Tuesday, January 10, 2012

condensed summary of "Under A Green Sky"

Notes by P.J.Werbos, Jan 8, 2012. Book costs $7 from Amazon.

The book begins with extensive discussion of Ward’s personal role and prior history of the field. Detailed citations by chapter are on pages 205-224.

The first four chapters discuss what led up to Ward’s theory – how we know that the PT dieoff was the worst dieoff in the history of earth, what other major dieoffs were like, and what the earlier inadequate theories were like.

Chapter 1:
Page 18 gives a graph from Norman Neville showing how many families of life were
killed off by various extinctions. PT, at the start of the Mesozoic era, was the biggest. Ward was part of the group which verified the Alavarez theory that the end-of-mesozoic dieoff (KT) was caused by an asteroid impact, but gives extensive evidence explaining the new consensus that none of the other big extinctions were caused that way.
Pages 24-25: C12/C13 isotope ratios tell us when there are big dieoffs of plant life on earth. At KT it shows a massive death of plants, but a total recovery in less than 100,000 years – a”single dip depression.”
Page 27: big “flood basalts” indicate when and where huge outbreaks of volcanoes have occurred. The big outbreaks of volcanoes match the big extinctions. The biggest of all was the “Siberian traps” (volcanoes) leading to PT. Next biggest was TJ,
the extinction which marks the boundary between the Triassic and the Jurassic, the first two of the three eras in the Mesozoic.
Page 29: Two big shelled organisms, cousins of clams, teemed in the oceans for most of its history: ammonites and nautiloids. Ward visited Zumaya, Spain, and showed the ammonites went extinct at KT, but nautiloids survived.

Chapter 2: The Overlooked Extinction:
Even after the dieoff of dinosaurs, there was a big dieoff of mammals, eliminating many basic types, at the Paleocene/Eocene boundary (P/E), and also a dieoff in the middle of the Cretaceous (late Mesozoic), which are instructive examples.
Page 43: Just as C12/C13 isotope ratios give us an historic measure of plant dieoffs, O16/O18 ratios give us an historic measure of the temperature of earth.
Page 45: Kennett/Stott report new data on P/E (Nature 1991): deep ocean warms suddenly and big dieoff of plants in deep ocean
Page 46: Kunio Kaiho 1991 says that the P/E dieoff was due to low O2 in the water. Why? Warm bottom had come from warm tropical surface waters where evaporation makes surface saltier, denser; then transported worldwide along bottom like a conveyer belt. (Not like today where cold O2 water flows to bottom at poles, from there worldwide.)
Page 49: Gingerich shows that at P/E land mammals experienced mass extinction at same time. Lots of amazing families of mammals were lost.
Page 51: At P/E, sudden increase in volcanic activity (ash) – volcanism and deep sea hydrothermal, aridity; winds reduced by factor of three, due to a lower difference in termperature between the poles and the equator, due to warming of the poles.
Page 53: SUMMARY OF what caused the dieoffs at P/E: first volcanoes and hydrothermal vents in the ocean, emitting greenhouse gasses; then warming; then warmth and resulting reduction of O2 in water O2 kills deep sea life, and some land mammals, but less than in the big 5 extinctions. Then the volcanoes slowed, and a slow return to normal.
Page 56: mid-Cretaceous: flowers blossom, ammonites mostly plentiful with clams and snails
Page 57-58: but in the geological beds of ammonites etc from that time, there is a six foot black bed of dieoff, the Cenomanian-Turonian ; Schlanger/Jenkyns showed 3 dieoffs over 20m years: ocean currents stopped, organic material rained down causing low O2 , anoxia ever higher .

Cbapter 3: Mother of all Extinctions (PT).
Page 62: South Africa, fossils dwindle gradually a million years up to PT, not sudden like KT. Towards the end, two land species survived -- Dicynodon, gorgon.
Page 64: alternation of red and olive layers right at PT boundary in the geological strata; just past that boundary of death, there were lots more fossils (recovery of life), all one species, Lystrosaurus a piggy reptile.
Page 67: At PT as many as 90% of species on earth disappeared.
Page 68 Erwin: PT took 165,000 years or less to happen, much slower than KT which was maybe only decades. O2 has been measured to be low both in shallow and in deep waters leading into the event. The low O2 killed many ocean organisms as quickly as red tides do today. Global warming and Siberian volcanoes happened at the same time.
Page 69: Erwin discussed several possible theories. Besides asteroids (now discredited unless you think they caused volcanoes), CO2 and methane from volcanoes may have caused climate change and acid rain, causing the dieoffs, as suggested by Paul Renne.
Pages 78-79: Krull/Retallack: coal formation stopped at PT, methane in air ‘way up. Temperature and sedimentation up; they say the sedimentation was due to runoff from deforrested land.
Page 79 Buick (an expert on the preCambrian extinction) proposed that PT was due to repeated insults, like maybe pulses of melting of methane hydrates, overturns of stratified oceans, volcanoes
Pages 81-82 Knoll (another preCambrian expert) proposes a theory: low O2 in LOWER ocean only, then something (volcanoes?) changes pattern, CO2 and dissolved biostuff bubbles up. Killer CO2. But models have problems with that; some shellfish die from CO2, but land animals wouldn’t be killed so easily by it.
Page 84: Ward’s data show not one extinction but several; one very big thousands of years, but several before and soon after., spread over several million years.
Page85: e.g. C12/C13 showed multiple dieoff, return, dieoff in photosynthesis levels.

