2. What is the "normal" rate of extinction?
3. What is the current rate of extinction?
4. How much extinction can be directly related to human activities?
ca. 4,800 prokaryotes
ca. 26,900 algae
ca. 30,800 protozoa
ca. 69,000 fungi
ca. 248,400 plants
ca. 281,000 animals (non-insect)
ca. 751,000 insects
2. Estimates suggest there may be more than 30 million species
based on sampling in tropical forests
(that's a lot of undescribed species! - 85 to 99% of species unknown to science)
example: 1990 study by Norwegian scientists
estimated 4,000 different species of bacteria in 1 gram of soil from one location
there are only 4,800 known species of bacteria!
Estimates suggest there are 10,000,000 species in tropical forests
1. One million years is the normal life span of a species
2. Extinction rate of 10 species per year can be expected under normal conditions
- 0.0001% extinction rate
- evidence from island models and fossil histories
10,000,000 X 0.0027 = 27,000
conversion of farm land to urban areas
increased emissions of greenhouse gasses (global warming)increased waste (water, soil, and air pollution)
depletion of ozone layer
increased soil erosion
2. Background rate of extinction = 10 spp per year; estimated current rate = 27,000 spp per year
Current rate exceeds normal rate by 2,700X!!!!
3. Concept of the Ecological Footprint
a measure of the "load" imposed by a given population on nature
represents the land area necessary to sustain current levels of resource consumption and waste discharge