more abundant leaves than non-tropical climates. A study of the girth of 70,000 trees across Africa has shown that tropical forests fix more carbon dioxide pollution than previously realized. The research suggested almost one-fifth of fossil fuel emissions are absorbed by forests across Africa, Amazonia and Asia. Simon Lewis stated, "Tropical forest trees are absorbing about 18% of the carbon dioxide added to the atmosphere each year from burning fossil fuels, substantially buffering the rate of change." [73]Forestry projects have faced increasing criticism over their integrity as offset or credit programs. A number of news stories from 2021 to 2023 criticized nature-based carbon offsets, the REDD+ program, and certification organizations. [74] [75] [76] In one case it was estimated that around 90% of rainforest offset credits of the Verified Carbon Standard are likely to be "phantom credits". [77]
Tree planting projects in particular have been problematic. Critics point to a number of concerns. Trees reach maturity over a course of many decades. It is difficult to guarantee how long the forest will last. It may suffer clearing, burning, or mismanagement. [78] [79] Some tree-planting projects introduce fast-growing invasive species. These end up damaging native forests and reducing biodiversity. [80] [81] [82] In response, some certification standards such as the Climate Community and Biodiversity Standard require multiple species plantings. [83] Tree planting in high latitude forests may have a net warming effect on the Earth's climate because tree cover absorbs sunlight thus creating a warming effect that balances out their absorption of carbon dioxide. [84] Tree-planting projects can also cause conflicts with local communities and Indigenous people if the project displaces or otherwise curtails their use of forest resources. [85] [86] [87]As a consequence of reduced evapotranspiration, precipitation is also reduced. This implies having a hotter and drier climate, and a longer dry season. [88] [89] This change in climate has drastic ecological and global impacts including increases in severity and frequency of fires, and disruption in the pollination process that will likely spread beyond the area of deforestation. [89] [88]
According to a study published in 2023, tropical deforestation has led to a significant decrease in the amount of observed precipitation. [90] By the year 2100, researchers anticipate that deforestation in the Congo will diminish regional precipitation levels by up to 8-10%. [90]
Deforestation changes the landscape and reflectivity of earth's surface, i.e. decreasing Albedo. This results in an increase in the absorption of light energy from the sun in the form of heat, enhancing global warming. [91]
The Bali Action Plan was developed in December 2007 in Bali, Indonesia. [99] [100] It is a direct result of the Kyoto Protocol of December 1997. [101] [102] One of the key elements of The Bali Action Plan involves a concerted effort by the member countries of the Kyoto Protocol to enact and create policy approaches that incentivize emissions reduction caused by deforestation and forest degradation in the developing world. [103] It emphasized the importance of sustainable forest management and conservation practices in mitigating climate change. This coupled with the increased attention to carbon emission stocks as a way to provide additional resource flows to the developing countries. [102]
The Billion Tree Campaign was launched in 2006 by the United Nations Environment Programme (UNEP) as a response to the challenges of climate change, as well as to a wider array of sustainability challenges, from water supply to biodiversity loss. [104] Its initial target was the planting of one billion trees in 2007. Only one year later in 2008, the campaign's objective was raised to 7 billion trees—a target to be met by the climate change conference that was held in Copenhagen, Denmark in December 2009. Three months before the conference, the 7 billion planted trees mark had been surpassed. In December 2011, after more than 12 billion trees had been planted, UNEP formally handed management of the program over to the not-for-profit Plant-for-the-Planet initiative, based in Munich, Germany. [105]
The Amazon Fund (in Portuguese: Fundo Amazônia) is an initiative created by the Brazilian Government and managed by the National Bank for Economic and Social Development (BNDES). It was established on 1 August 2008, with the aim of attracting donations for non-reimbursable investments in actions for the prevention, monitoring, and combat of deforestation, and for the promotion of conservation and sustainable use of the Amazon rainforest. [106] Additionally, the fund supports the development of monitoring and control systems for deforestation in the rest of Brazil and in other tropical countries. [106] [107] [108] [109] [110]
The fund is used in various areas, including the management of public forests and protected areas, control, monitoring and environmental enforcement, sustainable forest management, economic activities developed from the sustainable use of the forest, ecological and economic zoning, land planning and regularization, conservation and sustainable use of biodiversity, and the recovery of deforested areas. The projects supported by the fund must be aligned with applicable public policies and the guidelines and criteria, in addition to demonstrating their direct or indirect contribution to the reduction of deforestation and forest degradation. The actions foreseen in the projects must be coherent with the proposed objective, with the budget and with the schedule of its implementation. [111] Eligibility for accessing the Amazon Fund is determined based on compliance with several plans and criteria, including the PPCDAm (Action Plan for Prevention and Control of Deforestation in the Legal Amazon Region), ENREDD+ (National Strategy for REDD+), state plans for preventing and combating deforestation, and BNDES Operational Policies. Projects eligible for funding should directly or indirectly contribute to reducing deforestation in the Amazon. Various types of entities can submit projects for funding, including public administration bodies, NGOs, private companies, cooperatives, and research institutions. [109]
Until 2018, the fund received R$3.4 billion in donations, with the majority coming from Norway, followed by Germany and Petrobras. [112] [107] Since 2023, several countries announced contributions to the fund or interest in contributing, including Germany, Norway, the United States, the United Kingdom, Switzerland, Denmark, France, Spain, Japan and others. [113] [114] [115] [116] [117] [118] [119]A carbon sink is a natural or artificial carbon sequestration process that "removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". These sinks form an important part of the natural carbon cycle. An overarching term is carbon pool, which is all the places where carbon on Earth can be, i.e. the atmosphere, oceans, soil, florae, fossil fuel reservoirs and so forth. A carbon sink is a type of carbon pool that has the capability to take up more carbon from the atmosphere than it releases.
Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. About 31% of Earth's land surface is covered by forests at present. This is one-third less than the forest cover before the expansion of agriculture, with half of that loss occurring in the last century. Between 15 million to 18 million hectares of forest, an area the size of Bangladesh, are destroyed every year. On average 2,400 trees are cut down each minute. Estimates vary widely as to the extent of deforestation in the tropics. In 2019, nearly a third of the overall tree cover loss, or 3.8 million hectares, occurred within humid tropical primary forests. These are areas of mature rainforest that are especially important for biodiversity and carbon storage.
The Amazon rainforest, also called Amazon jungle or Amazonia, is a moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin encompasses 7,000,000 km2 (2,700,000 sq mi), of which 6,000,000 km2 (2,300,000 sq mi) are covered by the rainforest. This region includes territory belonging to nine nations and 3,344 indigenous territories.
Reforestation is the practice of restoring previously existing forests and woodlands that have been destroyed or damaged. The prior forest destruction might have happened through deforestation, clearcutting or wildfires. Three important purposes of reforestation programs are for harvesting of wood, for climate change mitigation, and for ecosystem and habitat restoration purposes. One method of reforestation is to establish tree plantations, also called plantation forests. They cover about 131 million ha worldwide, which is 3% of the global forest area and 45% of the total area of planted forests.
Resource depletion is the consumption of a resource faster than it can be replenished. Natural resources are commonly divided between renewable resources and non-renewable resources. The use of either of these forms of resources beyond their rate of replacement is considered to be resource depletion. The value of a resource is a direct result of its availability in nature and the cost of extracting the resource. The more a resource is depleted the more the value of the resource increases. There are several types of resource depletion, including but not limited to: mining for fossil fuels and minerals, deforestation, pollution or contamination of resources, wetland and ecosystem degradation, soil erosion, overconsumption, aquifer depletion, and the excessive or unnecessary use of resources. Resource depletion is most commonly used in reference to farming, fishing, mining, water usage, and the consumption of fossil fuels. Depletion of wildlife populations is called defaunation.
Tree planting is the process of transplanting tree seedlings, generally for forestry, land reclamation, or landscaping purposes. It differs from the transplantation of larger trees in arboriculture and from the lower-cost but slower and less reliable distribution of tree seeds. Trees contribute to their environment over long periods of time by improving air quality, climate amelioration, conserving water, preserving soil, and supporting wildlife. During the process of photosynthesis, trees take in carbon dioxide and produce oxygen.
Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes. Tropical rainforests are a type of tropical moist broadleaf forest, that includes the more extensive seasonal tropical forests. True rainforests usually occur in tropical rainforest climates where no dry season occurs; all months have an average precipitation of at least 60 mm (2.4 in). Seasonal tropical forests with tropical monsoon or savanna climates are sometimes included in the broader definition.
A secondary forest is a forest or woodland area which has regenerated through largely natural processes after human-caused disturbances, such as timber harvest or agriculture clearing, or equivalently disruptive natural phenomena. It is distinguished from an old-growth forest, which has not recently undergone such disruption, and complex early seral forest, as well as third-growth forests that result from harvest in second growth forests. Secondary forest regrowing after timber harvest differs from forest regrowing after natural disturbances such as fire, insect infestation, or windthrow because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. Secondary forests are notably different from primary forests in their composition and biodiversity; however, they may still be helpful in providing habitat for native species, preserving watersheds, and restoring connectivity between ecosystems.
