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CLIMATE CHANGE AND THE GREAT OCEAN CONVEYOR BELT Sam Miller

CLIMATE CHANGE AND THE GREAT OCEAN CONVEYOR BELT Sam Miller. Intergovernmental Panel on Climate Change (IPCC), American Meteorological Society (AMS), American Geophysical Union (AGU), and other professional organizations Other peer-reviewed scientific papers

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CLIMATE CHANGE AND THE GREAT OCEAN CONVEYOR BELT Sam Miller

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  1. CLIMATE CHANGE AND THE GREAT OCEAN CONVEYOR BELT Sam Miller

  2. Intergovernmental Panel on Climate Change (IPCC), American Meteorological Society (AMS), American Geophysical Union (AGU), and other professional organizations Other peer-reviewed scientific papers Government agency scientific websites (NOAA, NASA, etc.) News articles derived from peer-reviewed scientific papers Paul Mayewski – UNH Climate Change Research Center “The Glacial World According to Wally” (Wallace S. Broecker) “A Brain for All Seasons” (William H. Calvin) “The Long Summer” (Brian Fagan)

  3. A matter of belief?

  4. Climate change is an extremely complex subject Who do you believe?

  5. Global warming is “the greatest hoax ever perpetrated on the American people.” U.S. Senator James Inhofe (R – OK)

  6. “The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action.” U.S. National Academy of Sciences http://www.nasonline.org/site/PageServer

  7. Climate change is an extremely complex subject Who do you believe? How do you decide who to believe?

  8. Climate change is an extremely complex subject Who do you believe? How do you decide who to believe? PEER REVIEW

  9. Does the question have a sound theoretical* basis? • Data to answer question are drawn from the observational record • Results are produced via sound scientific methods; can be reproduced from the same data by someone with a similar background • Conclusions are drawn from results via deductive reasoning Climate change is an extremely complex subject Who do you believe? How do you decide who to believe? PEER REVIEW *Means “law of nature.” For example, the Law of Gravity is a “theory.”

  10. Physical science is not “belief” or ideology Conclusions are logically drawn from results, derived by the careful analysis of data to answer specific questions

  11. Discussion topics: • Natural climate variations • Greenhouse effect and human-induced variation • Projections for the next century • Is warming actually happening? • Complex determinism • Thermohaline circulation • Global climate experiment: Can we induce a repeat of the Younger Dryas Event?

  12. Natural climate variations

  13. When asked, one answer given to the question of the causes of climate change is that all climate variations seen in the instrumental and proxy records are entirely natural. • This has sometimes been phrased as “the climate is always changing.” • Another answer to the question has been “I’m not a scientist.”

  14. MILANKOVITCH CYCLES Milutin Milankovic Serbian civil engineer and geophysicist Worked in Scandinavia (1879 – 1958)

  15. MILANKOVITCH CYCLES • Originally formulated in an attempt to explain ice ages noted in the geologic record • Astronomical variations that cause changes in the amount of sunlight reaching a given point on the Earth’s surface • Account for some (more than half) – but NOT all – of natural range of climate variation

  16. MILANKOVITCH CYCLES • Variations in the shape of the Earth’s orbit (eccentricity)

  17. MILANKOVITCH CYCLES 2. Precession of the Perihelion with respect to the seasons

  18. MILANKOVITCH CYCLES 3. Variations in the tilt of the axis (obliquity)

  19. MILANKOVITCH CYCLES 4. Precession of the axis

  20. MILANKOVITCH CYCLES Variations add up to net Solar Forcing NET

  21. MILANKOVITCH CYCLES Variations are not enough to account for all observed climate variations NET OBSERVED

  22. THERE ARE OTHER FORCES AT WORK • Variations in the Solar “constant”. (Scale is years – centuries for oscillations; billions of years for long-term increase) 2. Variations in global ocean circulation. (Scale is decades – millennia) • Variations in arrangement of land masses. (Scale is millions of years – hundreds of millions of years) • “Other” – Volcanic activity, natural oscillations like El Nino, collisions with celestial objects, etc. (All scales.)

