Session 2: Know your subject

By the end of this session participants will be able to:

  • Understand the various systems that interact on planet Earth.
  • Explore the role of the Ocean in the context of the other systems on Earth.
  • Understand sea salinities with regard to geographical contexts through analysis of diagrams.

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(MyNASAData, 2023)

(MyNASAData, 2023)

The ocean plays a central role in the redistribution of heat energy from the tropics to the polar regions. The key drivers of the movement of the ocean are winds, tides, the Earth’s rotation, and the relationships between the temperature, salinity, and density of the ocean’s water.

In the ocean, there is a complex interplay between the temperature, salinity, and density of the ocean’s water. As a result, the highest surface salinities occur in the middle of ocean basins, where the evaporation rate is high, and the rainfall rate is low. Low salinity areas are often near sources of fresh water, such as major rivers and melting ice. Sea surface movement is greatly affected by winds.

(ES) Activity 1: Research

Research Activity

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Ocean Climate

Deep density-driven currents move like rivers along underwater valleys towards the deepest parts of the ocean. The cold, saline waters that drive the thermohaline circulation form near the poles. In the north, the topography of the sea floor channels the dense water southwards to join with the sinking waters of the Southern Ocean. Blocked by a shallow ocean floor to the west, the thermohaline circulation turns to the east and splits. One branch flows up the east coast of Africa into the Indian Ocean, while the other continues east along the south coast of Australia and then north into the Pacific basin.

The thermohaline circulation plays an important role in redistributing heat from the tropics to the polar regions. As a result, it influences the rate of sea ice formation near the poles, which in turn affects other aspects of the climate system such as the albedo. The fact that water makes this long trip in the depths of the ocean, far from the influence of surface water and contact with the atmosphere, means that there is a lag time between climate forcings and our planet’s reactions to them. Heat and dissolved carbon dioxide, carried to the ocean’s depths by the thermohaline circulation, may remain “buried” for centuries, delaying and hiding the initial effects of global climate change.

Reading: Useful website: http://www.csir. co.za/nre/coasts_and_oceans/osc.html.  The CSIR’s Southern Ocean Carbon and Climate Observatory studies the patterns in the Southern Ocean in order to establish how it operates as a carbon sink or source.

Engage on the course forum

The polar albedo feedback loop:

To understand how these amplifiers work, here is a video of the end of a glacial maximum when large ice sheets in the northern hemisphere melt rapidly.
Extended Readings

http://oceanservice.noaa.gov/education/literacy/ocean_literacy.pdf The National Oceanic and Atmospheric Administration Ocean Service Education website has information for teachers including this pdf called Ocean Literacy and Learner Activities.

http://www.exploratorium.edu/ifi/workshops/fundamentals/ A series of workshops to introduce teachers to inquiry.

http://www.discoveringantarctica.org.uk/alevel_1_2.html Discovering Antarctica education website.

http://cleanet.org/resources/41833.html Climate Literacy and Energy Awareness Network has resources for the classroom including the ‘Understanding Albedo’ experiment.

http://svs.gsfc.nasa.gov/vis/a010000/a011200/a011244/Arctic_sea_ice_max_2013_ipod_ sm.mp4 This NASA video has current information regarding Arctic ice sheet information.

Climate Change Amplifiers

To make matters even more complicated, the Earth has a 41,000-year “wobble cycle” on its axis, changing the amount of energy received from the sun at the poles. Dramatic climate change results as we swing from periods of large quantities of ice cover over Earth (glacial maximums) to warmer periods of less ice coverage (inter-glacial periods). The diagram below shows the cycle of ice ages.

Temp and CO2 Graph

Source: CCHEAP Resources (2008), Schools Development Unit and DEADP, developed from Vostok Ice Core Data, NOAA National Climatic Data Center, 1998. http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html (Open Access to Data)

ES - Activity 2: Respond and Reflect

Extended Readings Related to Earth Systems

Click the links below to access readings related to the Earth Systems:

http://oceanservice.noaa.gov/education/literacy/ocean_literacy.pdf The National Oceanic and Atmospheric Administration Ocean Service Education website has information for teachers including this pdf called Ocean Literacy and Learner Activities.

http://cleanet.org/resources/41833.html Climate Literacy and Energy Awareness Network has resources for the classroom including the ‘Understanding Albedo’ experiment.

http://svs.gsfc.nasa.gov/vis/a010000/a011200/a011244/Arctic_sea_ice_max_2013_ipod_ sm.mp4 This NASA video has current information regarding Arctic ice sheet information.