Changing Climate and Sea Level

George A. Maul, PhDProfessor of Oceanography and Department HeadDepartment of Marine and Environmental Systems

Florida Institute of Technology

Outline of the talk

Scales and Causes of Climate ChangeTemperature as an Indicator of ClimateClimate ModelingRelative Sea LevelCauses of Sea Level ChangeClimate ProjectionsSummary and Questions

Space-Time of Climate Change

Greenhouse Effect (left) Atmospheric Effect (right)

Earth’s Air Temperatures

100 million years of temperature change

100 years of temperature change

How do we know?

•Ice Cores (left)•Tree Rings (below)•Pollen (right)

Proxy Records

Instrumental Records

Quantifying Earth’s Radiation Balance

( ) 414 EARTHSBSUN

GHE TAQQ σ=−+

Milankovitch Cycles

Earth’s Orbital Changes Eccentricity + Tilt + Precession = Received Insolation

The Carbon Cycle

2226126 666 COOHOOHC +⇔+

Biosphere Changes

Other Contributors

Sunspots

Productivity

Dust

Snowfall

Deforestation

Pollution

Human Population (left) and Atmospheric CO2 (right)

Population Carbon Dioxide

Sample Warming CalculationΔT = fT⋅ΔQ =Σi fT⋅qi⋅Δri

If temperature feedback parameter fT = 0.5 °C / W⋅m−2

Gas Change in Concentration

[Δr](ppmv)

Forcing Parameter

[q](W⋅m−2⋅ppmv)

Change in Forcing

[ΔQ](W⋅m−2)

Change in Temperature

[ΔT](°C)

CO2 300 - 600 0.015 4.5 2.25

CH4 1.7 – 3.0 0.53 0.7 0.35

N2O 0.3 – 0.5 2.0 0.4 0.20

CFCs 0 – 0.005 280 1.4 0.70

Total 7.0 3.5

Positive Feedback ModelfT Very UncertainfT from Q = σ⋅T4 ≈ 0.2°C / W⋅m−2

Global Models Estimate 1.5°C - 4.5°C

IPCC 2007 Summary

Data

16 cm/century

0.65 oC/century

Seawater Temperature Changes at USA Tide Gauge Sites

0

5

10

15

20

25

30

1900 1925 1950 1975 2000Year

SST

(Cel

sius

)

Atl Cty, NJ

Bal, MD

Bos, MA

Chas, SC

NY, NY

SF, CA

La J, CA

Key W, FL

Sea, WA

Sew, AK

Gal, TX

N Bay, WA

Data Archeology

Station Years N ΔT* SE*

Boston 1921-1994 69 3.6 0.3

New York 1926-1994 61 1.8 0.4

Atlantic City 1911-1991 54 0.9 0.4

Baltimore 1914-1993 65 0.9 0.5

Charleston 1921-1992 70 -0.1 0.3

Mayport 1944-1993 46 0.2 0.6

Key West 1926-1994 36 0.0 0.3

Galveston 1921-1992 36 -0.1 0.5

La Jolla 1916-1996 79 0.7 0.3

Los Angeles 1923-1991 40 0.8 0.4

San Francisco 1921-1994 57 0.5 0.4

Seattle 1922-1994 41 0.0 0.4

Neah Bay 1935-1994 53 1.1 0.4

Seward 1925-1993 29 0.1 0.4

Seawater Temperature Trends

(ΔT) ± Standard Error (SE) from Tide Gauges(°C⋅100yr-1)

Bretherton Diagram

Climate Modeling

Temperature vs. Latitude

Future Temperature

1900-2000 = 0.65 oC

Coastal Florida Temperature Trends from Three Databases

Ensemble trend: +0.2 ± 0.9 ºC per century

Correlation between datasets r2 = 0.1

Stations

There are three kinds of lies: lies, damned lies, and

statistics.

Ocean Circulation

and Climate

The Earth System

•Cosmosphere

•Geosphere

•Atmosphere

•Hydrosphere

•Biosphere

•Anthroposphere

Sea Level Over Time

Barbados Sea Level last 18,000 years

Maximum rate of rise ~100 cm/century

How do we know?BeringLandBridge

Ancient Beaches

Ancient Shells

Melting sea ice does not cause sea

level rise.

