Earth's Life Support Systems

• What is the role of water in supporting life?

  It provides a medium for organic molecules
• How does water contribute to the formation of complex structures?

  By allowing organic molecules to mix
• What effect do oceans have on temperatures on Earth?

  They moderate temperatures by absorbing heat
• How do clouds influence surface temperature?

  They reflect solar radiation and lower temperature
• What is the role of water vapor in the atmosphere?

  It is considered a greenhouse gas
• What are the thermal properties of water that support life on Earth?

  • Oceans moderate temperatures by absorbing heat, store heat and release it slowly
  • Reflects solar radiation through clouds
  • Water vapor acts as a greenhouse gas
• What percentage of living organisms is made up of water?

  65-95%
• How do plants use water in their food manufacturing process?

  Through photosynthesis, transpiration, and respiration
• What role does water play in animals and humans?

  It serves as a medium for chemical reactions
• Why is water essential for economic growth?

  It is vital for electricity generation and irrigation
• What are the main uses of water for flora, fauna, and people?

  • Constituent of living organisms (65-95%)
  • Food manufacturing in plants (photosynthesis, transpiration, respiration)
  • Medium for chemical reactions in animals and humans
  • Essential for economic growth (electricity generation, crop irrigation)
• What is the significance of carbon to life on Earth?

  Carbon is essential for life processes
• Where is carbon stored on Earth?

  In carbonate rocks, sediments, water, atmosphere, biosphere
• What are some economic resources that use carbon?

  Fossil fuels
• How does agriculture relate to carbon usage?

  Agriculture uses large amounts of carbon
• What are the main components of the global water cycle?

  • Atmosphere
  • Oceans
  • Land
• What type of systems are the water and carbon cycles on a global scale?

  Closed systems between atmosphere, biosphere, oceans, land
• What processes move water between stores in the water cycle?

  Precipitation, evapotranspiration, run-off, groundwater flow
• What does the global carbon cycle consist of?

  • Long-term stores
  • Flows of carbon
• Where is the majority of carbon stored on Earth?

  In sedimentary rocks
• What percentage of all carbon on Earth is held in sedimentary rocks?

  99.9%
• What are the main pathways between carbon stores?

  • Photosynthesis
  • Respiration
  • Oxidation (decomposition and combustion)
  • Weathering
• What does the global water cycle link to?

  Reservoirs where water is stored
• What percentage of all water on the planet is contained in the ocean?

  97%
• What proportion of freshwater is frozen?

  Three quarters
• How much of all freshwater is stored underground in permeable rocks?

  ⅕ of all freshwater
• What is the average residence time of water in the atmosphere?

  9 days
• What is the annual water budget of the global water cycle?

  505,000 km³ of water
• What processes contribute to the inputs of water to the atmosphere?

  • Water vapor evaporates from oceans, lakes, rivers, and soils
  • Vapor transpired through the leaves of plants
  • Combined process is called evapotranspiration
• How does moisture leave the atmosphere?

  As precipitation and condensation
• What processes release water from ice sheets, glaciers, and snowfields?

  Ablation (melting and sublimation)
• Where does most river water flow into?

  Oceans
• How does a large amount of precipitation reach rivers?

  After infiltration into the soil
• What happens to water after it infiltrates the soil?

  It may percolate into permeable rocks or aquifers
• What eventually happens to groundwater?

  It reaches the surface and contributes to runoff
• What does the global carbon cycle consist of?

  A number of sinks and flows
• What are the largest carbon stores?

  Carbonate rocks and deep-ocean sediments
• What are the two strands of the carbon cycle?

  The slow carbon cycle and the fast carbon cycle
• What characterizes the slow carbon cycle?

  • Carbon stored in long-term sinks for millions of years
  • Circulates between 10 and 100 million tonnes a year
  • Typical residence time is around 150 million years
  • Carbon-rich sedimentary rocks can vent during volcanic eruptions
  • Erosion or tectonic movement can expose carbon-rich rocks
  • Partly decomposed organic material can form carbonaceous rocks like coal
• What is the typical residence time for carbon in the slow carbon cycle?

  Around 150 million years