1. What causes sea level to change?
Unit 2: Part 1

2. Sea level has changed a lot throughout Earth’s history:
Modified from:
In groups, brainstorm about processes that cause sea level to change (you should think of at least four).

3. Processes that cause sea level to change:

4. Which process do you think is currently causing the most sea level rise?
Changes in terrestrial water storage
Subsidence in coastal regions
Ocean circulation changes
Warming ocean causing water to expand
Melting of glaciers and ice sheets

5. Which process do you think is currently causing the most sea level rise?
Changes in terrestrial water storage
Subsidence in coastal regions
Ocean circulation changes
Warming ocean causing water to expand
Melting of glaciers and ice sheets

6. Estimated contributions vs. observed rates of sea level rise
Thermal expansion currently accounts for roughly half of the observed sea level rise;
While Greenland and Antarctica have the potential to contribute substantial amounts of ice (around 120m of global sea level if they both completely melted), their current contribution is dwarfed by small mountain glaciers and ice caps;
Sea level rise that is measured with satellites and tide gauges is larger than the sum of the components. This discrepancy highlights the need for additional measurements!
Author: Hugo Ahlenius, UNEP/GRID-Arendal

7. While sea level changes are global, local geologic controls cause large differences in measurements.
We will learn about these local differences throughout the module.