Glaciers and climate change Jon Ove Hagen, Department of Geosciences University of Oslo

Size: px

Start display at page:

Download "Glaciers and climate change Jon Ove Hagen, Department of Geosciences University of Oslo"

Austen Bridges
6 years ago
Views:

1 Glaciers and climate change Jon Ove Hagen, Department of Geosciences University of Oslo Department of geosciences, Faculty of Mathematics and Natural Sciences

2 Glaciers and climate change The global impact - sea level The regional and local impacts - hydrology - runoff - water supply Department of geosciences

3 Sea level is rising now by 3.1 mm per year, double the average rate of the 20th century. UNEP, 2007 What effects the sea level? 1) Thermal expansion of the ocean water 2) Land-based ice masses 1) Antarctica 2) Greenland 3) Local glaciers and ice caps 3) (Ground water, permafrost, artificial water reservoirs)

Sea Level Rise (mm yr 1 ) G A 1961-2003 1993-2003 GIC Thermal Expansion 0.42 ± 0.12 1.6 ± 0.5 Glaciers and Ice Caps 0.50 ± 0.18 0.77 ± 0.22 Greenland Ice Sheet 0.05 ± 0.12 0.

4 Sea Level Rise (mm yr 1 ) G A GIC Thermal Expansion 0.42 ± ± 0.5 Glaciers and Ice Caps 0.50 ± ± 0.22 Greenland Ice Sheet 0.05 ± ± 0.07 Antarctic Ice Sheet 0.14 ± ± 0.35 Sum 1.1 ± ± 0.7 Observed 1.8 ± ± 0.7 Difference (Obs. Sum) 0.7 ± ± 1.0 Ther mal exp. Obs. (From IPCC, 2007)

5 Contributions to Sea level rise from glaciers 2008 Antarctica = 0.54 Greenland = 0.74 Glaciers and Ice Caps = 1.1 mm/yr Total 2,4 mm/yr SLE IPCC, 2007 Different sources

6 Greenland mass balance IPCC Alley (2007): H and B surface mass balance T-green (laser altimetry), Z-violet (radar altimetry), blue (GRACE gravity), R- red (SARinterferometry discharge+surface )

7 Mass loss uncertainties from Greenland Bromwich and Nicolas, 2010

8 Greenland ice streams speed up and increase calving Triggering increased sea level?

9 Modeled sea level rise (from IPCC 2007) 2100: ( ) m but with dynamic loss ~ 1 m?

10 Regional trends in mean sea-leve change (mm yr 1 ) for 1955 to 2003 (Church et al., 2004)

12 The combined relative sea level variations for all ice masses (mm/yr) From Bamber and Riva, 2010

13 Glaciated areas outside the large ice sheets From Gregory et al. (2001)

14 Relative glacier area (%) and contribution to changes (%) (UNEP, 2007)

15 Glaciers and ice caps - global mass change?? From Lemke et al. IPCC 2007, AR4, WG1

16 Future runoff from small glaciers and ice caps

17 Department of geosciences Eriksson, ICIMOD)

18 Himalaya ~ 2400 km x km Large climatic gradients! Department of geosciences

Central Asia region Glacier area ~115 000 km 2 Himalaya ~

19 Central Asia region Glacier area ~ km 2 Himalaya ~ km 2 feeding large river basins Indus Y. Ganges Br.

20 How important are glaciers for freshwater supply downstream? Storage of water in glaciers may result in lags between precipitation and runoff. Glacier melt is important for irrigation purposes - but mainly for the upstream part of the basin! For the lower parts of the basin, this depends on the precipitation contribution and timing. This differs from basin to basin and should be made specific over the stretch of the river. From discussion at High mountain glacier conference, Tromsø 2009

21 Eriksson, ICIMOD)

22 From Alford and Armstrong, 2010

23 Short timeseries of mass balance Wagnon et al. (2007) J.Glac. 53(183, )Dyurgerov& Meier (2005) -INSTAAR58

24 What do we know about Himalayan glaciers? The glaciers are retreating but at different rate Measurements are mainly length and area retreat Regional distribution taken from remote sensing data Very little volume change data - Very few mass balance series Large uncertainties A lot of contradictory information! Two sets of problems: 1. The glacier mass balance and runoff 2. The Glacier lake outburst floods (GLOFS) Discussion at High mountain glaciers conference, Tromsø 2009

25 From J. Reynolds

26 GLOFS- Glacier lake outburst floods Hazards Frequency and intensity has increased. Number of glacier lakes and the volume of lakes are increasing Risk is increasing, also because more people live in the hazardous zones. Mapping and monitoring is needed From discussion at High mountain glaciers conference, Tromsø 2009

27 Record? retreat of some glaciers in Himalaya Glaciers in the Himalaya are receding faster than in any other part of the world (WWF, 2005) Climate change-related melting of glaciers could seriously affect half a billion people in the Himalaya- Hindu-Kush region and a quarter of a billion people in China who depend on glacial melt for their water supplies (Stern, 2007)?

28 The 30.2 km long Gangotri glacier has been receding alarmingly in recent years (Hasnain, 2002)?

29 Gangotri glacier

Krakoram in Pakistan glacier areas in km 2 - no change 1979-2000 Glacier 1979 1999 2000 BUT: from Rakhshan Roohi, WRRI, NARC/PARC, 2009 Western

30 Krakoram in Pakistan glacier areas in km 2 - no change Glacier BUT: from Rakhshan Roohi, WRRI, NARC/PARC, 2009 Western Himalaya, Himachal Pradesh, India: annual ice thickness loss of about 0.8 m w.e. per year ( ). (Berthier et al., 2007Remote Sensing of Environment)

31 What are the knowledge gaps? Understanding the impact of climate changes on glaciers and glacier-fed rivers requires: 1) long-term monitoring of glacier mass and velocity 2) quantified volume change data 3) meteorological and hydrological records 4) satellite data analysis 5) need for predictive models Research and monitoring funding strategies must be adapted to these needs. From discussion at High mountain glaciers conference, Tromsø 2009

32 We need field data! Thank you! Department of geosciences UNESCO-Mass balance training course Nepal, 2009

MODELLING FUTURE CHANGES IN CRYOSPHERE OF INDUS BASIN

MODELLING FUTURE CHANGES IN CRYOSPHERE OF INDUS BASIN ANIL V. KULKARNI DISTINGUISHED VISITING SCIENTIST DIVECHA CENTRE FOR CLIMATE CHANGE INDIAN INSTITUTE OF SCIENCE BANGALORE 560012 INDIA Presented at