Biodiversity means “variety of living things”, so loss of biodiversity describes any reduction in this variety, or the extinction of any species. Although new plants and animals are being discovered all the time, thus ‘compensating’ to some extent for those who become extinct, we do not know enough about the overall numbers of species to talk about net losses or net gains.
In our earlier article “Biodiversity: What is it and why is it important?“, we said that biodiversity is as important as the air we breathe, the water we drink and the food we eat. Because the availability of these critical necessities – oxygen, freshwater and food – depends ultimately on plants and animals. For example, without plants, human life would be impossible.
But without insects and animals to pollinate them and spread their seeds, plants would cease to thrive. What’s more, the cycle of life – during which plants and animals recycle chemicals and nutrients into the air and soil when they’re alive and also when they die – examples include the water cycle and the carbon cycle – makes the biosphere a self-supporting and self-regulating system. In short, any significant loss of biodiversity would have serious knock-on effects across the globe. Without its amazing variety of living things, our planet would quickly become uninhabitable.
What Causes Loss of Biodiversity?
We do. That’s right, we humans are the culprits. We are the biggest threat to animals and plants and the biomes in which they live. We are the new super-predator.
We poach and kill animals for their body parts
In Africa, poachers kill an average of 96 elephants each day for their ivory. (Source: Wildlife Conservation Society.) Over the same 24-hour period, they kill an average of three rhinos. (Source: One Green Planet.) Each year, we kill more than 100 million sharks to make shark-fin soup. (Source: World Wildlife Fund.)
We tear down their forest habitats
As many as 70 percent of all plant and animal species live in forests. Up to 28,000 species can disappear by 2045 due to deforestation and degradation of habitat. (Source: The World Counts.) For more, see: Effects of Deforestation.
We introduce invasive species of plants and animals that wipe out local species
Over 40 percent of threatened or endangered species are at risk to due invasive species. (Source: The National Wildlife Federation.)
We pollute the oceans with plastics
Plastic pollution, which has increased tenfold since 1980, has been found in all parts of the ocean, from shallow coastal waters down to the bottom of the 36,000-foot Mariana Trench. (Source: IPBES 2019 Global Assessment Report.) An estimated 90 million tonnes of plastic – including 5 trillion pieces of microplastic – enter the oceans each year. According to recent studies that examined marine species for pollution, pieces of plastic were found in marine turtles (100 percent), whales (59 percent), seals (36 percent) and seabirds (40 percent). For more about the damage we’re causing to marine ecosystems, see: Effects of Global Warming on Oceans.
We pollute the oceans with heavy metals and other chemicals
Around 300-400 million tons of heavy metals, solvents, and other toxic slurry from industrial plants are dumped annually into the world’s oceans. (Source: IPBES 2019 Global Assessment Report.) And until the practice was legally banned in 1994, much of our nuclear waste was dumped in the ocean, as well.
We overfish, exhausting fish stocks around the world
Almost 90 percent of the world’s marine fish stocks are now fully exploited, over-exploited or depleted. (Source: United Nations Conference on Trade and Development. UNCTAD)
We devastate habitats and contaminate groundwater by mining and drilling
The mining of fossil fuels has resulted in massive fish kills in the Red River, New Mexico, the Sacramento River, California, and the Alamosa River, Colorado, among several others. In addition, thousands of migratory birds have died from poisoning after landing at mine pit lakes in California, Nevada and Ontario. Acid mine drainage is the main source of water pollution from mining. It leaches toxic metals, like arsenic, cadmium, chromium, lead, from tailings, and can continue polluting for decades after mining operations cease. (Source: Alaskans for Responsible Mining.) For more details, see: Environmental Effects of Fossil Fuels.
We burn fossil fuels whose CO2 emissions cause climate change
Climate change is a major driver of both the extinction and emergence of new species. An excellent example of this is the Carboniferous rainforest collapse, which happened around 305 million years ago. This climate-induced collapse led to the extinction of many plant and animal species, and also contributed to the evolution of reptiles. 1 See also: 7 Effects of Climate Change on Plants and Trees.