Annual cycle of Arctic Sea IcePerito Moreno Glacier

Factors AffectingRelative Sea Level (RSL) Change

RSL = Height thermal expansion+ Height land motion+ Height glacial melt+ Height ocean circulation+ Height winds+ Height barometric pressure+ Height tides+ Residual

Mississippi Delta (above)

Midway Island (right)

Glacial Retreat

Sea Level Trends at Selected Small Islands

Typical Tide Gauge

GPS Continuously Operating Reference Stations (CORS)

CORS Site Years Rate (mm/yr) Repeatability

Mobile Point 1997-2006 –2.29 0.07 9.4 mm

Mac Dill AFB 2001-2006 +1.71 0.16 8.3 mm

Key West 1997-2006 +0.24 0.08 9.7 mm

Miami 1998-2006 –0.17 0.09 8.8 mm

CapeCanaveral

1999-2006 –1.94 0.09 10.4 mm

CORS Antennas

-5 ± 16 cm/century

Key West Sea LevelAmericas’ Longest Record

Station RSL UncertaintyCedar Key 19 cm/century ± 1 cmFernandina Beach 22 cm/century ± 1 cmKey West 22 cm/century ± 1 cmMayport 24 cm/century ± 2 cmMiami Beach 24 cm/century ± 2 cmPensacola 22 cm/century ± 2 cmSt. Petersburg 25 cm/century ± 2 cm

Key West (1850) and TodayNo discernible acceleration in Key West sea level since 1846

Projected effect of a one-meter sea level rise on Florida

At the current rate of Florida sea level rise of 2.3 mm per year, this will take >400

years.

Miami 300 years from now

Future Sea Level?

Projected sea level to 2100

Factors affecting future climate and sea level

It is tough to make predictions, especially

about the future.

Intergovernmental Panel on Climate Change 2007

Projections

Example Calculation

Let T1= 3°C, S1= 35 psu, then ρ1=1027.9 kg⋅m-3

If T2= 4°C, S2= 35 psu, thenρ2 = 1027.8 kg⋅m-3

If z1= 4000 m and g= 9.8 m⋅s-2,since p1= p2

z2 = 4000.39 m or Δz = 39 cm

From the hydrostatic equation p = ρgz

Δz

So a 1°C temperature increase over the average ocean depth of 4000m will increase eustatic sea level 39 cm.

p1 = p2

Summary

As with Atmospheric Temperature - Sea Level is Always ChangingComplex Measurement ProblemUncertainty in Future Projections

Sphere InteractionsOcean-Atmosphere Coupling

Impact of Humankind

Annual cycle of snow and ice

…there is always an easy solution to every human

problem - neat, plausible, and wrong.

Selected G.A. Maul ReferencesDuedall, I.M., and G.A. Maul. Future Coastal populations. In: M. Schwartz,

(editor), Encyclopedia of Coastal Science, Kluwer Academic Publishers, Dordrecht, 2005.

Hanson, K., G.A. Maul, and T.R. Karl. Are Atmospheric "Greenhouse" Effects Apparent in the Climatic Record of the Contiguous U.S. (1895-1987)? Geophys. Res. Lett., 16(1), pp: 49-52, 1989.

Maul, G.A. Temperature and Sea Level Change. In: B.G. Levi, D. Hafemeister, and R.A. Scribner (editors), Global Warming: Physics and Facts. ©American Institute of Physics, pp: 78-112, 1992.

Maul, G.A., and D.M. Martin. Sea Level Rise at Key West, Florida, 1846-1992: America's Longest Instrument Record? Geophys. Res. Lett., 20(18), pp: 1955-1959, 1993.

Maul, G.A. (author/editor). Climatic Change in the Intra-Americas Sea: Implications of future climate on the ecosystems and socio-economic structure in the marine and coastal regions of the Caribbean Sea, Gulf of Mexico, Bahamas, and the northeast coast of South America. ©United Nations Environment Programme, Edward Arnold Publishers, London, 389 pp., 1993.

Maul, G.A., A.M. Davis, and J.W. Simmons. Seawater Temperature Trends at USA Tide Gauge Sites. Geophys. Res. Lett. 28(20), pp: 3935-3937, 2001.

Maul, G.A., and H.J. Sims. Florida Coastal Temperature Trends: Comparing independent datasets. Florida Scientist, 70(1), pp: 71-82, 2007.