NASA CC&E Meeting 29 April 2008

1. Ecosystem Changes/Processes in High LatitudesA. David McGuireU.S. Geological Survey/Institute of Arctic BiologyUniversity of Alaska Fairbanks NASA CC&E Meeting 29 April 2008

2. Contributors • K. Arrigo – Stanford University • J. Comiso – Goddard Space Flight Center • S. Doney – Woods Hole Oceanographic Institute • S. Goetz – Woods Hole Research Center • E. Kasischke – University of Maryland • J. Kimball – University of Montana • P. Matrai – Bigelow Laboratory for Ocean Sciences • K. McDonald – Jet Propulsion Laboratory • D. Walker – University of Alaska Fairbanks • T. Zhang – University of Colorado

3. Ecosystem Services:The benefits people obtain from ecosystems Millennium Ecosystem Assessment 2005

4. Ecosystem Services: Issues in Polar Regions (based on Chapin et al. 2005. Millenium Assessment. Polar Regions Chapter) • Climate Regulation • - carbon exchange with the atmosphere • methane exchange with the atmosphere • water/energy exchange • snow-vegetation interactions • vegetation changes • sulfate biogeochemistry and aerosols • Biodiversity, Health, and Provisioning • caribou and reindeer • marine fisheries • threatened/endangered species • invasive species • contaminants: oil, heavy metals, POPs • stratospheric ozone and UV-B

5. Organization of Talk • Ecosystem Changes/Processes in • Northern Terrestrial Regions • Ecosystem Changes/Processes in • the Northern Oceans • Ecosystem Changes/Processes in • the Southern Ocean • Summary

6. Ecosystem Change and Processes in Northern Terrestrial Regions

7. Major Arctic Feedbacks to the Climate System From Arctic Climate Impact Assessment. 2005.

8. 30-45% of Global Soil Carbon in the Top 1 – 2 m of Soil is Stored in High Latitude Terrestrial Ecosystems (Figure from Bajtes 1996)

9. 0.0381 – 0.0388 ºC year-1 0.0078 – 0.0354 ºC year-1 1910 - 1940 Air temperature anomaly (ºC) 1970 - 2000 1940 1970 2000 1910 Air temperature anomaly (ºC, five year running mean) Five-Degree Latitudinal band (ºN) 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year From Euskirchen et al. 2007

10. Between 1970 -2000, the number of days of snow covered ground decreased by an estimated 2.5 days per decade across the pan-Arctic. Change in the duration of snow covered ground (anomaly): Days per year shorter Days per year longer <- 0.4 -0.4 - -0.3 -0.3 - -0.2 -0.2 - -0.05 -0.05 - 0.01 0.01 - 0.1 >0.1 1970 -2000 From Euskirchen et al. 2007

11. Changes in atmospheric heating due to changes in the snow season, 1970-2000 -0.25 - -3 3 - 5 0.1 - -0.1 -1 - -0.25 2 - 3 0.5 - 1 0.25 - 0.5 0.1- 0.25 1 - 2 Cooling Heating W m-2 decade-1 Across the pan-Arctic, an overall reduction in the duration of snow covered ground by ~2.5 days per decade resulted in atmospheric heating of ~1.0 W m-2 per decade. 1970 -2000 From Euskirchen et al. 2007

12. Spring Thaw vs LAI Mean Primary Springtime Thaw Date (SSM/I; 1988-2000) Spring Thaw vs NPP Spring Thaw Timing Influences Northern Productivity r = -0.688, P=0.009 r = -0.857, P<0.001 • Annual variability in AK springtime thaw from SSM/I record is ~ ±7 days (SD), with corresponding impacts to annual NPP of ±1% per day. • Satellite (SSM/I) record shows earlier springtime thawing of -4.6 days per decade, sufficient to explain Northern greening and magnitude of satellite (AVHRR) productivity growth trends. Source: Kimball, McDonald, and Zhao, 2006. Earth Interactions. 10, 21 .

