APES 9.4 Increases in the Greenhouse Gases

Sea Level Rise

  • Causes of Sea Level Rise:

    • Thermal Expansion: Water molecules expand when heated, causing ocean levels to rise as temperatures increase due to greenhouse gases.

    • Melting Polar and Glacial Ice: Increased temperatures cause ice sheets and glaciers to melt, contributing additional water to the oceans.

Visualizing Sea Level Changes

  • Graph Analysis:

    • Graph from NASA shows global sea level rise since 1993, with over 8 cm increase attributed to thermal expansion and meltwater.

    • Even slight sea level increases can significantly impact coastal populations and ecosystems.

Environmental Impacts of Rising Sea Levels

  • Flooding Coastal Ecosystems:

    • Estuaries, salt marshes, and mangroves are at risk as ocean levels rise, leading to loss of biodiversity and disruption of commercial fishing.

    • Flooded ecosystems convert to open ocean, leading to habitat loss.

  • Loss of Polar and Arctic Ecosystems:

    • Warming disproportionately affects polar regions, decreasing habitat for species like polar bears and reindeer, leading to reduced biodiversity.

    • The freeze-thaw cycle of glaciers is vital for water supply in surrounding ecosystems, and its loss disrupts both ecological and human water access.

  • Example of Glacier Loss:

    • Visual comparison of glacial cover in Alaska from 1941 to 2004 demonstrates significant decrease, impacting local ecosystems.

Human Impacts of Sea Level Rise

  • Relocation of Coastal Communities:

    • Increased flooding risks force communities to move inland, particularly in vulnerable areas like New Orleans.

    • The rise in sea levels necessitates expensive infrastructure improvements to defend against flooding.

  • Increased Flood Frequency and Severity:

    • Flooding leads to property damage, heightened insurance costs, and community displacement.

  • Saltwater Intrusion:

    • Rising sea levels increase pressure on the freshwater table, allowing saltwater to contaminate drinking water supplies and impact agriculture.

  • Creation of Refugees:

    • Coastal residents may become refugees, facing emotional and economic hardships as they relocate from their flooded homes, particularly in less developed nations.

Disease Vectors and Public Health

  • Definition of Disease Vectors:

    • Organisms, such as mosquitoes and ticks, that transmit diseases.

    • Examples include malaria, Zika virus, and dengue fever.

  • Expansion of Disease Vector Range:

    • Global warming allows vectors to move into previously unsuitable colder regions; increased temperatures enable their survival further from the equator.

Mosquito Range Projections

  • Current vs. Projected Range:

    • Map analysis of Aedes aegypti mosquito highlights expanded survival range by 2080 due to climate change, increasing risk for regions previously unharmed by these diseases.

    • Some equatorial areas may become too hot and lose mosquito populations, creating a complex landscape for disease transmission.

Impact of Climate Goals on Vector Range

  • Comparative Maps of Disease Vectors:

    • Meeting the Paris Agreement limits range expansion of disease vectors.

    • Failing to meet these goals could lead to widespread disease in areas of the world that previously had no exposure.

Malaria Projections by 2050

  • Map Analysis of Malaria Suitability:

    • Identification of potential regions for increased malaria rates by 2050 based on climate change influences.

    • Understanding climate's role in shifting mosquito distribution and malaria risks will be a focus of FRQ practice.