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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.
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