Biodiversity Loss
Biological diversity — or biodiversity — is the variety of life on Earth, in all its forms, from genes and bacteria to entire ecosystems such as forests or coral reefs. The biodiversity we see today is the result of 4.5 billion years of evolution, increasingly influenced by humans.
Biodiversity forms the web of life that we depend on for so many things – food, water, medicine, a stable climate, economic growth, among others. Over half of global GDP is dependent on nature. More than 1 billion people rely on forests for their livelihoods. And land and the ocean absorb more than half of all carbon emissions.
But nature is in crisis. Up to one million species are threatened with extinction, many within decades. Irreplaceable ecosystems like parts of the Amazon rainforest are turning from carbon sinks into carbon sources due to deforestation. And 85 per cent of wetlands, such as salt marshes and mangrove swamps which absorb large amounts of carbon, have disappeared.
- This refers to the variation in genes within and between populations of a species, which is the foundation for adaptation and evolution.
- This focuses on the variety of different species in a given area, including their abundance and distribution.
- This encompasses the variety of ecosystems, encompassing different habitats, communities, and the interactions between them.
How is climate change affecting biodiversity?
The main driver of biodiversity loss remains humans’ use of land – primarily for food production. Human activity has already altered over 70 per cent of all ice-free land. When land is converted for agriculture, some animal and plant species may lose their habitat and face extinction.
But climate change is playing an increasingly important role in the decline of biodiversity. Climate change has altered marine, terrestrial, and freshwater ecosystems around the world. It has caused the loss of local species, increased diseases, and driven mass mortality of plants and animals, resulting in the first climate-driven extinctions.
On land, higher temperatures have forced animals and plants to move to higher elevations or higher latitudes, many moving towards the Earth’s poles, with far-reaching consequences for ecosystems. The risk of species extinction increases with every degree of warming.
In the ocean, rising temperatures increase the risk of irreversible loss of marine and coastal ecosystems. For instance, 14 per cent of the coral from the world’s coral reefs was lost between 2009 and 2018, mostly due to climate change, and further warming threatens to destroy almost all remaining reefs.
Overall, climate change affects the health of ecosystems, influencing shifts in the distribution of plants, viruses, animals, and even human settlements. This can create increased opportunities for animals to spread diseases and for viruses to spill over to humans. Human health can also be affected by reduced ecosystem services, such as the loss of food, medicine and livelihoods provided by nature.
Why is biodiversity essential for limiting climate change?
When human activities produce greenhouse gases, around half of the emissions remain in the atmosphere, while the other half is absorbed by the land and ocean. These ecosystems – and the biodiversity they contain – are natural carbon sinks, providing so-called nature-based solutions to climate change.
Protecting, managing, and restoring forests, for example, offers roughly two-thirds of the total mitigation potential of all nature-based solutions. Despite massive and ongoing losses, forests still cover more than 30 per cent of the planet’s land.
Peatlands – wetlands such as marshes and swamps – cover only 3 per cent of the world’s land, but they store twice as much carbon as all the forests. Preserving and restoring peatlands means keeping them wet so the carbon doesn’t oxidize and float off into the atmosphere.
Ocean habitats such as seagrasses and mangroves can also sequester carbon dioxide from the atmosphere at rates up to four times higher than terrestrial forests can. Their ability to capture and store carbon make mangroves highly valuable in the fight against climate change.
Conserving and restoring natural spaces, both on land and in the water, is essential for limiting carbon emissions and adapting to an already changing climate. About one-third of the greenhouse gas emissions reductions needed in the next decade could be achieved by improving nature’s ability to absorb emissions.
Is the UN tackling climate and biodiversity together?
Governments deal with climate change and biodiversity through two different international agreements – the UN Framework Convention on Climate Change (UNFCCC) and the UN Convention on Biological Diversity (CBD), both established at the 1992 Rio Earth Summit.
Similar to the historic Paris Agreement made in 2015 under the UNFCCC, parties to the Biodiversity Convention in December 2022 adopted an agreement for nature, known as the Kunming-Montreal Global Biodiversity Framework, which succeeds the Aichi Biodiversity Targets adopted in 2010.
The framework includes wide-ranging steps to tackle the causes of biodiversity loss worldwide, including climate change and pollution, and should work in synergy with the Paris Agreement.
“Delivering on the framework will contribute to the climate agenda, while full delivery of the Paris Agreement is needed to allow the framework to succeed,” said Inger Andersen, the head of the UN Environment Programme. “We can’t work in isolation if we are to end the triple planetary crises.”
At COP15 in December 2022, governments met in Montreal, Canada, and agreed on the new framework to address biodiversity loss, restore ecosystems and protect the rights of Indigenous Peoples, who suffer disproportionately from biodiversity loss.
“Indigenous Peoples, people of African descent, and local communities are guardians of our nature,” said the UN Secretary-General. “Their traditional knowledge is a living library of biodiversity conservation. They must be protected. And they must be part of every biodiversity conversation.”
At the meeting, the parties also adopted the Multilateral Mechanism on the fair and equitable sharing of benefits arising from the use of digital sequence information on genetic resources.
In November 2024, at COP16 in Cali, Colombia, countries reached a historic consensus, including on the functioning of a fund, known as the Cali Fund, aimed at mobilizing new streams of funding for biodiversity action worldwide and boosting the implementation of the framework.
