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Ecology Team

Sweco UK

What is biodiversity, and why is it important?


Biodiversity is all around us. It is the rich variety of life across the globe, in a particular country or in any one area. It’s all the different living things, from bacteria and the smallest insect to the largest animal or tree. Biodiversity is not just restricted to rare species and threatened habitats; it includes the whole of the natural world. Biodiversity is also about people and how we share the environment with these other species.

All species work and live together in an ecosystem, like an intricate web, to maintain and support life on earth. Scientists have estimated that there are around 8.7 million species of plants and animals in existence. However, only 2.16 million species have been identified and described so far.

The phrase “biological diversity” was first used back in 1916 by botanist J. Arthur Harris. The contracted form ‘biodiversity’ itself was coined in 1985 and is now widely used across the world.

Biodiversity includes all levels, starting at the molecular level, then individual species, communities and populations, and finally entire ecosystems, such as rainforests or deserts. All of the Earth’s species work together to survive and maintain their ecosystems. We rely on ecosystems to provide us with food, clean water, many medicines and even the air we breathe. The Dasgupta Review describes nature as “our most precious asset” and a healthy biodiversity means a healthy and sustainable world.

Why is biodiversity important?

Biodiversity underpins every aspect of our lives and there has never been a more important time to work together to protect it. Here are five reasons why conserving (and enhancing) biodiversity is so important:

1. We depend on healthy ecosystems

In the 1980s, biological researchers Paul and Anne Ehrlich put forward the ‘rivet popper hypothesis’ which likened species in an ecosystem to rivets in a plane’s wing. Losing one rivet might not be a disaster, but each additional loss increases the likelihood of a serious problem.

Terrestrial, freshwater and marine ecosystems provide us with services that are essential for human wellbeing. These services include food, medicines, energy and materials. Ecosystems such as forests, grasslands, wetlands, mangrove swamps and the oceans regulate climate, natural hazards and extreme weather events, air quality, the quantity and quality of fresh water, pollination and seed dispersal, pests and diseases, soils, ocean acidification, and the creation and maintenance of habitats.

These ecosystems also provide us with physical and psychological experiences, learning and inspiration, and support identities and a sense of place. Ecosystems weakened by the loss of biodiversity are less likely to deliver those services, especially given the needs of an ever-growing human population.

2. Biodiverse ecosystems contribute to human health

Biodiversity has long contributed to advances in medical science. Plants are essential for medicines, with 25% of drugs used in modern medicine being derived from rainforest plants and 70% of cancer drugs being either natural products, or synthetic products inspired by nature. Many useful drugs have also been derived from fungi, including antibiotics, cholesterol biosynthesis inhibitors, antifungals and antivirals. Biodiversity loss reduces the availability of raw materials for drug discovery and therefore has direct effects on the discovery of potential medicines.

According to the World Health Organisation, there has been a 63% increase in the number of zoonotic outbreaks (infections originating in animals and then jumping to humans) in Africa in the decade from 2012-2022 compared to 2001-2011. This has been attributed to rapid population growth, creating increased demand for food derived from animals and increased urbanisation, in turn leading to encroachment of habitats and increased exposure to wild animals and the diseases they may carry. Similar effects have been cited as playing a major role in the global COVID-19 pandemic.

There is further evidence to suggest that biodiversity loss increases disease transmission. Research by Keesing et al (2010) found that more biodiverse ecosystems reduce disease transmission, as the population size of host species that would otherwise leave habitats and thus come into contact with humans is kept below threshold levels through increased predation. In addition, wholesale habitat loss such as deforestation accelerates global warming, which in turn may boost the spread of disease by allowing disease carriers, like mosquitoes, to extend their geographic ranges and infect new populations.

3. Biodiversity is essential in combating the climate crisis

Research by The Nature Conservancy and 15 other institutions, published in the Proceedings of the National Academy of Sciences, demonstrates that nature-based solutions provide up to 37% of the emission reductions needed by 2030 to keep global temperature increases under 2°C. According to the same research, nature’s mitigation potential is estimated at 11.3 billion tons of CO2e (CO2 and other greenhouse gases) in 2030.

This is the equivalent of stopping burning oil globally. Add to this that many natural ecosystems offer additional benefits, such as water filtration, flood buffering, improved soil health, protection of habitat and enhanced climate resilience, and it’s easy to see that protecting biodiversity is a key part of the solution to climate change.

