Arctic Ocean primary productivity and climate change

Transcription

1 Arctic Ocean primary productivity and climate change Patricia Matrai Bigelow Laboratory for Ocean Sciences with help from many colleagues!

2 Arctic sea ice loss Snow cover loss

3 Ice melt and surface warming result in stratification that prevents vertical mixing Low (?) nutrient supply to surface and thus low harvestable productivity Low (?) light supply through surface coastal waters (snow + ice, CDOM, suspended solids) nutrients sediment Courtesy P Wassmann

4 Today s extreme Same seasonal amount of nutrients variation disappears Same Sub-ice harvestable blooms production increase? Time Wassmann 2011, and those before him

5 Where is Arctic Primary Production now?

6 Integrated Annual Net Primary Production (NPP) ( field data at satellite data) Algorithm-estimated NPP based on: Field Chl SeaWiFS Chl gc m -2 yr -1 Hill, Matrai et al. 2013

7 Net Community Production 30 - = NCP / f factor = NPP (or NP?) (0-200) (0-40) gc m -2 yr -1 0 Codispoti, Matrai et al. 2013

8 A biological model applied regionally using ocean color and sea ice satellite data Pan-arctic decadal trend Open water Light! Annual net PP Field data? Pabi et al. 2008; Arrigo & van Dijken 2011; Van Dijken & Arrigo 2014

9 NSIDC Change in timing of annual Chl max Change in June ice concentration Is the light field changing? We have proxies Kahru et al With respect to satellite median for: Chl ice fraction change yr -1

10 Clouds and light (satellite data: ) PAR % yr -1 PAR % yr -1 PP % yr -1 + clouds = Light decrease (8-20%) ABOVE sea (ice) surface + clouds = Light change (+3 to -3%) JUST BELOW sea (ice?) surface PP increase estimated below sea (ice?) surface - GIN/Barents Sea ~21-26% reduction Bélanger et al BG

11 A biological model applied regionally using ocean color and sea ice satellite data Variable regional decadal trends Field data? Pabi et al. 2008; Arrigo & van Dijken 2011; Van Dijken & Arrigo 2014

12 That s a whole nother talk! Nutrients? Nutrients!! WOA Annual mean DIN [mmol N m -3 ; year 2000] Simulation Popova et al. 2013

13 Wind! => wind-driven turbulence Upwelling => nutrients Eddies => mixing, +/- nutrients?, nitrate consumption With ice Mahadevan, Woodgate, Rainville, Wang, Matrai, in prep Without ice

14 Pan-Arctic representation of the present Mean annual water column PP [gc m -2 y -1 ] by 5 models and a satellite-derived estimate 2012 Popova et al Deal et al Zhang et al Dupont et al Yool et al. 2011

15 Maximum depth of upper mixed layer Nutrients! Simulated mixed layer depth examples Same for DIN fields Popova et al. 2012

16 ESMs in the Arctic: CMIP5 simulation for 2100 Ice Integrated PP (2013) But regional GCM BIOMAS by Zhang et al does get the coastal complexity! Surf. NO 3 Stratification index -> NO 3

17 Three empirical estimates of Arctic annual, regional, integrated PP Hill et al Pabi et al. 2008; Arrigo and Dijken 2011 GIN Seas (Tg C y -1 ) Sakshaug Arrigo & van Dijken Hill et al Ardyna et al (104 gc m -2 y -1 ) Wassmann et al gc m -2 y -1 Bélanger et al SOLAS/SCOR BEPSII FAMOS, IOC PPARR-5 Arctic Ocean!

18 Who?

19 Simulated subsurface chlorophyll maximum (surf. Chl + Ardyna, Bélanger, Babin et al model): Where are the phytos and when? Depth [m] 350 days Which spp.? Chl (mg m -3 ) and also Hill, Matrai et al Arrigo, Matrai, van Dijken 2011

20 Dinoflag. (Micro) Phytoplankton taxa Pennate diatoms Centric diatoms Ice algae taxa Poulin et a Nano/Picoplankton: flagellates (e.g. Micromonas; no marine cyanobacteria) =%??

21 More than late spring and summer!

22 Matrai & Apollonio 2013 UNDER ICE DOY

23 Thus, a whole microbial food web develops much before the spring bloom appears. We know very little about this food web, but it certainly sets the stage for later biological and biogeochemical developments in the spring.

24 Le Fouest et al More than bottom up processes! Mahadevan et al. 2014

25 Summary Sea ice is thinning, ice extent is reduced, especially in summer, and snow cover is changing Primary production season is expected to increase in duration (light) but not in PP magnitude (nutrients) at pan-arctic scales Primary production and productivity increase in certain continental shelves and breaks; and move => Whose fisheries!? Primary production and productivity are not expected to increase in the deep Arctic Basin (not enough nutrients) The ecosystems of the Arctic Ocean will change their present day equilibrium. We do not know how the new equilibrium will support ecosystem services Our predictions are only as good as our process understanding and validating data are

26 Thank you!