The Cali Fund was launched in Rome, Italy, in February 2025 on the margins of the resumed session of COP16. It is set to receive contributions from private sector entities making commercial use of data from genetic resources, with the aim to raise an additional $200 billion each year by 2030 to close the global biodiversity finance gap.
“Those profiting from nature cannot treat it like a free, infinite resource. They must step up and contribute to its protection and restoration,” the UN Secretary-General said.
Causes of biodiversity loss
Climate Change
Pollution
Destruction of habitats
Invasive alien species
Overexploitation of the natural environment
The overexploitation of natural resources, that is, their consumption at a speed greater than that of their natural regeneration, has an obvious impact on the planet's flora and fauna.
Biodiversity loss has bad effects on the functioning of ecosystems. This in turn affects humans,[45] because affected ecosystems can no longer provide the same quality of ecosystem services, such as crop pollination, cleaning air and water, decomposing waste, and providing forest products as well as areas for recreation and tourism.[122]
Two key statements of a 2012 comprehensive review of the previous 20 years of research include:[45]
- "There is now unequivocal evidence that biodiversity loss reduces the efficiency by which ecological communities capture biologically essential resources, produce biomass, decompose and recycle biologically essential nutrients"; and
- "Impacts of diversity loss on ecological processes might be sufficiently large to rival the impacts of many other global drivers of environmental change"
Permanent global species loss (extinction) is a more dramatic phenomenon than regional changes in species composition. But even minor changes from a healthy stable state can have a dramatic influence on the food web and the food chain, because reductions in one species can adversely affect the entire chain (coextinction). This can lead to an overall reduction in biodiversity, unless alternative stable states of the ecosystem are possible.[183]
For example, a study on grasslands used manipulated grassland plant diversity and found that ecosystems with higher biodiversity show more resistance of their productivity to climate extremes.[184]
On food and agriculture
In 2019, the UN's Food and Agriculture Organization (FAO) produced its first report on The State of the World's Biodiversity for Food and Agriculture. It warned that "Many key components of biodiversity for food and agriculture at genetic, species and ecosystem levels are in decline."[185][186]
The report also said, "Many of the drivers that have negative impacts on BFA (biodiversity for food and agriculture), including overexploitation, overharvesting, pollution, overuse of external inputs, and changes in land and water management, are at least partially caused by inappropriate agricultural practices"[187]: 6 and "transition to intensive production of a reduced number of species, breeds and varieties, remain major drivers of loss of BFA and ecosystem services."[187]: 6
To reduce biodiversity loss related to agricultural practices, FAO encourages the use of "biodiversity-friendly management practices in crop and livestock production, forestry, fisheries and aquaculture".[187]: 13
On health and medicines
The WHO has analyzed how biodiversity and human health are connected: "Biodiversity and human health, and the respective policies and activities, are interlinked in various ways. First, biodiversity gives rise to health benefits. For example, the variety of species and genotypes provide nutrients and medicines."[188] The ongoing drivers and effects of biodiversity loss has the potential to lead to future zoonotic disease outbreaks like the COVID-19 pandemic.[189]
Medicinal and aromatic plants are widely used in traditional medicine as well as in cosmetic and food industries.[188]: 12 The WHO estimated in 2015 that about "60,000 species are used for their medicinal, nutritional and aromatic properties".[188]: 12 There is a global trade in plants for medicinal purposes.[188]: 12
Biodiversity contributes to the development of pharmaceuticals. A significant proportion of medicines are derived from natural products, either directly or indirectly. Many of these natural products come from marine ecosystems.[190] However, unregulated and inappropriate over-harvesting (bioprospecting) could potentially lead to overexploitation, ecosystem degradation and loss of biodiversity.[191][192] Users and traders harvest plants for traditional medicine either by planting them or by collecting them in the wild. In both cases, sustainable medicinal resource management is important.[188]: 13
Solutions
Most scientists agree that the most effective way to thwart further invasions of exotic species and contribute to the protection of biodiversity is to prevent the new species introductions in the first place. Although international trade and travel continue to provide opportunities for “exotic stowaways,” ecologists note that governments and citizens have the power to reduce the risk of the release of such organisms into new environments. Closer inspection of pallets, containers, and other international shipping materials at ports of departure and arrival could uncover insects, seeds, and other stowaway organisms. Some ecologists and government officials have advocated for tougher fines and the threat of incarceration to deter buyers, sellers, and transporters of illegal exotic pets.Increased controls at ports will not work for invasive species already established, however. In addition, climate change may afford some invasive species new opportunities. The continued rise in atmospheric carbon dioxide concentrations has been shown to fuel photosynthesis (and thus growth and reproductive success) in some plants. For botanical invaders, such as kudzu and another ornamental plant from Asia called Oriental bittersweet (Celastrus orbiculatus), and insect invaders, as well the diseases they may carry, climate warming associated with increases in atmospheric carbon will likely allow these species to gain footholds in habitats formerly off-limits to them. To prevent such scenarios from playing out, some ecologists have called for aggressive monitoring and eradication programs. Indeed, many habitat restoration efforts have dual priorities of replanting and reintroducing native species while simultaneously removing invasive species. Ecologists argue that these actions, combined with effective education programs that give citizens the knowledge and resources to deal with exotic plants, animals, and other species in their regions, will prevent the further loss of biodiversity caused by invasive species.
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