Climate Change and the Ocean

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Climate Change and the Ocean
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The Greenhouse Effect
http//www.ucar.edu/learn/images/gheffect.gif
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Global Warming

• Increase in the average temperature of the
  biosphere

http//meteo.lcd.lu/globalwarming/hockey_stick/man
n_hockeystick.jpg
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Increase in Average Temperature

• The average temperature worldwide is 58?F
• 5 increase means
• Only 1-2? at the Equator
• More than 12 at the North Pole

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What causes Global Warming?

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The Carbon Cycle
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http//gis1.ucsc.edu/ericw/co2percap1998p.gif
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Visual of rising temperatures and CO2
concentrations from An Inconvenient Truth
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Threats to the OceanRelated to Global Warming

• Changes in sea surface temperatures
• Melting Polar Ice Caps
• Coral Bleaching
• Thermohaline Circulation
• Extra CO2
• Rising Sea Level

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Seawater Chemistry

• Ionic Bond-attraction between ions that have
  opposite charge
• Ionic bonds between Cl and Na
• Sodium and chloride are the two most abundant
  ions

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Properties of Water

• Water is densest at 4?C
• Hot water floats and cold water sinks
• Ice floats
• Surface tension makes water sticky
• Up-wellings

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Polar Molecule

• Water is a polar molecule
• It has a negative side and a positive side
• This allows water to easily dissolve ionic
  compounds

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http//news.nationalgeographic.com/news/2006/09/06
0914-arctic-ice.html
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Positive Feedback
http//forces.si.edu/arctic/02_02_00.html
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The Arctic Ocean could be ice free in summer by
2050.

• Arctic Climate Impact Assessment. 2004. Impacts
  of a Warming Arctic. Cambridge, UK Cambridge
  University Press.

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The number of Category 4 and 5 hurricanes
has almost doubled in the last 30 years.

• Emanuel, K. 2005. Increasing destructiveness of
  tropical cyclones over the past 30 years. Nature
  436 686-688

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http//www.fws.gov/home/hurricane/katrina-nasa.jpg
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http//www.ci.huntington-beach.ca.us/images/users/
fire/Hurricane20Katrina20Response3.jpg
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Coral Reefs in Danger

• 2005, the hottest year on record
• Massive loss of coral reefs
• 1998, 2nd hottest year on record, lost 16 of
  coral reefs
• Coral bleaching occurs when little, colorful
  algae living within the coral are stressed by
  heat and other factors. They are then forced to
  evacuate and this reveals the colorless calcium
  carbonate skeleton.
• Pollution, dynamite fishing practices, more
  acidic ocean watersbut rising ocean temperatures
  is causing the most damage.

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The link between global warming and large-scale
bleaching of corals, considered controversial
only 10 to 15 years ago, is now universally
accepted.
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Acid-Base Balance
An acid is a substance that releases a hydrogen
ion (H) in a solution. Acidity is caused by an
excess of H ions. A base is a substance that
combines with a hydrogen ion (H) in solution.
Alkalinity is caused by an excess of OH-
(hydroxide) ions. The acidity or alkalinity of a
solution is measured by the pH scale.
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The pH Scale
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pH of Seawater
The ocean has an average pH of 8.0, meaning it is
slightly alkaline. Note that the pH of seawater
varies slightly with depth.
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Dissolved Gases in Sea Water

• Gases dissolve more readily in cold water than
  in warm water.
• O2 and CO2 levels are controlled mostly by the
  activity of living things.
• N2, O2 and CO2 - most common gases in seawater
• Photosynthesis by plants and phytoplankton
  produces oxygen and uses up carbon dioxide.
• Respiration by animals, bacteria, and other
  organisms produces carbon dioxide and uses up
  oxygen.

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Dissolved Gases in Seawater

• The figure shows how O2 and CO2 levels vary with
  depth.
• Photosynthesis by plants at the ocean surface
  causes high levels of O2 and low levels of CO2.
• Below the surface where there is not enough light
  for plants, respiration by animals causes lower
  levels of O2 and higher levels of CO2.

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Increasing CO2 Concentrations

• 33-50 of CO2 emissions sink into the ocean where
  it converts to calcium carbonate
• CO2 turns into carbonic acid which changes the pH
  of the ocean.
• Increases the acidity of the water and slows down
  calcification
• Could cause the ocean to be more acidic than the
  last 800,000 yrs
• Reduces the ability to absorb more CO2
• Impact on organisms with shells, plankton, coral
  reefs?

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Al Gore on Ocean Acidification
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More than a million species worldwide could be
driven to extinction by 2050.

• Time Magazine, Feeling the Heat, David Bjerklie,
  March 26, 2006

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http//www.spiegel.de/img/0,1020,29758,00.jpg
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Polar bears and climate change from Planet Earth

• http//www.youtube.com/watch?vqpob8_jAyVU

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http//www.geekculture.com/joyoftech/joyimages/956
.gif
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What causes currents?

• Wind (surface currents)
• Salinity
• Temperature
• Gravity
• Topography
• Earths rotation

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Salinity

• The total quantity of dissolved inorganic solids
  in water.
• The most abundant dissolved solids are chloride,
  sodium, and sulfate.

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Salinity

• Oceanographers more commonly measure salinity as
  parts per thousand (ppt)
• In the ocean the average is around 35 ppt
• Measured using a refractometer

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http//www.bgrg.org/pages/education/alevel/coldenv
irons/Gulf20Stream20Map201.gif
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European Ice Age

• 10,000 years ago, when the last glacial ice sheet
  in North America melted, it formed a giant pool
  of fresh water (forming the Great Lakes) It was
  held in place by a giant ice dam.
• The ice dam broke and the freshwater rushed into
  the Atlantic. This caused the Gulf Stream to stop
• Europe no longer received all of the heat from
  the evaporating Gulf Stream and went into an ice
  age for 900-1000 years.
• Scientists concerned about the rapid melting of
  ice in Greenland

http//www.whoi.edu/page.do?pid12455tid282cid
17906
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Local Issues

• Warmer sea water pushes cod and lobster north to
  cooler waters.
• In 2005, NH brought in more than 14 million in
  lobster and 1.9 million in cod
• Concern about NHs coastline
• Concord Monitor July 12, 2007

http//www.dirnat.no/multimedia.ap?id32407
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Salt Marshes

• Sea level change of 2 feet would inundate New
  Hampshires salt marshes and beaches

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Sea Level Prediction of IPCC

• In the Intergovernmental Panel on Climate
  Changes most recent report they predict
• Sea level rise between 19-58 centimeters by 2100
• But many scientists argue that this is an
  underestimate
• Many think that the sea-level rise will be close
  to the worse-case predictions

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Global sea levels could rise by more than 20
feet with the loss of shelf ice in Greenland and
Antarctica, devastating coastal areas worldwide.

• Washington Post, "Debate on Climate Shifts to
  Issue of Irreparable Change," Juliet Eilperin,
  January 29, 2006, Page A1.

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How can we influence climate change with the
choices we make everyday?
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Homework assignmentDue Tuesday

• What havent we talked about? Research an
  additional threat to the ocean because of climate
  change that wasnt mentioned in class.
• Please summarize your ocean threat in a paragraph
  and cite the resource that you used.