The Loss of Biodiversity from Human Activity
Herd of African impalas.
Scientists have tracked the loss of biodiversity on Earth for decades. Studies from physical, geological, and biological data show that Earth has had declines in populations and even mass extinctions in the past. So, why are we worried?
At first, much of the species loss in the 20th century was attributed to the “regular” changes in biodiversity that occur in living ecosystems. Simply put, environments change. Most changes occur slowly enough to allow species to adapt—either through emphasis of different traits or movement to a new, more hospitable environment.
It has now become clear that the loss of biodiversity scientists have been reporting for the last few decades is more than the usual fluctuations seen in ecosystems full of living organisms. Back in August 1999 the Environment New Science reported,
The rainforest of the Gambia River in Senegal’s Niodolo-Koba National Park. Rainforests have a huge amount of biodiversity but are being deforested at alarming rates. Source: http://en.wikipedia.org/wiki/Ecosystem
“The current extinction rate is now approaching 1,000 times the background rate and may climb to 10,000 times the background rate during the next century, if present trends continue.” In 2005 the Millennium Ecosystem Assessment reported that 10-30 percent of mammal, bird, and amphibian species are threatened with extinction because of human activity.
Global climate changes are just that—global. They threaten the world’s biodiversity and in surprising ways. The International Union for Conservation of Nature (IUCN) reported that 75 percent of genetic diversity of agricultural crops has been lost, 75 percent of the world’s fisheries are over exploited, and one-third of coral reefs are threatened with extinction. The statistics may be startling, but they don’t have to be irreversible.
Of course, climate changes are not the only pressure on our environments. Habitat loss and degradation, pollution, overexploitation, and invasive species also play significant roles in biodiversity decline. Note that these pressures are also because of human activity.
Source: IUCN as compiled by Secretariat of the Convention on Biological Diversity (2010, May), Global Biodiversity Outlook 3.
Ecosystems will be further stressed by the combined impacts of loss of biodiversity in neighboring environments. At a rate of one thousand times higher than the average rate of the last 65 million years, destabilization of ecosystems is likely.
The latest reports estimate that more than a million species will be lost in the next 50 years, greatly reducing the world’s biodiversity. The most significant cause is expected to be climate change.