4. Biodiversity is good for the economy

According to the World Economic Forum’s recent Nature Risk Rising Report, more than half of the world’s GDP ($44 trillion) is highly or moderately dependent on nature.

Around 75% of global food crops rely on animals and insects such as bees to pollinate them, but with many of these pollinator populations in decline, this could put more than $235 billion of agricultural products at risk.

The Economics of Ecosystems and Biodiversity (TEEB) initiative estimates that global sustainable business opportunities from investing in natural resources could be worth US$ 2 to 6 trillion by 2050.

Millions of people also depend on nature and species for their day-to-day livelihoods. This is particularly true for struggling communities in developing countries, who often turn to high-biodiversity ecosystems as their source of food, fuel, medicines and other products made from natural materials for their own use and as sources of income. Nature-related tourism is also a significant income generator.

5. Biodiversity is an integral part of culture and identity

Species are frequently integral to religious, cultural and national identities and this interaction has given rise to the use of terms like ‘biocultural’ and ‘biocultural diversity’. ‘Biocultural’ is an adjective which implies a state resulting from the interaction of people and nature at a given time and in a given place. ‘Biocultural diversity’ can be defined as a dynamic, place-based, aspect of nature arising from links and feedbacks between human cultural diversity and biological diversity. Essentially, it describes how the culture of indigenous peoples has developed through strong links with the particular habitats and species that exist around them.

The strong links between biodiversity, culture and identity are readily evidenced by the fact that all major religions include elements of nature and 231 species are formally used as national symbols in 142 countries.

Biodiversity is also integral to the wellbeing of communities through providing opportunities for recreation and psychological experiences and is an important source of inspiration for artists and writers, who collectively add to their respective cultures.

Threats to biodiversity

According to the World Wildlife Fund (WWF) “The major direct driving forces for the degradation of terrestrial, freshwater and marine systems are changes in land and sea use, the overexploitation of plants and animals, climate change, pollution and invasive alien species. These direct drivers of biodiversity loss, and the degradation of ecosystems and their services, stem from increasing demands for energy, food and other materials because of rapid economic growth, increases in population, international trade, and choices of technology, especially over the last 50 years.”

Let’s look at each of these five threats in turn:

1. Changes in land and sea use

Land use change is one of the biggest impacts that humans have had on the global environment. Converting wild spaces to farmland or development destroys vital ecosystems, pushes wild animals to extinction, and threatens global biodiversity. More than a third of the world’s land surface and nearly 75% of freshwater resources are now devoted to crop or livestock production.

The Dasgupta review presents some disturbing figures: “Today, we ourselves, together with the livestock we rear for food, constitute 96% of the mass of all mammals on the planet. Only 4% is everything else – from elephants to badgers, from moose to monkeys. And 70% of all birds alive at this moment are poultry – mostly chickens for us to eat. We are destroying biodiversity, the very characteristic that until recently enabled the natural world to flourish so abundantly. If we continue this damage, whole ecosystems will collapse. That is now a real risk.”

According to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services there has been a doubling of urban area since 1992. This unprecedented expansion of infrastructure, linked to growing population and consumption, has come mostly at the expense of forests, wetlands and grasslands, all of which are important carbon ‘sinks’, absorbing more carbon than they release. Clearing vegetation, draining wetlands, cutting down trees, and ploughing soil to convert wild areas into farmland releases stored carbon into the atmosphere, mainly in the form of carbon dioxide, and reduces the capacity of the land to capture and store human-caused carbon emissions.

Changing how we use terrestrial and marine environments also removes other natural processes that directly benefit human society, including the capture of excess storm water by wetlands, the prevention of coastal erosion by mangroves, and the cooling effect of woodland.

Changes in land and sea use therefore have far-reaching effects beyond simply the loss of biodiversity as a result of habitat loss.

2. Overexploitation of natural resources

In conservation biology, the term overexploitation is typically used in the context of human economic activity that involves the taking of biological resources, or organisms, in larger numbers than their populations can withstand.

Overexploitation falls into four main categories: overfishing/overhunting for food; overhunting for trophies or perceived medicinal value; overhunting to supply the pet trade; and overexploitation of natural materials (minerals, metals etc).

