booklet 2 - global water stores and changes

• Where is most of the Earth's water stored?

  In the ocean
• What percentage of all water is stored in the ocean?

  97%
• What percentage of Earth's freshwater is locked up in ice caps and glaciers?

  70%
• How much ice is stored in ice caps and glaciers?

  Approximately 26,300 thousand km³
• What percentage of freshwater is easily accessible surface water?

  1%
• Where is the majority of easily accessible freshwater found?

  In lakes
• What percentage of freshwater is found in soil?

  3%
• What percentage of freshwater is found in the atmosphere as water vapor?

  8%
• What percentage of freshwater is groundwater?

  20%
• Why is groundwater important?

  It forms aquifers
• Where are aquifers typically found?

  In porous permeable rocks
• What are fossil aquifers?

  Ancient aquifers formed in wetter climates
• Why are many aquifers being exploited unsustainably?

  For irrigation needs
• In which regions are aquifers and groundwater stores found?

  Africa, Middle East, Australia
• In how many forms does water exist on Earth?

  Three forms
• What are the three forms of water?

  Liquid, solid, gaseous
• What is evaporation?

  Liquid water changes to gas from solar energy
• What factors affect evaporation?

  Solar energy, water availability, humidity, temperature
• What is condensation?

  Air cools and excess water vapor converts to liquid
• What do water molecules require to condense?

  Surfaces below dew point temperature
• What is sublimation?

  Solid water transitions to gas without liquid
• What is deposition?

  Water vapor becomes solid without liquid state
• When does condensation occur?

  When air cools to dew point or volume increases
• How does latent heat relate to evaporation and condensation?

  Evaporation uses latent heat, cooling surroundings
• What is the impact of global warming on the cryosphere?

  Less ice due to melting, rising sea levels
• What happens to glaciers due to global warming?

  They melt faster, causing flooding
• What is the impact of global warming on the hydrosphere?

  Increased flooding and coastal erosion
• How does global warming affect evaporation rates?

  Increased evaporation regulates sea level rise
• What is the impact of global warming on the atmosphere?

  More intense precipitation due to warmer air
• How much more moisture can the atmosphere hold for every 1°C increase?

  7% more moisture
• How does warming affect underground water stores?

  They take longer to absorb surface water
• What has recent warming done to cryospheric stores?

  Caused glaciers to shrink and retreat
• What would complete melting of polar ice sheets result in?

  60m sea level rise
• What percentage of Greenland's ice is two miles thick?

  80%
• How has the amount of water on the Greenland ice sheet changed?

  Doubled in 50 years
• How do lakes contribute to glacier melting?

  Lakes absorb heat from the sun
• What effect does meltwater have on glaciers?

  It accelerates their movement
• How much has the Helheim glacier retreated in one year?

  Two miles
• What is Greenland's largest source of sea level rise?

  Melting ice
• What happens to the surface of Greenland as ice melts?

  It darkens, increasing albedo rate