Josh K' Willis

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Observing Climate Change in the Oceans for the
Decade(s) to Come
When the Ocean Speaks Who Listens?

• Josh K. Willis
• joshua.k.willis_at_jpl.nasa.gov
• Jet Propulsion Laboratory

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How inappropriate to call this planet Earth when
it is quite clearly Ocean. Arthur C. Clarke
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Natural Climate Changeand the Oceans
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El Niño La Niña
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La Niña
El Niño
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The Pacific Decadal Oscillation
Negative Phase
Positive Phase
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The Pacific Decadal Oscillation
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Altimeters and the PDO
Lack of high frequencies suggest SSH is the
better predictor
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Global Warmingand the Oceans
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What happens to the heat?
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Where does the heat go?
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Thermal Inertia Energy Balance
Balance is restored
Atmosphere
Atmosphere
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Thermal InertiaThe Ocean Planet
To raise Earths temperature The Oceans must warm
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Thermal InertiaThe Ocean Planet

• A water-free planet finishes warming after 10
  years
• The Ocean planet takes 1000 years!!!

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Triumphs of the Global Ocean Observing Systems
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The altimeter record
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The altimeter record
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Argo
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Steric height from Argo
From Roemich and Gilson, Progress in
Oceanography, submitted
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Greenland Ice Mass Loss from GRACE
362 Gt 1 mm GMSL
-140 Gt/year 0.4 mm/year GMSL
Credit Roger Braithwaite
Luthcke et al., 2006
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Causes of Sea Level Rise
Total sea level rise


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Todays Observing Systems
Total sea level rise


Argo
Jason
GRACE
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The recent sea level budget
Jason
Argo
GRACE
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Sea Level Budget
Seasonal cycles agree to within random
error 4-year trends have discrepancy larger than
random error gt systematic error remains!
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Drifting Buoys
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Drifting Buoys
From Maximenko, N.A., and P.P. Niiler (2004),
Recent Advances in Marine Science and Technology,
2004.
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Hydrographic surveys
WOCE
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Hydrographic surveys
2006-1984
1991-1984
2006-1991
From Johnson et al., Journal of Climate, 2007
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Hydrographic surveys
1999-1985
From Fukasawa et al., Nature, 2004
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High density XBT lines
Repeat sections still important for resolving
eddies, estimating transport, etc.
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Sea Level the old fashion way
Tide Gauges with Greater Than 10 Years of
Measurements
Tide Gauges with Greater Than 50 Years of
Measurements
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Tide Gauge Observations
3.2 mm/year
2.0 mm/year
8 inches (20 cm)
0.8 mm/year
16,000 cubic miles!!!
Average Rate 1.8 mm/year
(67,000 cubic km)
Church and White, 2006
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The Ugly Truth
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Whats missing? Deep Ocean
Implications for thermal inertia and climate
sensitivity
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Whats missing? Continuity
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Whats missing? Continuity
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Ocean cooling results pose a problem for sea
level
Sea level continued to rise despite cooling and
decrease in thermosteric sea level
6 mm drop in thermosteric sea level
From Lyman et al., GRL, 2006
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My brush with Rush
Proving again, that they really dont know much
about anything when it comes to climate, climate
change and so forth. ? Rush Limbaugh
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To overturn the world economy based on the
musings of a few idiot leftist scientists is just
stupid, and thats what Global Warming is all
about. ? Rush Limbaugh
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Was Rush right???
No!But neither were we!
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A correction to recent cooling
Ocean Heat Content from 2004 to 2006
Removing the bad float data reduces the cooling
but does not completely eliminate it.
From Willis et al., JAOT, accepted.
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A correction to recent cooling
Ocean Heat Content from 2004 to 2006
Another bias XBTs are biased warm, which also
causes spurious cooling.
From Willis et al., JAOT, accepted.
Intercomparison is critical!!!
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XBT bias fall-rate error
Comparison of Isotherm Displacements
XBT/Argo pairs 12,000
Argo/CTD pairs 2,000
From Willis et al., JAOT, accepted.
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XBT bias fall-rate error
Time dependence of bias in Sippican Deep Blue XBT
probes

• Bias increases over time
• Hi bias in later years may reflect double
  application of Hanawa et al. (1995) correction

From Wijffels et al., J. Climate, accepted.
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"Human beings are now carrying out a large scale
geophysical experiment of a kind that could not
have happened in the past nor be reproduced in
the future. " Roger Revelle, 1957
Every decade is different from the last!
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Additional Slides
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Sea Level Rise

• Coastal Erosion
• Loss of wetlands
• Saltwater intrusion
• Inundation

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Historical Ocean Warming
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Revised thermosteric sea level
Equivalent to 0.55 W/m2 of radiative imbalance
Trend 1.4 mm/yr
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Combining Altimeter and Argo Data
The Argo Array
Altimeters provide information about surface
velocity
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Argo profiles, displacements and altimetry
2004 2006 mean SSH

• Altimeter is used to reduce eddy variability in
  both types of Argo data
• Integrating from 0 to 1000 m and from east to
  west may provide estimate of AMOC transport

• Estimate of overturning transport
• Infer heat transport

Absolute geostrophic velocity from 0 to 2000 db
at 37N
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The recent sea level budget
Total (Jason)
Global MSL, no seasonal cycle, no trend
Removal of trend brings all three estimates into
excellent agreement
Steric (Argo)
Mass (GRACE)
RMS difference 1.6 mm
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4-year Trends in sea level
The recent sea level budget
Jason
General agreement is encouraging
Jason-GRACE
But, difference in S. Hemisphere trends is
concerning
Argo
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How fast will sea level rise?
Satellite Observations
Tide Gauge Observations
Rahmstorf et al., 2007
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Ice Sheet melting
Speeds up
Water lubricates the glacier
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Accelerated ice discharge
Difficult to predict sea level rise!!!
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Sea Level Change Potential Contributions
Thermal Expansion 1 meter
Mountain Glaciers 0.5 meters
Greenland Ice Melt 7 meters
Antarctic Ice Melt 60 meters
Land Water Storage lt 0.5 meters
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The tide gauge record of Sea Level
0.76C
17 cm (20th Century)
From IPCC, 4th assessment report
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Historic Sea Level Rise
Recent rates of sea level rise are 100 times
larger than historic rates.
Plots by Robert A. Rohde for Global Warming Art
http//www.globalwarmingart.com/
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Time Varying Bias
Shallow probes
Deep probes
Common time history by profile type suggests
manufacturing changes cause time varying bias
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Pseudo-pair comparison
Comparison of Sippican Deep Blue probes with
nearby Argo pairs (2004 2006), 12,000

• Pseudo-pairs give same bias, but have narrower
  distribution
• More comprehensive means of test XBT bias because
  of SSH data availability

From Wijffels et al., manuscript in prep.
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The Thermohaline Circulation
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The Thermohaline Circulation
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What would happened if the THC shut down?
Rahmstorf, (Nature, 2002)