L10_Water Resources Ocean Currents

Water Resources Overview

  • Covers both freshwater and ocean currents, important aspects of environmental science.

Freshwater Resources

Distribution of Water on Earth

  • Freshwater constitutes only about 2.5% of the Earth's total water supply.

  • Most freshwater is either:

    • Locked in ice (glaciers)

    • In the ground (groundwater)

  • Only 1% of freshwater is readily available in surface water (lakes and rivers).

Changes Over Time

  • The total amount of water on Earth has remained constant over nearly 5 billion years.

  • Water exists in different forms but is not created anew; its cycle is what changes.

Climate Change Impacts

  • Climate change affects freshwater distribution leading to:

    • Altered precipitation patterns.

    • Variability in water availability, particularly in areas reliant on snowmelt.

Ocean Currents

Fundamentals of Ocean Currents

  • Winds drive surface ocean currents in the upper 100 meters.

  • Currents also exist at varying depths, influencing global climate and weather patterns.

Effects of Global Warming

  • Increased rainfall and melting ice add freshwater to oceans, disrupting natural salinity and current formation.

  • Sea surface salinity decrease makes water less dense, therefore less able to sink, affecting currents like the Atlantic Meridional Ocean Circulation (AMOC).

AMOC Importance

  • AMOC shifts can alter weather patterns, affecting agriculture and regional climates.

  • Ongoing research indicates potential weakening of AMOC due to climate change.

Ocean Acidification

Causes and Effects

  • Rising CO2 levels from fossil fuel combustion increase ocean acidity, affecting marine ecosystems.

  • Important marine species (like corals and shellfish) rely on carbonate ions for shells, which diminish in acidic waters.

Economic Impact

  • The fishing industry significantly relies on healthy oceans; for example:

    • The West Coast fishing sector in the U.S. is valued at $35.2 billion annually.

    • Ocean acidification directly threatens this industry by impacting key species like Dungeness crab.

Global Freshwater Challenges

Water Scarcity

  • One billion people lack access to safe drinking water.

  • 70% of freshwater is used for agriculture in water-scarce regions.

Climate Change Consequences

  • Projected declines in terrestrial water storage (1 cm/year) threaten global water security.

  • Salinization of groundwater levels will escalate due to rising sea levels, impairing freshwater availability in coastal areas.

Future Projections

  • Intricate connection between climate change and water distribution:

    • Wet regions getting wetter and dry regions getting drier (per IPCC).

    • Increasing evaporation rates and altered rainfall patterns worsen water resource challenges.