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Available
Call number
Collection
Publication
Columbia University Press (2009), 448 pages
Description
The field of paleoclimatology relies on physical, chemical, and biological proxies of past climate changes that have been preserved in natural archives such as glacial ice, tree rings, sediments, corals, and speleothems. Paleoclimate archives obtained through field investigations, ocean sediment coring expeditions, ice sheet coring programs, and other projects allow scientists to reconstruct climate change over much of earth's history. When combined with computer model simulations, paleoclimatic reconstructions are used to test hypotheses about the causes of climatic change, such
User reviews
LibraryThing member setnahkt
I’ve been reading this one for a long time now, and finally finished; as a reference book, it was fairly slow going. Full of really interesting stuff; it covers what’s know about paleoclimate for all of Earth history, although, understandably a good half the book is about the Cenozoic and about
* The Faint Early Sun Paradox; astrophysics suggests the early (Proterozoic) sun was a lot fainter than it is now, in fact not hot enough to allow liquid water on the Earth. Yet there is abundant geological evidence for liquid water. What’s up with that? Even a 100% carbon dioxide atmosphere won’t provide enough of a greenhouse effect to allow liquid water. The best guess is other atmospheric gases were involved, but nobody’s quite sure what. Lots have gas combinations have been proposed, some fairly exotic – carbonyl sulfide, for example. Calculations show that enough carbonyl sulfide will give enough of a greenhouse effect to keep the oceans from freezing, but the problem is why would there be that much carbonyl sulfide in the atmosphere and how do you test the hypothesis. That’s just one proposed greenhouse gas.
* Was there or was there not a Cryogenic? (i.e., a Snowball Earth). The Cryogenic hypothesis is that whatever combination of atmospheric gases kept the oceans liquid through most of the Proterozoic fell apart in the Neoproterozoic and stuff started to freeze over. The evidence is tillites and dropstones at tropic paleolatitudes. The counterarguments are the stuff interpreted as tillites and dropstones aren’t really tillites and dropstones.
* Once life shows up there are more climate proxies available; the most important being oxygen isotope ratios. The way this works is isotopically light water is favored for evaporation, therefore the oceans get enriched in heavy water (classically, the “heavy” in heavy water means deuterium; in this case it’s oxygen-18 rather than oxygen-16). You would think the light water would just rain out again so everything would stay constant; however, water can be sequestered on land – in icecaps. Marine organisms – coral, etc. – pick up oxygen to make their calcium carbonate skeletons, and corals exhibit growth lines that can be used for chronology. Thus if there’s proportionally more oxygen-18 in coral skeletons, it’s assumed there’s more water sequestered as ice on land, and the next step in the chain is to assume that means global climate is cooler. This works well and has been calibrated with other proxies in the Holocene; it becomes more questionable as you go backward in time.
* There are a host of other paleotemperature proxies of varying degrees of reliability; in fact, there’s a whole appendix devoted to them and other proxies (ocean acidity, for just one of many examples). Some of them I can’t figure out – for example, why is the strontium/calcium ratio in fluvial sediments a temperature proxy? I’m sure it was explained somewhere in the text, but I must have skipped over it.
* Of course, the meat of the text is in the Pleistocene/Recent, and even if you’re a die-hard global warming denier (or advocate) there’s a ton of stuff to learn here. The chapter on orbital forcing is pretty interesting; this is what used to be called Milankovitch cycles but apparently now “orbital forcing” is preferred; I have the sneaking suspicion this is because Milankovitch is now politically incorrect but it’s not so documented. At any rate, orbital forcing has to do with long (multi-million year) slow changes in the Earth’s orbital parameters: eccentricity, axial inclination, etc. This is another paradox; the orbital cycles are clearly visible in paleotemperature proxy records, but the calculated magnitude of changes in insolation should be much too small to have a noticeable effect. The best guess is that there’s some sort of unknown feedback mechanism magnifying things. I’m a little surprised to find that none of the more vehement AGW advocates haven’t jumped on this as evidence that minor changes in climate conditions can have massive effects, (see the Day After) but perhaps it’s a matter of not wanting to admit the Sun has any effect on climate.
