Biodiversity loss

Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in biological diversity in a given area. The decrease can be temporary or permanent. It is temporary if the damage that led to the loss is reversible in time, for example through ecological restoration. If this is not possible, then the decrease is permanent. The cause of most of the biodiversity loss is, generally speaking, human activities that push the planetary boundaries too far.^[1][2][3] These activities include habitat destruction^[4] and land use intensification (for example monoculture farming).^[5][6] Further problem areas are air and water pollution (including nutrient pollution), over-exploitation, invasive species^[7] and climate change.^[4]

Many scientists, along with the Global Assessment Report on Biodiversity and Ecosystem Services, say that the main reason for biodiversity loss is a growing human population because this leads to human overpopulation and excessive consumption.^{[8][9][10][11][12]} Others disagree, saying that loss of habitat is caused mainly by "the growth of commodities for export" and that population has very little to do with overall consumption. More important are wealth disparities between or within countries.^[13]

Climate change is another threat to global biodiversity.^[14][15] For example, coral reefs—which are biodiversity hotspots—will be lost by the year 2100 if global warming continues at the current rate.^[16][17] Still, it is the general habitat destruction (often for expansion of agriculture), not climate change, that is currently the bigger driver of biodiversity loss.^[18][19] Invasive species and other disturbances have become more common in forests in the last several decades. These tend to be directly or indirectly connected to climate change and can cause a deterioration of forest ecosystems.^[20][21]

Deforestation also plays a large role in biodiversity loss. More than half of the worlds biodiversity is hosted in tropical rainforest.^[22] Regions that are subjected to exponential loss of biodiversity are referred to as "hotspots", since 1988 the hotspots increased from 10 to 34, of the total 34 hotspots currently present, 16 of them are in tropical regions.^[23] Researchers have noted that only 2.3% of the world is covered with biodiversity loss hotspots, even though only a small percentage of the world is covered in hotspots, it host a large fraction (50%) of vascular plant species.^[24]

Groups that care about the environment have been working for many years to stop the decrease in biodiversity. Nowadays, many global policies include activities to stop biodiversity loss. For example, the UN Convention on Biological Diversity aims to prevent biodiversity loss and to conserve wilderness areas. However, a 2020 United Nations Environment Programme report found that most of these efforts had failed to meet their goals.^[25] For example, of the 20 biodiversity goals laid out by the Aichi Biodiversity Targets in 2010, only six were "partially achieved" by 2020.^[26][27]

This ongoing global extinction is also called the holocene extinction or sixth mass extinction.