Presentation on theme: "Prospects for Biodiversity Author: Martin Jenkins Summary: Chase Mahoney Critique: Asa Angeles."— Presentation transcript:
Prospects for Biodiversity Author: Martin Jenkins Summary: Chase Mahoney Critique: Asa Angeles
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.
Overview Assumptions for extrapolation Human influences and their impacts –Terrestrial Ecosystems –Aquatic Ecosystems Do these impacts matter?
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 –1 o C to 2 o C increase in average surface temperature. –100 to 200 ppm increase in CO 2 concentration.
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
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.
Major Human Influences on Aquatic Ecosystems Habitat Conversion –Destruction by siltation Land runoff Coastal development –Pollution –Large-scale Hydroengineering
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
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.
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)
Does it Matter? Benefits are marginal and local –Few cases have shown benefits of natural systems Forest destruction –Infertile unusable land has obvious impacts on human existence. –Replacement shows no negative impacts.
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.
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.
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.
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.
Prospects for Biodiversity By Martin Jenkins Summary: Chase Mahoney Critique: Asa S. Angeles
Positive Critique Evidence –24 citations, including links to web sources
Living Planet Index 282 species195 species217 species
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
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?!