Biodiversity loss is one of the most pressing global challenges, impacting plants and animals, food production, and the variety of life that sustains life on earth.
Human activities, such as deforestation, pollution, and overfishing, are driving the rapid decline of plant and animal species, with up to a million species at risk. This loss disrupts ecosystems and threatens the natural resources vital for over a billion people.
As habitats are destroyed and human activity accelerates, the balance of oceans and terrestrial environments is disturbed, affecting everything from natural resources to global food production. Urgent action is needed to preserve life on Earth.
What is Biodiversity Loss?
Biodiversity is the variety of living things on the planet, such as the trillions of genes, the billions of species, the thousands of ecosystems, and the countless ecological functions they all perform.
Together, this intricate web of life sustains our planet, and the ongoing biodiversity loss in the current “6th mass extinction” underscores the urgent need to protect and restore it before more irreversible damage is done.
While this “extinction” is driven largely by biodiversity loss, the 5 before it were not:
The first was from rapid global cooling and glaciation, the second from ocean anoxia and cooling likely triggered by volcanic activity, the third from massive volcanic eruptions causing global warming and ocean acidification, the fourth from volcanic activity linked to the breakup of Pangaea, and the fifth from a massive asteroid impact resulting in climate disruption.
While the first 5 were nature-led, the 6th is entirely human-led, and happening 100-1,000 times faster than the natural rates. This is due to habitat destruction, climate change, pollution, overexploitation, invasive species—and with biodiversity loss at its core.
Habitat Destruction
Many human activities such as deforestation involve the immediate removal and wiping out of habitats, including various micro-habitats and microclimates. Animal species can depend on single trees for their nesting, shelter or food resources, however deforestation goes all the way to hundreds of thousands of hectares removed in one go.
Trees maintain healthy soils, and when removed, soils become eroded, with lower qualities of remaining habitats for animals and plants.
Remaining habitats can be left fragmented, with fewer habitats in isolated patches, separated by dangerous barriers such as busy roads with traffic that some fauna will struggle to safely cross.
Habitat Fragmentation
A prime example of habitat fragmentation today is the Amazon Rainforest, now a patchwork of forests, roads, and agricultural land, once an unbroken expanse of one of the world’s most biodiverse ecosystems.
The most common causes are roads—convenience for humans at the expense of populations that may have very well depended on a stream on one side for their water, but a hunting ground or nesting site on the other side for their food, now forced to cross a dangerous road to maintain their livelihoods.
In recognition of this, wildlife corridors are becoming more popular. Natural or human-made, they provide spaces for nature that connect ranges of habitats to ensure safe passages between landscapes.
Climate Change
Biodiversity loss causes climate change by increasing greenhouse gas emissions, ocean changes (rising temperatures and acidification), and disrupting carbon sinks such as forests, wetlands, and peatlands.
From decades of unsustainable practices on a global scale, weather patterns become unpredictable, including rising global temperatures, disruptions in weather cycles, and extreme weather events.
For example, Typhoon Haiyan in 2013 was exacerbated by the destruction of mangrove forests and coastal wetlands from ocean warming and deforestation. These habitats usually absorb storm surges and reduce coastal erosion.
Another example was the Australian bushfires. The increased temperatures, prolonged droughts, and destruction of vegetation that was fire-resistant—such as native eucalyptus forests adapted to periodic fires—intensely worsened the event. Due to a range of factors including biodiversity loss, the fires roared from September 2019 to March 2020.
Global efforts are underway to combat climate change, most prominently the Paris Agreement.
Overexploitation
Humans have exploited nature from the start, but technology really expedited the process. Simple farming was once fine, but satellite-guided, AI-powered, 50-ton industrial harvesters that can strip an entire field in minutes are not.
This is where overexploitation comes in—the resources are extracted faster than they can naturally replenish.
This is seen most in forests, fisheries, wildlife, freshwater resources, and medicinal plants, such as the Pacific yew, which has been overharvested for its bark to produce the cancer drug Taxol.
To combat this, sustainable harvesting practices, stricter conservation policies, and the development of synthetic or alternative materials are being implemented.
Pollution (Air, Water, Soil)
Biodiversity loss causes pollution in several ways.
Air pollution comes from deforestation, habitat destruction, and loss of vegetation that filters pollutants. Water pollution is driven by wetland destruction and the loss of aquatic species that regulate water quality. Soil pollution stems from agricultural runoff, chemical fertilisers, and industrial waste contaminating degraded ecosystems.
With tech advancing, pollution is rising, but sustainable innovations offer hope for reduction.