* The Pleistocene has changed considerably since I was in college. Back then there were four glaciations – Nebraskan, Kansan, Illinoian, and Wisconsinan in North America corresponding to Günz, Mindel, Riss and Würm in Europe. That’s all pretty much out the window now, with the number of glacial advances unclear but way more than 4. Wisconsinan is still used, Illinoian is dubious, and the rest are dismissed. Lots of interesting things go on – Dansgaard-Oeschger events are documented from isotope ratios in Greenland ice cores (equivalent events in Antarctica are Antarctic Isotope Maxima). A D-O is a rapid rise in temperature (8-16° C in decades) followed by a gradual cooling; there are 25 numbered D-O events in the Pleistocene. Interested parties may note that a temperature rise of that magnitude in that time period is much greater than the worst predictions of the IPCC for AGW. Interestingly, the Antarctic events are usually (but not always) out of phase with the D-O events. D-O events are related – but not always exactly – to Heinrich events, which are sediment layers in deep North Atlantic cores characterized by lots of dropstones and other stuff dumped by icebergs; thus a Heinrich event is a large increase in the amount of icebergs making it to the Atlantic. There are 6, 7, or 8 Heinrich events in the Pleistocene, depending on who’s counting.
* The final chapter discusses AGW; Cronin is pretty much in the “science is settled” camp, even though many of the earlier chapters demonstrate dramatically that it isn’t. Global warming skeptics are mentioned politely and dismissed. There isn’t much discussion of actual climate measurement, placement of stations, etc., which is only fair; the book is about paleoclimatology. Cronin accepts without question the Medieval Warm Period and the Little Ice Age, and doesn’t mention Mann’s attempt to turn these into “local” phenomena; to be fair, though, while they were global climate phenomena they had different manifestations in different parts of the world – I assume this is why Cronin uses Medieval Warm Period rather than Medieval Climate Optimum; what was a climate optimum in Europe was a disastrous long-term drought in the American Southwest.
I’ve only scratched the surface of what’s an enormous mine of data. The book has some flaws, to be sure. This is a collection and consolidation of an immense amount of scientific literature. Sometimes the transcription of original tables, graphs, and diagrams suffers. Illustrations that were colored in originals are gray scale here; that can cause major difficult if hues that were easily distinguishable in the original – blue and red, say – happen to come out the same shade in gray scale. Cronin’s aware of this and provides other means of distinguishing graph lines and map areas, but they are clumsier than colors.
A second problem is graph orientation. In a book about paleoclimatology, there’s obviously going to be a lot of time-series graphs. It was – and I certainly sympathize – way too much effort to redraw all the graphs to a common axis labeling. Thus some of the graphs are absolute age, and some of these have the present on the right and others have it on the left. Then still other graphs will be years before present – again sometimes with the present on the left and other times with it on the right. In a few, the time scale is missing altogether, and you have to figure it out from accompanying text. Again, I don’t see how Cronin could have done otherwise without an unreasonable amount of work, plus the danger of introducing errors when redrawing the originals – but the reader has to be really careful to make sure what’s going on when examining graphs, especially when there are several on the same page.
Another problem is annoying and could have been fixed: Cronin is acronym-crazed. Admittedly, a few are acceptable – D-O for Dansgaard-Oeschger event is probably inevitable – but it gets to the point where a single paragraph will have multiple acronyms – ENSO (El Nino-Southern Oscillation) and PDO (Pacific Decadal Oscillation) and IPO (Interdecadal Pacific Oscillation) affect SST (sea surface temperature) and SSS (sea surface salinity) and the location of the SPCZ (South Pacific Convergence Zone). What’s worse, the same acronym is sometimes used for two different things – MWP is both Meltwater Pulse and Medieval Warm Period. There is a list of acronyms in the front matter, which includes which chapters use a particular acronym, but it’s incomplete (it didn’t include SPCZ, for instance, so when giving the example above I had to page through text until I found the first use of SPCZ).