Chapter 4: The Misinterpreted Extinction (refuting dumb asteroids)
Page 104: approaching Triassic/Jurassic, ammonites dwindle to zero. Clams too; a new clam, Monotis, apparently adapted to low-O2 bottoms, emerged but also disappeared in the final stage. All is dead in the Rhaetian, the last period within the Triassic, showing geological beds striped gray/black. Death in the seas and perhaps on land as well.
Page 105: Rhaetian 12 million years world dead except for oceanic plankton. (?)

Chapter 5: A New Paradigm for Mass Extinction
Page 109: Ward visits Palau (Micronesia) to study: why did ammonites outdo nautiloids at PT and TJ, but reverse and die off 100% at KT?
Page 111: he tracked nautiloids: they live at 1500 feet in day, 400-500 night to eat, stay deep and dark, versus ammonoids in more shallow. water PT and TJ were hard on deep guys, KT while killed shallow.
Page 112: Ward visited freshwater lake in island. Thin O2 rich layer at surface full of life, but below that -- no animals, no O2, purple color. Purple and green bacteria needed sunlight and sulfur. Third type(s) of life too small to see produced H2s as waste; only O2 kept them from surface.
Page 113: Lake was like Canfield ocean. (Don Canfield and Berner of Yale did classic research). Before the modern era (after preCambrian), oceans were highly toxic due to H2S saturation, vs O2-rich today top to bottom.
Page 114: Near Palau after Ward left: warm low-O2 water rose to surface, killed Palau corals, coral bleaching. Greenhouse gasses?
Page 115: We now rely on a recent breakthrough, “molecular fossils” or “biomarkers”: certain molecules like types of lipids left behind by certain types of microbes.
Page 116: We use new instruments -- gas chromatographic mass spectrometers -- to detect molecules left by bacteria which live in high H2S. Like photosynthetic purple bacerterium, today in Black Sea and Palau, which oxidize H2S and the like. They are one of the two kinds of bacteria which live in water low in O2, but high in light and H2S.
Page 117 Bombshell: Lee Kump and Mike Arthur (PSU) and Pavlov(UC) in 2005: lots of these bacteria near end of Permian, implicated in extinctions. In waters like Black Sea, purple and green live in “chemocline,” stable interface between O2 above and H2S below. But when H2S gets to the surface: “Kump hypothesis” for extinction.
Page 118: Kump shows H2S in late Permian from this source would be 2000 times more than what comes from today’s volcanoes. It is also enough to zap the ozone layer. PT fossil spores from Greenland show UV damage, verifying the ozone hole effect. Modern ocean plant biomass “rapidly decreases” under ozone holes. Also, CO2 and methane would be in the bubbles along with H2S.
Page 119: Kump used a global circulation model (GCM) to model what happened at PT. At end of Permian, sea level DROPPED, freeing phosphorus, fertilizing these bacteria in ocean from runoff. In 2006, Roger Summons of MIT showed biomarkers for H2S production at the PT boundary in nine sites.
Page 120: In March 2006, NASA hosts the world’s main meeting on astrobiology in DC astrobiology. At the extinction session, Kump model’s shows a series of burps, like actual data on extinctions, & enough H2S to kill most land life, and push shallow water life over due to H2S and acid from CO2 combined. Ward spoke too. Oceans did it, but why did they change state?
Page 123: Since the Eocene (one full period after the dinosaurs died off), O2 has been high evefrywhere in the ocean, shallow and deep, due to conveyer belt of currents driven by big temperature differences between poles and tropics. But this “mixed ocean” (like a well-stirred aquarium) is basically new in earth history.
Page 124: older oceans all had low O2 at bottom. They left lots of pyrite – fool’s gold, formed where there is high sulfur but low oxygen. Ocean was stratified by temperature, salinity, dissolved O and reduced carbon. (Like CO2..) Most of earth history was like this. O2 above, not below. This also caused formation of black shales on the ocean bottom, going back 3.5 billion years. When life in shallow water sinks to that kind of low oxygen bottom, it yields nice well-preserved fossils.
Page 125: There are wo varieties of stratified ocean – low O2 bottom, vs. almost no O2 in the bottom layers. No animals live in the deep layers either way, but really low O2 encourages more sulfur producing microbes; that’s a Canfield ocean. Before Cambrian, the microbes producing H2S also inhibited nitrogen fixation, a double killer.
Page 126. Kliti Grice et al, Science 2005, showed Canfield ocean by biomarkers at PT. TJ maybe, now (2007) being checked.
Page 127: what causes ocean to switch between mixed versus stratified versus Canfield? CHANGE between the three causes extinctions, and is driven by conveyer system. 2005: Jeffrey Kiehl and Christine Shields of NCAR used GCM, to show global warming would move the conveyer belt..
Page 128: by end of Permian, Earth had lost its ice caps. That already gives low O2 stratified ocean. WARD’S THEORY: At PT and P/E, GHG from volcanoes (1st Siberia, 2nd Atlantic Ocean) gave huge greenhouse gas emission, the trigger which changed the oceans.
Page 129: PT was bigger because there was burping of noxious gas from virtually all shallow water on earth; unlike Paleocene, rich in CO2 and CH4, the latter accelerating warming. Anthony Hallam and Paul Wignall’s book Mass Extinctions… showed that 12 of 14 included low O2 oceans.