Invasive Species
Biodiversity loss equates to habitat loss, which can wipe out the species depending on them for their livelihoods. Numbers of species lower as displaced animals that cannot survive outside of their natural habitats die.
With populations decreasing, some even taken into extinction, species diversity is lost and ecosystems lose foundational structure. This makes them heavily susceptible to external harm like climate change.
With changed environments inhabitable to native species, the remaining animals may easily be outcompeted. Invasive alien species can easily displace or prey on the native species, rupturing ecosystem stabilisation.
Deforestation
Deforestation is when trees and forests are cut down at a small or large scale for the purposes of agriculture, logging, urbanisation, infrastructure development, resource extraction or other needs. It’s globally recognised as extremely harmful to the environment, as well as displacing indigenous communities and robbing the livelihoods of forest-dependent people.
Forests, woods and trees are some of the strongest carbon dioxide sinks on the planet, and wiping them out causes a huge increase in CO2 levels, enhancing global warming and enhancing disruptions in weather patterns. Deforestation obstructs water cycles, leading to further unseen weather changes.
Reforestation is a mitigation strategy, but at times cannot compete. Sustainable forestry practices and conservation programs have administered widespread global efforts to combat deforestation and aid the environment.
Agricultural Expansion
Since the Industrial Revolution, one of the most prominent reasons for biodiversity loss has been agricultural expansion. With demands for food and biofuels increasing as biodiversity levels decline, needs for finite sources are lowering. This means that forests are cleared to make room for cropland for agricultural purposes.
Agriculture is one of the main causes of forest conversion in the Amazon. This causes erosion in soil and river siltation, harmful for biodiversity and nature. The chemicals used for agriculture such as those in pesticides and fertilisers pollute water and degrade aquatic habitats.
Urbanisation
Urbanisation is a primary driver of biodiversity loss due to the rapid conversions of a natural habitat into a built environment, disrupting ecosystems and displacing wildlife.
As a result, green areas succumb to habitat fragmentation, polluted nature, non-native species introduction, heat island effects, and losses of genetic diversity. These can pose significant challenges for nature, such as busy roads, human disturbance, and various types of pollution.
The effects of urbanisation on nature are most visible in areas such as Shanghai—30 years ago, it was a landscape of wetlands, farmland, and forests, and today it’s a dense megacity with limited natural spaces. This is happening similarly in Jakarta or São Paulo, where urban sprawl has rapidly replaced forests, wetlands, and other crucial ecosystems.
Land Use Change
Once the planet’s sole land use was biodiversity—now only around 25% left is nature. The most common land use changes are agriculture, development, transport, or resource extraction. This allows economies to grow but means that natural ecosystems are continuously shrinking.
Roads or bridges that cross through forests, for instance, create habitat barriers for local wildlife, lowering species diversity and leaving populations vulnerable. Forests are wiped out for infrastructure, cities grow and develop, and the strain on forest resources cyclically worsens. This leads to tourism development, especially in areas with beautiful forests, resulting in increased infrastructure from hotels or resorts.
Land use change will nearly always be from natural ecosystems to human-modified landscapes, ultimately meaning that biodiversity is displaced, degraded, or lost in the process.
Resource Depletion
When habitats are lost, crucial species such as pollinators or soil microorganisms are lost. This leads to less production of crops like nuts, fruits, and vegetables. Without this in the human diet, there would be widespread malnutrition, risk of disease, premature death, and weakened immune systems.
Vegetables pollinated by wind, such as grains and rice are less at threat from biodiversity loss, however would still be at risk from climate change like soil degradation, instability, or water scarcity.
Moreover, without sufficient nutrient cycling and soil structures, all agricultural productivity declines, leading to less crop variety and resilience to disease. Without natural pest controls such as ladybirds or birds of prey, more crop diseases and pests could significantly harm yields.
Climate Variability (Natural)
Climate variability is when there are short (e.g., seasonal temperature fluctuations) to medium (e.g., multi-year droughts) changes in climate patterns. Prime examples are El Niño and La Niña events, monsoon variations, and prolonged droughts.
These are caused by natural factors, such as solar cycles or ocean currents. These climate pattern changes can cause biodiversity loss by altering habitats, disrupting food availability, and forcing species to migrate or adapt faster than they can naturally.
Overfishing
Fishing isn’t just removing masses of fish from their natural environments—it’s impacting entire food webs, causing shifts in ecosystems, reducing predator populations, and altering marine biodiversity. Overfishing is synonymous with biodiversity loss, leading to species declines, habitat destruction, and ecosystem imbalances.
With declines in fish populations, many communities lose their only protein source. In West Africa, for instance, depleted fish stocks have negatively impacted the livelihoods of millions of people, from losses of jobs to people’s inability to afford rising fish prices.