13. Trends In Photosynthetic Activity 1982-2005+Trend (-Feedback)-Trend (+Feedback) Goetz et al. 2007 ERL

14. Process studies across high-latitude ecosystems have provided synthetic analyses of how vegetation responds to climate change, including their water, energy, and CO2 exchange with the atmosphere. Beringer et al., 2005

15. Results indicate that transitions to shrub tundra and forest are likely to lead to greater summer C storage. Carbon fluxes at Council, Alaskacourtesy of C. Thompson Summer net C exchange measured by a mobile eddy covariance tower compared with a reference stationary tower located in tundra

16. Studies at Council, Alaska indicate that changes in vegetation distribution of Arctic Ecosystems will have substantial effects on summer water and energy exchanges between the land surface and the atmosphere (Thompson et al. 2005) Tundra Strong relationships (R2 = 0.68 – 0.87; p < 0.0001) also exist between aboveground biomass and latent heat, sensible heat, and net radiation. Low shrub Summer Albedo Tall shrub Woodland Forest Aboveground biomass (g m-2)

17. Combining remote sensing and traditional knowledge “…in addition to taking part in daily life and seeing with our own eyes exactly how the animals are managed we … do more formal semi-structured interviews. Some of these are recorded on either digital tape or film, or both. In these cases we have medium or very high resolution satellite imagery of the areas we are discussing to focus on specific places and features that the herders can recognize easily.” --Bruce Forbes Walker et al., 2008, Yamal NASA LCLUC project

18. Trends In Photosynthetic Activity 1982-2005+Trend (-Feedback)-Trend (+Feedback) Goetz et al. 2007 ERL

19. Fire in the North American Boreal Region Ignitions are for fires > 2 km2 in size E. Kasischke

20. E. Kasischke Frequency of large fire years in Alaska 1 every 6 years 1 every 3 years Key: less than 1% of land area burned, 1-2% of land area burned, 2-3% of land area burned,> 3% of land area burned

21. Upland black spruce fire chronosequence in Delta Junction, Alaska (64ºN) Photos: J. Randerson

22. Changes in surface albedo at the Delta Chronosequence Grey line = Recent burn Black line = Control Liu et al., 2005

23. 4 ha 73 ha 11 ha 1951 B&W Aerial Photography 1978 B&W Orthophotograph 2000 Landsat ETM+ 36/24 ha 1.5/3 ha 16/9 ha Drying of northern wetlands Riordan et al. JGR. 2006

24. Net Water Surface Area Loss in Alaska

25. AMSR-E Topographic Information MODIS Polarization Difference DEM (m) Slope (deg.) LAI Iterative Multivariate Clustering No Data or Excluded Very High Very Low Ocean Lake RFI High Medium Low Principal Component Analysis Inundation Fraction Floodplain vs. Lake Discrimination Monthly Inundation Fraction June – September 2005 June July August September Wetland Characterization with Microwave Remote Sensing Inundation Monitoring with AMSR-E and MODIS Construct for derivation of monthly inundation data sets, showing example products for the NEESPI domain. Algorithm input data sets include AMSR-E brightness temperature and polarization difference, topography, and MODIS-based leaf area index (LAI). An iterative unsupervised multivariate clustering approach is employed to identify potential inundated areas and the corresponding inundation fraction, and principal component analysis applied to differentiate critical features within the inundated regions. The derived data sets show monthly mean relative inundated area fraction. The algorithm is applied globally and shown here for the NEESPI region K. McDonald

26. Scatter plot of yearly averaged CH4 column burden by SCIAMACHY vs. MATCH (on each model grid). Slope is 1.01, i.e., good agreement in spatial gradient. Large offsets (~8%), contamination by clouds, aerosols? R. Prinn

27. Ecosystem Change and Processes in the Northern Oceans

28. Changes in Arctic Productivity • Sea ice extent has dropped recently, especially in 2007 • Primary production increased by 27.5 Tg C yr-1 between 2003 and 2007 • Primary production increased by 35 Tg C yr-1 between 2006 and 2007 • 30% of the increase due to increased open water habitat Courtesy K. Arrigo

