Biodiversity losses and species ex2nc2on. Biodiversity losses and species ex2nc2on. Earth has experienced five mass ex2nc2ons

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1 Ex#nc#on Biodiversity losses and species ex2nc2on Occurs when the last member of a species dies Ex#rpa#on Species ceases to exist Disappearance of a par2cular popula2on locally not the en2re species globally Can lead to ex2nc2on 99% of all species ever existed are now ex2nct Biodiversity losses and species ex2nc2on Background rate of ex#nc#on Natural ex2nc2ons for a variety of reasons Compe22on Mammal and marine species 1 species out of 1,000 become ex2nct every 1,000 to 10,000 years Translates to: 1 ex2nc2on per 1 10 million species per year Earth has experienced five mass ex2nc2ons Past 440 million years Mass ex2nc2ons eliminated at least 50% of all species Dinosaurs ex2nct at end of the Cretaceous period 65 million years ago Made way for mammals 1

2 The current mass ex2nc2on is human caused Quaternary period Modern era May lose more than half of all species 6th mass ex2nc2on differs because Caused by humans Humans will suffer because of it Current global ex2nc2on rate 100 to 1,000x background rate Will increase 10x in future decades People have hunted species to ex2nc2on for millennia Ex#nc#ons followed human arrival on islands and con#nents 2

3 Current ex2nc2on rates are higher than normal The Red List Updated list of species facing high risks of ex2nc2ons 22% of mammal species 12% of bird species 16 86% of all other species Since fish species, 9 bird species, and 2 mammal species have gone ex2nct West African black rhinoceros, Baiji white dolphin (both last decade) U.S. in the last 500 years 236 animal and 17 plant species are confirmed ex2nct Actual numbers are undoubtedly higher Biodiversity loss is more than ex2nc2on Popula2on is declining With shrinking geographic ranges Gene2c, ecosystem, and species diversity are being lost Living Planet Index summarizes trends in popula2ons Between 1970 and 2003, the Index fell by 30% Biodiversity loss has many causes Reasons for biodiversity losses Mul2faceted, complex, and hard to determine Four primary causes Habitat altera2on Invasive species Pollu2on Overharves2ng Global climate change now is the fibh cause 3

4 Biodiversity Loss Habitat Altera2on Greatest cause of biodiversity loss Farming Grazing Clearing forests Hydroelectric dams Urbaniza2on and suburban sprawl A few species (i.e., pigeons, rats) benefit from changing habitats Less than 1% of North America s Great Plains remains, and grassland bird popula2ons have declined 82 99%. Biodiversity Loss Invasive Species Introduc2on of non- na2ve species to new environments Accidental: zebra mussels Inten2onal: food crops Island species very vulnerable Invaders have no natural predators, compe2tors, or parasites Cost billions of dollars in economic damage each year Air pollu2on Degrades forest ecosystems Water pollu2on Biodiversity Loss Pollu2on Adversely affects fish and amphibians. Agricultural runoff Harms terrestrial and aqua2c species Oil and chemical spills Kill wildlife Although pollu2on is a substan2al threat It tends to cause less damage than habitat altera2on or invasive species 4

5 Biodiversity Loss Overharves2ng Vulnerable species are large, few in number long- lived have few young Siberian 2ger Hunted without rules and regula2ons Early 1990s increased 2ger poaching because of powerful economic incen2ves Today the oceans contain only 10% of the large animals they once did. Biodiversity Loss Climate change Emissions of greenhouse gases warm temperatures Modifies global weather paierns Increases the frequency of extreme weather events Increases stress on popula2ons Forces organisms to shib their geographic ranges Biodiversity benefits: Ecosystem Services Provides food, shelter, fuel Purifies air and water and detoxifies wastes Stabilizes climate, moderates floods, droughts, wind, temperature Generates and renews soil fer2lity and cycles nutrients Pollinates plants and controls pests and disease Maintains gene2c resources Provides cultural and aesthe2c benefits Allows us to adapt to change The annual value of just 17 ecosystem services = $16-54 trillion per year 5