Climate-driven Trends in Contemporary Ocean Productivity

1. Robert O’Malley Jorge Sarmiento Wayne Esaias Don Shea Gene Feldman Robert Frouin Dave Siegel Allen Milligan Compton Tucker Emmanuel Boss Ricardo Letelier Dorota Kolber Toby Westberry James Randerson Nathan Pollack Chuck McClain Christopher Field Stephane Maritorena Paul Falkowski Sietse Los Climate-driven Trends in Contemporary Ocean Productivity or “The World According to SeaWiFS” Michael Behrenfeld Oregon State University

2. Biospheric NPP increased 6 Pg from 1997 El Nino • to 1999 La Nina, with clearest response in oceans

3. In most central ocean gyres, chlorophyll • concentrations decreased between • 1997 and 2003

4. Declines in mid-ocean gyres chlorophyll associated • with increases in sea surface temperature

5. global > 15oC 7 December 2006 Vol. 444 Nature • Tidbits • Based on Vertically Generalized • Production Model (VGPM) • Initial increase = 1,930 TgC/yr • Subsequent decrease = 190 TgC/yr • Global trends dominated by changes • in permanently stratified ocean • regions (ann. ave. SST < 15oC)

6. Low Latitude SST Anomaly * * Multivariate ENSO Index

8. a +3 +2 +1 SST Changes ( 0C ) 0 -1 -2 -3 b +60 +30 NPP Changes (%) 0 -30 -60 c NPP NPP SST SST

9. Tidbits • Six different coupled climate models • Ocean biological responses to climate • warming from industrial revolution to 2050 • Marginal sea-ice biome area decreases 42% • (N) and 17% (S) • Expansion of low production permanently • stratified ocean by 4% (N) to 9.4% (S) • Subpolar gyre biome expands 16% (N) and • 7% (S) • Stratification decreases nutrient supply and • thus productivity in permanently stratified • oceans • Stratification, extended growing season, and • sea ice retreat enhance production at high • latitudes • Significant shifts in community composition

10. global > 15oC < 15oC 1998 2000 2004 2006 1998 2000 2004 2006 2002 2002 Year Year

11. Low Latitude SST Anomaly • So, what do we really know?.... • Satellites measure neither NPP or chlorophyll, they tell us about optics • SeaWiFS has recorded changes in ocean optical properties over vast regions • These changes are clearly linked to effects of climate variability on upper • ocean temperature and stratification - not instrument or atmospheric artifacts …are there alternative explanations? • Nutrient-driven changes in NPP • Photo-oxidation of cDOM • Light-driven changes in • photoacclimation ‘97 ‘98 ‘99 ‘00 ‘01 ‘02 ‘03 ‘04 ‘05 ‘06 Year

12. Spectral matching algorithms are a path to a solution… • Do not rely on the ‘bio-optic’ assumption – now known to be wrong • Would allow changes in cDOM photo-oxidation to be detected • Would allow changes in photoacclimation to be detected from Chl:C • Are not optimized with heritage ‘ocean color’ wavebands Difference in chlorophyll estimates for standard wavelength-ratio and spectral matching algorithms cDOM from spectral matching algorithm • Uncertainty in remote sensing products reflects inadequacy of heritage wavebands for separating different absorbing and scattering components.

13. Ultraviolet 5 nm resolution (335 – 865 nm) 17 aggregate bands Visible SeaWiFS MODIS NIR CZCS VIIRS 2 SWIR bands SWIR Visible NIR Key SWIR Few science products Extensive science products 1 2 3 4 5 6 7 8 approaches limits on performance Advanced Mission (2013 - ) 8 7 Climate Data Record Quality 6 Desired Trajectory SeaWiFS (1997 - ) 5 Measurement Quality Index * Current trajectory MODIS (2002 - ) 4 VIIRS (2009 - ) Insufficient for Climate Data Record CZCS (1978-1985) 3 2 * NOTE: MODIS Aqua climate-quality ocean biology data have only been achieved because SeaWiFS data were available for comparison potential science return 1 Measurement Maturity Index no known use for measurement measured operationally

14. Credit really belongs to the Ocean Color Group at NASA Goddard Space Flight Center and Ocean Biology and Biogeochemistry Program at NASA Headquarters Contemporary Changes in Ocean Chlorophyll during the SeaWiFS Era Backup Slides El Nino – La Nina changes Chlsat vs Chleuphotic Other NPP models Chlorophyll and MEI NPP and MEI update Zonal temperature changes Surface chlorophyll updates The 2006 minimum > 15oC Surface Chlorophyll Anomaly (Tg) 1998 2000 2002 2004 2006 Year

15. (C) • Biospheric NPP increased 6 Pg from 1997 El Nio • to 1999 La Nia, with clearest response in oceans (D)

16. Surface Chlorophyll Anomaly (Tg) Depth-integrated global > 15oC 1998 2000 2002 2004 2006 Year

17. Tidbits • Three models: • VGPM – polynomial • VGPM – Eppley • CbPM – Chl:C-based growth • All show 2 primary trends • Biggest differences is in slope • of initial El Nino – La Nina • period

18. Chl VGPM Polynomial Chl SST SST Chl VGPM Eppley Chl SST SST matchup / mismatch Match Mismatch

20. MEI 1998 2000 2002 2004 2006 Year

21. SST changes

22. All bins > 15C Chlorophyll anomalies < 15C Global SeaWiFS time series – sequential months

23. Surface Chlorophyll Anomaly (Tg) SeaWiFS time series – sequential months

24. Quality and Maturity Definitions Measurement Maturity Index 1 = No known operational use for measurement 2 = Parameter identified as having potential for operational significance 3 = Operational significance demonstrated through simulations 4 = Pathfinder mission launched. Need for long term record widely accepted 5 = Pilot decision support tool (DST) use of space-based measurements 6 = Space ops over sustained period. Adds value to DSTs. 7 = Ready for transfer to operational use 8 = Measured operationally. Used operationally in existing DSTs. Measurement Quality Index 1 = Measurement identified as potentially providing significant science return 2 = Initial measurements produced and calibrated 3 = Geophysical, biological, or chemical properties inferred or estimated from calibrated measurements 4 = Geophysical, biological, or chemical properties inferred or estimated from calibrated measurements and validated 5 = Significant improvement in calibration, spatial resolution, spectral resolution, temporal revisit, and/or spatial coverage over initial measurements 6 = Second significant improvement in calibration resolution, temporal revisit, and/or spatial coverage over initial measurements 7 = Further significant improvement in calibration resolution, temporal revisit, and/or spatial coverage over initial measurements 8 = Measurement approaches theoretical or practical limits on performance