1. Ice-Atmosphere Interaction: Melting of Mountain Glaciers Rebecca Miller Atmospheric Sciences

2. Tropical glaciers, recorders and indicators of climate change, and disappearing globally Thompson et. Al. 2011 Picture: Thompson at Kilimanjaro, 1999

3. Introduction: Overview Interaction of ENSO variability and warming trends recorded in ice- core records Melting Impacts o Glaciers o Societies

4. Introduction: Ice Core Paleoclimate record Oxygen and hydrogen isotopes, accumulation, dust Variability in precipitation, temperature, aridity, and atmospheric and oceanic circulation Thompson in Guliya, China, 1992 Objective: “the acquisition of a global array of ice cores that provide high-resolution climatic and environmental histories that will contribute to our understanding of the complex interactions within Earth’s climate system”

5. Introduction: Warming Earth’s average temperature has increased ~0.7°C since 1900 Twice as much warming at higher elevations in the tropics than at Earth’s surface due to greenhouse- gas-forced warming, upper-tropospheric humidity and water- vapor feedback

6. Snow Melts, Ice Melts Darker land surface Absorption of radiation Increases

7. Fig. 1 Temperature SST Intense Precipitation “Heat Engine” Tropical disturbances distribute tropical energy pole-ward

8. Tropical Ice-core Evidence of ENSO Enriched isotopic ratios occur during strong El Niño events Dust

9. Fig. 3 Extended reconstruction of SST (b) detrended – long term warming trend removed Variability of ENSO through time Changes in the tropical freezing level

10. Fig. 4 Melting impacts the isotopic records Meltwater homogenizes the seasonal changes

11. Temperature is projected to increase more with higher elevation

12. 1000 year records of oxygen isotopes Increasing Elevation

13. Warming And Retreat Of Tropical Ice Fields Rate at which a glacier responds to climate change is inversely proportional to its size Temperature is a dominate factor o Ice masses are sensitive to temperature change o Exist very close to the melting point If the current rates continue or accelerate, many tropical ice caps may disappear within the first half of the 21 st century

14. Rate of ice loss per year

15. Warming And Retreat Of Tropical Ice Fields Quelccaya Rate of retreat is accelerating

16. Warming And Retreat Of Tropical Ice Fields Tibetan Plateau, Himalaya, Naimona’nyi Kilimanjaro surface temperature measurements satellite observation studies persistent warming = ice loss Ice cover 86% disappeared since 1912 27% of that present in 2000 is now gone

17. Impact On Water Resources Changes in water supply o Hydroelectricity o Irrigation o Public water supply Flooding o Crops o Grazing animals Avalanches

18. Conclusion Warming trends across tropical glaciers Rising temperatures more pronounced with increasing elevation Melting is already effecting people who depend on the meltwater Qori Kalis

19. Potential impacts of a warming climate on water availability in snow-dominated regions Barnett et. Al. 2005 Climate Research Division, Scripps Institution of Oceanography, California

20. Introduction: Overview Increasing temperature has consequences for the hydrological cycle Changes in this cycle effect water supply from melting snow or ice Earlier runoff in spring or winter, reduced flow in summer and autumn

21. Global Distribution 2000 – approximately 1/6 th the world’s population lives within snowmelt-dominated and low-reservoir storage domain Snowmelt dominated regions: o Greater than ~45° o Mountainous regions Red – snowmelt-dominated, inadequate reservoir storage Black – water availability is influence by snowmelt

22. Evapotranspiration Little agreement on direction and magnitude of evapotranspiration trends Observations show pan evaporation has been decreasing 1. Increasing evapotranspiration Cool and humid 2. Decreasing evapotranspiration Reduced energy available for evaporation

23. Impacts on regional water supply Western USARhine River in Europe Spring stream flow will come a month earlier Not enough reservoir storage to handle this shift By 2050 the Columbia River system will not be able to accommodate both hydroelectricity and the summer releases for salmon Increasing temperature = rainfall-dominated Reduction in water availability, increase of low flow days Ships will not be able to travel the river, decrease in hydroelectricity, shortened ski season

24. Impacts on regional water supply Canadian Prairies … earlier snowmelt → decrease in soil moisture Increase in frequency and severity of drought Sensitive to drought due to irrigation needs

25. Glacier Impacts Himalaya-Hindu KushSouth American Andes Melting rate is increasing → runoff Water shortage is not being experienced yet but will arrive more abruptly Glacier covered area reduced 25% in last three decades Current dry season water resources will be depleted once glaciers have disappeared

26. Conclusion Uncertainties Capability of models Inclusion of aerosols and clouds Models predict warming Alterations of the hydrological cycle Earlier runoff Insufficient reservoir storage Reduction in dry- season water

27. What Happens Now? More Research… Better water management Better models and predictions