The Ice Chronicles: The Quest to Understand Global Climate Change

Illustrations

Illustrations I.1. “The Ice Core Time Machine” xxviii I.2. GISP2 team members extracting an ice core in the drill dome 2 I.3. Celebrating recovery of the final section of the GISP2 ice core 3 I.4. Global map of ENSO anomalies in temperature and precipitation 11 I.5. Glacier retreat in Ladakh, Himalayas, 1906 –1980 11 I.6. Idealized diagram of transition from snow into ice in a glacier 12 I.7. Global distribution of glaciers 13 I.8. Earth as seen from Apollo spacecraft 16 1.1. Wright Valley, Southern Victoria Land, Antarctica 22 1.2. The Labyrinth in Wright Valley, Southern Victoria Land, Antarctica 23 1.3. The observed record of CO2 in the atmosphere at the time it became recognized 26 1.4. Scott’s hut, Cape Evans, Antarctica 30 1.5. Deposits marking the former edge of Shackleton Glacier, Antarctica 31 1.6. North Atlantic winter sea surface temperatures during the last glacial maximum and today’s situation 33 1.7. 100,000-year “cycles” of climate 34 2.1. Greenhouse gas and temperature records from the Vostok ice core, Antarctica 40 2.2. Tent camp in Antarctica 45 2.3. Snowpit 40 km from South Pole 46 2.4. The Antarctic ozone hole 47 2.5. Human source radioactivity in a snowpit near South Pole 56 2.6. Ski-equipped C-130 aircraft at the GISP2 site 57 2.7. Snowmobile team in Northern Victoria Land, Antarctica 58 2.8. Heavy oversnow vehicle in Greenland 58 2.9. Yaks near Mount Everest 59 2.10. The north side of Mount Everest 60 2.11. Solar-powered ice coring in Greenland 61 2.12. Location of GISP2 63 2.13. The GISP2 camp in central Greenland 64 2.14. Schematic of the GISP2 ice core drill 67 2.15. The drill control room 69 2.16. The ice core cutting plan 70 2.17. Schematic representation of the GISP2 ice core processing line (CPL) 71 2.18. Excavating the core processing line 72 2.19. Cutting ice core 72 2.20. Annual layer structure, as shown in a core sample 74 2.21. Layers of snow in a snowpit 75 3.1. Northern Hemisphere ice cover 21,000 to 7,000 years ago 81 3.2. Greenland ice cores changed our view of climate change 83 3.3. Ice flow and age of layers in the Greenland ice sheet 86 3.4. Sources for the chemical species transported to the Greenland ice sheet 89 3.5. The Younger Dryas event 92 3.6. Methane record from the GRIP core 93 3.7. Global distribution of rapid climate change events (RCCEs) 94 3.8. Natural cycles in the 110,000-year-long GISP2 climate record 98 3.9. Differences in insolation between the Northern and Southern Hemispheres 99 3.10. Earth’s orbital cycles 100 3.11. Regions of ice discharge during the last glacial period 102 3.12. Antarctic icebergs forming off the Ross Ice Shelf 103 3.13. The Great Ocean Conveyor Belt 105 3.14. The additive effect of multiple controls on climate 109 4.1. Ladakhi porters and scientists climbing the Nun Kun icefalls in 1980 112 4.2. Change in the concentration of continental source dust and sea salt in the 110,000 year GISP2 record 113 4.3. Climate change during the Holocene (last 11,500 years) 115 4.4. Potential causes for change in climate during the Holocene 117 4.5. Change in sea ice extent in the North Atlantic over the last 10,000 years 121 xii Illustrations ç 5.1. Mt. Everest from north and south 128 5.2. Retreat of the Far East Rongbuk Glacier 1966 –1997 129 5.3. The ancient city of Petra 132 5.4. Potential controls on modern climate 134 5.5. Sea level pressure centers associated with change in GISP2 ice core chemistry 137 5.6. Comparison between changes in sea level pressure and GISP2 ice core chemistry 138 5.7. GISP2 ice core chemistry proxy for the last 1,400 years of sea level pressure 140 5.8. Natural controls on climate and human controls on climate meet head-on during the twentieth century 144 5.9. The carbon cycle 147 5.10. Carbon dioxide concentrations in the atmosphere over the past 1,000 years 149 5.11. Methane concentrations in the atmosphere over the past 1...