Florida Sea Level Rise: Past, Present, and Future George A. Maul, PhD Department of Marine and Environmental Systems Florida Institute of Technology Laser Day November 19, 2014

Outline of the Talk Outline of the Talk  Eustatic Historical Sea Level Change  Relative Sea Level (RSL) Change  What is Happening Around Florida?  Global Sea Level Change Today  Projections of Future Sea Level  Questions & (maybe…) Answers

Eustatic Sea Level Over Time Global Sea Level last 24,000 years Maximum rate of rise ~3 feet per century 18,000 ypp

Florida coast 20 and 10 kiloyears before the present Ice Age Mammoth from Melbourne FL

What is Mean Sea Level?  Surveyors define it as the average of the hourly water heights at a tide gauge for 19 years.  Questions: What is a tide gauge? What is a tide gauge? What tide gauge? What tide gauge? Why 19 years? Why 19 years? Which 19 years (epoch)? Which 19 years (epoch)? Captain James Cook’s sea level mark in Tasmania

Measuring Relative Sea Level Typical Tide Gauge Virginia Institute of Marine Science

Calculating Annual Mean Relative Sea Level Key West sea level rose steadily during

Factors Affecting Relative Sea Level Change RSL = Height thermal expansion + Height land motion + Height glacial melt + Height ocean circulation + Height winds + Height barometric pressure + Height tides + Residual We’ll examine each of these next CORS

Thermal Expansion and Ice Sheet Contributions Global estimates from NASA Deep Ocean Thermal Expansion ≈+0.06 feet/century

Like Mathematics? y y x

Vertical Land Motion VLM (ft/cen)MethodSource -0.16±0.52CORSNASA, JPL +0.12±0.60GPSSella et al ±0.16Tide GaugeZervas et al ±0.14ModelsMaul&Martin No statistically significant evidence of Florida VLM Sella et al., ft/cen

Ocean Circulation (increased Florida Current geostrophic velocity v g = lower Florida sea level) ~ 0.01 ft/century

Inverted Barometer Effect (decreasing atmospheric sea-level-pressure = rising sea level) ~ ft/century

RSL Trends at Selected Florida Stations Ensemble Average = 0.73±0.09 feet/century Florida Vertical Land Movement -0.02±0.15 feet/century StationLongitude (°W) Latitude (°N) Trend (feet/century) SE (feet/century) EpochN (years) Cedar Key ± Fernandina Beach ± Key West ± Mayport ± Miami Beach ± Pensacola ± St. Petersburg ± MEAN ± SD 0.73±0.09

Global Sea Level Trend from satellite altimetry global average trend 1.02±0.13 feet/century regional trends in sea level No evidence of Florida sea level falling

Projections for Global Sea Level Rise Maximum rate of rise during last years IPCC projected sea level to 2100 NOAA projected sea level to feet

Projected effect of a 3 foot relative sea level rise on Florida At the current rate of Florida sea level rise of 0.75 feet per century, this will take ~400 years.

Key West Sea Level Revisited No Statistically Significant Evidence of Accelerated Sea Level Rise

Summary  Sea Level Is Always Changing  Complex Measurement Problem Vertical Land Motion Vertical Land Motion Thermal Expansion Thermal Expansion Glacial Melt Glacial Melt  Projections NOAA, IPCC, others NOAA, IPCC, others Key West – no acceleration Key West – no acceleration  Advising Coastal Managers Applying Global Projections Locally Applying Global Projections Locally Coastal Infrastructure Lifetime Coastal Infrastructure Lifetime It is tough to make predictions, especially about the future.