  23. HOW DO WE KNOW WHAT THE ACTUAL CLIMATE VARIATIONS ARE?

  24. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD VOSTOK ICE CORE

  25. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD • TEMPERATURE RECORD DERIVED BY SEVERAL MEANS, SOME OF WHICH ARE: • Ratio of Oxygen-18 to Oxygen-16 isotopes (d18O) in benthic foramanifera and ice cores • Mg/Ca ratios in benthic foramanifera • Alkenones • Pollen distributions • Carbon-13/Oxygen-18 bonds in CO2 gas bubbles

  26. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD • DATING ALSO PERFORMED BY SEVERAL MEANS: • Counting annual layers in ice cores • (GISP2 Ice Core) • Seasonal chemical transport • Isotopic/radioisotopic methods

  27. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD MILANKOVITCH-DERIVED SOLAR FORCING NOT A VERY GOOD INDICATOR OF TEMPERATURE

  28. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD CO2 BUBBLES IN ICE SAMPLES ARE A BETTER INDICATOR OF AIR TEMPERATURE

  29. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD CO2 BUBBLES IN ICE SAMPLES ARE A BETTER INDICATOR OF AIR TEMPERATURE THERE IS A VERY HIGH DEGREE OF CORRELATION BETWEEN THE TWO, AND NO ASSOCIATED TIME LAG

  30. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD 2015 Berkeley study confirms direct physical link between CO2 gas and global warming in Earth’s atmosphere (originally proposed by Svante Arrhenius in 19th Century) Scientists used an array of extremely precise instruments that the U.S. Department of Energy installed at climate research facilities in Barrow, AK, and Lamont, OK. Instruments measured the amount of infrared radiation coming down to the Earth’s surface from the Sun, and the amount of heat radiation the Earth emits back up.  (http://www.sfgate.com/science/article/Berkeley-experts-study-strengthens-human-link-6101054.php)

  31. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD HOLOCENE RECORD ENDS BEFORE BEGINNING OF INDUSTRIAL AGE

  32. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD LAST GLACIAL MAXIMUM (LGM) 20,000 YEARS AGO

  33. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD LAST INTERGLACIAL 120,000 YEARS AGO

  34. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD BEGINNING OF MIGRATION OUT OF AFRICA BY MODERN HUMANS BEGAN DURING THE LAST INTERGLACIAL

  35. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD MIGRATION CONTINUED THROUGHOUT THE LAST ICE AGE

  36. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD INTERGLACIAL ~250,000 YEARS AGO

  37. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD MODERN HUMANS NOW NEANDERTHAL 40 kY HUMAN SPECIATION EVENT 250 kY HOMO ERECTUS

  38. 40 kY MODERN HUMANS NEANDERTHAL 250 kY HOMO ERECTUS

  39. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD MODERN HUMANS NOW ? NEANDERTHAL 40 kY HUMAN SPECIATION EVENT 250 kY HOMO ERECTUS

  40. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD MODERN HUMANS NOW NEANDERTHAL 40 kY THE OTHER TWO SPECIES OF HUMANS DID NOT SURVIVE THE MOST RECENT ICE AGE 250 kY HOMO ERECTUS

  41. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD GLACIAL/INTERGLACIAL A REPEATING PATTERN

  42. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD Longer record indicates about 8 interglacials over last 800,000 years (European Project for Ice Coring in Antarctica - EPICA)

  43. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD NATURAL RANGE OF CO2 VARIABILITY

  44. ANTARCTIC ICE CORES ONE TYPE OF CLIMATE RECORD WARMING AFTER LGM NOT A SMOOTH TRANSITION TO HOLOCENE CLIMATE

  45. Greenhouse effect and human-induced variations

  46. GLOBAL RADIATIVE BALANCE Incoming Terms Solar “constant” ≈ 1367 Wm-2 30 % bounces off About half makes it to the surface

  47. GLOBAL RADIATIVE BALANCE Outgoing Terms

  48. GLOBAL RADIATIVE BALANCE Outgoing Terms

  49. HOW DO GREENHOUSE GASES TRAP TERRESTRIAL RADIATION?

  50. HOW DO GREENHOUSE GASES TRAP TERRESTRIAL RADIATION? Visible sunlight comes in through this window

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