Biodiversity and Humans

Despite knowing about the importance of biodiversity for a long time, human activities have caused a great deal of damage to the environment. As the Environment New Service, reported back in August 1999 (previous link): "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 [resulting in] a loss that would easily equal those of past extinctions." (Emphasis added)

The International Union for Conservation of Nature (IUCN) notes in a video that many species are threatened with extinction. In addition,

• At threat of extinction are75% of genetic diversity of agricultural crops has been lost
  • 1 out of 8 birds
  • 1 out of 4 mammals
  • 1 out of 4 conifers
  • 1 out of 3 amphibians
  • 6 out of 7 marine turtles
• 75% of the world's fisheries are fully or over exploited
• Up to 70% of the world's known species risk extinction if the global temperatures rise by more than 3.5°C
• 1/3rd of reef-building corals around the world are threatened with extinction
• Over 350 million people suffer from severe water scarcity

 

In different parts of the world, species face different levels and types of threats. But overall patterns show a downward trend in most cases.

Proportion of all assessed species in different threat categories of extinction risk on the IUCN Red List, based on data from 47,677 species.Source: IUCN, pie chart compiled bySecretariat of the Convention on Biological Diversity (2010) Global Biodiversity Outlook 3, May 2010

As explained in the UN's 3rd Global Biodiversity Outlook, the rate of biodiversity loss has not been reduced because the 5 principle pressures on biodiversity are persistent, even intensifying:

1. Habitat loss and degradation
2. Climate change
3. Excessive nutrient load and other forms of pollution
4. Over-exploitation and unsustainable use
5. Invasive alien species

Most governments report to the UN Convention on Biological Diversity that these pressures are affecting biodiversity in their country (see p. 55 of the report).

The International Union for the Conservation of Nature (IUCN) maintains the Red List to assess the conservation status of species, subspecies, varieties, and even selected subpopulations on a global scale.

Extinction risks out pace any conservation successes. Amphibians are the most at risk, while corals have had a dramatic increase in risk of extinction in recent years

The world environmental situation is likely to be further aggravated by the increasingly rapid, large scale global extinction of species. It occurred in the 20th century at a rate that was a thousand times higher than the average rate during the preceding 65 million years. This is likely to destabilize various ecosystems including agricultural systems.

…In a slow extinction, various balancing mechanisms can develop. Noone knows what will be the result of this extremely rapid extinction rate. What is known, for sure, is that the world ecological system has been kept in balance through a very complex and multifaceted interaction between a huge number of species. This rapid extinction is therefore likely to precipitate collapses of ecosystems at a global scale. This is predicted to create large-scale agricultural problems, threatening food supplies to hundreds of millions of people. This ecological prediction does not take into consideration the effects of global warming which will further aggravate the situation.

Industrialized fishing has contributed importantly to mass extinction due to repeatedly failed attempts at limiting the fishing.

A new global study concludes that 90 percent of all large fishes have disappeared from the world's oceans in the past half century, the devastating result of industrial fishing. The study, which took 10 years to complete and was published in the international journal Nature, paints a grim picture of the Earth's current populations of such species as sharks, swordfish, tuna and marlin.

The loss of predatory fishes is likely to cause multiple complex imbalances in marine ecology.

Another cause for extensive fish extinction is the destruction of coral reefs. This is caused by a combination of causes, including warming of oceans, damage from fishing tools and a harmful infection of coral organisms promoted by ocean pollution. It will take hundreds of thousands of years to restore what is now being destroyed in a few decades.

According to the most comprehensive study done so far in this field, over a million species will be lost in the coming 50 years. The most important cause was found to be climate change.

 

 

Source : articlesbase.com