Amazingly, many communities have taken charge of this, introducing managed fishing zones with regulated fish stocks and initiatives like the West Africa Regional Fisheries Program (WARFP), which curbs illegal fishing and encourages sustainability.
International Trade in Endangered Species (CITES) are working to combat wildlife trafficking and protect vulnerable species.
Water Scarcity
Wetland habitats are frequently targeted for drainage, agriculture, and urban development. When biodiversity is lost and ecosystem services are threatened, water sources are threatened.
The more biodiversity (pigeons, great lions, or even just bacteria), the more ecosystem services. These encompass any positive benefit from wildlife or ecosystems provided to people, involving water purification, flood regulation, and climate moderation, affecting water scarcity.
Species that manage nutrients reduce the risk of algal blooms, which suffocate water life. Resilient ecosystems adapt to environmental changes, recover from disturbances, and sustain life.
They in turn reward us with clean air, fresh water, and abundant food—and their weakening threatens us with pollution, climate instability, and scarcity of natural resources.
Soil Erosion
In agriculture, soil erosion occurs when tilling breaks up the soil, bare fields are exposed to the elements after harvest, rain and wind carries the topsoil away, and the soil’s nutrients and organic matter are lost. The less-productive land, then, becomes dependent on chemical fertilisers to produce crops.
Regenerative farming uses cover cropping as a solution—protecting the soil and maintaining its fertility by planting (typically) non-harvested crops with deep roots holding the soil in place.
Beyond this, soil erosion occurs when biodiversity is lost for deforestation or urban expansion. Loss of vegetative cover, for example, leaves soils exposed to eroding winds, or removes root systems that would otherwise bind the soil together, preventing it from being washed away by rain or blown away by wind.
Disease and Pathogens
Disease and pathogens are major drivers of biodiversity loss, as they can rapidly spread through populations, weaken species, and disrupt entire ecosystems.
With losses of habitat, wildlife is brought closer to humans, increasing the spread of zoonotic diseases.
Furthermore, invasive species can introduce new pathogens that native species have no immunity against, leading to mass die-offs.
Illegal Wildlife Trade
The illegal wildlife trade is worth up to $20 billion annually and operates across more than 150 countries.
With the most popular animals being pangolins from Africa and Asia, tigers from South and Southeast Asia, and parrots from South America, they are overexploited and plucked from their natural habitats.
Thankfully, global conservation efforts, stricter law enforcement, and initiatives like the Convention on
Ocean Acidification
Ocean acidification is happening because of climate change and global warming. It means that excess carbon dioxide (CO₂) is absorbed by the ocean, lowering pH levels and making seawater more acidic.
The coral reefs turning white, being weakened and dissolved by rising acidity and warmer temperatures, are a poignant visual reminder. This also leads to the loss of marine food sources such as shellfish and plankton, ecosystem imbalances causing declines in fish populations, and disruptions to entire marine food webs.
Efforts are underway that have been focused on reducing CO₂ emissions to slow ocean acidification by transitioning to renewable energy, protecting marine ecosystems, and reducing pollution.
Nutrient Overload (Eutrophication)
When biodiversity is lost in situations such as wetland destruction or deforestation, nutrient overload can occur. This—eutrophication—means that there has been a buildup of nutrients.
In the Gulf of Mexico, for instance, nutrient overload is occurring due to massive agricultural runoff from fertilisers and animal waste. As a result, there are harmful algal blooms that deplete oxygen levels, creating “dead zones” where marine life cannot survive. Local fisheries are disrupted, with reduced shrimp and fish populations, impacting many coastal communities and contaminating seafood and water.
With biodiversity lost, declines in filter-feeding organisms (such as oysters and mussels) and aquatic plants (such as seagrasses and reeds) can cause nutrient overload on a major scale.
Fragmented or Altered Ecosystem Services
‘Ecosystem services’ encompass any positive benefit from wildlife or ecosystems provided to people. This could be climate regulation, water purification, soil fertility, food and fuel, or pollination.
Without natural water filters such as in forests and wetlands, pollutants could flow in excess into waters, further harming aquatic life and destabilising soils. Without species managing nutrients, nutrient overload can cause algal blooms, which float on top of a water surface and suffocate everything beneath it.
With pest populations not controlled by predators like birds, amphibians and bats, farmers are left to rely on harmful chemical pesticides to manage agriculture, encouraging short-term yields but doing long-term lasting damage to the environment.
More Information
https://researchbriefings.files.parliament.uk/documents/CDP-2024-0101/CDP-2024-0101.pdf