Biodiversity Threats

Discussion

Land clearing and other economic activities have caused many species to go extinct within a relatively short time. Global warming threaten many more in the near future.

To avoid a massive extinction event, we need to return land to biodiversity usage, protect and enhance existing habitats, slow global warming by reducing greenhouse emissions, control the trade in wildlife, and prevent the spead of invasive species.

Readings

Sixth Mass Extinction Event

The Sixth Extinction. Niles Eldredge, June 2001

Earth is currently faced with a mounting loss of species that threatens to rival the five great mass extinctions of the geological past.

Causes:

Conservation measures, sustainable development, and, ultimately, stabilization of human population numbers and consumption patterns seem to offer some hope that the Sixth Extinction will not develop to the extent of the third global extinction, some 245 million years ago, when 90% of the world's species were lost.

Sixth Mass Extinction Event

Is a "sixth" extinction looming? Ed Stoddard. Planet Ark. 2002.7.23

Many credible scientists fear that the sixth mass extinction in the planet's long history is unfolding.

Leakey and Lewin estimate that perhaps 50 percent of all species will become extinct in the next 100 years. Others take a more measured view but agree that a crisis is looming.

Most scientists concede that the number of recorded extinctions to date is far less than the "so many lost each day" estimates cited in the more alarmist literature. The Committee on Recently Extinct Organisms says at least 70 species of fish, birds and mammals have disappeared since 1970.

Mass extinctions have occurred five times in the four billion year history of life. They are loosely defined as moments in geological history when half or more of all marine species - which today are preserved in fossils - die off in a short period of time. (Terrestrial life is also not believed to fare well during these periods).

Herbal Remedies as Biodiversity Threat

Demand for Herbal Remedies Threatens Plants: Study. ABC. 2004.1.8

Worldwide demand for herbal remedies is threatening natural habitats and endangering up to a fifth of wild medicinal plant species which are being harvested to extinction, a leading science magazine says. A study to be published later this year by the conservation organisation World Wildlife Fund (WWF) warns that between 4,000 and 10,000 plants may be at risk.

Global Warming as Biodiversity Threat

Global warming 'threatens 1 million species'. ABC.2004.1.8

Global warming could wipe out a quarter of all species of plants and animals by 2050 in one of the biggest mass extinctions since the dinosaurs, according to an international study.

Emissions from cars and factories could push temperatures up to levels not seen for 1 million to 30 million years by the end of the century, threatening many habitats.

Global Warming as Biodiversity Threat

One Million Species Extinct by 2050: Scientists

The Age. 2004.1.8

A quarter of all land animals and plants, more than one million species could be extinct by 2050 as human-induced climate change heats up the earth, an international group of scientists has predicted.

[A temperature rise of] 0.8 to 1.7 degrees celsius by 2050 - 18 per cent of species would be lost. [If] 1.8 to 2 degrees - 24 per cent of species will die. If temperatures rise more than 2 degrees, 35 per cent will become extinct.

Some species will be forced to shift to areas where they will have a better chance of survival. Some will be forced - along with other species - into smaller areas, causing extinctions, and some will have nowhere to go.

Refer:

Extinction Risk From Climate Change. Nature. 2004.1.8

Ecology: Clouded Futures. Nature. 2004.1.8

Extinction Threat to Mammals, Birds and Plants

World's mammals under threat of extinction: UN report. ABC. 2003.5.24

A United Nations report has warned a quarter of the world's species of mammals could be extinct within 30 years. But many problems could be rectified if the world implements environmental treaties signed since the Rio Summit a decade ago. More than 11,000 endangered animal and plant species, including more than 1,000 mammals, a quarter of the world's total. One in eight bird species is also in danger of extinction and more than 5,000 different plants.

Global Warming and Polar Bears

Arctic Warming Imperils Polar Bears. ABC. 2003.5.16

A reduction caused by global warming in the massive sheets of Arctic sea ice that polar bears prowl for their prey could have devastating consequences for the world's largest land predator, says a World Wildlife Fund report. Polar bears are facing a series of threats, including large-scale habitat fragmentation, pollution and excessive hunting, but the climate change forecast to occur over the coming decades as the gravest of them all. "Within the lifetime of our children, unless we do something now and starting taking steps, there is a serious risk of losing polar bears."

Extinction Event - Australia

Australian Ecosystems Facing Rapid Extinction. ABC. 2003.4.23

Twenty-two mammal species have become extinct since European settlement in Australia Nearly 3,000 of Australia’s ecosystems are threatened with extinction, and half of those are beyond rehabilitation, says a new Federal Government report - the Australian Terrestrial Biodiversity Assessment 2002.

According to the report, 2891 individual Australian ecosystems are at risk. Land clearing has been one of the major contributors. A Labor environment spokesman estimates 500,000 hectares (1.236 million acres) is lost to land clearing every year.

Biodiversity Assessments - Australia

Australian Terrestrial Biodiversity Assessment 2002. Environment and Heritage, Australia

Threatened Ecosystems and Species

2891 threatened ecosystems and other ecological communities are identified across Australia.

94% of bioregions in Australia have one or more threatened ecosystems, with the greatest numbers in the highly cleared regions of southern and eastern Australia.

Nearly half of the threatened ecosystems are eucalypt forest and woodlands with shrubby or grassy understorey that have been extensively cleared.

The highest number of threatened species occurred in southern and eastern Australia, within the subregions from the southern highlands in Victoria and NSW and along the coast from Sydney to north of Brisbane.

Threatening Processes

Vegetation clearing is the most significant threat to species and ecosystems in eastern Australia.

Overgrazing, exotic weeds, feral animals and changed fire regimes are additional key threats to wetlands, riparian zones, threatened species and threatened ecosystems across much of Australia. These threats are widespread and pervasive.

Implementing fire regimes and sustainable grazing management will provide major returns for biodiversity from investment as key protective management activities for much of Australia's rangelands.

Fragmentation of remnants, increased salinity and firewood collection are threats to biodiversity in the highly modified regions of southern and eastern Australia.

Biodiversity Crisis - Australia

Australia's Biodiversity Crisis. Australian Wildlife Conservancy

Australia is one of only 17 countries recognised as "mega-diverse", meaning we support a significant proportion of the world’s biodiversity. Over 80% of our mammals, reptiles and flowering plants are endemic (found only in Australia).

However, the destruction and fragmentation of habitat, particularly as a result of clearance of vegetation for agriculture, and the impact of feral animals and invasive weeds has had a substantial impact on our biodiversity.

Links

Australian Conservation Foundation

Australian Wildlife Conservancy

National Land & Water Resources Audit

World Wildlife Fund

2007.7.5