WANT TO MINIMIZE THE LOSS OF BIODIVERSITY THAT YOU CAUSE?
Read our article: How To Reduce Your Carbon Footprint.
Today, rising temperatures caused by man-made greenhouse gas emissions are triggering destructive marine heatwaves, causing our corals to wither and our fish to die. On land, they are creating tinder-dry forests that are igniting with dangerous frequency, impacting wildlife on every continent and in every ocean. Here are three brief examples:
As warmer temperatures spread north and south, many species have expanded their ranges away from the equator towards the poles and also upwards in elevation. In addition, populations of numerous species have declined, and although global warming is believed to have contributed to the decrease, apportioning a precise share of responsibility is not yet possible. There have also been changes in species phenology (the timing of events). Many insects as well as birds are showing life-cycle changes, such as earlier onset of migration, egg-laying and breeding. (Source: UNEP)
Another affected group is phytoplankton. One particular species, foraminifera, is responsible for the sequestration of 25-50 percent of the carbon absorbed by the oceans and thus plays a vital role in limiting atmospheric carbon dioxide levels. Now, researchers have discovered that foraminifera shells are being significantly thinned by ocean acidification, caused by the enormous amounts of CO2 being released through the burning of fossil fuels. 2
Wildfires exacerbated by global warming
During the summer of 2019-2020, prolonged droughts and heatwaves across the country triggered the worst Australian bushfires ever seen. The blazes destroyed 46 million acres of animal habitat, raised air pollution to 23 times higher than the hazardous level and killed more than 1 billion animals. They also emitted over 350 million tonnes of carbon dioxide into the atmosphere – more than half of Australia’s entire greenhouse gas emissions for the year.
During the previous 2019 summer in the Northern Hemisphere, Arctic fires had raged through the boreal forests of Canada, Alaska and Siberia, causing a smoke cloud covering an area the size of the EU.
For more about the impact of rising temperatures on biodiversity and animal habitats, see: Effects of Climate Change on Animals.
Have We Entered The Anthropocene Epoch?
Planet Earth has existed for more than 4.5 billion years. If this period of time were to be compressed into a single year, modern humans would emerge at 8 minutes to midnight on December 31st. And yet despite this late arrival, humans have had a far greater impact on the planet than any other species. All across the world, we are cutting down forests, bulldozing habits, monopolizing water supplies and over-exploiting natural resources. As a result, we are destroying ecosystems and pushing animals to extinction. We are the world’s new super-predator.
Several studies show that since (at least) the mid-20th century, the level of damage caused by mankind to Planet Earth – involving nuclear contamination, fossil fuel burning, pollution of the land and seas, deforestation, and disregard for wildlife – now calls for the present era to be renamed the “Anthropocene epoch” in recognition. 3 4
Are We Facing a Catastrophic Loss of Biodiversity?
According to some scientists, Planet Earth is already experiencing a mass extinction of wildlife, with the number of animals falling by 50 percent since 1970. 5 Tiger populations have plummeted by 97 percent (Source: Worldwildlife.org) while about 96 percent of black rhinos have been wiped out. Around 90 percent of large predatory fish have disappeared over the past few decades, while the Western Gorilla, native to the Congo Rainforest, suffered a 50 percent fall in population between 1980 and 2008. (Source: UNCTAD)
More recently, the WWF’s Living Planet Index 2018, reveals that there has been an overall fall of 60 percent in species population since 1970. Losses are even greater in the tropics, with South and Central America experiencing an 89 percent loss of biodiversity since 1970. Produced for WWF by the Zoological Society of London, researchers tracked data on 16,704 populations of mammals, birds, fish, reptiles and amphibians, across more than 4,000 species, to arrive at their assessments.
Another study shows that insect populations in Germany have fallen by three-quarters, over the last 25 years. 6 Co-author Dave Goulson, professor of biology at Sussex University, says that the study suggests that humans “appear to be making vast tracts of land inhospitable to most forms of life, and are currently on course for ecological Armageddon. If we lose the insects then everything is going to collapse.”