Nevertheless, this is an immense and rewarding work. The Earth’s climate history and the way that history is being explicated is fascinating stuff. There is a lot of ammunition for both sides in the climate change debate; I know the next time somebody jumps me with “Anthropogenic Global Warming is causing unprecedented temperature rises!” I’m going to come back with “What about the 25 Pleistocene Dansgaard-Oeschger events?” and see if that takes the wind out of their sails.
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two thirds of that is about the Pleistocene/Holocene. It’s a magnificent effort by author Thomas Cronin. With a book this long and detailed I really can’t do a review on everything, but there are some highlights:* The Faint Early Sun Paradox; astrophysics suggests the early (Proterozoic) sun was a lot fainter than it is now, in fact not hot enough to allow liquid water on the Earth. Yet there is abundant geological evidence for liquid water. What’s up with that? Even a 100% carbon dioxide atmosphere won’t provide enough of a greenhouse effect to allow liquid water. The best guess is other atmospheric gases were involved, but nobody’s quite sure what. Lots have gas combinations have been proposed, some fairly exotic – carbonyl sulfide, for example. Calculations show that enough carbonyl sulfide will give enough of a greenhouse effect to keep the oceans from freezing, but the problem is why would there be that much carbonyl sulfide in the atmosphere and how do you test the hypothesis. That’s just one proposed greenhouse gas.
* Was there or was there not a Cryogenic? (i.e., a Snowball Earth). The Cryogenic hypothesis is that whatever combination of atmospheric gases kept the oceans liquid through most of the Proterozoic fell apart in the Neoproterozoic and stuff started to freeze over. The evidence is tillites and dropstones at tropic paleolatitudes. The counterarguments are the stuff interpreted as tillites and dropstones aren’t really tillites and dropstones.
* Once life shows up there are more climate proxies available; the most important being oxygen isotope ratios. The way this works is isotopically light water is favored for evaporation, therefore the oceans get enriched in heavy water (classically, the “heavy” in heavy water means deuterium; in this case it’s oxygen-18 rather than oxygen-16). You would think the light water would just rain out again so everything would stay constant; however, water can be sequestered on land – in icecaps. Marine organisms – coral, etc. – pick up oxygen to make their calcium carbonate skeletons, and corals exhibit growth lines that can be used for chronology. Thus if there’s proportionally more oxygen-18 in coral skeletons, it’s assumed there’s more water sequestered as ice on land, and the next step in the chain is to assume that means global climate is cooler. This works well and has been calibrated with other proxies in the Holocene; it becomes more questionable as you go backward in time.
* There are a host of other paleotemperature proxies of varying degrees of reliability; in fact, there’s a whole appendix devoted to them and other proxies (ocean acidity, for just one of many examples). Some of them I can’t figure out – for example, why is the strontium/calcium ratio in fluvial sediments a temperature proxy? I’m sure it was explained somewhere in the text, but I must have skipped over it.
* Of course, the meat of the text is in the Pleistocene/Recent, and even if you’re a die-hard global warming denier (or advocate) there’s a ton of stuff to learn here. The chapter on orbital forcing is pretty interesting; this is what used to be called Milankovitch cycles but apparently now “orbital forcing” is preferred; I have the sneaking suspicion this is because Milankovitch is now politically incorrect but it’s not so documented. At any rate, orbital forcing has to do with long (multi-million year) slow changes in the Earth’s orbital parameters: eccentricity, axial inclination, etc. This is another paradox; the orbital cycles are clearly visible in paleotemperature proxy records, but the calculated magnitude of changes in insolation should be much too small to have a noticeable effect. The best guess is that there’s some sort of unknown feedback mechanism magnifying things. I’m a little surprised to find that none of the more vehement AGW advocates haven’t jumped on this as evidence that minor changes in climate conditions can have massive effects, (see the Day After) but perhaps it’s a matter of not wanting to admit the Sun has any effect on climate.
