Paleo-CO2

Watch this video! It is an amazing display of atmospheric carbon dioxide trends. My favourite portion kicks in after 1:40mins - so, make sure to watch it till the end:

Carbon dioxide content in the atmosphere is a crucial parameter that plays a major role in mediating the surface temperature of the Earth through radiative forcing. Its inherent molecular makeup traps the outgoing longwave radiation (OLR) that the Earth emits. This balance of incoming solar radiation (the radiative budget, in heat transfer terminology) is vital for the climate system of the Earth which encompasses the atmosphere, biosphere, cryosphere, hydrosphere etc.

In 1958, Charles Keeling, from the Scripps Institute of Oceanography, started collecting and monitoring carbon dioxide in the atmosphere at the Mauna Loa Observatory in Hawaii. Shown in the figure above, this dataset represents the longest continuous record of atmospheric CO2 measurements - a mere 54 years. How do we know what CO2 was doing in the past when the Earth system was very different than it is now (eg. the ice ages, prolonged warm periods)? For this, we turn towards proxies.

Here is a list of some proxies (to the best of my knowledge) that are useful in reconstructing atmospheric carbon dioxide content, with links to a few articles that deal with them (most are pdfs, though some links are paywalled - I will be happy to send particular papers if requested):

• Bulk inorganic/organic carbon content in marine sediments [ref 1, 2]
• Air bubbles trapped in ice cores [refs 1, 2]
• Paleosols - ancient soils buried under sedimentary deposits [refs 1, 2]
• Boron isotopes in planktic foraminifera, a proxy for paleo-pH levels in the ocean [refs 1, 2, 3]
• Alkenone & lipid biomarkers derived from haptophyte algae [refs 1, 2]
• Fossil plants and leaves [refs 1, 2]

This is an incomplete list, but covers most of the widely used proxies for paleo-CO2 reconstructions (please post more examples in the comments if you know 'em). Each record obtained from a different proxy varies in terms of resolution of the estimates (decadal, centennial, millenial etc.) and length of the record (how far can they go back?). Together though, they paint a cohesive picture - as can be seen in the second half of the video above.

Planktic, not planktonic!

Who knew that Cesare Emiliani was a practitioner of linguistic prescription? Emiliani had a journal article titled Nomenclature & Grammar [Journal of the Washington Academy of Science, 1952] where he called for the "proper usage of Greek & Latin in taxonomic pursuits". In 1991, he published another paper entitled Planktic/Planktonic, Nektic/Nektonic, Benthic/Benthonic [Journal of Paleontology, 1991]. To put things in context:

• Planktic/Planktonic: 'to drift'; used as a prefix for organisms (plankton) that float around (in the upper column of the ocean) and drift due to oceanic currents.
• Nektic/Nektonic: 'to swim'; used to describe creatures that can propel themselves so as to swim voluntarily.
• Benthic/Benthonic: 'deep'; an adjective for organisms that live in the deep ocean.

In the paper, he details the Greek origin of the words and states that the proper derivatives of the words always end with ic as opposed to onic (ie planktic is correct usage & planktonic is not). Personally, I have seen more papers that adopt the term planktonic rather than planktic (eg. planktonic foraminifera). Interestingly enough, through a customary spell-check, the word planktic is displayed as an error while planktonic is not.

In any case, both are currently acceptable in the scientific community. However, I try to adhere to the recommended terms - not necessarily "in deference to the Greeks, who did so much to get the Western civilization going", as Emiliani puts it.

It is also interesting to note that Emiliani's contemporary, Nicholas Shackleton (another paleoceanography great) is the only one I could find who has used the less popular benthonic as opposed to benthic (with respect to foraminifera). Hmmm.... a friendly rivalry in literature perhaps? Those were different times...

Geologic Genealogy

Ever since I read Ian Stimpson’s blog post on his academic genealogy, I have been fascinated in trying to figure out my geologic lineage.

My Ph.D. advisor Terry Quinn (and committee member Fred Taylor) were both graduate students of Robley K. Matthews at Brown University (though Fred went on to do his Ph.D. with Art Bloom at Cornell). He also advised Tom Crowley, Richard Poore, Bill Curry, & Rick Fairbanks amongst other paleoclimate/paleoceanography stalwarts. R. K. Matthews was a sedimentary geologist who worked on the Bahama Bank, Barbados, and Belize and was also interested in foraminiferal sediments and paleoclimate. He is (in)famous for writing a letter with George Kukla to (then) President Nixon, which many of you will be familiar with, about global cooling and an imminent ice age for the Earth. RK Matthews seems to be a fascinating man.

