Your Outlines? Exam 2?

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Your Outlines?Exam 2?

• ?? -gt what is the latest news??

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Coastal Zones and Marine Ecosystems

• Chapter 6, IPCC (2001)

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Oceans so what?

• 70 of the Earths surface
• Regulate the Earths climate
• Modulate the global biogeochemical cycles
• Supplies of resources and products worth
  trillions of dollars each year
• Function as areas of recreation and tourism,
  medium for transportation, repository of genetic
  and biological information, sinks for wastes
  (these functions are also shared by the coastal
  margins of the oceans)

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Humans and Oceans

• 20 of the worlds human population live w/in
  30 km of the sea 40 live w/in the nearest 100
  km of the coast
• 600 million people will occupy coastal floodplain
  land below the 1,000-year flood level by 2100
• ?climate change will affect the physical,
  biological, and biogeochemical characteristics of
  the oceans and coasts at different time and space
  scales ? positive feedback on the climate system
• Note the oceans already under stress. From what?
  Consequence of this stress?

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• ? what are the potential impacts of climate
  change on the coastal zone, marine ecosystems,
  and marine fisheries
• First what do we know

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State of Knowledge

• Global warming will affect the oceans through
  changes in sea-surface temperature (SST), sea
  level, ice cover, ocean circulation, and wave
  climate
• Ocean conveyor belt -gt global ocean thermohaline
  circulation system emphasizes the role of the
  global ocean as a climate regulator
• Projections
• SST-induced shifts in the geographic distribution
  of marine biota and changes in biodiversity,
  particularly in high latitudes
• Decrease in ice-infested waters
• Sea-level changes from thermal expansion

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State of knowledge Low certainty

• Changes in the efficiency of carbon uptake
  through circulation and mixing effects on
  nutrient availability and primary productivity
• Changes in ocean uptake and storage capacity for
  GHG
• Potential instability in the climate system
  caused by freshwater influx to the oceans and
  weakening of the ocean conveyor belt

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Marine Ecosystems

• A general warming of a large part of the world
  oceans during the past 50 years
• Overall increase associated with land-based
  global temperature trends
• Global mean sea-level has risen by about 0.10.2
  mm yr-1 over the past 3,000 years and by 12 mm
  yr-1 since 1900, with a central value of 1.5 mm
  yr-1
• Suggested maximum intensity of tropical cyclones
  may rise by 10-20 might persist for longer time
  due to increased SST

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Ocean conveyor belt.

• Role in controlling the distribution of heat and
  GHG
• Circulation driven by differences in seawater
  temperature and salinity
• Some evidence will weaken (Slow down? Stop?) due
  to climate change
• (more on this later)

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Marine Ecosystems Sea Ice

• 11 of the ocean (seasonal)
• Affects
• salinity
• ocean-atmosphere thermal exchange
• Determining the intensity of convention in the
  ocean, and thus the mean time scale of deep-ocean
  processes affecting carbon dioxide update and
  storage
• Changes
• Large reductions in the extent, thickness and
  duration of sea ice
• Already significant decrease in spring and
  summer sea-ice by 10-15 since the 1950s in the
  northern hemisphere
• may be underestimated due to significant thinning
  of sea ice in the Arctic may be as much as
  25between 1950s-1970s

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Marine Ecosystems Biological Processes

• Can sequester CO2 and remove carbon to the ocean
  interior biological pump
• Rise in temperature ? faster biodegradation
  faster dispersal of global organic pollutants
• Photosynthesis (the major process by which marine
  biota sequester carbon dioxide) controlled by
  the availability of nutrients and trace elements
  (eg iron)
• Climate change could affect the inputs of
  nutrients and iron to the ocean
• Greatest impact in semi-enclosed seas and bays

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Also

• CC can shift structure of biological communities
  in the upper ocean. Change stratificationcan
  impact the biological bump

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Marine Ecosystems Marine Carbon Dioxide Uptake

• Oceans taken up 30 (great uncertainty) of
  carbon dioxide emissions between 1980 and 1989
• How?
• Burial of organic carbon in marine sediment -gt
  removing atmospheric carbon dioxide for prolonged
  time periods
• But
• If CC could reduce ability to carbon uptake
• (latest news you tell me)
• Also weakening the conveyor belt -gt reduce
  oceans ability to absorb carbon dioxide
• With a doubling of CO2 scenario, ocean uptake of
  CO2 dropped by 30 over a 350-yr period

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Marine Ecosystems Marine Fish

• Because climatic factors affect the biotic and
  abiotic elements -gt they influence the numbers
  and distribution of fish species
• What are the abiotic factors?
• Water temperature
• Salinity
• Nutrients
• Sea level
• Amount of sea ice
• And the biotic factors?
• Food availability
• Presence and species composition of competitors
  and predators
• Water temperature directly impacts
• Spawning and survival of larvae and juveniles,
  and fish growth
• Biological production rate -gt food avalability

