There is not much happening in deniersville right now. Anthony Watts has another alarmist article by Paul Driessen from the denier lobby group CFACT. It starts off talking about ISIS (I guess WUWT is branching out) and he's trying to link ISIS to both President Obama and climate change - and re the latter, not in the way that most people do.
Judith Curry is asking her denier readers to critique an "essay" she's written. It reads as if it's written hastily for a first term, first year, undergrad Phil101 class. She waffles and meanders from pillar to post in a most unacademic manner, so I don't think she'll get a very good grade. (Her denier fans fawn as usual.)
Given the relative quiet, I figured I'd let you know of two new papers I came across about the Permian-Triassic mass extinction. This was the biggest extinction period in the history of Earth - with different stages, or pulses.
Exploring the Permian-Triassic extinction and ocean acidification
The first paper is from last week's issue of Science. It's by a team of scientists from all over, led by Matthew Oliver Clarkson. The extinction event is described in the paper as:
The PTB extinction event spanned ~60,000 years (2) and can be resolved into two distinct marine extinction pulses (3). The first occurred in the latest Permian [Extinction Pulse 1 (EP1)] and was followed by an interval of temporary recovery before the second pulse (EP2), which occurred in the earliest Triassic.
Here is the Editor's summary of the research findings, from Science:
The largest mass extinction in Earth's history occurred at the Permian-Triassic boundary 252 million years ago. Several ideas have been proposed for what devastated marine life, but scant direct evidence exists. Clarkson et al. measured boron isotopes across this period as a highly sensitive proxy for seawater pH. It appears that, although the oceans buffered the acidifiying effects of carbon release from contemporary pulses of volcanism, buffering failed when volcanism increased during the formation of the Siberian Traps. The result was a widespread drop in ocean pH and the elimination of shell-forming organisms.
Using both computer simulations and observations from a shallow marine, open-water carbonate succession from the United Arab Emirates, and using both boron and carbon isotopes, the scientists identified quite distinct stages. The last paragraph of the paper probably describes it best, and compares it to the current surge of atmospheric CO2. (I've broken it into two for ease of blog-reading):
The PTB was a time of extreme environmental change, and our combined data and modeling approach falsifies several of the mechanisms currently proposed. Although the coincident stresses of anoxia, increasing temperature, and ecosystem restructuring were important during this interval, the δ11B record strongly suggests that widespread ocean acidification was not a factor in the first phase of the mass extinction but did drive the second pulse.
The carbon release required to drive the observed acidification event must have occurred at a rate comparable with the current anthropogenic perturbation but exceeds it in expected magnitude. Specifically, the required model perturbation of 24,000 PgC exceeds the ~5000 PgC of conventional fossil fuels and is at the upper end of the range of estimates of unconventional fossil fuels (such as methane hydrates). We show that such a rapid and large release of carbon is critical to causing the combined synchronous decrease in both pH and saturation state that defines an ocean acidification event (11).
Permian-Triassic vulcanism and shellfish
The second paper is also about new evidence relating to the Permian Triassic extinction. This paper was by an even bigger team, led by Galina P. Nestell, and published in International Geology Review. As I understand it, the paper is about how shellfish have provided evidence indicating the timing of the extinction event - caused by massive volcanic eruptions - not just from Siberian flood basalt, but from what is now Australia and southern China. I found a press release about it at the University of Texas Arlington, and seeing I'm still caught up with other matters, I'll be lazy and just post it holus bolus:
A new study led by scientists with The University of Texas at Arlington demonstrates for the first time how elemental carbon became an important construction material of some forms of ocean life after one of the greatest mass extinctions in the history of Earth more than 252 million years ago.
As the Permian Period of the Paleozoic Era ended and the Triassic Period of the Mesozoic Era began, more than 90 percent of terrestrial and marine species became extinct. Various proposals have been suggested for this extinction event, including extensive volcanic activity, global heating, or even one or more extraterrestrial impacts.
The work is explained in the paper, "High influx of carbon in walls of agglutinated foraminifers during the Permian-Triassic transition in global oceans," which is published in the March edition of International Geology Review.
