2. Ice-Atmosphere Interaction (2): Melting of Greenland Ice Sheet By: Eric DoBroka

3. Professor Edward Hanna Professor of Climate Change -Edward Hanna received a BS in Planetary Science (First Class Honors) from University College London in 1995 -He was appointed as lecturer in climate change in 2003 in Sheffield, UK -Member of both Meteorological and Astronomical Societies; International Glaciological Society -Published over 80 research papers -Got questions? Call +44-144-222-7965

4. Increased Runoff from Melt from the Greenland Ice Sheet: A Response to Global Warming (2008) Greenland IS Going Green!!

5. 22  Attributes significant ice melt for 3 reasons:  1) Increased Summertime Temperatures (Numerous records smashed)  2) Significant Increasing Trend in Water Runoff  3) Change in NAO from positive to less positive/more neutral state Where’d all the ice go??

6. Topography of Greenland

7. 1) Increased Summertime Temperatures

8. Top 10 Warmest Summers in Southern Greenland

9. 2) Excessive Water Runoff  1998, 2003, and 2006 were respectively the first, second, and third highest runoff years  5 highest runoff years have all occurred since 1995  During these years, significant 24.3% increase in runoff (113 cubic km as opposed to the standard deviation of 68.7 cubic km)

10. 3 ) Changing of the North Atlantic Oscillation  Breaks down after the early 1990s Breaks down after the early 1990s  Changes in atmospheric circulation (jet Streams) Changes in atmospheric circulation (jet Streams)  Positive Phase for most of period between 1960s and 1980s Positive Phase for most of period between 1960s and 1980s  More neutral phase More neutral phase  Less positive state reduced the insularity of Greenland by encouraging WAA over land masses Less positive state reduced the insularity of Greenland by encouraging WAA over land masses

11. Conclusions  Both Greenland and the Northern Hemisphere summer temperatures exhibit common strong warming trends since the early 90s  Period of temperature recovery from volcanic eruptions  Significant glacier melting is in fact taking place at an alarming rate  Uncertainties: As observed since 1987 at Summit, summer temps near top of the ice sheet have declined slightly  Dichotomous Response due to high thermal inertia, higher atmospheric cooling, or changes in wind, cloud, radiation patterns?

12. Aud Venke Sundal University of Leeds (UK) Several publications on changing climate, glaciers; effects on Norway Geological Mapping (GIS) “Aud Venke Sundal.” - I Norge er mye av løsmassene avsatt av rennende vann. Slike masser består av grov sand og grus med lite finstoff, noe som gjør at radongassen som blir

13. Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage (2011)  Fluctuations in surface melting effects speeds of glaciers and ice sheets  Impact of warming climate decreases acceleration of Greenland’s flow despite melting??  Satellite observations of ice motion in SW Greenland  Rates of ice speed positively correlated w/ degree of melting; mean flow rates are NOT  Warmer years, ice flow is 3x shorter; overall flow slower

14. Explored spatial and temporal variations comparing velocities Overall, significant flow increase in summer for all 6 glaciers w/ speed- ups of 50% to 125% Seasonal surface melting drives seasonal cycles in ice sheet flow Dependent upon altitude

15.  Mirrors mountain glaciers  Melt induced acceleration of flow ceases during years of high melting once subglacial drainage becomes efficient!!

16. Video Clip of Greenland Ice Melt https://www.youtube.com/watch?v=b4QjyrGkaUg

17. Conclusions  Data shows that subglacial drainage system in SW Greenland evolves in response to variable surface melting similar to mountain glaciers.  Rates of surface melting at the Greenland ice sheet are predicted to double over the course of this century.  Would add.15m to.4m in sea level rise

18. Conclusions Cont.  BUT….their data is first to indicate a drop in summer speed-up of glaciers in years of high melting compared to years of low melting  Supports views that subglacial drainage system may adjust to accommodate increased melting  Uncertainties  “The net effect of melt- induced speed-up and efficient drainage remains uncertain.”

19. Let’s Play 20 Questions No really let’s not