Past Climate Change. Lecture 2: Thomas Stocker Climate and Environmental Physics, University of Bern

Transcription

1 14th International Seminar on Climate System and Climate Change, Zhuhai Lecture 2: Past Climate Change Thomas Stocker Climate and Environmental Physics, University of Bern

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4 14th International Seminar on Climate System and Climate Change, Zhuhai Lecture 2: Past Climate Change 1. Ice cores: Unique paleoclimate archive 2. Gas records from polar ice cores 3. Abrupt climate change, bipolar seesaw 4. Oldest ice: Frontier in ice core research

5 Thule NEEM N, E Kangerlussuaq

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13 27. July 2010 Last core from m depth NEEM Station N, E

14 Polar ice cores: A unique climate archive accumulation zone flow lines ablation zone bed rock

15 Polar ice cores: A unique climate archive snow firn accumulation zone ablation zone flow lines ice bed rock

16 m -45 C, 2892 m 6.4 cm(h 2 O)/yr Total: m ice ~ 800'000 years m -54 C, 3233 m 2.5 cm(h 2 O)/yr

17 14th International Seminar on Climate System and Climate Change, Zhuhai Lecture 2: Past Climate Change 1. Ice cores: Unique paleoclimate archive 2. Gas records from polar ice cores 3. Abrupt climate change, bipolar seesaw 4. Oldest ice: Frontier in ice core research

18 The top 100 meter of a polar ice core 0 m 1 m 10 m 80 m bubbles in the ice contain a sample of air taken at the time of enclosure

19 Gas species measured in polar ice cores CO 2, d 13 C(CO 2 ), d 14 C(CO 2 ) CH 4, d 13 C(CH 4 ), d 14 C(CH 4 ), d 2 H(CH 4 ) N 2 O, d 15 N(N 2 O), d 18 O(N 2 O) N 2 /O 2, d 15 N(N 2 ) d 18 O(O 2 ), d 17 O(O 2 ) Ar, Kr, Xe air content

20 Greenhouse gas records of the last 800,000 years (Schilt et al., 2010)

21 Temperature reconstructions of abrupt warmings Kindler et al., 2014

22 Current CO 2 concentrations are unprecedented 2017: 404 ppm

23 14th International Seminar on Climate System and Climate Change, Zhuhai Lecture 2: Past Climate Change 1. Polar ice cores: Unique paleoclimate archive 2. Gas records from polar ice cores 3. Abrupt climate change, bipolar seesaw 4. Oldest ice: Frontier in ice core research

24 (Oeschger et al., 1984) (Dansgaard et al., 1984)

25 (Oeschger et al., 1984) (Dansgaard et al., 1984)

26 25 Dansgaard/Oeschger events during the last ice age (NorthGRIP Members, 2004) Abrupt warmings of up to 16.5 C within < 50 years

27 Abrupt change and interhemispheric connections (Broecker, 1985)

28 Abrupt change and interhemispheric connections HadCM3 (Stocker & Johnsen, 2003) (Vellinga, 2002)

29 A minimum model for the bipolar seesaw dts (t) dt 1 ( T N (t) T S (t)) Laplace Transform T S (t) 1 t 0 T N (t t ) e t / dt T S (0) e t / Stocker & Johnsen (2003)

30 A minimum model for the bipolar seesaw dt dt S 1 ( T N T S ) Stocker & Johnsen (2003)

31 Abrupt change and interhemispheric connections (Stocker & Johnsen, 2003) Temperature change S ~ Duration of cold N

32 Abrupt change and interhemispheric connections (EPICA, 2006)

33 Abrupt change and interhemispheric connections Temperature change S ( C) (EPICA, 2006) Duration of cold N (yr)

34 Abrupt change and interhemispheric connections Capron et al., 2010)

35 Abrupt change and carbon cycle Abrupt climate change clathrate gun? unlikely (Steffensen et al. 2008) CH 4 (Bock et al. 2010) dd(ch 4 )

36 Abrupt change and carbon cycle (Bereiter et al. 2012)

37 Abrupt change and carbon cycle MIS 3: 30 60,000 yr BP (Bereiter et al. 2012)

38 Abrupt change and carbon cycle MIS 3: 30 60,000 yr BP MIS 5: ,000 yr BP (Bereiter et al. 2012)

39 Abrupt change and carbon cycle MIS 5 (Bereiter et al. 2012)

40 Abrupt change and carbon cycle MIS 5 MIS 3 (Bereiter et al. 2012)

41 14th International Seminar on Climate System and Climate Change, Zhuhai Lecture 2: Past Climate Change 1. Ice cores: Unique paleoclimate archive 2. Gas records from polar ice cores 3. Abrupt climate change, bipolar seesaw 4. Oldest ice: Frontier in ice core research

42 Mid-Pleistocene Transition: Slowdown of ice age cycles d 18 O stacked record from benthic formaminifera = global ice volume proxy various measures of insolation (Raymo and Huybers, 2008)

43 Sun Land PAGES 2009 Ocean CO 2 CH 4 N 2 O Greenhouse Gases

44 Determinants of oldest ice: Accumulation (FIscher et al., 2013)

45 Determinants of oldest ice: Ice thickness and bed elevation (FIscher et al., 2013)

46 Determinants of oldest ice: Basal temperature (FIscher et al., 2013)

47 Simulated age scale T S = 60 C Q = 55 mw/m 2 H = 2400 m A = 1.8 cm ice eq./yr (FIscher et al., 2013)

48 Oldest ice: Most promising sites (FIscher et al., 2013) v B < 2 m/yr T B < 5 C

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50 40 kyr cycles well preserved AIM events damped (Bereiter et al., 2014) FS: high permeability SS: low permeability

51 (simulations by P. Huybrechts, IPICS, 2007)

52 RADIX ( ) Latest technology in polar mechanics and analytics Smallest ice drill in the world (2.0 cm ) tested in Greenland June 2017 Schwander et al., 2014 Schwander et al., 2014

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54 RADIX Test at East GRIP Station, June 2017

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56 Lecture 2: Take-home messages Polar ice cores are a unique climate archive providing information about the physical, chemical and biological changes in the Earth System. Gas records from polar ice cores permit the reconstruction of the three major greenhouse gases over the past 800,000 years. The sequence of abrupt warmings during the last ice age indicate the operation of the bipolar seesaw caused by switches in the ocean circulation The search and recovery of a 1.5 Million-year old ice core from Antarctica represents the newest frontier in polar research.