According to the United Nations Food and Agriculture Organization (FAO), the world’s authority on fisheries, 34.2% of fisheries are overfished. Overfishing can lead to fish stock collapse, which can take many decades to recover. This threatens livelihoods, communities and food security. Furthermore, overfishing can also remove keystone species from ecosystems, resulting in ecosystems collapse. Even if that doesn’t happen, major reductions in the numbers of a species in a given locale can place pressure on food systems elsewhere, as predators are forced to seek out new hunting grounds.

Today illegal hunting to supply the demand for so-called traditional medicine still threatens many species, in particular large mammals such as tigers, rhinoceros, bears, and primates, whose body parts are highly valued in some parts of the world.

Many birds, reptiles, amphibians, fish and invertebrates are collected, often illegally and at unsustainable levels, to supply the international pet trade. Certain types of plants, such as orchids, have also been harvested by collectors to the point that they are now endangered and laws have had to be put in place to protect them.

3. The climate crisis

The climate crisis is having a major effect globally. Rising temperatures are affecting biodiversity, while changing rainfall patterns, extreme weather events, and ocean acidification are putting pressure on species already threatened by other human activities.

If current rates of warming continue, by 2030 global temperatures could increase by more than 1.5°C compared to before the industrial revolution. A major impact of climate change on biodiversity is the increase in the intensity and frequency of fires, storms and periods of drought.

Rising global temperatures also have the potential to alter ecosystems over longer periods by altering the species assemblage, favouring those able to adapt to a warmer climate.

Rising temperatures in the oceans affect marine organisms. Corals are particularly vulnerable to rising temperatures and ocean acidification can make it harder for shellfish and corals in the upper ocean to form shells and hard skeletons. About 50% of warmwater corals have already been lost due to a variety of causes. A warming of 1.5°C will result in a loss of 70-90% of warm-water corals, and a 2°C warming will result in a loss of more than 99%.

4. Pollution

Air and water pollution have far-reaching negative effects on biodiversity. Pollution from burning fossil fuels can remain in the air as particle pollutants or fall to the ground as acid rain. Acid rain, which is primarily composed of sulphuric and nitric acid, causes acidification of lakes, streams and sensitive forest soils, and contributes to slower forest growth and tree damage at high elevations.

Chemical pollutants such as pesticides and herbicides leach into soils and watersheds. Some fish species, such as salmonids, require small freshwater streams to spawn. Polluted streams result in the abandonment of traditional spawning areas and ultimately in the loss of salmon populations.

Phosphorus is a leading cause of water pollution, as the runoff from fertiliser use in fields produces an excess of nutrients that upset the natural balance of rivers and ponds, leading to algae blooms that harm fish and plants.

Species vary in their sensitivity to pollution, however many species are vulnerable to the indirect effects of pollution through the concentration of toxic chemicals in top predators of food chains and disruption of predator-prey interactions.

5. Invasive species

Invasive species are species outside their normal ranges that have a negative impact on other organisms or environments. They tend to have escaped controlling species (which might be predators, herbivores or parasites) in their normal ranges, which would have otherwise limited their survival, and they are often well suited to their new environment.

Invasive species have devastating impacts on native fauna and flora, causing the decline or even extinctions of native species, and negatively affecting ecosystems. They reproduce rapidly, out-compete native species for food, water and space, and are one of the main causes of global biodiversity loss. Species are introduced either deliberately through, for example, fish farming, the pet trade, horticulture, biocontrol; or unintentionally, through such means as land and water transportation, travel, and scientific research.

The global economy, with increased transport of goods and travels, has facilitated the movement of live species over long distances and beyond natural boundaries. While only a small percentage of transported organisms become invasive, they have a huge impact on the health of plants, animals and even humans, threatening lives and affecting food security and ecosystem health.

The negative impact of invasive species on the economy costs countries billions of dollars in losses to agricultural production and some trillion dollars of environmental cost worldwide annually.

Since the 17th century, invasive species have contributed to 40% of all known animal extinctions.

Sweco’s ecology consultants and biodiversity experts can manage all ecological aspects of a project – identifying pragmatic nature-based solutions to help protect and enhance biodiversity and the wider natural environment. If you need support with any aspect of biodiversity protection, conservation or enhancement please contact us below.