* The Pleistocene has changed considerably since I was in college. Back then there were four glaciations – Nebraskan, Kansan, Illinoian, and Wisconsinan in North America corresponding to Günz, Mindel, Riss and Würm in Europe. That’s all pretty much out the window now, with the number of glacial advances unclear but way more than 4. Wisconsinan is still used, Illinoian is dubious, and the rest are dismissed. Lots of interesting things go on – Dansgaard-Oeschger events are documented from isotope ratios in Greenland ice cores (equivalent events in Antarctica are Antarctic Isotope Maxima). A D-O is a rapid rise in temperature (8-16° C in decades) followed by a gradual cooling; there are 25 numbered D-O events in the Pleistocene. Interested parties may note that a temperature rise of that magnitude in that time period is much greater than the worst predictions of the IPCC for AGW. Interestingly, the Antarctic events are usually (but not always) out of phase with the D-O events. D-O events are related – but not always exactly – to Heinrich events, which are sediment layers in deep North Atlantic cores characterized by lots of dropstones and other stuff dumped by icebergs; thus a Heinrich event is a large increase in the amount of icebergs making it to the Atlantic. There are 6, 7, or 8 Heinrich events in the Pleistocene, depending on who’s counting.
* The final chapter discusses AGW; Cronin is pretty much in the “science is settled” camp, even though many of the earlier chapters demonstrate dramatically that it isn’t. Global warming skeptics are mentioned politely and dismissed. There isn’t much discussion of actual climate measurement, placement of stations, etc., which is only fair; the book is about paleoclimatology. Cronin accepts without question the Medieval Warm Period and the Little Ice Age, and doesn’t mention Mann’s attempt to turn these into “local” phenomena; to be fair, though, while they were global climate phenomena they had different manifestations in different parts of the world – I assume this is why Cronin uses Medieval Warm Period rather than Medieval Climate Optimum; what was a climate optimum in Europe was a disastrous long-term drought in the American Southwest.
I’ve only scratched the surface of what’s an enormous mine of data. The book has some flaws, to be sure. This is a collection and consolidation of an immense amount of scientific literature. Sometimes the transcription of original tables, graphs, and diagrams suffers. Illustrations that were colored in originals are gray scale here; that can cause major difficult if hues that were easily distinguishable in the original – blue and red, say – happen to come out the same shade in gray scale. Cronin’s aware of this and provides other means of distinguishing graph lines and map areas, but they are clumsier than colors.
A second problem is graph orientation. In a book about paleoclimatology, there’s obviously going to be a lot of time-series graphs. It was – and I certainly sympathize – way too much effort to redraw all the graphs to a common axis labeling. Thus some of the graphs are absolute age, and some of these have the present on the right and others have it on the left. Then still other graphs will be years before present – again sometimes with the present on the left and other times with it on the right. In a few, the time scale is missing altogether, and you have to figure it out from accompanying text. Again, I don’t see how Cronin could have done otherwise without an unreasonable amount of work, plus the danger of introducing errors when redrawing the originals – but the reader has to be really careful to make sure what’s going on when examining graphs, especially when there are several on the same page.
Another problem is annoying and could have been fixed: Cronin is acronym-crazed. Admittedly, a few are acceptable – D-O for Dansgaard-Oeschger event is probably inevitable – but it gets to the point where a single paragraph will have multiple acronyms – ENSO (El Nino-Southern Oscillation) and PDO (Pacific Decadal Oscillation) and IPO (Interdecadal Pacific Oscillation) affect SST (sea surface temperature) and SSS (sea surface salinity) and the location of the SPCZ (South Pacific Convergence Zone). What’s worse, the same acronym is sometimes used for two different things – MWP is both Meltwater Pulse and Medieval Warm Period. There is a list of acronyms in the front matter, which includes which chapters use a particular acronym, but it’s incomplete (it didn’t include SPCZ, for instance, so when giving the example above I had to page through text until I found the first use of SPCZ).
Nevertheless, this is an immense and rewarding work. The Earth’s climate history and the way that history is being explicated is fascinating stuff. There is a lot of ammunition for both sides in the climate change debate; I know the next time somebody jumps me with “Anthropogenic Global Warming is causing unprecedented temperature rises!” I’m going to come back with “What about the 25 Pleistocene Dansgaard-Oeschger events?” and see if that takes the wind out of their sails.
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Language
Original language
English
Physical description
448 p.; 8.6 inches
ISBN
0231144946 / 9780231144940