1. Prospects for Biodiversity
Author: Martin Jenkins
Summary: Chase Mahoney
Critique: Asa Angeles

2. Introduction 9,000,000,000 people Imagine their impact.
“What will be the state of the world’s biodiversity in 2050?”
Prospects for Biodiversity offers an answer to this question.

3. Overview Assumptions for extrapolation
Human influences and their impacts
Terrestrial Ecosystems
Aquatic Ecosystems
Do these impacts matter?

4. Assumptions for Extrapolation
United Nations global population estimation
9 Billion (2050)
6-7 Billion (2003)
The human race will conduct its affairs in much the same manner as today.
Intergovernmental Panel on Climate Change Scenarios
1oC to 2oC increase in average surface temperature.
100 to 200 ppm increase in CO2 concentration.

5. Major Human Influences on Land
Habitat conversion
Clearing land for farming
Intensification
At least 120 ha by 2030
By 2050 much more
South America and sub-Sahara Africa
Most biologically diverse regions in the world.
Disproportionate loss in biodiversity

6. Major Human Influences on Land
Habitat conversion
Clearing land for farming
Dense tropical forest -> Fragmented/Degraded
Resemble temperate forests of North America
350 species of avifauna (3.5%) will become extinct.
Surviving species live in heavily protected managed areas.

7. Major Human Influences on Aquatic Ecosystems
Habitat Conversion
Destruction by siltation
Land runoff
Coastal development
Pollution
Large-scale Hydroengineering

8. Major Human Influences on Aquatic Ecosystems
Habitat Conversion
Fresh water biodiversity has suffered the heaviest losses over the last 30 years.
These losses are expected to continue
Coral Reef destruction

9. Major Human Influences on Aquatic Ecosystems
Exploitation of wild resources
Direct exploitation through fishing
Current rates lead to extinction
Large species and top marine predators scarce or extinct.

10. Does it Matter?
Ecologists and Conservationists struggle to demonstrate benefits of diverse intact systems.
Diverse species-rich systems
Intensively managed systems of nonnative species (farms)

11. Does it Matter? Benefits are marginal and local Forest destruction
Few cases have shown benefits of natural systems
Forest destruction
Infertile unusable land has obvious impacts on human existence.
Replacement shows no negative impacts.

12. Does it Matter?
Experts agree most large terrestrial species are extinct as result of human influence.
40,000 to 50,000 years
Systems we consider natural aren’t so.
Don’t show catastrophic consequences.

13. Does it Matter? Real life example
38 species of avifauna existed in New Zealand.
9 exist today
Most of which are endangered
Huge loss of biodiversity
No signs of suffering from a crisis.
On what grounds can we base our belief that similar losses will result in crisis in other areas.

14. Does it Matter? Still may not abuse the biosphere indefinitely.
Unforeseen threshold
Catastrophic consequences
More likely cause of catastrophic consequences will be abrupt climate shifts.
May begin with manipulation and abuse of the biosphere.

15. Conclusion Jenkins scenario assumptions
Climate
Population
Similar method of conduct
Human actions have direct influences on surrounding ecosystems.
Losses in biodiversity do not have immediate negative impacts on human existence.
Still be aware our impact may eventually trigger other catastrophic events.

16. Prospects for Biodiversity
By Martin Jenkins
Summary: Chase Mahoney
Critique: Asa S. Angeles

17. Critique Outline Positive Critique Constructive Criticism Questions
Citations
Good Points
Constructive Criticism
Questions

18. Positive Critique Evidence
24 citations, including links to web sources

19. Living Planet Index
282 species
195 species
217 species

20. Other Good Aspects of the Article
Honest tone; mostly not over-dramatized
Says estimating extinction rates is difficult
Admits that scientists struggle to show human benefits from “intact” wild systems
New Zealand went from 38 to 9 species of birds in a few centuries, but does not suffer
The future will probably be this way

21. Constructive Criticism
Minor: Of the 24 citations, 7 are Science articles
How much does it matter?
Says “natural” systems that really aren’t natural still function (recall New Zealand)
But somewhat dramatizes at the end: “…some threshold may be crossed, with unforeseeable but probably catastrophic consequences for humans.”
Then he immediately takes back this claim: “It seems more likely that these consequences would be brought about by other factors.”
So…How much does it matter?!

22. Questions?