ga-alevel-wc-geography-matters-carbon-cycle-bundle

GA Post-16 and HE Phase Committee

  • The Carbon Cycle articles compiled for the Geography Matters newsletter to assist teachers in A-level planning (2016).

  • Full content available at: www.geography.org.uk/cpdevents/curriculum/geographymatters

Contents Overview

  1. Starting to teach the carbon cycle – Helen Hore (2015)

  2. Climate change and development in the Tonlé Sap Region, Cambodia – Emma Rawlings Smith (2015)

  3. Iceland – innovations in green energy production – Emma Rawlings Smith (2014)

  4. Global climate change and water supplies: the winners and losers – Emma Rawlings Smith (2010)

Starting to Teach the Carbon Cycle (Helen Hore, 2015)

  • Importance: An essential topic in Geography A Level linked to the water cycle.

  • Key Content:

    • Distribution and size of major carbon stores: Land, oceans, and atmosphere.

    • Driving factors changing the magnitude and cycling processes within carbon stores.

    • Climate context exploring links between carbon and water cycles.

  • Significance for Students:

    • Understanding these cycles aids in evaluating conflicting media views on climate change and carbon manipulation.

    • Relevant current topics include Japan's drilling for offshore methane hydrates, linking geography and environmental issues.

Global Stores and Transfers of Carbon

  • Starting Point for Discussion:

    • Introduce carbon stores (reservoirs) and transfers (fluxes), utilizing prior science knowledge.

  • Figures:

    • Major carbon stores (in Gtons) include:

      • Atmosphere: 720 (CO2, CH4)

      • Ocean Surface: 620 (dissolved CO2)

      • Ocean Deep: 36,730 (dissolved CO2, CaCO3)

      • Lithosphere: >60,000,000 (CaCO3 in limestone)

      • Biosphere (living): 600-1,000 (sugars, starches)

      • Dead Organic Matter: 1,200 (soil humus)

      • Fossil Fuels: 4,000 (hydrocarbons)

  • Volume of Transfers:

    • Photosynthesis: 120 Gt/year

    • Respiration: 120 Gt/year

    • Emissions from human activities: 9 Gt/year

    • Increases (red numbers) in CO2 due to human activity highlighted.

Natural Processes in the Carbon Cycle

  • Variability in Carbon Stores:

    • Residence time varies: Fast carbon cycles (minutes/hours) vs. slow cycles (millennia).

  • Rapid Cycles:

    • Carbon recycled quickly through atmospheric exchanges and photosynthesis; biomass stores carbon.

  • Slower Cycles:

    • Decomposition processes recycle carbon into soil; natural wildfires can release carbon quickly.

  • Very Slow Cycles:

    • Burial and weathering processes release CO2 from sediments over millions of years:

      • Fossil fuels result from anaerobic conditions; formation involves woody material and planktonic matter.

  • Carbon Sources:

    • Volcanoes also contribute CO2 emissions, albeit much less than fossil fuel combustion.

    • Methane hydrates as a significant and stable reservoir.

Human Processes Impacting Carbon Cycle

  • Deforestation:

    • Alters global carbon biomass; the difficulty in estimating CO2 release post-regrowth.

  • Energy Use:

    • Fossil fuel combustion remains the primary contributor to increased atmospheric carbon.

    • Historical data on CO2 emissions illustrates growth from 5.5 billion tons in the 1980s to 8.7 billion in 2008.

  • Inquiry Starting Point:

    • Consider in teaching: "What part do people play in the carbon cycle?"

Teaching Tools

  • Explore relational maps between carbon stores and flows.

  • Discuss overlapping roles of hydrosphere, biosphere and lithosphere using time scale comparisons.

  • Use scenario questions to generate discourse about human activity and climatic impacts.

References

  • Several resources listed for further exploration on the carbon cycle and associated research.