Researchers focused on a section of the latest Permian aged rocks in Vietnam, just south of the Chinese border, where closely spaced samples were collected and studied from about a four-meter interval in the boundary strata.
Merlynd Nestell, professor of earth and environmental sciences in the UT Arlington College of Science and a co-author of the paper, said there was extensive volcanic activity in both the Northern and the Southern Hemispheres during the Permian-Triassic transition.
"Much of the volcanic activity was connected with the extensive Siberian flood basalt known as the Siberian Traps that emerged through Permian aged coal deposits and, of course, the burning of coal created CO2," Nestell said.
He noted that there was also synchronous volcanic activity in what is now Australia and southern China that could have burned Permian vegetation. The carbon from ash accumulated in the atmosphere and marine environment and was used by some marine microorganisms in the construction of their shells, something they had not done before.
This new discovery documents elemental carbon as being a major construction component of the tiny shells of single-celled agglutinated foraminifers, ostracodes, and worm tubes that made up part of the very limited population of bottom-dwelling marine organisms surviving the extinction event.
"Specimens of the boundary interval foraminifers seen in slices of rock that were ground thin and studied from other places in the world revealed black layers," said Galina P. Nestell, study co-author and adjunct research professor of earth and environmental sciences at UT Arlington. "But nobody really checked the composition of the black material."
Nestell said this phenomenon has never been reported although sequences of rocks that cross this important Permian-Triassic boundary have been studied in Iran, Hungary, China, Turkey, Slovenia and many other parts of the world.
For the study, Asish Basu, chair of earth and environmental sciences at UT Arlington, analyzed clusters of iron pyrite attached to the walls of the foraminifer shells for lead isotopes. Data from these pyrite clusters support the presence of products of coal combustion that contributed to the high input of carbon into the marine environment immediately after the extinction event.
Brooks Ellwood, emeritus professor of Earth and Environmental Sciences at UT Arlington and a professor in the Louisiana State University Department of Geology and Geophysics, collected the samples to study the Permian-Triassic boundary interval using magnetic and geochemical properties. He and his colleague Luu Thi Phuong Lan of the Vietnamese Academy of Science and Technology in Hanoi, Vietnam, also collected the samples used in the biostratigraphic work by the Nestells and Bruce Wardlaw of the Eastern Geology and Paleoclimate Science Center at the U.S. Geological Survey and adjunct professor at UT Arlington.
By using time-series analysis of magnetic measurements, Ellwood discovered the extinction event to have lasted about 28,000 years. It ended about 91,000 years before the actual Permian-Triassic boundary level -- as defined worldwide by the first appearance of the fossil conodont species Hindeodus parvus -- identification done by Wardlaw.
Galina Nestell said the high carbon levels began after the extinction event about 82,000 years before the official boundary horizon and continued until about 3,000 years after the Permian-Triassic boundary horizon. The boundary horizon is calculated to be 252.2 million years before present.
Other co-authors who contributed to parts of the study include Andrew Hunt, EES associate professor at UT Arlington, Nilotpal Ghosh of the University of Rochester; Harry Rowe of the Bureau of Economic Geology at the University of Texas at Austin; Jonathan Tomkin of the University of Illinois, Urbana; and Kenneth Ratcliffe of Chemostrat Inc. in Houston.
ReferencesM. O. Clarkson1, S. A. Kasemann, R. A. Wood, T. M. Lenton, S. J. Daines, S. Richoz, F. Ohnemueller, A. Meixner, S. W. Poulton, E. T. Tipper. "Ocean acidification and the Permo-Triassic mass extinction." Science 10 April 2015: Vol. 348 no. 6231 pp. 229-232 DOI: 10.1126/science.aaa0193 (subs req'd)
Galina P. Nestell, Merlynd K. Nestell, Brooks B. Ellwood, Bruce R. Wardlaw, Asish R. Basu, Nilotpal Ghosh, Luu Thi Phuong Lan, Harry D. Rowe, Andrew Hunt, Jonathan H. Tomkin, Kenneth T. Ratcliffe. "High influx of carbon in walls of agglutinated foraminifers during the Permian–Triassic transition in global oceans." International Geology Review, 2015; 57 (4): 411 DOI: 10.1080/00206814.2015.1010610 (subs req'd)