Home > Environmental Issues > Article >

Humans cause a surge of extinctions

United Nations Convention on Biological Diversity reports extinctions 1000 times faster than historical rates

22 March 2006

The United Nations reports that humans are responsible for the worst spate of extinctions since the dinosaurs and must make unprecedented efforts to reach a goal of slowing losses by 2010.

The Secretariat of the United Nations Convention on Biological Diversity stated in the report issued at the March 20-31 meeting in Curitiba, Brazil, that habitats ranging from coral reefs to tropical rainforests face mounting threats.

Other than the disappearance of the dinosaurs at the end of the Cretaceous period, the other large extinctions were 205, 250, 375 and 440 million years ago, which scientists believe were caused by volcanic eruptions, asteroid strikes, or sudden climate changes.

The present rising world population of 6.5 billion is undermining the environment of animals and plants with global warming; urban expansion; industrial, agricultural and human pollution; deforestation; and the introduction of alien species.

The Global Biodiversity Outlook 2 report says "... we are currently responsible for the sixth major extinction event in the history of Earth, and the greatest since the dinosaurs disappeared 65 million years ago ..."

Ecosystems across the planet have been impacted by biodiversity loss. Deforestation continues at an alarmingly high rate. Since 2000, 6 million hectares of primary forest have been lost annually, mainly through conversion to agricultural land. Six million hectares is equal to 22 percent of the land area of New Zealand.

Marine and coastal ecosystems have suffered due to human activities, with reduced coverage of kelp forests, seagrasses and corals.  In the Caribbean, average hard coral cover declined from 50 to 10 percent in the last three decades, and 35 percent of mangroves have been lost in the last two decades.

While protected areas cover 13 percent of the world's land area and are increasing in number and area, they are unevenly distributed, with only 40 percent of the world's ecoregions reaching the 10 percent benchmark.

Marine ecosystems in particular are poorly represented, with approximately 0.6 percent of the ocean's surface area, and about 1.4 percent of the coastal shelf protected.  Not all of these areas are effectively managed.

Between 12 percent and 52 percent of species within well-studied higher taxa are threatened with extinction.

Birds show a continuing deterioration across all biomes over the last two decades.  Preliminary findings for other major groups such as amphibians and mammals, indicate that the situation is worse than for birds.

The trend of 3,000 wild populations of species show a decline in average abundance of 40 percent between 1970 and 2000.  Species present in rivers, lakes and marshlands have declined by 50 percent.

Declines are evident in amphibians globally, African mammals, birds in agricultural lands, British butterflies, Caribbean and Indo-Pacific corals, and commonly harvested fish species.

Unsustainable consumption continues, as indicated by our growing ecological footprint.  The demand for resources at the global level now exceeds the biological capacity of the Earth by 20 percent.

Forests, river systems and other habitats are becoming increasingly fragmented, affecting their ability to maintain biodiversity and deliver ecosystem goods and services.  Within 292 large rivers systems assessed, only 12 percent of the river basin area was unaffected by dam impacts.

The intensification of fishing has led to a decline of large high-value fish such as tuna, cod, sea bass and swordfish.  In the North Atlantic their numbers have declined by 66 percent in the last 50 years.

The threats causing this biodiversity loss are generally increasing.

Humans are contributing more nitrogen to ecosystems than all other natural processes combined. This contributes to so-called "nutrient-loading", leading to problems such as the creation of "dead zones" in marine systems, as observed in the Gulf of Mexico.

The rate and risk of the introduction of alien invasive species, such as the zebra mussel or the water hyacinth, has increased significantly in the last few years, and will continue to rise as result increased travel, trade and tourism, with significant economic costs.

The upland moa Megalapteryx didinus was one of 13 endemic species of moa that became extinct in New Zealand just 100 to 150 years after human settlement in the fourteenth century. The moa's only predator was the extinct Haast's eagle Harpagornis moorei (skull left), the world's largest eagle which died out with the moa.

Illustration above permission of Peter Schouten
View larger image

The need for increased political will and resources to cause positive change

The UNEP-CBD Global Biodiversity Outlook outlines priority issues for engaging with the key sectors of food and agriculture, trade, poverty reduction, and development.

The Outlook also notes the importance of integrating biodiversity concerns into the energy sector, given that climate change is an increasingly significant driver of biodiversity loss, and that the conservation and sustainable use of biodiversity can contribute to both mitigation and adaptation measures.

The food and agriculture sector contributes to pressures on biodiversity primarily through land-use change, which is expected to remain the largest driver of biodiversity loss beyond 2010 and at least to 2050 - but also through nutrient loading and over exploitation of wild resources.

These pressures point to a five-fold approach to minimizing biodiversity loss, encompassing actions to: improve agricultural efficiency; more effectively plan agricultural expansion to avoid encroaching on habitats of high biodiversity value; moderate demand for food (particularly for meat among affluent sectors of society); halt over-fishing and destructive fishing practices; and protect critical ecosystems and habitats.

To implement this approach, a mix of planning, regulations and incentive measures will be required, building on existing tools developed under the Convention. In addition, creating markets for ecosystem services, where appropriate, will encourage producers and consumers to accurately value biodiversity, and plan for its sustainable use.

Since economic development, including food and agricultural production, is strongly affected by policies on trade, the Global Biodiversity Outlook discusses the need to integrate biodiversity concerns into trade discussions.

Whereas commitments under the Doha Development Agenda of the World Trade Organization (such as the removal of subsidies for fisheries and agriculture) have the potential to benefit biodiversity, trade liberalization is projected to lead, in the short term, to acceleration in the rate of biodiversity loss in some regions and countries, unless accompanied by proactive measures to conserve biodiversity.

Economic development is essential to meeting the Millennium Development Goals, yet long-term sustainability will be undermined if biodiversity issues are not taken into account. Furthermore, many of the actions that could be taken to eradicate extreme poverty are likely to accelerate biodiversity loss in the short-run.

The existence of trade-offs but also of potential synergies implies that environmental considerations, including those related to biodiversity, should be integrated into the implementation of all of the relevant Millennium Development Goals.

There is substantial scope for better protection of biodiversity through actions justified on their economic merits. Realizing this potential requires making greater efforts towards understanding the total value of biodiversity and ecosystem services for human well-being, and taking into account this value in decision-making processes across all sectors.