2005 American Geophysical Union Bowie Lecture: The Record of Sea Level Change From Satellite Measurements: What Have We Learned? presented by Professor R. Steven Nerem of the University of Colorado at Boulder.

2. Many Thanks! “ Unselfish Cooperation in Research”

3. Global Surface Temperature Anomalies GISS [ Hansen et al ., 2005]

4. Global Climate Model Predictions [ Suzuki et al ., 2005]

5. Global Climate Model Predictions [ Suzuki et al ., 2005]

6. Earth’s Heat Balance (1955-1998) Estimates of Earth's heat balance components (10 22 J) for the 1955 - 1 998 period. [ Levitus et al ., 2005]

7. Effects of Sea Level Rise 1 meter 2 meters 4 meters 8 meters GFDL

8. The Bathtub Sea Level Model

9. The Bathtub Sea Level Model + -

10. Sea Level Measurements

11. Causes of Sea Level Change Inflow Bathtub Outflow

12. Causes of Sea Level Change

15. Satellite Measurements of Sea Level Change G RAVITY R EBOUND

16. Glacial Isostatic Adjustment [ James et al ., 2005]

17. Glacial Isostatic Adjustment -7.0 -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 25.0 Present-Day Radial Deformation (mm/year) [ Milne , 2005]

18. Sea Level Change Budget Total Sea Level Last Decade (mm/year) 20th Century (mm/year)

19. Past Sea Level Changes Alley et al. [2005] Avg 10 mm/yr Peak 50 mm/yr

20. PSMSL Sea Level Records > 10 years

21. PSMSL Sea Level Records > 50 years

22. Tide Gauge Sea Level Measurements Rate ~ 1.8 mm/year

24. TOPEX/Poseidon and Jason

25. The Jason Mission

26. Tide Gauges versus Satellite Altimetry

27. TOPEX/Poseidon and Jason 10-day Groundtrack

28. TOPEX Sea Level: January 1998

29. TOPEX/Poseidon: In the beginning…… Nerem, R. S., “Global Mean Sea Level Variations from TOPEX/POSEIDON Altimeter Data,” Science , Vol. 268, pp. 708-710, May 5, 1995. Nerem, R. S., Global Mean Sea Level Change: Correction, Science , Letters to the Editor, Vol. 275, p. 1053, February 21, 1997.

30. Tide Gauges Available for Altimeter Calibration

31. TOPEX Tide Gauge Calibration

32. TOPEX and Jason Tide Gauge Calibrations TOPEX Jason

33. Platform Harvest Calibration Site GPS ANTENNA (JPL) WVR (JPL) BUBBLER (NOAA) ACOUSTIC (NOAA) EQUIP SHED MET SENSORS Point Arguello, CA + 54 m + 27 m + 6 m LASER SENSOR (CU)

34. Global Mean Sea Level Variations

35. Global Mean Sea Level Variations

36. Global Mean Sea Level Variations Seasonal variations removed

37. Global Mean Sea Level Variations Seasonal variations removed GIA correction applied (0.3 mm/year) Rate = 3.2 ± 0.4 mm/year http://sealevel.colorado.edu

38. Sea Level Change Budget Thermal Expansion 3.2 1.8 Last Decade (mm/year) 20th Century (mm/year)

39. Thermosteric Sea Level Change [ Levitus et al ., 2005; Antonov et al ., 2005] Rate = 0.4 mm/year (1955-2004) Rate = 1.2 - 1.6 mm/year (1993-2004)

40. Decadal Variability Due to Volcanic Forcing? [ Church et al ., 2005]

41. Total versus Thermosteric Sea Level Change [ Willis et al ., 2005]

42. Global Sea Level Trends: 1993-2005

43. Global Sea Level Trends Altimetry Climate Model (MIROC)

44. Sea Level Variations versus Latitude

45. Sea Level Change versus Latitude

46. Sea Level Change Budget Greenland and Antarctica Ice Melt 3.2 1.8 1.2 0.4 Last Decade (mm/year) 20th Century (mm/year) Mountain Glaciers and Water Storage Water mass redistribution changes the Earth’s gravity field

47. GRACE Gravity Recovery and Climate Experiment

48. GRACE Surface Water Mass Variations Swenson, Leuliette, Nerem, 2005

49. GRACE Global Ocean Mass

50. The Global Water Cycle

51. Ocean/Continents Mass Change from GRACE

52. GRACE Continental Water Mass Estimates

53. GRACE Ocean Water Mass Estimates

54. GRACE Surface Water - South America [ Lemoine et al ., 2005]

55. Contribution of Amazon to Sea Level Change

56. GRACE Geoid Change Trend: 2002-2005

57. Sea Level Change Budget Greenland and Antarctica Ice Melt 3.2 1.8 1.2 0.4 Last Decade (mm/year) 20th Century (mm/year)

