Remote Sensing 4 Global mass changes from remote sensing

Transcription

1 Remote Sensing 4 Global mass changes from remote sensing Nick Barrand School of Geography, Earth & Environmental Sciences University of Birmingham, UK

2 Why glacier mass changes? o Water resources o Energy generation o Sea-level rise o Climate

3 Global mass changes : an overview o Glaciers Which regions matter for sea level? Regional overview of mass changes The global picture o Ice Sheets

4 RGI glacier area Pfeffer et al (2014)

5 Where s the ice? Gardner et al (2013)

6 From area to volume Bahr et al (1997)

7 Potentially important regions for SLR Radic & Hock (2010)

8 δv/δa = Ma Mm Mc ± Mb

9 Regional overview of mass changes : Canadian Arctic o SMB model constrained by observations o Increasingly ve mass balance since ~2006 Gardner et al (2011)

10 Regional overview of mass changes : Canadian Arctic Gardner et al (2011)

11 Regional overview of mass changes : Canadian Arctic Image: A. Gardner

12 Regional overview of mass changes : Canadian Arctic methods agree o : 31 ± 8 Gt yr -1 o : 92 ± 8 Gt yr -1 ice loss from increased ablation resulting from warmer summer temp o 64 ± 14 Gt yr -1 K -1 Gardner et al (2011)

13 Regional overview of mass changes : Gulf of Alaska Luthcke et al (2008)

14 Regional overview of mass changes : Gulf of Alaska Luthcke et al (2008), courtesy A. Arendt

15 Regional overview of mass changes : Patagonia o Gt yr -1 o GIA = ~+9 Gt yr -1 Ivins et al (2011)

16 Regional overview of mass changes : Russian Arctic Moholdt et al (2012)

17 o Gt yr -1 o 80% from Novaya Zemlya o 20% from FJL & SZ Moholdt et al (2012)

18 Regional overview of mass changes : Svalbard o Low elevation thinning o High elevation thickening o -4.3 Gt yr -1 o 20% from FJL & SZ o NE Spitzbergen & Austfonna gaining mass Moholdt et al (2010) RSE

19 Global glaciers

20 148 +/- 30 Gt yr / mm yr -1 SLR Jacob et al. (2012)

21 Global glacier mass changes o : Global mass budget : -259 ± 28 Gt yr -1 o : 0.71 ± 0.08 mm SLE yr -1 Gardner et al (2013) Science

22 Global glacier mass changes Global mass budget : -259 ± 28 Gt yr -1 Gardner et al (2013) Science 0.71 ± 0.08 mm SLE yr -1

23 Gardner et al (2013) Science

24 Greenland and Antarctica?

25 Pritchard et al. (2009)

26 Ice Sheets Ice Sheet Mass Balance Intercomparison Exercise (IMBIE)

27 IMBIE o 30+ estimates since 1989 o Lack of clarity in estimates o Allow for combined ice sheet SL contribution between 0.2 mm yr -1 fall and 1.9 mm yr -1 rise Altimetry : changes in ice sheet shape InSAR : changes in ice sheet flow Gravimetry : changes in ice sheet weight

28 Past estimates of GIS mass balance Sea level rise (mm per year) Gravimetry Radar altimetry Input-output method Laser altimetry Year

29 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

30 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

31 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

32 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

33 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

34 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

35 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

36 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

37 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

38 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

39 Past estimates of GIS mass balance 1.00 Gravimetry Sea level rise (mm per year) Radar altimetry Input-output method Laser altimetry Year

40 Reconciling the estimates o Community assessment o Supported by ESA and NASA o 47 participants, 26 research groups o 10 satellites, 54 total years of data Greenland Antarctic Peninsula West Antarctica East Antarctica Image: A. Shepherd

41 IMBIE define common periods Gravimetry- GRACE Laser Al=metry- ICESat Radar Al=metry - EnviSat Radar Al=metry - ERS IOM/InSAR IOM/SMB Image: A. Shepherd

42 IMBIE define common periods Gravimetry- GRACE Laser Al=metry- ICESat Radar Al=metry - EnviSat Radar Al=metry - ERS IOM/InSAR IOM/SMB AR4 AR s 2000 s Image: A. Shepherd

43 IMBIE define common periods Overlap Gravimetry- GRACE Laser Al=metry- ICESat Radar Al=metry - EnviSat Radar Al=metry - ERS IOM/InSAR IOM/SMB AR4 AR s 2000 s Image: A. Shepherd

44 IMBIE : patterns of imbalance InSAR Altimetry Gravimetry Shepherd et al (2012) Science

45 IMBIE : patterns of imbalance Shepherd et al (2012)

46 IMBIE : basin mass loss Radar altimetry green Budget / IOM - red Shepherd et al (2012)

47 Shepherd et al (2012)

48 IMBIE : no more box plots 1.00 Sea level rise (mm per year) Year

49 IMBIE : no more box plots 1.00 Sea level rise (mm per year) Year

50 Antarctic sea-level curves Shepherd et al (2012)

51 Ice sheet sea-level curves o /- 3.8 mm SLR since 1992 o 20% of global SLR trend o 2/3 from Greenland Ice Sheet o Greenland now losing 5 x as in 1990s Shepherd et al (2012)

52 Antarctic Peninsula

53 the Antarctic Peninsula ice sheet would benefit from measurements with greater spatial sampling Shepherd et al. (2012)

54 AP mass balance o increased air and ocean temperatures o Glacier retreat, acceleration, thinning o more melting o Ice shelf collapse and inland response

55 AP mass balance Mass Budget Method < 50 % coverage Radar Altimetry (ERS/EnviSat) < 50 % coverage Gravimetry 100% coverage Low spatial resolution

56 AP mass balance basins Complex terrain Gaps in data Large variability in glacier behaviour Large uncertainty in extrapolation and interpolation

57 APMB 2013 to institutions dm/dt of APIS Altimetry, Gravimetry and Mass Budget methods Combine and reconcile techniques Maximise data coverage optimise techniques use new datasets (e.g. CryoSat-2)

58

59 Summary o GLACIERS ( ) 0.71 ± 0.08 mm SLE yr -1 o ICE SHEETS ( ) 0.59 ± 0.20 mm SLE yr -1 o ICE SHEETS ( ) 0.82 ± 0.16 mm SLE yr -1