Afforestation is the establishment of a forest or stand of trees in an area where there was no recent tree cover. There are three types of afforestation: natural regeneration, agroforestry and tree plantations. Afforestation has many benefits. In the context of climate change, afforestation can be helpful for climate change mitigation through the route of carbon sequestration. Afforestation can also improve the local climate through increased rainfall and by being a barrier against high winds. The additional trees can also prevent or reduce topsoil erosion, floods and landslides. Finally, additional trees can be a habitat for wildlife, and provide employment and wood products.
Carbon offsetting is a carbon trading mechanism that enables entities to compensate for offset greenhouse gas emissions by investing in projects that reduce, avoid, or remove emissions elsewhere. When an entity invests in a carbon offsetting program, it receives carbon credit or offset credit, which account for the net climate benefits that one entity brings to another. After certification by a government or independent certification body, credits can be traded between entities. One carbon credit represents a reduction, avoidance or removal of one metric tonne of carbon dioxide or its carbon dioxide-equivalent (CO2e).
Peat swamp forests are tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat. Large areas of these forests are being logged at high rates.
Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in limiting climate change by reducing the amount of carbon dioxide in the atmosphere. There are two main types of carbon sequestration: biologic and geologic.
Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, forest protection, and forest regulation. This includes management for timber, aesthetics, recreation, urban values, water, wildlife, inland and nearshore fisheries, wood products, plant genetic resources, and other forest resource values. Management objectives can be for conservation, utilisation, or a mixture of the two. Techniques include timber extraction, planting and replanting of different species, building and maintenance of roads and pathways through forests, and preventing fire.
Brazil once had the highest deforestation rate in the world and in 2005 still had the largest area of forest removed annually. Since 1970, over 700,000 square kilometres (270,000 sq mi) of the Amazon rainforest have been destroyed. In 2001, the Amazon was approximately 5,400,000 square kilometres (2,100,000 sq mi), which is only 87% of the Amazon's original size. According to official data, about 729,000 km² have already been deforested in the Amazon biome, which corresponds to 17% of the total. 300,000 km² have been deforested in the last 20 years.
The extensive and rapid clearing of forests (deforestation) within the borders of Nigeria has significant impacts on both local and global scales.
The Amazon rainforest, spanning an area of 3,000,000 km2, is the world's largest rainforest. It encompasses the largest and most biodiverse tropical rainforest on the planet, representing over half of all rainforests. The Amazon region includes the territories of nine nations, with Brazil containing the majority (60%), followed by Peru (13%), Colombia (10%), and smaller portions in Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana.
The Verified Carbon Standard (VCS), formerly the Voluntary Carbon Standard, is a standard for certifying carbon credits to offset emissions. VCS is administered by Verra, a 501(c)(3) organization. Verra is a certifier of voluntary carbon offsets. As of 2020 there were over 1,500 certified VCS projects covering energy, transport, waste, forestry, and other sectors. In 2021 Verra issued 300 MtCO2e worth of offset credits for 110 projects. There are also specific methodologies for REDD+ projects. Verra is a program of choice for most of the forest credits in the voluntary market, and almost all REDD+ projects.
Forest restoration is defined as "actions to re-instate ecological processes, which accelerate recovery of forest structure, ecological functioning and biodiversity levels towards those typical of climax forest", i.e. the end-stage of natural forest succession. Climax forests are relatively stable ecosystems that have developed the maximum biomass, structural complexity and species diversity that are possible within the limits imposed by climate and soil and without continued disturbance from humans. Climax forest is therefore the target ecosystem, which defines the ultimate aim of forest restoration. Since climate is a major factor that determines climax forest composition, global climate change may result in changing restoration aims. Additionally, the potential impacts of climate change on restoration goals must be taken into account, as changes in temperature and precipitation patterns may alter the composition and distribution of climax forests.
Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed. Restoration can be defined as "the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed." Mangroves can be found throughout coastal wetlands of tropical and subtropical environments. Mangroves provide essential ecosystem services such as water filtration, aquatic nurseries, medicinal materials, food, and lumber. Additionally, mangroves play a vital role in climate change mitigation through carbon sequestration and protection from coastal erosion, sea level rise, and storm surges. Mangrove habitat is declining due to human activities such as clearing land for industry and climate change. Mangrove restoration is critical as mangrove habitat continues to rapidly decline. Different methods have been used to restore mangrove habitat, such as looking at historical topography, or mass seed dispersal. Fostering the long-term success of mangrove restoration is attainable by involving local communities through stakeholder engagement.
Due to its geographical and natural diversity, Indonesia is one of the countries most susceptible to the impacts of climate change. This is supported by the fact that Jakarta has been listed as the world's most vulnerable city, regarding climate change. It is also a major contributor as of the countries that has contributed most to greenhouse gas emissions due to its high rate of deforestation and reliance on coal power.