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Human impacts on biodiversity depend in part on population size

Human impacts on biodiversity depend in part on population size. Today’s estimate: 6,663,153,207. http://www.census.gov/ipc/www/popclockworld.html. Human population impacts via:. Food production Water use Energy Urbanization Disease emergence. Human Effects: Climate Change.

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Human impacts on biodiversity depend in part on population size

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  1. Human impacts on biodiversity depend in part on population size Today’s estimate: 6,663,153,207 http://www.census.gov/ipc/www/popclockworld.html

  2. Human population impacts via: • Food production • Water use • Energy • Urbanization • Disease emergence

  3. Human Effects: Climate Change • If the climate is changing, why aren’t we seeing the effects? • 12 years ago: ‘The effects are just starting, but tough to see within natural variance.’ • Now: The effects are seen everywhere. • Does it matter to biodiversity?

  4. “Biodiversity” includes a lot: Species (richness) Genetic variability within species Population structure across space Communities – species across space Ecological processes (competition, predation, symbiosis) Abiotic processes that maintain the first 5 Biological phenomena – large migrations, species aggregations

  5. Biomes = largest spatial scale ecologically recognized • Driven by climate -15 -10 -5 0 5 10 15 20 25 30 Mean Annual Temperature (ºC) 0 50 100 150 200 250 300 350 400 450 Mean Annual Precipitation (cm)

  6. Note: effects are not uniformly distributed; some places are cooling

  7. Reminder: climate is not just temperature

  8. Evidence of climate change • Surface temperature  • Melting glaciers & permafrost • Mountain peak air temperature records • Sea level rise • atolls disappearing under water • Freezing elevations in the tropics have risen • Crop production • growing season 11 days longer in Europe, 1959-93

  9. Even if temperatures increase a few degrees, what’s the big deal?

  10. Last time Earth 3oC warmer peccary [peccary] SW U.S. manatee

  11. Effects on Wildlife • Frogs & toads on tropical mountain tops in cloud forest (Monteverdi, Costa Rica) • 20/50 species went extinct • Due to global warming,  cloud elevation = decreasing habitat • Also allowed fungal pathogen to invade Pounds et al. 1999

  12. Coral reef bleaching = expelling algal symbiont • low or high sea temperatures can induce bleaching • Occurs naturally – occurrence rate  • leads to  photosynthesis, failure to grow, death • seaweed overgrowth due to inability to compete

  13. Range & Phenology Shifts (Parmesan & Yohe, 2003, Nature) • Range = where species live; phenology = timing of events (return of birds in spring, flowers emerging) • Reviewed literature on effects of climate change on biodiversity • >1700 species • woody plants, herbaceous plants, birds, amphibians, fish, invertebrates • Looked for: • range shifts • advancement of spring events

  14. range shifts averaging 6.1 km / decade towards the poles • mean spring advancement by 2.3 days / decade

  15. Speckled wood 1915–1939 1940–1969 1970–1997 Range shift towards poles in many butterflies

  16. Exotic species invasion Number of exotic species

  17. Disrupting Ecological Processes Beetle damage to white spruce in Alaska – warmer winters kill fewer beetles http://www.worldviewofglobalwarming.org/

  18. Disrupting Food Chains pied flycatcher caterpillars plants

  19. pied flycatcher (Both & Visser, Nature 2001) National Geographic 9/04

  20. Disrupting Ecological Processes • Disaster At Sea As Global Warming Hits Seabirds • The Independent – UK 7/04 • Hundreds of thousands of Scottish seabirds have failed to breed this summer in a wildlife catastrophe which is being linked by scientists directly to global warming. • a rise in sea temperature is believed to have led to the mysterious disappearance of a key part of the marine food chain - the sandeel, the small fish whose great teeming shoals have hitherto sustained larger fish, marine mammals and seabirds in their millions. • the sandeel stocks have been shrinking for several years, and this summer they have disappeared: the result for seabirds has been mass starvation.

  21. Black-billed magpie Egg laying date USFWS 1971 1995 a=corn bunting b=chiffchaff c=black-billed magpie earlier egg laying in temperate birds • 20 species, avg. 8.9 days (range = 4-17 days) Tree Swallow Crick, et al. 1997. Nature 388:526.

  22. For doubters that humans are the primary cause of global climate change, given observed climate change & its effects, if human-caused emissions are not the primarycause of climate change, should our response be different than if human-caused emissions are the primary cause? "I hate to say we told you so, but we told you so." J. Cosimo, NASA researcher, Goddard Space Flight Center 9/06

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