Changes in the Arctic and their Climate Feedback Implications. Cherskiy region, NE Siberia

Transcription

1 Changes in the Arctic and their Climate Feedback Implications Cherskiy region, NE Siberia

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3 Some of WHRC s work in the Arctic Remote sensing & field measurements documenting changes in Arctic vegetation properties and processes Modeling of future Arctic vegetation change Remote sensing and field measurements documenting changes in Boreal vegetation properties and processes Permafrost observations, monitoring & manipulation experiments Likely implications of these changes wrt climate feedbacks & policy

4 Why focus on the Arctic? Warming is Amplified

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6 Satellite observed productivity increases across tundra ecosystems So-called Arctic greening Guay et al Global Change Biology

7 Multiple lines of evidence for increased arctic shrub abundance Historical Ecology Dendroecology Experiments Increasing shrubs Ecological Monitoring Stable populations Decreasing populations Myers-Smith et al. ERL 2011

8 Is observed greening from increased shrub cover? To find out we mapped shrub cover at higher resolution Beck, Goetz, Tape (2011) Arctic, Antarctic and Alpine Research

9 Increasing productivity trends are not restricted to areas with higher shrub cover time series normalized to a mean of 0 and standard deviation of 1 Beck, Goetz, Tape (2011) Arctic, Antarctic and Alpine Research

10 Tundra Boreal Transitions (treeline) observed from satellites Loranty et al GCB

11 MODIS satellite tree cover & albedo seasonality across circumpolar latitudinal gradients Biophysical treeline Albedo Tree Canopy Cover Land Cover April July Water Forest Shrub Herb Other A MODIS ESM B MODIS ESM Distance to Tree Line (km) C

12 What s likely to happen in future? How important is plant productivity & related carbon sequestration in biomass? Does it matter if change is primarily in shrubs or some other vegetation type(s)? How does disturbance factor in?

13 Changes in store for future Arctic vegetation cover with climate feedback implications 40 E 20 E 0 20 W 40 W 50 W a Current (CAVM) b 2050 (predicted) 40 E 20 E 0 20 W 40 W 50 W 5 Vegetation classes G1 G2 G3 G4 T1 T2 P1 P2 S1 S E W 140 W 160 E W 140 W Fig. 1

14 Current (CAVM) 2050 (predicted) Predicted Change in in Arctic Vegetation Photo: Olof Carmel Graminoids Trees present Prostrate shrubs Erect-shrubs Pearson et al. (2013)

15 Current 2050 (predicted) Predicted Change in Arctic Albedo Albedo Predicted Change in Arctic Mean MODIS albedo for each CAVM vegetation class.

16 Current 2050 (predicted) Predicted Change in Arctic Net Shortwave Radiation Mean for each CAVM vegetation class. W/m 2

17 Change Under 2050 Climate Compared to Present Albedo Net Shortwave Radiation Arctic veg changes will feedback to climate largely as a biophysical medium. Forcings associated with biomass and evapotranspiration changes are small by comparison.

18 Other processes that could amplify this outcome 2007 Anatuvik Tundra Fire O

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20 Science, Aug 2015

21 In the Boreal Forest Satellite observed productivity declines with warming & drying Drought / high VPD The New North Science Aug 2015

22 Tree ring data support evidence for satellite observed productivity declines Beck et al., Ecology Letters 2011

23 Browning, Drying & Drought can lead to increased tree mortality Temperature Cooler Warmer High Low Drought Intensity Short Drought Duration Long Tree Mortality Threshold MORTALITY NO MORTALITY Wetter Precipitation Drier Craig Allen et al 2010

24 Browning, Drying & Drought can lead to increased tree mortality Temperature Cooler Warmer High Low Drought Intensity Short Drought Duration Long Tree Mortality Threshold MORTALITY NO MORTALITY Wetter Precipitation Drier Craig Allen et al 2010

25 Boreal Forest Mortality: Satellite & Forest Inventory Evidence

26 Tree mortality events are preceded by negative trends in satellite vegetation productivity indices ( press stress) GIMMS3g 8km CAFI plots - Alaska MODIS 250m mortality events control

27 Climate warming & drying / drought also intensify the fire regime

28 Boreal fire is common & widespread but now increasingly intense (more severe burning)

29 An intensified fire regime changes the composition of regrowth burn severity post-fire organic layer depth OL = 10 cm OL = 5 cm OL = 2 cm

30 Fire disturbance deepens thaw depth and mobilizes permafrost carbon 2010 Fire on Tanana Flats, AK Photos by Torre Jorgenson

31 Permafrost occupies ~24% of northern hemisphere land area

32 Models approximate 30% to 70% permafrost area loss Lawrence et al. 2012

33 Climate warming CO 2 & CH 4 Thaw

34 Permafrost thaw could substantially modify climate What is likely to be the magnitude, timing, and form of permafrost carbon release to the atmosphere in a warmer world? Cumulative C Emissions: (2012) Fossil Fuel Emissions 365 Gt Land Use Change 151 Gt Future (2100) Permafrost Zone C Emissions? 7-11% Loss Gt (Expert Survey) Gt CO 2 -C eq Ted Schuur & Permafrost RCN

35 How might permafrost thaw affect emissions targets? < 2 C target: 790 Gt To date: ~515 Gt Remaining: 275 Gt Permafrost: >160 Gt (~10% of the pool) IPCC SPM 2013

36 Permafrost thaw impacts ecosystems

37 Permafrost thaw impacts infrastructure

38 Synopsis: in the Arctic Boreal region.. Climate change is greater and more rapid than elsewhere Predicted warming will change arctic vegetation & feedbacks (as a biophysical medium ) Recent warming has led to vegetation productivity changes tree mortality events changes in albedo & energy balance intensification of the fire regime Warming-induced drought (high VPD) is a driver Fire and associated vegetation changes have the potential to speed permafrost thaw & mobilize previously frozen carbon (a tipping point?)

39 IPCC AR5, WG2, Chap.4

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41 What can we do about it? Arctic policy hooks Arctic Council (8 Arctic nations) Arctic Circle forum (all interested parties) Global Arctic Leadership Forum (GLACIER) Arctic 21 (NGO groups) UNFCCC COP21 Native peoples & Management agencies

42 What can we do about it? Arctic policy hooks Visits to US State Department Special Representative Arctic Region Key player in the Arctic Council & GLACIER

43 permafrost stores massive amounts of carbon. When the permafrost is no longer permanent, when it thaws or burns, these gases are released into our atmosphere over time, and that could mean that the Arctic may become a new source of emissions that further accelerates global warming.

44 We call for additional research to characterize the response of Arctic permafrost and other carbon reservoirs to warming especially in hotspots that have the potential to release particularly large stores of greenhouse gases. Joint Statement from Glacier Conference

45 What more can we do about it? Influence arctic science policy International science policy IARPC Permafrost RCN, ITEX, ShrubHub US arctic science policy NSF ARCSS DOE NGEE NASA ABoVE

46 above.nasa.gov

47 31 Aug 2015

48 Training the next generation of Arctic researchers The Polaris project Research, Education, and Outreach in the Siberian Arctic