Climate Change: Impacts, Solutions, and Perceptions (part 2) OLLI, Spring 2013

Transcription

1 Climate Change: Impacts, Solutions, and Perceptions (part 2) OLLI, Spring 2013

2 Climate Change: Impacts, Solutions, and Perceptions Spring 2013 (part 2) February 19 Ocean acidification and the increase of greenhouse gases. Dr. Christopher L. Sabine, Oceanographer, NOAA Pacific Marine National Laboratory, Seattle February 26 America s choices for mitigation of climate change impacts Robert W. Fri, Resources for the Future and Claudia Mengelt, National Research Council (NAS) March 5 Ethics and issues surrounding geo-engineering as a strategy to mitigate climate change Dr. Michael MacCracken, Climate Institute, Washington, D.C. March 12 American attitudes and opinions on global warming Dr. Matthew Nisbit, American University, School of Communication

3 Links to Class Information OLLI/GMU/NOAA lectures (8): All eight presenter Powerpoints and supplemental information from Gary and Dennis on OLLI blog at: Extreme Ice Survey - James Balog Dennis Silverman blog

4 Sea Level, Ice Sheets and Glaciers Image of Greenland Glaciers from USGS

5 ??* *AR5 most likely estimate Sea levels (4-6m) higher than today with temps 5-9ºF higher (~2100 prediction) Last ice age peaked ~20,000 years ago, sea levels about 390 (120m) lower

6 ~0.1mm/yr

7 3.18 mm/yr = ~1.3 /decade over Range mm/yr NASA: Mean SLR = mm/yr

8 From U.S. Army Corps of Engineers, 2011

9 Estimates and likely ranges for projections of globalmean sea level rise for RCP2.6 (blue) and RCP8.5 (red) scenarios From: IPCC, Draft AR5, 2012

10 Ice sheets at both of Earth s poles are melting rapidly, and the pace is accelerating The sheets are melting so quickly that they are likely becoming the number one cause of rising sea levels - Eric Rignot, UC Irvine/JPL Photo by Eric Rignot

11 - Ice formations hold 80% of world s fresh water - Of this total: - 87% in Antarctica - 12% in Greenland - 1% in glaciers and ice caps - If melted would raise SL by 57m, 8m and 0.7m respectively Andes Ice Cap photo by Byrd Polar Research Center, Ohio State Univ.

12 Causes of Sea Level Rise* Warming expands water (27%) (28% ) Glacier (31%) and ice sheet (42%) melt (24.5%) (47.5%) Wilkins Ice Shelf, Antarctica South Cascade Glacier, WA 1960 and 2004 (NAS, 2008) *Percentages currently under much discussion and change, but come from IPCC, Draft AR5, 2012 and Rignot, 2012

13 Ice Loss Equivalents From , the average amount of ice lost by the two ice sheets combined was 475 Gt/yr (glaciers and ice caps est. 400 Gt/yr), rate of increase at end reaching 36.6 Gt/yr (Rignot, 2012) This rate now three times faster than mountain glaciers and growing At their current rate of mass loss increase per year, these ice sheets are already on pace for a meter level sea level rise per century 360 Gt ice loss = 1mm SLR, so above totals = 2.4mm/yr or ~ 75% of today s mm/yr SLR 875 Gt ice = 14 x (quadrillion gallons) Source: Eric Rignot, 2012

14 Some IPCC-AR5 Draft Findings Paleo-records from warm periods during the last 3 million years show that global mean sea level was more than 6 m higher than present when global temperature was 2 C 3 C warmer than present Ice/glacier loss and sea level rise (SLR) have greatly accelerated since the late 20 th Century Both the Greenland and Antarctic ice sheets are losing mass at present and their mass loss is increasing with time and exceeds total from glaciers and ice caps Reduction of A/G ice sheets results from both atmospheric temperature rise and contact with warming ocean water

15 Some IPCC-AR5 Draft Findings The rate of global mean sea level rise during the 21st century will exceed the rate observed during the 20th century for all AR5-RCP* (IPCC modeling) scenarios Ice will continue to melt for at least the next 1,000 years from current CO 2 build-up Warming in this century might be enough to commit future generations to 4 6 m of sea-level rise, or even more, beyond 2100 unless GHG emissions are reduced dramatically to keep the Earth from warming above 2 C *RPC = representative concentration pathway; modeling approach AR5 = IPCC s Assessment Report #5

16 Some IPCC-AR5 Draft Findings Quantifying future ocean warming around Greenland and Antarctica is critical to understanding ice sheet dynamics and predicting global sea-level rise Data gaps are still large, especially for ice-edge dynamics (ex. bed bathymetry, ocean temp, ice thickness, basal melting conditions, accurate models)

17 Buttress

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19 Ice Ablation at the Ocean Margin

20 Ilulissat Glacier in Western Greenland Extreme Ice Survey, May

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22 Bedrock topography of the Greenland and Antarctic ice sheets shown with 500-meter contours of ice surface elevation From IPCC, AR5 Draft, 2012

