Download Environmental Problems

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Historical documents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