A more recent study – the first global scientific review of the loss of biodiversity in the insect kingdom – warns of a “catastrophic collapse of nature’s ecosystems”, and says that more than 40 percent of insect species are threatened with extinction and 33 percent are endangered: the most vulnerable being Lepidoptera, Hymenoptera and dung beetles (Coleoptera). Habitat loss caused by harmful land use as well as intensive agriculture is the main threat, it says, while agro-chemical pollutants, pesticide use, and global warming are additional factors. 7 See also: Why is Soil So Important to the Planet?
In another major study with implications for loss of biodiversity, scientists are predicting that at least half of the world’s killer whales are doomed to extinction within 30-50 years because of toxic and persistent pollution of the oceans. Although banned for decades, PCBs are still leaking into the seas where they pass up the food chain. Killer whales, being the top ocean predators, end up being the most contaminated and are suffering from cancer, and damaged reproductive organs and immune systems. Unfortunately, the poisons are passed on to their calves through their milk. 8
A recent historical comparison of different types of biomass, reveals that since the beginning of human civilization, 83 percent of wild mammals, 80 percent of marine mammals, 50 percent of plants and 15 percent of fish have disappeared. At present, livestock accounts for 60 percent of the biomass of all mammals on earth, followed by humans (36 percent) and wild mammals (4 percent). As for birds, only 30 percent are wild: the remainder being domesticated. 9
Convention On Biological Diversity (CBD)
In order to stem the loss of flora and fauna, it was decided at the Rio de Janeiro Conference of the United Nations for Environment and Sustainable Development (UNCED) in 1992, to establish a Convention on Biological Diversity (CBD) – known informally as the Biodiversity Convention. Over 193 Contracting Parties joined this international nature protection agreement, which has set numerous goals. Some are likely to be reached – for example, protecting 17 percent of all land and 10 percent of the oceans by 2020. Others are not.
Despite widespread support for the CBD, the world has witnessed a continuing loss of biodiversity. In response, a new set of diversity-preservation goals were prepared for 2020, known as the Aichi targets. In addition, a new international body known as The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), was formed in April 2012 to create a coordinated global plan for sustainable management of the world’s plants and animals.
In its 2019 Global Assessment Report, the IPBES stated that good progress had been made on components of only four of the 20 Aichi Biodiversity Targets, and that therefore few of the targets will be achieved by the 2020 deadline.
- Sahney, S., Benton, M.J. & Falcon-Lang, H.J.; Benton; Falcon-Lang (2010). “Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica“. Geology. 38 (12): 1079–1082.
- Moy, A., Howard, W., Bray, S. et al. Reduced calcification in modern Southern Ocean planktonic foraminifera. Nature Geosci 2, 276–280 (2009).
- “The Anthropocene is functionally and stratigraphically distinct from the Holocene.” Colin N. Waters. et al; Science Jan 8, 2016: Vol. 351, Issue 6269
- Chapin III, F., Zavaleta, E., Eviner, V. et al. Consequences of changing biodiversity. Nature 405, 234–242 (2000).
- “Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines.” Gerardo Ceballos, Paul R. Ehrlich, Rodolfo Dirzo. PNAS July 25, 2017.
- “More than 75 percent decline over 27 years in total flying insect biomass in protected areas.” Caspar A. Hallmann, et al; (2017)
- “Worldwide decline of the entomofauna: A review of its drivers.” Francisco Sanchez-Bayo, Kris A.G. Wyckhuys. Biological Conservation Volume 232, April 2019, Pages 8-27.
- “Predicting global killer whale population collapse from PCB pollution.” Jean-Pierre Desforges et al; Science Sept 28 2018: Vol. 361, Issue 6409, pp. 1373-1376.
- Bar-On, Yinon M; Phillips, Rob; Milo, Ron (2018). “The biomass distribution on Earth“. Proceedings of the National Academy of Sciences. 115 (25): 6506–6511.