Global mean sea level rise

Definition

Global mean sea level rise refers to the average increase in the world's oceans' surface level due to factors such as melting ice sheets, thermal expansion of seawater, and the contributions from glaciers. This phenomenon is closely linked to climate change, as the warming climate accelerates these processes, leading to significant implications for coastal communities, ecosystems, and weather patterns.

5 Must Know Facts For Your Next Test

1. Global mean sea level has been rising at an average rate of about 3.3 millimeters per year since the early 1990s, with this rate accelerating in recent years.
2. Melting glaciers and polar ice sheets account for a significant portion of sea level rise, with Greenland's ice sheet alone contributing around 0.7 mm per year.
3. Thermal expansion contributes to roughly half of the observed sea level rise as warmer ocean waters expand, increasing overall sea levels.
4. Projections suggest that if current trends continue, global mean sea levels could rise by 1 to 2 meters by the end of the century, significantly impacting coastal regions worldwide.
5. Higher sea levels increase the risk of flooding during storms and high tides, threatening infrastructure, ecosystems, and freshwater supplies in coastal areas.

Review Questions

• How does thermal expansion contribute to global mean sea level rise?
  • Thermal expansion occurs when water warms up and increases in volume. As global temperatures rise due to climate change, ocean waters absorb heat and expand, which contributes significantly to the overall rise in sea levels. This process is a major factor in the observed increase in global mean sea level alongside melting ice sheets.
• Discuss the impact of melting ice sheets on global mean sea level rise and how this relates to climate change.
  • Melting ice sheets are a critical contributor to global mean sea level rise. As temperatures continue to rise due to climate change, large ice masses in Greenland and Antarctica are losing their structural integrity and discharging freshwater into the oceans. This process not only raises sea levels but also reflects broader changes in our climate system, indicating that warming temperatures have far-reaching effects beyond just atmospheric conditions.
• Evaluate the potential socio-economic consequences of projected global mean sea level rise for coastal communities by the end of this century.
  • Projected global mean sea level rise poses severe socio-economic consequences for coastal communities. As sea levels could rise by 1 to 2 meters by the end of this century, many areas may face increased flooding, loss of land, and damage to infrastructure. Additionally, these changes threaten freshwater supplies due to saltwater intrusion and can lead to displacement of populations, increased costs for disaster recovery, and greater challenges for local economies reliant on tourism or fisheries. Such impacts highlight the urgent need for adaptive strategies and policies to mitigate risks associated with climate change.

Related terms

Thermal Expansion: The increase in water volume that occurs when water heats up, contributing to sea level rise as global temperatures increase.

Ice Sheet Melting: The process by which large masses of ice, particularly in Greenland and Antarctica, lose mass due to rising temperatures, adding freshwater to the oceans and contributing to sea level rise.

Coastal Erosion: The wearing away of land along the coastlines, often exacerbated by rising sea levels and increased storm intensity, leading to loss of land and habitat.