Although, obtaining information about R. K. Matthews on the internet proved to be quite the tricky task. Cursory internet scouring only took me so far before I hit a dead-end: I couldn’t find out who his advisor was. Distressed, I asked Fred about the matter (which I should’ve done earlier), and he informed me that Edward Purdy at Rice oversaw Matthews’ Ph.D. Armed with this information, I stepped the sleuthing up a notch. From here on, it was quite easy as all the academic ancestors turned out to be eminent professors with detailed biographies (or obituaries) up till a certain degree of separation. Without further ado, my academic genealogy:

1. Terry Quinn
Paleoceanography/Paleoclimatology
Brown University
Trivia: Coincidentally, Terry is a panel member with my summer-research advisor in India, Rengaswamy Ramesh on the IPCC & PAGES project. [Image Source & Source]

2. Robley K.Matthews (1935-)
Sedimentary Geology/Paleoclimatology/Paleoceanography
Rice University
Trivia: Wrote a letter to President Nixon warning him of imminent global cooling. [Image Source]

3. Edward Purdy (1931-2009)
Carbonate/Petroleum Geology
Columbia University
Trivia: His first paper was titled A Bahamian Faecal-Pellet Sediment [link] [Image Source]

4. Norman Newell (1909 – 2005) & John Imbrie (1925-)
Paleontology/Paleoclimatology/Paleoecology
Yale University
Trivia: Norman Newell was the curator of the American Museum of Natural History & advised Stephen Jay Gould & Niles Eldridge amongst others. John Imbrie was a paleoclimate giant who worked out that Ice Ages were due to Milankovitch Cycles. [Image Source & Source]

5. Carl Owen Dunbar (1891-1979) 
Invertebrate paleontology/Stratigraphy
Yale University
Trivia: He grew up in Kansas and operated machinery on a ranch to harvest wheat before turning to geology. [Image Source]

6. Charles Schuchert (1856-1942)
Paleogeography/Paleontology
Did not formally get his PhD though he went on to become a professor at Yale.
Trivia: He coined the term paleobiology. [Image Source]

Here ends my 6 degrees of separation that I can trace down via doctoral advisors. However, since Schuchert was ‘mentored’ by James Hall, I can go further back if I sweep Schuchert not doing a PhD under the rug. To continue:

7. James Hall (1811-1898)
Chemistry/Stratigraphy/Paleontology
Rensselaer Polytechnic Institute
Trivia: Founding member of the National Academy of Sciences & first president of the Geological Society of America. [Image Source]

8. Ebenezer Emmons (1799-1863)
Stratigraphy/Geology
Rensselaer Polytechnic Institute
Trivia: Known as the founder of American Paleozoic stratigraphy. [Image Source]

9. Amos Eaton (1776-1842)
Botany/Chemistry/Mineralogy
Yale University
Trivia: Co-founded the Rensselaer Polytechnic Institute [Image Source]

10. Benjamin Silliman (1779-1864)
Chemistry
University of Pennsylvania
Trivia: First scientist to distill petroleum. [Image Source]

11. James Woodhouse (1770-1809)
Chemistry/Medicine
University of Pennsylvania
Trivia: Well-voiced opponent of the phlogiston theory. [Image Source]

At this point things start to get fuzzy, but here is the full list (of mainly physicians and medicine men) that follows, with snippets of trivia wherever I could find some:

12. Benjamin Rush (1746-1813)
13. William Cullen (1710-1790)
14. Alexander Monro (primus) (1697-1767)
15. Charles Alston (1683-1760) – Alstonia, a genus of evergreen trees was named after him by eminent botanist Robert Brown (of Brownian motion fame). Curiously, Alstonia is the official state tree of West Bengal.
16. Herman Boerhaave (1668-1738) – Founder of the modern, academic hospital. He was also the first to isolate urea from urine!
17. Burchard de Volder (1643-1709)
18. Franciscus Sylvius (1614-1672)
19. Adolph Vorstius (1597-1663)
20. Gibert Jachaeus (1578-1628) – Famed Aristotelian philosopher
21. Duncan Liddel (1561-1613)
22. John Craig (d. 1620)
23. Theodor Zwinger (1533-1588)
24. Bassiano Landi (?)
25. Giovanni Battista della Monte (?)
26. Niccolò Leoniceno (1428-1524)

With that, I couldn’t find any more leads. I was most impressed by the broad evolution of profession and specialty over the years and how the nationality of advisors changes from time to time. To sum up, I like what Stephen Jay Gould had to say about his advisor:

"The work of graduate students is part of a mentor's reputation forever, because we trace intellectual lineages in this manner. I was Norman Newell's student, and everything that I ever do, as long as I live, will be read as his legacy."

What is your academic/geologic genealogy?