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 * years

Projected Rise

rise_cm = total_rate * years / 10

Projected Rise

rise_inches = total_rate * years / 25.4

Variables

VariableDescriptionDefault
thermal_rateThermal Expansion Rate(mm/year)1.4
ice_melt_rateIce Melt Contribution Rate(mm/year)2.2
yearsProjection Period(years)50
total_rateDerived value= thermal_rate + ice_melt_ratecalculated

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.

thermal_rate = 1.4ice_melt_rate = 2.2years = 50
  1. 01Total rate = 1.4 + 2.2 = 3.6 mm/year
  2. 02Rise over 50 years = 3.6 x 50 = 180 mm
  3. 03In centimeters: 180 / 10 = 18 cm
  4. 04In inches: 180 / 25.4 = 7.09 inches