Next-Generation Ecosystem Experiments (NGEE Arctic)

Transcription

1 Next-Generation Ecosystem Experiments (NGEE Arctic) Stan D. Wullschleger Environmental Sciences Division Oak Ridge National Laboratory Subsurface Biogeochemical Research PI Meeting April 28, 2011

2 High-Resolution Global Climate Model Regional Model (RASM) Global Model (CESM) Community Land Model (CLM) Next-Generation Ecosystem Experiments

3 High-Resolution Global Climate Model Regional Model (RASM) Global Model (CESM) Community Land Model (CLM) Translation of fundamental science is problematic Next-Generation Ecosystem Experiments

4 High-Resolution Global Climate Model Regional Model (RASM) Global Model (CESM) Community Land Model (CLM) Explore high-resolution, intermediate-scale process and landscape models, and generate datasets appropriate to this scale Next-Generation Ecosystem Experiments

5 NGEE Arctic Science Team Stan Wullschleger, Oak Ridge National Laboratory Larry Hinzman, University of Alaska, Fairbanks Susan Hubbard, Lawrence Berkeley National Laboratory Cathy Wilson, Los Alamos National Laboratory Alistair Rogers, Brookhaven National Laboratory

6 Arctic and Prevalence of Permafrost Land area in the Arctic is estimated at 29 x 10 6 km 2 Permafrost occupies approximately 19 x 10 6 km 2 Permafrost contains 1672 Pg C 6 to 11 x 10 6 km 2 of permafrost lost by to 200 Pg C potential loss by 2100 Additional consequences associated with CH 4 emissions A positive feedback to climate warming

7 Arctic and Net Energy Balance

8 Arctic is unique, sensitive to change, and already in transition Ice-rich, permafrost-dominated system; highly complex, Tipping point defined by surface and subsurface physical, thermal, and hydrologic properties, Consequences are observed at landscape to regional scales, with implications for land-atmosphere interactions Carbon stored in permafrost is vulnerable to loss, but the timing, rate, and magnitude of CO 2 and CH 4 fluxes due to a deepening of the active layer are highly uncertain, Greening of the Arctic; mechanisms unidentified, and Feedbacks to climate are numerous, yet poorly understood with a critical need for improved representation in regional and global climate models.

9 Arctic is unique, sensitive to change, and already in transition Ice-rich, permafrost-dominated system; highly complex, Tipping point defined by surface and subsurface physical, thermal, and hydrologic properties, Consequences are observed at landscape to regional scales, with implications for land-atmosphere interactions Carbon stored in permafrost is vulnerable to loss, but the timing, rate, and magnitude of CO 2 and CH 4 fluxes due to a deepening of the active layer are highly uncertain, Greening of the Arctic; mechanisms unidentified, and Feedbacks to climate are numerous, yet poorly understood with a critical need for improved representation in regional and global climate models.

10 Ground ice, ice lens, and ice wedges

11 Thawing????

12 Thermokarst Thawing Thermal erosion

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19 NGEE Arctic: Science Goals Use experiments, observations, and process models to Understand and quantify the response and sensitivity of physical, ecological, and biogeochemical processes to atmospheric and climatic change across molecular to landscape scales, Focus on important interactions that drive climate feedbacks through greenhouse gas fluxes and changes in surface energy balance, Consider how process-level mechanisms are linked to the concept of landscapes in transition, and Use fundamental knowledge to improve representation of ecosystem dynamics, subsurface biogeochemistry, land-atmosphere processes, and landscape dynamics in regional and global models to reduce uncertainty and improve prediction of climate impacts and climate change in high-latitude ecosystems.

20 NGEE Arctic Site Selection

21 Barrow Council

22 Overarching Science Question: How does permafrost degradation, and the associated changes in landscape evolution, hydrology, soil biogeochemical processes, and plant community succession, affect feedbacks to the climate system? Our research tasks are organized around four components that determine whether the Arctic is, or in the future will become, a negative or positive feedback to climate: Water Complexity due to hydrology and surface and subsurface interactions Nitrogen Driver of large-scale changes in vegetation Carbon Microbial transformation of SOM to CO 2 and CH 4 Energy Permafrost dynamics and Greening of the Arctic Multi-scale research activities are organized around these focus areas, and are designed to identify and quantify the complex interactions between climate, permafrost degradation, geomorphology, hydrology, soil biogeochemistry, plant productivity and structure, net energy balance, and greenhouse gas fluxes.

