PETM = Paleocene-Eocene Thermal Maximum
Guest Aeuhhh???? by David Middleton
“Ancient climate change triggered warming that lasted thousands of years”…
Climate change caused climate change???
Ancient climate change triggered warming that lasted thousands of years
January 21, 2019
UNIVERSITY PARK, Pa. — A rapid rise in temperature on ancient Earth triggered a climate response that may have prolonged the warming for many thousands of years, according to scientists.
Their study, published online in Nature Geoscience, provides new evidence of a climate feedback that could explain the long duration of the Paleocene-Eocene Thermal Maximum (PETM), which is considered the best analogue for modern climate change.
The findings also suggest that climate change today could have long-lasting impacts on global temperature even if humans are able to curb greenhouse gas emissions.
“We found evidence for a feedback that occurs with rapid warming that can release even more carbon dioxide into the atmosphere,” said Shelby Lyons, a doctoral student in geosciences at Penn State. “This feedback may have extended the PETM climate event for tens or hundreds of thousands of years. We hypothesize this is also something that could occur in the future.”
Increased erosion during the PETM, approximately 56 million years ago, freed large amounts of fossil carbon stored in rocks and released enough carbon dioxide, a greenhouse gas, into the atmosphere to impact temperatures long term, researchers said.
Global temperatures increased by about 9 to 14.4 degrees Fahrenheit during the PETM, radically changing conditions on Earth. Severe storms and flooding became more common, and the warm, wet weather led to increased erosion of rocks.
Lyons was studying PETM core samples from Maryland, in a location that was once underwater, when she discovered traces of older carbon that must have once been stored in rocks on land. She initially believed the samples were contaminated, but she found similar evidence in sediments from other Mid-Atlantic sites and Tanzania.
Carbon in these samples did not share common isotope patterns of life from the PETM and appeared oily, as if it been heated over long periods of time in a different location.
“That told us what we were looking at in the records was not just material that was formed during the PETM,” Lyons said. “It was not just carbon that had been formed and deposited at that time, but likely represented something older being transported in.”
They estimated the climate feedback could have released enough carbon dioxide to explain the roughly 200,000-year duration of the PETM, something that has not been well understood.
This actually looks like some really good science turned into press release psychobabble. So, first, I will ridicule the press release.
Press Release Psychobabble
Only a delusional alarmist half-wit would describe the PETM as any sort of “analogue for modern climate change”, much less the “best” analog (which does not end with -ue on this side of the Atlantic Ocean, except maybe in Canada).
Note how the PETM (55 Ma) is about as far from a CO2 analog to modern times as it possibly could be… unless the PETM stomata data are correct, in which case AGW is even more insignificant than previously thought.
Regarding temperatures, the PETM is also about as far from being an analog to modern times as it possibly could be.
Note that the Early Eocene Climatic Optimum (EECO) was just as warm as the PETM and lasted longer.
To demonstrate how utterly ridiculous it is to describe the PETM as an analog for modern climate change, we just have to look at the Miocene Epoch, which was much cooler than the PETM and EECO.
Bear in mind that the HadSST3 data are of much higher resolution than the δ18O time series. The amplitude of the proxy time series on multi-decadal to centennial time-scales should be considered to be the minimum of the true variability on those time-scales, due to the much lower resolution than the instrumental data (Ljungqvist, F.C. 2010). Despite this, the modern ~1 °C rise since pre-industrial times doesn’t even break out of the Pleistocene noise level… another 1 °C rise won’t even break out of the Pleistocene noise level.
The PETM is also often cited as an analog for Chicken Little of the Sea…
I literally couldn’t make this sort of schist up if I was trying.
Some Really Good Science
Palaeocene–Eocene Thermal Maximum prolonged by fossil carbon oxidation
A hallmark of the rapid and massive release of carbon during the Palaeocene–Eocene Thermal Maximum is the global negative carbon isotope excursion. The delayed recovery of the carbon isotope excursion, however, indicates that CO2 inputs continued well after the initial rapid onset, although there is no consensus about the source of this secondary carbon. Here we suggest this secondary input might have derived partly from the oxidation of remobilized sedimentary fossil carbon. We measured the biomarker indicators of thermal maturation in shelf records from the US Mid-Atlantic coast, constructed biomarker mixing models to constrain the amount of fossil carbon in US Mid-Atlantic and Tanzania coastal records, estimated the fossil carbon accumulation rate in coastal sediments and determined the range of global CO2 release from fossil carbon reservoirs. This work provides evidence for an order of magnitude increase in fossil carbon delivery to the oceans that began ~10–20 kyr after the event onset and demonstrates that the oxidation of remobilized fossil carbon released between 102 and 104 PgC as CO2 during the body of the Palaeocene–Eocene Thermal Maximum. The estimated mass is sufficient to have sustained the elevated atmospheric CO2 levels required by the prolonged global carbon isotope excursion. Even after considering uncertainties in the sedimentation rates, these results indicate that the enhanced erosion, mobilization and oxidation of ancient sedimentary carbon contributed to the delayed recovery of the climate system for many thousands of years.
Some Really Good Science Is Behind a Pay-wall
Which is unfortunate, because it might just explain the Paleocene-Eocene carbon isotope excursion.
Although the prolonged carbon isotope excursion actually occurred after the PETM, during the EECO. Isn’t it “funny”? Prior to ExxonMobil, carbon isotope excursions (depletion of δ13C) routinely accompanied periods of warming. Since ExxonMobil, carbon isotope excursions have been caused by fossil fuel combustion. Maybe climate “scientists” should adopt a new dating system… Instead of years BP, they should use years BXOM (before ExxonMobil)… That even made Mr. Data laugh!
Ljungqvist, F.C. 2010. A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia. Geografiska Annaler: Physical Geography, Vol. 92 A(3), pp. 339-351, September 2010. DOI: 10.1111/j.1468-459.2010.00399.x
Lyons, Shelby L. & Baczynski, Allison & Babila, Tali & J. Bralower, Timothy & A. Hajek, Elizabeth & Kump, Lee & G. Polites, Ellen & Self-Trail, Jean & M. Trampush, Sheila & R. Vornlocher, Jamie & Zachos, J.C. & Freeman, Katherine. (2018). Palaeocene–Eocene Thermal Maximum prolonged by fossil carbon oxidation. Nature Geoscience. 12. 10.1038/s41561-018-0277-3.
Middleton, David H. The Total Myth of Ocean Acidification, Part Deux: The Scientific Basis. WUWT. 2018
Middleton, David H. No. The Miocene is not an example of the “last time it was as warm as it’s going to get later this century”… Argh!. WUWT. 2018
Pagani, M., J.C. Zachos, K.H. Freeman, B. Tipple, and S. Bohaty. 2005. Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene. Science, Vol. 309, pp. 600-603, 22 July 2005.
Pearson, P. N. and Palmer, M. R.: Atmospheric carbon dioxide concentrations over the past 60 million years, Nature, 406, 695–699,https://doi.org/10.1038/35021000, 2000.
Royer, et al., 2001. Paleobotanical Evidence for Near Present-Day Levels of Atmospheric CO2 During Part of the Tertiary. Science 22 June 2001: 2310-2313. DOI:10.112
Tripati, A.K., C.D. Roberts, and R.A. Eagle. 2009. Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years. Science, Vol. 326, pp. 1394 1397, 4 December 2009. DOI: 10.1126/science.1178296
Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, K. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292, 686–-693 (2001).