29. Annual productivity in Arctic Regions • Annual productivity is highly variable, driven • by open water area. • Chukchi Sea is the only region with a significant • positive trend. Out-flow shelf In-flow shelf Basin >500 m Interior shelf Patterns in Arctic Ocean Productivity: The 10 year SeaWiFS record VHill, R Zimmerman, P Matrai, E Olson

30. Each 106 km2 loss of sea ice could increase annual production by 163 Tg C yr-1 (K. Arrigo) • Complete loss of spring-summer ice could boost annual Arctic primary productivity by as much as 1300 Tg C yr-1 (3-fold higher than the 1998-2002 mean) (K. Arrigo) • Loss of ice could cause a shift from ice-obligate to pelagic fauna (K. Arrigo) • Will responses of DMS biogeochemistry of the Arctic Ocean in response to less sea ice result in a negative feedback to climate associated with increased aerosols? • As the sea ice continues to decline, the location, timing, and species make-up of the blooms is changing, vastly decreasing the amount of food reaching the living things on the ocean floor. This radically changes the species make-up and populations of the fish and other marine life forms, with significant repercussions for fisheries (from SAP 4.3) Impacts of Changes in Sea Ice on Northern Oceans

31. Snow crab Rock sole Halibut Pollock Mean shift = 31 km One-sample t = 3.50 P = 0.0005 Rate similar to North Sea (Perry et al. 2005) Shifts in center of distribution for 45 taxa in SE Bering Sea, 1982-2006

32. Ecosystem Change and Processes in the Southern Ocean

33. ocean land Distribution (fraction) Distribution (fraction) 1990 1960 1980 2000 1970 Dynamics of the Airborne Fraction Atmosphere [Airborne Fraction] Distribution (fraction) 1960 1970 1980 1990 2000 Canadell et al. 2007

34. Southern Annular Mode (SAM) Regression Patterns GEOPOTENTIAL HEIGHT (m) WINDSTRESS (dyne cm-2) Positive Southern Annular Mode (SAM) represents stronger lows over Antarctica and stronger highs over adjacent ocean, which results in higher winds. Positive SAM has been linked to increasing [CO2] and decreasing stratospheric ozone.

35. SAM and CO2 Flux Variability NCAR CCSM (FGM) REGRESSION (mol m-2 yr-1) CORRELATION Positive SAM related to outgassing of CO2 Lovenduski et al. 2007

36. Stronger venting of “natural CO2”

37. Trends in spatially-integrated Southern Ocean CO2 fluxes Lovenduski et al. in press

38. Changes in Southern Ocean Primary Productivity K. Arrigo

39. Total annual production in waters south of 50°S averaged 1949±70.1 Tg C yr-1 between 1998 and 2006, approximately half that of previous estimates. The large but relatively unproductive pelagic province accounted for ~90% of Southern Ocean production. Surprisingly, production in the marginal ice zone was only slightly higher than in the pelagic province. Unlike the Arctic Ocean, there was no secular trend in either sea ice cover or annual primary production in the Southern Ocean during our nine-year study. Interannual variability was most closely tied to changes in sea ice cover, although changes in sea surface temperature also played a role. Annual primary production could increase in the future as stronger winds increase nutrient upwelling. Changes in Southern Ocean Primary Productivity K. Arrigo

40. Summary

41. How are responses of northern terrestrial ecosystems to climate change influencing the exchanges of CO2, CH4, water, and energy, particularly with respect to changes in precipitation minus evaporation? • Analyses of CO2 exchange need to consider physiological responses and responses to multiple disturbances in northern terrestrial ecosystems. • It is important to evaluate the integrated effects of multiple ecosystem responses on the climate system to understand whether the changes will act to mitigate or enhance climate change. • How will primary productivity of the northern oceans change with the continued loss of sea ice? • Will changes in DMS biogeochemistry result in substantial negative feedback to climate warming in the Arctic? • How are changes in sea ice influencing marine food webs, and what are the implications of these changes for fisheries? • How will primary production and CO2 exchange of the Southern Ocean respond to continued changes in climate? • How will changes in ecosystem structure and function influence lifestyles of indigenous peoples?