60. Sea Level “Enigma” Ancient Eclipse Data Drift of Rotation Pole Oblateness Variations Satellite Laser Ranging

61. Earth’s Rotational Stability [ Mitrovica et al ., 2005]

63. Salinity Changes - Ocean Freshening [ Munk , 2003]

64. Greenland Ice Contributions [ Johannessen et al ., 2005] [ Rignot and Kanagaratnam , 2005] InSAR: 0.23-0.55 mm/yr [ Krabill et al. , 2004] Laser Alt: 0.25 mm/yr Radar Alt: Accumulation

65. Greenland Melt Extent

66. Antarctic Ice Mass Flux from InSAR Rapid coastal thinning in Bellinghausen and Amundsen sectors of West Antarctica -177±30 km 3 /yr Interior thickening and peripheral thinning in East Antarctica +9±30 km 3 /yr SLR 0.4 to 0.6 mm/yr -114 km 3 /yr - 37 ±20 km 3 /yr +33 km 3 /yr -38 km 3 /yr +48 km 3 /yr -2 km 3 /yr +5 km 3 /yr -22 km 3 /yr -3 km 3 /yr +5 km 3 /yr -2 km 3 /yr -56 km 3 /yr -2 km 3 /yr +21 km 3 /yr -4 km 3 /yr -33 km 3 /yr -4 km 3 /yr - 49 ±20 km 3 /yr Peninsula: loss in Graham land, gain in Palmer land. [ Rignot , 2005]

67. Antarctic Ice Changes from Radar Altimetry Interior thickening in East Antarctica - coastal thinning or near balance of coastal East Antarctica (-0.12 mm/yr SLR). Rapid thinning in Amundsen/ Belliingshausen sea sectors of West Antarctica. [ Davis et al ., 2005]

68. Ice Height from Radar Altimeter Measurements [ Zwally et al ., 2005] Greenland Margins ~ -0.12 mm/year Greenland Interior ~ +0.14 mm/year WAIS ~ -0.12 mm/year EAIS ~ +0.04 mm/year

69. Greenland Mass Variability from GRACE [ Velicogna and Wahr , 2005] 0.45 ± .06 mm/year

70. Antarctica Ice Mass Change from GRACE [ Velicogna and Wahr , 2005] 0.44 ± .23 mm/year

71. Ice Mass Variability from GRACE [ Luthcke et al ., 2005]

72. Preliminary ICESat Results dh/dt Laser 3a (10/7 - 11/7, 2004) - Laser 2a (9/25 - 11/18, 2003) [ Luthcke et al ., 2005]

73. Sea Level Change Budget Melting of Mountain Glaciers 3.2 1.8 Last Decade (mm/year) 20th Century (mm/year) 1.2 0.4 0.4 0.2 0.5 0.3

74. GPS Crustal Uplift in Alaska [ Larsen et al ., 2005]

75. Alaska Glacier Mass Changes from GRACE [ Tamisiea et al ., 2005] Sea Level Contribution of 0.3 mm/year over 2002-2004

76. Ice Volume Changes in Patagonia 1975 - 1995 - 2000  MSL = 0.04 mm/year (1975 - 1990s)  MSL = 0.1 mm/year (1995-2000) [ Rignot et al ., 2003]

77. Mountain Glaciers: Contribution to Sea Level [ Dyurgerov and Meier , 2005] 1961-2003: 0.5 mm/year 1994-2003: 0.9 mm/year

78. Sea Level Change Budget Land Water Storage 3.2 1.8 Last Decade (mm/year) 20th Century (mm/year) 1.2 0.4 0.4 0.2 0.5 0.3 0.9 0.4

79. Sea Level Change Budget 3.0 = 1.2 0.4 0.5 0.9 ? ? 1.4 = 0.4 0.2 0.3 0.5 ? ? 20th Century: 1.8 mm/year (observed) Last Decade: 3.2 mm/year (observed) Last Decade (mm/year) 20th Century (mm/year)

81. Satellite Missions Studying Sea Level Change Planned/Pending approval In orbit Approved JASON-2/OSTM TOPEX/POSEIDON JASON-1 Envisat RA-2 Medium accuracy RA (SSH) from high-inclination orbit High accuracy RA (SSH) from mid-inclination orbit CRYOSAT-2/LRM OceanSat-3 AltiKa ERS-2 RA GMES S-3 ICESAT Geosat Follow-On NPOESS GRACE GRACE follow-on Laser Altimetry (ice) Temporal Gravity (ocean mass) ICESAT-2 ? 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14

82. Future Greenland Ice Changes Alley et al. [2005]

83. Stay Above Sea Level!

84. Thanks and Happy Holidays!