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Environmental Problems • Climate Change • Pollution • Overfishing Determining Causes of Earth’s Climate Change • Paleoclimatology • Proxy data – indirect evidence using natural recorders of climate variability – – – – – – Sea floor sediments Coral deposits Glacial ice rings Tree rings Pollen Historical documents © 2011 Pearson Education, Inc. Natural Causes of Climate Change • Solar energy changes, Variations in Earth’s Orbit, Volcanic eruptions, Movement of Earth’s Plates • Linked to Pleistocene Ice Age, Little Ice Age, Medieval Warm Period • Recent change unprecedented – More likely result of human activity than natural causes © 2011 Pearson Education, Inc. Global Warming: Causes • “Green house effect” Fig. 15-40, p. 378 Global Warming: Causes • Green house gases (chloroflourocarbons =CFCs, methane, CO2, water vapor) • Increasing CO2 – Deforestation & burning fossil fuels Table 16.01 Today – CO2 highest it has been in 10 million years Fig. 15-31, p. 326 Ice Core Data © 2011 Pearson Education, Inc. Global Warming • The 8 warmest years have occurred since 1998 • Earth’s surface temperature has risen 0.8°C (1.4°F) in last 140 years. © 2011 Pearson Education, Inc. Fig. 15-43, p. 380 Changes in the Oceans Changes in deep-water circulation • North Atlantic especially sensitive • Melting glaciers • Warmer surface waters © 2011 Pearson Education, Inc. Changes in the Oceans Polar Ice Melting • Arctic amplification • Loss of more than 2 million square kilometers (800,000 square miles) of Arctic sea ice in last decade • Loss of ice = enhanced warming due to lower albedo © 2011 Pearson Education, Inc. The North Pole 1996 Fig. 15-33, p. 327 Changes in the Oceans Polar Ice Melting • Arctic ice melting affects polar bear survival. • Food sources are dwindling for human Arctic dwellers. – Marine species migration © 2011 Pearson Education, Inc. Changes in the Oceans • Rising Sea Level – already occurring • Main contributors: – Melting of Antarctic and Greenland ice sheets – Thermal expansion of ocean surface waters – Melting of land glaciers and ice caps – Thermal expansion of deep-ocean waters © 2011 Pearson Education, Inc. Global Sea Level Rise © 2011 Pearson Education, Inc. The Maldives in the Indian Ocean – 80% pop. live only 1m above sea level Rising Sea Level • Severely affect areas with gently sloping coastlines – U.S. Atlantic and Gulf Coasts • Models predict rise between 0.5 and 1.4 meters (1.6 and 4.6 feet) by year 2100 • Affects coastal ecosystems like corals © 2011 Pearson Education, Inc. Coral Bleaching Linked to Increased Temperatures Fig. 14-15, p. 340 Changes in the Oceans Ocean acidity increase • Some atmospheric carbon dioxide dissolves in ocean water. – Acidifies ocean • Threatens calcifying organisms – – – – Coccolithophores Foraminifers Sea urchins Corals © 2011 Pearson Education, Inc. Organisms Threatened by Increased Marine Acidity © 2011 Pearson Education, Inc. Global Climate Change: Solutions? • Alternative energy Fig. 15-9, p. 355 Fig. 15-10a, p. 355 Fig. 15-10b, p. 355 Marine Pollution • The introduction into the ocean by humans, substances that changes the physical, chemical or biological environment Fig. 15-27, p. 367 Each year 240 million gallons of used motor oil are dumped in storm drains…22x the amount spilled by Exxon Valdez Fig. 15-28, p. 368 Marine Pollution • Bioamplification – even small amounts of pollutants can have large effects • DDT example Stepped Art DDT in fish-eating birds (pelicans) 25 ppm DDT in large fish (needlefish) 2 ppm Concentration has increased 10 million times DDT in small fish (minnows) 0.5 ppm DDT in small zooplankton 0.04 ppm DDT in water 0.000003 ppm Fig. 15-32, p. 371 Marine Pollution • Eutrophication – Excess nutrients in water also lead to problems • HABs • Oxygen depletion Marine Fisheries • Commercial fishing • Most from continental shelves • Over 20% from areas of upwelling that make up 0.1% of ocean surface area © 2011 Pearson Education, Inc. Overfishing • Fish from standing stock – the mass present in the ecosystem at any given time • Overfishing – fish stock harvested too rapidly, juveniles not sexually mature to reproduce • Reduction in Maximum Sustainable Yield (MSY) © 2011 Pearson Education, Inc. Exploitation Status of Marine Fish © 2011 Pearson Education, Inc. Overfishing • 80% of available fish stock fully exploited, overexploited, or depleted/recovering • Large predatory fish reduced • Increased fishing effort, decreased stocks © 2011 Pearson Education, Inc. Overfishing: Causes • Hard to estimate maximum sustainable yield – Must know pop. size, growth & reproduction, life span • International waters • Economic Needs Bykill or By-catch • • • • Other species are accidentally caught Drift nets – banned in 1993 “Dolphin-Safe Tuna” Turtle exclusion devises (TEDs) Purse Seine Net © 2011 Pearson Education, Inc. Fig. 15-7a, p. 309 Fig. 15-7b, p. 309 Bycatch in a shrimp trawl www.blueocean.org TEDs Fig. 15-26, p. 323 Fisheries Management Effectiveness © 2011 Pearson Education, Inc. Fisheries Management • Consumer choices in seafood • Consume and purchase seafood from healthy, thriving fisheries – Examples: farmed seafood, Alaska salmon • Ecosystem-based fishery management • Avoid overfished or depleted seafood – Examples: tuna, shark, shrimp © 2011 Pearson Education, Inc. Seafood Choices © 2011 Pearson Education, Inc. www.seafoodwatch.org