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.