23 Antarctica (~5.4 M mi 2 ) Recent ice loses are better represented by a quadratic (curvilinear) trend than by a linear one, implying that the ice sheets (A and G) contribution to sea level has become larger with time The mass loss increased from 104 Gt/yr in to 246 Gt/yr in , i.e., an acceleration of -26 +/-14 Gt/yr in Velicogna, 2010 Ice sheet holds 70% of all world s fresh water If all ice sheet melts, SL rise ~57m (don t worry) Ice began to accumulate ~37 MYA; into deep freeze (current condition) ~ 14 MYA and has varied ever since Most recent SLR contribution ~0.73 mm/yr (~0.03 /yr)

24 West 10% East 90% Image from NASA

25 (increase from ) From: Bromwich et. al., 2012

26 Wilkins Ice Shelf, West Antarctica

27 Greenland (~850,000 mi 2 ) Greenland is gaining internal ice from increased snow but rapidly losing ice at perimeter ocean The mass loss ~doubled from 137 Gt/yr in to 286 Gt/yr in , i.e. an acceleration of -30 +/-11 Gt/yr in Velicogna, 2010 Holds enough ice to raise SL by +7m if melted Most recent SLR contribution ~0.61 mm/yr (0.02 /yr) Recent rapid mass loss of the Greenland ice sheet is attributable to the acceleration of outlet glaciers that was primarily triggered by subsurface ocean warming

28 FIG (a) Map of the 2011 anomaly (relative to a base period) for the number of melting days and (b) fractional area (%) of the Greenland ice sheet identified as melting. NOTE: In summer of 2012, 100% of ice sheet was subject to some melting Graphic from BAMS 2011 State of the Climate for 2011

29 From: Yin et. al., Observed mean Modeled Modeled

30 Greenland albedo - From NASA Photo by Henrik Egede Lassen/Alpha Film.

31 This shows how less ice added every year, with net loss to ice sheet beginning in 2007 (up until then, rate of addition decreased).

32 Glacier (outlet, valley) and Ice Cap in Iceland From: CLIMATE CHANGE SCIENCE COMPENDIUM, 2009

33 Glaciers and Ice Caps (~285,000 mi 2 ) Glaciers and ice caps (~122,000) currently store ~0.5 m of sea level equivalent, and their current mass loss contributes ~1 mm/yr to sea level rise (about 400 Gt/yr) IPCC, 2010 meeting on Ice and SLR Over the past 50 years, retreating glaciers and ice caps contributed ~1 to sea-level rise, and ~one-third of this contribution is believed to come from ice masses bordering the Gulf of Alaska Range of contributions to SLR by 2100 large at m, dropping rapidly as glaciers recede over next 100 years

34 Related Sea Level Changes IPCC 2007 AR4 predicted m SL increase by 2100 BUT did not include ice melting During warm Pliocene ~3-3.5 MYA SL ~7-20m higher than today; as temps were ~4-5 C warmer than today or about where we expect to be in the year 2100 with business as usual Sea level is estimated to have risen about 11 inches between 1880 and 2010 Sea level has been rising at least 50% faster in the past decades than projected by the early IPCC reports - Rahmstorf, 2012 Global warming appears to be accelerating and may increase to 4 C or more by the end of this century, twice the earlier IPCC projections. The sea level is now expected to rise by one meter or more by 2100; two or three times the earlier projections. E. Louis, 2012

35 Related Sea Level Changes World Bank, New measurement information on the rates of deglaciation in Greenland and the West Antarctic suggest that a threshold triggering many meters of sea level rise could be crossed well before the end of this century (Hansen et al., 2007; Helsen et al., 2008; Joughin et al., 2008; Kohler et al., 2007; Overpeck et al., 2006; Rignot, 2008; Van de Wall et al., 2008) Most researchers narrowing in on 1.0m (3.3 ) of SLR by 2100 with range ~ m (23-57 ) which is what CA Climate Change agency predicted in 2009 with ice melt

36 Sources: CA Climate Change Research Center, 2009 and LA Times

37 QUESTIONS?

38 Infrastructure Changes Are they important? What if the old 100-year storm occurs every 5 years now? Gord Miller Environmental Commissioner of Ontario

39 Gord Miller Environmental Commissioner of Ontario

40 Gord Miller Environmental Commissioner of Ontario

41 Gord Miller Environmental Commissioner of Ontario

42 Gord Miller Environmental Commissioner of Ontario

43 Gord Miller Environmental Commissioner of Ontario

44 Observed contributions to GMSL Observed GMSL IPCC, Draft AR5, 2012

45 From Rignot et. al., 2010

46 South Cascade Glacier, WA 1960 and 2004 (NAS, 2008) Glaciers and ice sheets hold 80% of all of the Earth s freshwater (UNEP, 2009)

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48 Climate Change: Impacts, Solutions, and Perceptions Fall 2012 (part 1) January 7 The discovery of global warming - a history of climate change. James Fleming, Colby College History Department January 14 What is the state of the climate today? Deke Arndt, Chief, Climate Monitoring Branch, NOAA National Climatic Data Center January 21 What is the difference between weather" and "climate"? Dr. Wayne Higgins, Director, NOAA Climate Prediction Center January 28 How global climate change impacts the United States Anthony C. Janetos, Director, Joint Global Change Research Institute (Pacific Northwest National Laboratory and University of Maryland)