|
|
Current trend
- Human activities are directly responsible for creating agroecosystems and cultural landscapes at the expense of
impoverishment of many natural communities and the reduction in ecosystem services.
- Since I 600, 484 animals and 654 plant species are recorded as having gone extinct, although this is almost certainly an
underestimate. Assuming animals and plants have an average lifespan of 5 to l 0 million years, the current extinction rate
for these species has been conservatively estimated to be 50 to I 00 times the average expected natural rate.
Underling causes of change
- The primary causes underlying the loss of biodiversity include: (i) increasing demands for biological resources due to
increasing populations and economic development; (ii) inappropriate use of technologies; (iii) failure of markets to
recognize the true value of biodiversity; (iv) failure of economic markets to appropriate the global value of biodiversity
at the local level; (v) institutional failures to regulate the use of biological resources; (vi) human migration, travel, and
international trade; and (vii) failure of people to consider the long-term consequences of their actions.
- These underlying causes manifest themselves through the loss, fragmentation, and conversion of natural habitats;
overexploitation of wild resources; introduction of exotic species; air and water pollution; and more recently, long-term
climate change.
Projected impact of human activities on biodiversity
- For some groups of vertebrates and plants, between 5 and 20 percent of the identified species are already listed as being
threatened with extinction in the foreseeable future.
- Assuming that recent rates of loss of closed tropical forests continue (0.5- I percent globally per year) for the next 30
years, the equilibrium number of species would be reduced by 5-10 percent. This would be equivalent to 1,000 to
1 0,000 times faster than the expected natural rate of species extinction.
- Even if species do not become extinct, habitat loss and fragmentation will put many of them into severe decline, includ-
ing the loss of distinct populations and the severe loss of genetic diversity that keeps any species healthy.
Social and economic consequences of projected changes
- Loss of biological resources and biodiversity interferes with essential ecological functions such as regulation of water
run-off, the control of soil erosion, the assimilation of wastes and purification of water, and the cycling of carbon and
other nutrients.
- In turn, this threatens food supplies, sources of wood, medicines and energy, recreation, and tourism.
- Loss of genetic diversity will affect the ability of ecological communities to resist or recover from disturbances and
environmental change, including long-term climatic change.
Technologies, policies, and measures to reduce the loss of biodiversity
- The conservation and sustainable use of biodiversity needs to become an integral component of sectoral economic
development (e.g., agriculture, forestry, coastal zone management) which would require correcting policy and market
failures.
- A wide variety of in-situ (e.g., legal protection of endangered species and the establishment of protected areas and safe
corridors), and ex-situ (arboreta, aquaria, botanical gardens, seed banks, gene banks, zoological gardens) techniques can
be employed to conserve biodiversity.
- The equitable sharing of benefits from the use of biodiversity requires that the local, regional, and global benefits of
biodiversity are appropriated at the local level through the creation of functioning markets.
Status of international agreements
- The Convention on Biological Diversity was signed in Rio and has since been ratified by 169 countries. In general, each
country has the obligation to conserve and sustainably use its own biological diversity. However, mechanisms to pro-
mote this goal have only been developed to a limited extent.
Source:
"Protecting Our Planet, Securing Our Future" UNEP / U.S. NASA / World Bank, 1997
|