The dramatic decline in global biodiversity is attributed principally to habitat loss, resulting from changes in the use of land. Further important causes, in order of impact, are over-exploitation of natural resources, climate change, pollution and invasive alien species.
Humanity is to blame for each of these causes of biodiversity loss, with the threat to species and degradation of ecosystems likely to continue beyond 2050, without fundamental change.
These were the conclusions of the 2019 Global Assessment on Biodiversity and Ecosystem Services carried out by IPBES, the world’s leading advisory body on the science of biodiversity. The Assessment noted that 75% of land-based habitat has been significantly altered to accommodate urbanisation, industrial development, and the expansion of agriculture. More than one third of the planet’s land surface is utilised for crops and grazing of livestock.
Inability to control the global fishing industry provides the most obvious example of unsustainable use of natural resources. According to the UN Food and Agriculture Organization, 28.8% of marine fisheries were over-exploited in 2011. The FAO has further warned that, without radical measures, commercial fishing may not survive beyond 2050.
Many of the world’s rivers have been rendered inert by dumping or careless use of industrial and agricultural chemicals. Nitrogen run-off from fertilizers encourages algae blooms which starve aquatic life of oxygen through eutrophication. On land, there is currently great alarm at the apparent link between the neonicotinoid range of insecticides and the plunging population of bumblebees.
The introduction of alien species has caused untold damage to native plants and animals. Some of this invasive interaction dates back centuries and has been accidental, for example through the inadvertent transport of rats, cats, and even jellyfish. Restoring the natural mix of species requires formidable resources as, for example, the eradication of rats on South Georgia island in 2018
In varying degree, each of these direct causes of biodiversity loss is a servant to humanity’s insatiable demand for food, water, energy and consumer goods. In turn these demands are inflated by indirect factors such as world population growth and increasing per capita incomes.
For example, the UN’s World Population Prospects estimates that cities in developing countries must expand in anticipation of doubling their populations by 2050. Most of these cities are located in biodiversity-rich tropical regions.
A further indirect cause of biodiversity loss is the dysfunctional performance of contemporary market economics. Inappropriate price signals are the inevitable consequence of attributing zero value to environmental assets.
This failing is compounded by political mismanagement of key global economic instruments. For example, even the highly developed economies of Europe and US have proved incapable of removing subsidies which are complicit in unsustainable farming practices. Global monopolies in agribusiness are permitted to flourish, narrowing the diversity of crops that feed the world.
more Biodiversity briefings (updated March 2021)
Importance of Biodiversity
Climate Change and Biodiversity
Conservation of Biodiversity
Solutions to Biodiversity Loss
Sustainable Development Goals for Biodiversity
Biodiversity Access and Benefit-Sharing
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