Presentation given during the kick-off of the TU Delft Climate Institute on March 1st 2012. Sea level rise is one of the reserach topics of the new institute. Dr Bert Vermeersen explained why.
5. … as Derived from Spatially Highly Variable Ups and Downs …
3.2 ± 0.4
(Courtesy: Steve Nerem)
6. Sea Level Rise: Two Principle Causes
2. Thermal Expansion (heating of the oceans)
3. Continental Ice Changes (present and past)
Sea Level Change by Continental Ice Changes
Relative sea level variations due to continental ice mass
changes have never been uniform, are not uniform today, and
will never be uniform due to accompanying
• gravity changes
• solid-earth deformation, and
• induced changes in Earth rotation (polar wander)
7. Relative Sea Level Change Fingerprinting
Gravity
Ice sheet formation: near field
2,200 km
instantaneous effect
6,700 km
Ice sheet melt: far field
long-term viscous effect
Deformation
True Polar Wander
Geodynamic mechanisms
leave their characteristic
regional records, from
which the cause(s) of relative
sea level change might be
determined
Rotation
8. ESA’s GOCE Gravity Satellite Mission
(launched March 17 2009)
“ half a TU Delft satellite “
9. Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet,
J. L. Bamber, R. E. M. Riva, L. L. A. Vermeersen, A. M. LeBrocq, Science, 324, 901-903, 2009.
10. NASA / DLR’s GRACE Gravity Satellite Mission
(launched March 17 2002)
11. Surface Mass Balance (SMB) Model vs. GRACE
Partitioning recent Greenland mass loss, M. van den Broeke, J. Bamber, J. Ettema, E. Rignot, E.
Schrama, W. v.d. Berg, E. van Meijgaard, I. Velicogna, B. Wouters, Science, 326, 841-986, 2009.
15. Sea Level Change Since to Glacial Isostatic Adjustment
Present-Day RSL Change Due Last Glacial Maximum
16. A vexing problem: how to disentangle postglacial rebound from
present-day mass changes over Antarctica ???
Satellite Gravity Satellite Altimetry
GRACE: observes mass changes ICESat & CryoSat: ice height changes
Combining gravity change with altimetry change observations might do the trick …
17. GRACE (gravity) data and ICESat (altimetry) data
CSR RL04, SLR C20, destriped 300 km Gaussian smoothing
R.E.M. Riva, B.C. Gunter, T.J. Urban, L.L.A. Vermeersen, R.C. Lindenbergh, M.M. Helsen, J.L. Bamber, B.E. Schutz, R.S.W. van de Wal, M.R. van den Broeke,
Glacial Isostatic Adjustment over Antarctica from combined GRACE and ICESat satellite data, Earth Planet. Sci. Lett., 288, 516-523, 2009.
18. Outlook
• Sea Level Change is Complicated: For many coastal regions in the
world, deviations from the average global mean of 3 mm/yr relative sea
level rise are observed to be large, in the range between -15 mm/yr
relative sea level fall and +15 mm/yr relative sea level rise.
• Global Processes, Regional Impact: Gravity Changes, Solid Earth
Deformation and Earth Rotation all influence relative sea level change
projections and must be taken into account, also for relative sea level
changes due to present-day ice melt! Vice Versa, observing “fingerprint
patterns” over the oceans might tell us more about their causes.
• Satellite Observations are Essential: For reliable predictions on
future regional sea level change a combination of data sets (satellite
altimetry and gravity, tide gauges, GPS, …) with geophysical models
(ocean dynamics, ice dynamics, postglacial rebound, …) is required.
• Collaboration: Not an Option, but Necessity: fruitful collaborations
already exist between TU Delft, KNMI, IMAU and other national (and
international) partners on sea level and ice research. The Delft Climate
Institute will further strengthen and expand these collaborations.
