Global Warming Threatens Water Systems and Coastal Stability
Melting Ice Caps and Thermal Expansion Drive Sea-Level Rise
- As polar ice melts and glaciers shrink, freshwater is released into the oceans, raising sea levels.
- Warmer waters expand, amplifying sea-level rise through thermal expansion.
The Greenland Ice Sheet alone loses about 280 billion tonnes of ice annually, contributing significantly to global sea level rise.
Common Mistake- Melting sea ice (like Arctic ice) does not contribute significantly to sea-level rise, as it is already floating.
- Only melting land ice (e.g., glaciers and ice sheets) adds to sea levels.
Flooding Threatens Coastal and Island Communities
- Rising seas endanger millions in low-lying areas, with the risk of losing entire islands or regions to submersion.
- Coastal flooding increases the demand for infrastructure like levees and relocation programs.
Kiribati is A Nation at Risk of Submersion
- Kiribati is a low-lying island nation in the Pacific Ocean that faces severe threats from rising sea levels caused by climate change.
- With much of its land sitting less than 2 meters above sea level, the country experiences frequent coastal flooding, saltwater intrusion into freshwater supplies, and the erosion of arable land.
- To address these challenges, the government has invested in seawalls and coastal protection but faces significant financial and technical limitations.
- In 2014, Kiribati purchased land in Fiji as a potential relocation site for its population, highlighting the drastic measures required to combat rising seas.
Water Cycle Intensifies, Increasing Flooding and Droughts
- Rapid hydrological cycles bring both heavier rainfall and prolonged dry spells, disrupting water availability.
- Flooding damages infrastructure, while water scarcity threatens human and agricultural needs.
Changes in Carbon Storage
Reduced Absorption by Oceans
- The oceans absorb about 25% of human-produced $CO_2$, but this ability is declining due to ocean acidification and rising water temperature.
- When $CO_2$ dissolves in seawater, it forms carbonic acid, lowering the pH of the ocean.
- Moreover, less $CO_2$ can be dissolved in warmer water.
Since 1750, the ocean's pH has dropped by 0.1, representing a 30% increase in acidity.
Why does this matter?
- Acidification reduces the availability of carbonate ions, which are essential for shell-building organisms like corals and mollusks.
- As these organisms struggle, entire marine ecosystems are at risk.
- Think of the ocean as a sponge soaking up $CO_2$.
- As the sponge becomes saturated, it absorbs less, leaving more $CO_2$ in the atmosphere to contribute to global warming.
Extreme Weather Events Are Occurring at a Higher Frequency and Intensity
- Climate change is driving more frequent and severe weather events, including hurricanes, droughts, wild fires, and heatwaves.
- This occurs because of:
- Warmer Atmosphere: Higher temperatures bring heatwaves and increase the probability of wild fires. On the other hand, warmer atmosphere holds more moisture, leading to heavier rainfall and flooding.
- Warmer Oceans: Warmer water provides more energy for tropical storms.
- Changes in Ocean Currents: Altering ocean currents due to temperature and salinity changes can lead to irregular weather patterns, such as El Niño and La Niña effects, causing extreme weather events globally.
- Shifts in Jet Streams: Changes in temperature gradients can alter the behavior of fast-flowing air currents in the atmosphere. A more meandering jet stream can lead to prolonged weather patterns, causing extended heatwaves or persistent rainfall in certain areas.
Hurricane intensity has increased due to warmer ocean temperatures providing more energy for storms and intensified evaporation increasing the amount of moisture in the air and leading to heavier rainfalls.
Impacts on Human and Natural Systems
- Agriculture: Droughts reduce crop yields, while floods destroy farmland.
- Infrastructure: Extreme weather damages roads, bridges, and buildings, leading to costly repairs.
- Biodiversity: Heatwaves and storms disrupt ecosystems, threatening species survival and forcing certain species to migrate.
| Feature | Impact |
|---|---|
| Ice and Snow | Loss of polar ice and glaciers reduces albedo and freshwater availability |
| Rising sea level | Rising seas increase coastal flooding and force relocation of communities |
| Water Cycle | Faster circulation leads to more extreme weather events: storms, flooding and droughts |
| Ecosystems | Species migration (shift towards poles and to higher altitudes) or habitat loss alter biodiversity |
| Agriculture | Farming becomes more vulnarable; new, more resistant crop varieties have to be introduced; food supply is altered |
| Human Health | Warmer climates heighten disease risks like malaria |
When analyzing extreme weather events, consider both their immediate impacts and long-term consequences, such as economic losses or ecosystem degradation.
Theory of Knowledge- How do cultural and economic factors influence our responses to rising sea levels or extreme weather events?
- Consider the ethical implications of climate adaptation strategies.
