Environmental Problems Climate Change Pollution Overfishing

© 2011 Pearson Education, Inc. 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natural recorders of climate variability –Sea floor sediments –Coral deposits –Glacial ice rings –Tree rings –Pollen –Historical documents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

Global Warming: Causes “Green house effect”

Fig , p. 378

Global Warming: Causes Green house gases (chloroflourocarbons =CFCs, methane, CO 2, water vapor) Increasing CO 2 –Deforestation & burning fossil fuels

Table 16.01

Fig , p. 326 Today – CO 2 highest it has been in 10 million years

© 2011 Pearson Education, Inc. 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.

Fig , p. 380

© 2011 Pearson Education, Inc. 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

Fig , p. 327 The North Pole 1996

© 2011 Pearson Education, Inc. 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

The Maldives in the Indian Ocean – 80% pop. live only 1m above sea level

© 2011 Pearson Education, Inc. 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

Fig , p. 340 Coral Bleaching Linked to Increased Temperatures

© 2011 Pearson Education, Inc. 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

Global Climate Change: Solutions? Alternative energy

Fig. 15-9, p. 355

Fig a, p. 355

Fig b, p. 355

Marine Pollution The introduction into the ocean by humans, substances that changes the physical, chemical or biological environment

Fig , p. 367

Fig , p. 368 Each year 240 million gallons of used motor oil are dumped in storm drains…22x the amount spilled by Exxon Valdez

Marine Pollution Bioamplification – even small amounts of pollutants can have large effects DDT example

DDT in water ppm DDT in fish-eating birds (pelicans) 25 ppm Concentration has increased 10 million times DDT in small fish (minnows) 0.5 ppm DDT in small zooplankton 0.04 ppm DDT in large fish (needlefish) 2 ppm Stepped Art Fig , p. 371

Marine Pollution Eutrophication –Excess nutrients in water also lead to problems HABs Oxygen depletion

© 2011 Pearson Education, Inc. 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

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)

© 2011 Pearson Education, Inc. Purse Seine Net

Fig. 15-7a, p. 309

Fig. 15-7b, p. 309

Bycatch in a shrimp trawl

TEDs

Fig , p. 323

© 2011 Pearson Education, Inc. 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