U.S. East Coast Sea Level Acceleration: Recent Evidence from Tide Gauges

John BoonVirginia Institute of Marine ScienceGloucester Point, Virginia 23062

Sea Level Trends: GMSL vs. RMSL

1952

New York (The Battery), NY 1893-2011 (N = 119 yrs)

Trend Estimate: 2.97 ± 0.09 mm/yr

Linear Trend: Trend estimate from a fitted mmsl* time series of fixed length N

* monthly mean sea level (seasonal cycle removed)

Serial Trends: Trend estimates from fitted series of fixed-length n < N ordered in time

1952

New York (The Battery), NY 1893-2011 (N = 119 yrs)

Trend Estimate: 2.97 ± 0.09 mm/yr

* monthly mean sea level (seasonal cycle removed)

Sea Level Trends: GMSL vs. RMSL(n=10 years)

Serial Trends: Trend Estimates from Fixed-length Series Ordered in Time

> 78 years

Principal Components Analysis (PCA) 1933-2011 mmsl x 8 stations for varying values of n

Serial Trends: PCA

Serial Trends: PCA

60-year oscillation? (Chambers, Merrifield, and Nerem GRL 2012)

Constant Acceleration over 1969-2011?

1 2

dYb b X

dX

210 1 22Y b b X b X

Y relative sea levelX time in years

(relative sea level rise rate)

Boston, MA F = 89.67 **

Norfolk, VA F = 15.37 **

Charleston, SC F = 0.01 ns

Critical Value: F = 6.69 99% confidence level

The 2011 La Niña: So strong the oceans fell

Boening et al., GRL 2012

95% Confidence Bands about individual mmsl heights

Acceleration: 0.300 mm/yr2

Linear Rate: 2.88 mm/yr

Acceleration: 0.186 mm/yr2

Linear Rate: 5.00 mm/yr

20 years not sufficient!

2050

2.07 ft

2100

5.85 ft

1.53 ft

U.S. Army Corps of Engineers Sea Level Calculator

Sea Level Acceleration U.S.-Canadian Atlantic Coast Tide Stations

• RSL rise rate history informs serial trends• PCA identifies 60-year cycle in addition to• Period of near-constant acceleration that began

about 1987 as evident from serial trends• Acceleration strongest in NE and progressively

weaker toward Chesapeake Bay region• Expect mmsl 0.8 to 0.9 m above 1983-2001

MSL by 2050 between Norfolk and Boston• .. If acceleration remains constant