Sea Level Rise Estimate Calculator Formula
Understand the math behind the sea level rise estimate calculator. Each variable explained with a worked example.
Formulas Used
Projected Rise
rise_mm = total_rate * yearsProjected Rise
rise_cm = total_rate * years / 10Projected Rise
rise_inches = total_rate * years / 25.4Variables
| Variable | Description | Default |
|---|---|---|
thermal_rate | Thermal Expansion Rate(mm/year) | 1.4 |
ice_melt_rate | Ice Melt Contribution Rate(mm/year) | 2.2 |
years | Projection Period(years) | 50 |
total_rate | Derived value= thermal_rate + ice_melt_rate | calculated |
How It Works
Estimating Sea Level Rise
Sea level rise comes from two main sources: thermal expansion of warming ocean water and meltwater from glaciers and ice sheets.
Formula
Total Rise (mm) = (Thermal Rate + Ice Melt Rate) x Years
Current observations show about 3.6 mm/year of total rise, with the rate accelerating. Thermal expansion accounts for roughly 40% and ice melt for 60%.
Worked Example
Thermal expansion adds 1.4 mm/year and ice melt adds 2.2 mm/year. Project 50 years forward.
- 01Total rate = 1.4 + 2.2 = 3.6 mm/year
- 02Rise over 50 years = 3.6 x 50 = 180 mm
- 03In centimeters: 180 / 10 = 18 cm
- 04In inches: 180 / 25.4 = 7.09 inches
Frequently Asked Questions
Is this a linear projection?
This calculator uses a linear rate, but actual sea level rise is accelerating. Satellite data show the rate has increased from about 2.5 mm/year in the 1990s to over 4 mm/year today.
What is thermal expansion?
As ocean water absorbs heat, it expands in volume. This thermal expansion has been the largest contributor to sea level rise historically, though ice melt is now dominant.
How much would seas rise if all ice melted?
If all land ice melted, seas would rise approximately 65 meters (213 feet). The Greenland ice sheet alone holds about 7.2 meters of potential rise.
Ready to run the numbers?
Open Sea Level Rise Estimate Calculator