Chapter : The Driver of Extinction (atmosphere as trigger to low O2 ocean and change in conveyer belt).
Page 133: Two ways to estimate past CO2: best a program by Berner of Yale, GEOCARB and GEOCARBSULF (for O2?) using isotope data, second measure fossil leaves. Of course, GHG explain climate changes.
Page 135-136: FIGURE: CO2 by year… all extinctions have also been CO2 peaks. Rapid rise preceded all but one or two extinctions. Rate important, not just level.
Page 136: confirmed by leaf approach. Before industry, earth was on course to C locked up, low CO2 problem.
Page 137: SUMMARY OF WARD’S THEORY: step 1, vast increase in CO2 and methane from volcanoes. Step 2: warmer world disrupts conveyer system, more low O2 bottom. Step 3: when chemocline is shallow enough for light to reach it, H2S producing bacteria go nuts. Step 4, H2S destroys ozone layer. Page 138: Wards calls it “conveyer disruption hypothesis.”
Page 139-141: green scary poetry about what it really looks like

Chapter 7: Bridging the Deep and the Near Past
Page 142: There has been remarkably little cooperation between people studying modern climate change (since the pliocene) and people like Ward studying older earth history. The most viable connection would be between the study of oceanic thermohaline conveyer currents and the study of extinctions.
Page 143: A quick swipe at the movie “Day After Tomorrow” (“ a mockery”)
Pages 144-146: Very rapid climate change has been the norm for the past 200,000 years full of unusual ice ages. See the work of Minze Stuiver, U Washington, using Greenland Ice cores. Been But the last 10,000 years have relatively calm. Average temperature would change as much as 18 degrees F in a few decades, 10 in one decade. The calm starts human civilization?
Page 147: But there wasn’t such change in the southern hemisphere (we think, but need to check more). Ward shows a poorly labelled figure on “temperature variation”. Most now believe fluctuations in the past 200,000 years are largely
due to orbital variations found by Malutin Milankovich.
Page 148: The study of orbits suggests we would normally remain calm another 10,000 years or so.
Page 149: For recent years (past 2.5 million years), people say the conveyer belt has turned on and off, not changed type. (Just in the north?) Willi Dansgaard
first, then Hans Oeschger reported this. Dansgaard-Oeschger cycles are cycles within a larger pattern, discussed by Gerard Bond. The pattern includes Heinrich events, severe icing of the north Atlantic, which happened six times in the past 100,000 years.
Page 152: turning the currents on and off cause warm periods, or v ice-versa? We don’t know, but we do know that cold fresh water melting off from Greenland has scary implications for the Gulf Stream, with some early measurements justifying (PJW: but not yet proving) worry.
Page 159: East Anglia model predicts BIGGER ice age 50K years hence, rebound from our warming, when fossil fuel is used up.
Page 160: Ruddiman has an interesting book suggesting humans have contributed to warming (and calmer climate) since 8000BC. Not just CO2; methane.
Page 164 Vostok ice cores measure CO2 and CH4 back 2 million years. 500 to 600 ppm would be equivalent to times with little or no ice.
Page 166: for most of geologic time CO2 was much higher g than today, yet acidity was mostly not so different. That’s because oceans can buffer the acidity caused by higher CO2, but BUFFERING TAKES TIME, therefore rate matters. CO2 is now rising about 100 times fast as it ever did, creating a huge risk of acidity (PJW: as was decisive in some periods of earth history)
Page 174-175 heat causes drug use and malaria

Interview with Battisti of U Wash.. imagine future conveyer and story…
195: clouds (recall NASA fast story)

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