23 Site Characterization Soil surveys Minerology Carbon and nitrogen ph Oxygen status Plant surveys Species Biomass Carbon and nitrogen Topography Geophysical surveys

24 Plot Plot Plot

25 Challenge Area 1: Water Rationale: Improving climate change prediction in high-latitude systems requires an accurate understanding of permafrost dynamics along with geomorphic processes that control hydrology and underpin ecosystem, soil biogeochemistry, and land-atmosphere interactions. Question: Does permafrost degradation lead to a predictable progression of landscape change, characterized by thermokarst development, increased heterogeneity in soil moisture and surface water distribution, and eventual large-scale drying of the landscape? Pore/Core: Assess mechanical properties of permafrost and freeze-thaw deformation of soils; lateral and vertical flux of water. Plot: Quantify active layer thickness and depth of water table; preferential flow paths; characterize lateral flow patterns. Landscape: Characterize surface topography and watershed-scale hydrologic fluxes and stocks; conduct high-resolution surveys of surface micro-topography.

26 Challenge Area 2: Nitrogen Rationale: Increasing dominance of shrubs over smaller statured tundra vegetation creates feedbacks to climate through changes in net energy balance and C fluxes; mechanisms uncertain. Question: Does permafrost degradation and thermokarst formation promote increased availability of N within ecosystems, and if so, what is its role in driving plant competition, community composition, and transitions in the arctic landscape? Pore/Core: Rates of microbial mineralization of organic compounds to ammonium and nitrate will be assessed; as will preferential uptake of N forms by plants. Plot: Plant community composition assessment along transects; nitrogen uptake and acquisition strategies determined; plant functional types for N developed for models (e.g., ArcVeg). Landscape: Leaf- and canopy-scale N concentrations determined by optical properties obtained through aircraft imaging spectroscopy; optical signatures evaluated for regional-scale prediction of GPP; variation analyzed in relationship to landscape patterns.

27 Challenge Area 3: Carbon Rationale: A predictive understanding of C transformation is needed, but does not yet exist given uncertainty in the biological and chemical reaction rates that are imposed by temperature and water. Question 1: What is the primary variable that governs organic C degradation and the contribution of CO 2 or CH 4 to greenhouse gas emissions? Question 2: Does organic C chemistry and geochemical interactions control microbial degradation in thawed permafrost? Pore/Core: Water films around soil aggregates during freeze-thaw cycles using neutron imaging; methane oxidation associated with microbial community structure and enzyme activities. Plot: Soil water and redox potentials measured via lysimeters and groundwater wells; 14 C to determine age of organic C and advanced imaging to assess chemical structure. Landscape: Tower-based CO 2 and CH 4 flux determinations.

28 Challenge Area 4: Energy Rationale: Energy budgets are fundamental to climate feedbacks. Models must incorporate land-surface properties associated with changes in net energy balance due to vegetation dynamics and thawing permafrost. Question: Will permafrost degradation result in a net positive feedback to the climate system through changes in albedo and energy exchange? Pore/Core: Heat capacity and related thermal properties of permafrost; determination of ice fraction during freeze-thaw cycles; and multi-phase modeling in support of measurements. Plot: Measure components of land-atmosphere energy fluxes (e.g., latent heat flux, sensible heat flux, shortwave radiation); albedo in relation to vegetation surveys and snow cover dynamics. Landscape: Remote-sensing approaches to reflectance characteristics, skin surface temperature, and heat capacities using MODIS-class sensors; Quickbird satellite and it successor Worldview; and leverage investments of the ARM Program at Barrow.

29 High-Resolution Global Climate Model Regional Model (RASM) Global Model (CESM) Community Land Model (CLM) Permafrost Degradation and Landscape Change Dynamic Vegetation Nutrient Biogeochemistry Regional Hydrology Energy Balance GHG Fluxes Next-Generation Ecosystem Experiments

30 High-Resolution Global Climate Model Regional Model (RASM) Global Model (CESM) Community Land Model (CLM) High-Resolution Process and Landscape Simulator Next-Generation Ecosystem Experiments

31 Summary: NGEE is motivated by models, driven by fundamental science Focused on feedbacks that connect ecosystems to climate Emphasize strong interactions between surface and subsurface science Tremendous range of spatial scales Pore/core to landscape measurements (um to km) Process to grid-scale modeling (7 orders of magnitude) Embrace a complex science paradigm; hybrid approach Acknowledge the importance of and then tackle coupled-processes Multi-disciplinary, integrated team Leverage existing BER Programs and User Facilities Complement existing and planned programs of other federal agencies Builds upon connections across the national laboratories and universities

32 Next-Generation Ecosystem Experiments (NGEE Arctic) Science Experiments and Observations Models

33 Next-Generation Ecosystem Experiments (NGEE Arctic) ALS CAMS EMSL Science JGI SNS AmeriFlux Experiments and Observations Outreach CDIAC Models ACRF NLCF National Universities International

34 Questions?