Evidence of Current Climate Change in the Polar Regions

Transcription

1 Evidence of Current Climate Change in the Polar Regions Dr. Mary Albert Cold Regions Research and Engineering Laboratory Thayer School of Engineering, Dartmouth College Hanover, NH

2 Overview How do we detect current changes in the Arctic and Antarctic? What is the greenhouse effect and why does it matter? What is albedo,, and why is it important? Should we expect changes in the Arctic and Antarctic to be similar?

3 How do we detect current changes in the Arctic and Antarctic?

4 Satellite-based measurements gather information over large areas

5 Ground-based direct measurements yield details of the areas in which they are done

6 Arctic sea ice decay September 1980: 7.8 million square kilometers Sept 1980 Siberia The Arctic sea ice cover Greenland Alaska

7 Arctic sea ice decay September 1980: 7.8 million square kilometers September 2007: 4.2 million square kilometers Sept 1980 Siberia The Arctic sea ice cover Greenland Alaska

8 Greenland ice sheet melt extene xtent t increasing

9 Ice shelves on the Antarctic coast are disintegrating

10 The response of East Antarctic ice sheet to global climate change is not yet understood Davis et al, 2005 Monadhan et al, 2006 Remote sensing signatures contain uncertainties, and few ice cores have been drilled in parts of the interior. Is East Antarctica growing or not?

11 greenhouse effect

12 FAQ 1.3, Figure 1 IPCC 2007

13 FAQ 1.3, Figure 1 IPCC 2007

14 We are adding more greenhouse gases to our atmosphere - increasing global warming IPCC 2007

15 Albedo

16 Sunlight can be measured with radiometers incident sunlight Photo courtesy Perovich

17 Albedo tells what fraction of the sunlight gets reflected Albedo = reflected sunlight incident sunlight Albedo ranges from 0 to 1 Reflected sunlight Photo courtesy Perovich

18 Melting ice changes the surface albedo. What happens when the albedo changes?

19 Open water has a lower albedo than ice - the water absorbs sunlight and then heats up Snow 85% Albedo 7% Ocean Largest albedo to smallest

20 Melting + + Absorbed sunlight Lower albedo +

21 The ice-albedo feedback is an amplifier of change in the Earth s s climate system Here global warming melts sea ice, which absorbs sunlight, heats up and emits heat, which then adds to more warming, which then melts more ice,.

22 Report from Intergovernmental Panel on Climate Change Is the Earth warming? Definitely. Is it a fluctuation or a trend? - Trend Is it a natural cycle or human impact humans likely

23 Should we expect changes in the Arctic and Antarctic to be similar?

24 The Arctic is an ocean with a floating ice cover that is six feet thick Alaska Canada From the Living Earth

25 The Antarctic is a mountainous continent covered by an ice sheet up to several miles thick NSF

26 The Arctic and Antarctic are very different - we should not be surprised that their response to global warming is not identical everywhere. But most m of the world s s surface fresh water is in Antarctica - what is going on in East Antarctica, the sleeping giant of the climate system??

27 Summary Both satellite data and ground-based measurements are helpful in climate science. Greenhouse gases in the upper atmosphere prevent heat from leaving the atmosphere, warming the planet. Changing albedo changes the amount of heat that is reflected (and absorbed) by the earth surface - impacting warming. The Arctic is an ocean with an ice cover 6 feet deep, and the Antarctic is a mountainous continent with two miles deep of ice on top. They will behave differently.

28 Is East Antarctica growing, shrinking, or staying the same? Evidence from the snow may hold the clues... Snow charatcteristics Albert for NSTA Courville et al 2007 Antarctica from space BPRC Ohio State

29 What is the sleeping giant doing? Let s s go to East Antarctica during IPY! Google it up at Polar Palooza Media Antarctic Traverse

30 Acknowledgements Thank you to the National Science Foundation and to the National Science Teachers Association for inviting me to speak at the NSTA Symposium. Thanks to Don Perovich for sea ice visuals. Thank you, teachers,, for nurturing, encouraging, and teaching the future scientists and engineers that our nation critically needs!