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Marine Ecosystems Marine Fish

• Variations (with cycles of 10-60 yrs) in the
  biomass volume of marine organisms depend on sea
  temperature and climate
• Eg fishing for cod in the Atlantic Ocean clear
  correlation between water temp and catch
• Thus important to consider the ecosystem impacts
  of climate variations changes for individual
  species

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More on marine fish

• Herrings, sardines and anchovies shortlived
  species that mature at an early age
• Large fluctuations in abundance associated with
  changes in the climate-ocean environment
• Most fishing regime changes can be related
  directly to sea-temperature changes, but changes
  in other physical attributes also can have an
  impact.
• Example a decrease in wind stress o f Tasmania
  that reduced large zooplankton production a ff e
  c ted the density of Jack mackerel, which
  eliminated the possibility of a commercially
  viable mackerel fishery

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• As ecosystems change, there may be impacts on the
  distribution and survival of fishes.
• Any changes in natural mortality would be
  associated with increased predation and other
  factors such as disease.
• Improved growth in the early life stages would
  improve survival, whereas decreased growth could
  facilitate increased mortality.
• cautious acceptance that climate change will have
  major positive and negative impacts on the
  abundance and distribution of marine fish.
• Fishing impacts may be particularly harmful if
  natural declines in productivity occur without
  corresponding reductions in exploitation rates.

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Marine Mammals and Seabirds

• Sensitive indicators of changes in ocean
  environments
• Fluctuations in marine bird and mammal
  populations in the North Pacific may be entirely
  related to climate variations and change
• Climate variations since 1990 overfishing ?
  behavioral changes in killer whales ? reduced sea
  otter abundance ? changed the ecology of the kelp
  forests
• The changes in prey resulting from persistent
  changes in climate appear to be one of the
  important impacts of a changing climate on the
  marine mammals that feed from the top of the food
  chain.
• CC ? effect access to prey among marine mammals
• Eg ice-free seasons in the Arctic ? prolong
  fasting of polar bears
• Reductions in sea ice have been predicted to
  alter the seasonal distributions, geographic
  ranges, migration patterns, nutritional status,
  reproductive success, and ultimately the
  abundance of Arctic marine mammals

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Seabirds

• May consume vast amounts of fish (600,000 t/yr in
  the North Atlantic 20-30 of the annual pelagic
  fish production)
• Hard to distinguish CC from overfishing
• How likely is it to survive? ? depends on its
  ability to alter its migration strategy
• Long lifespans and genetic variation within
  populations enable seabirds to survive adverse
  short-term environmental events,
• However, small populations tied to restricted
  habitat, such as the Galapagos Penguin may be
  threatened by long-term climate warming

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Diseases and Toxicity

• Changes in precipitation, pH, water temperature,
  wind, dissolved CO2, and salinity can affect
  water quality in estuarine and marine waters.
• Some marine disease organisms and algal species
  are strongly influenced by one or more of these
  factors
• increase in reports of diseases affecting closely
  monitored marine organisms, such as coral and
  seagrasses, particularly in the Caribbean and
  temperate oceans
• several viruses, protozoa, and bacteria affected
  by climatic factors can affect people, by direct
  contact or by seafood consumption.
• Example bacterium found in oysters cholera
  epidemics associated with marine plankton

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Coastal Systems

• Existence of many depends on the land-sea
  connection
• Wide range of environmental conditions
• Salinity (fresh to hypersaline)
• Energy (sheltered wetlands to energetic
  wave-washed shorelines)
• Spectrum of climate types tropical to polar
• Exposed to land-source and marine hazards, waves,
  river flooding, shoreline erosion, biohazards
  (algal blooms and pollutants)
• Know Box 6.3 and Box 6.4

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Coastal Systems

• Beaches, Barriers, Cliff Coasts
• More erosion with CC likely changes in wave or
  storm patterns
• What about presence/absence of biotic protection
  such as mangroves?
• Deltaic Coasts (low-lying coastal regions)
• Exposed to potential flooding
• Nile significant land loss can result from wave
  erosion also large portions of the Amazon
• Saltwater intrusion into freshwater aquifers
• Coastal Wetlands
• By 2080, sea-level rise ? loss of 22 of worlds
  coastal wetlands (mangrove forest and salt
  marsh) much already lost
• Tropical Reef Coasts
• More than 25 of all known marine fish food
  source 58 at risk from human activities. Global
  CC could be an additional cause
• Sea-level rise increased carbon dioxide levels
  temperature
• Latest news
• High-Latitude Coasts (ice-rich coasts)

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Latest News

• Based on current model simulations, the
  Meridional Overturning Circulation (MOC) of the
  Atlantic Ocean will very likelyslow down during
  the 21st century nevertheless temperatures over
  the Atlantic and Europe are projected to
  increase.