- Diversity is vital
- Beauty in jeopardy
- Ecological services
- What destroys biodiversity?
- The human manipulator
- Dialogue for Sustainability
- Changing Course
The Human Manipulator
All species continuously seek to better adapt to their environmental conditions. Over millions of years, this process, which we call evolution, has led to a complicated balance between predator and prey, between specialists and generalists, in all ecosystems.
Only recently have people begun to change the rules. We have confronted ecosystems with more new influences than any other species or natural event. Over a relatively short period of time, we have multiplied billion-fold, and have populated all parts of the planet. We have transported vast amounts of raw materials, animals and plants around the world.
As a result, alien species have been introduced to many ecosystems, either intentionally or unintentionally. More often than not, these introductions have devastating impacts on native biodiversity, causing extinctions and affecting natural and cultivated ecosystems. Since the 17th century, invasive alien species have contributed to nearly 40% of all animal extinctions for which the cause is known. The Nile Perch in East Africa’s Lake Victoria, for example, has flourished in its new environment to such a degree that it has caused the extinction of several hundred native species. Invasive alien species can also become significant pests or pathogens that cause enormous economic costs. The annual environmental losses caused by introduced pests in the United States, United Kingdom, Australia, South Africa, India and Brazil have been calculated at over US $ 100 billion.
Changing Climates, Invading Species
A major source of marine introductions of alien species is hull fouling and the release of ballast water from ships. Other vectors, such as aquaculture and aquarium releases, are also important and less well regulated than ballast water. Of the 150 species that have recently arrived in the Great Lakes (North America), 75% originated from the Baltic Sea. Similarly, migration flow from the Red Sea to the Mediterranean continues unabated with nearly 300 species having entered the Mediterranean since 1891.
Diseases such as the Dutch elm disease and “sudden oak death” are thought to have been accidentally introduced to Europe and North America from Asia. The Dutch elm disease has drastically changed the northern European landscape, wiping out most mature elm trees, which have not had the opportunity to develop resistance to the disease. Sudden oak death has only recently emerged and is causing great concern as it is spreading particularly through California.
Human intervention is also changing the composition of the Earth’s atmosphere. As a result of human activities, the concentration of carbon dioxide (CO2) and other “greenhouse gases” is reaching levels not seen for tens of thousands of years. The climate change this triggers is expected to cause the average global temperature to rise by anything between 1.4 and 5.8 degrees Celsius – with potentially devastating effects. That process has already caused the severity of extreme weather events to increase. It will have immense – and sometimes devastating – consequences for all ecosystems. The pace of global warming makes it difficult for species to adapt to new conditions, especially as fragmented habitats often prevent them from migrating to more suitable areas. Whether it is tropical marine turtles, Arctic polar bears, or gorillas in mountain ecosystems, the continued existence of many species is threatened.
Next chapter: Dialogue for Sustainability
Changes in levels of CO2 concentration in the Earth’s atmosphere
The consumption of fossil fuels and the destruction of those forests and peatlands that absorb large quantities of carbon have caused the atmosphere’s carbon dioxide content to rise exponentially over the last 250 years. Today, we know that this, combined with the exponential increase of other greenhouse gases such as methane and nitrous oxide, is contributing significantly to global warming and has to be reduced.
The current level of greenhouse gases in the atmosphere will amplify global warming for at least a further 50 years. Reduction of greenhouse gas emissions, through more efficient use of energy and the replacement of fossil fuels, is therefore an important element in the longterm protection of biodiversity. In addition, strategies that seek to facilitate the adaptation of biodiversity to climate change, such as the creation of corridors, which will allow species to migrate, will also be needed to conserve biodiversity. The world also needs to be sensitive to policies that, while aimed at reducing greenhouse gases, could however reduce biodiversity, at least in the medium term, as land in developing countries is converted to cropland to meet the demands for agricultural products and biofuels.
For example, 60% of all tropical peat soil occurs in Indonesia and bind about 50 billion tons of carbon. If those soils are dried and converted to cropland, bacteria will oxidise the meter thick soil and carbon will be released into the air. One quarter of 6.5 million hectares of palm oil (biofuel) plantations is situated on such soil and a further 3 million hectares are planned.