Wood Romances

The Paleocene–Eocene Thermal Maximum (PETM) was a period of time beginning about  56 million years ago. Temperatures increased by 5–8°C[2][4] due to a large excursion of biogenic carbon. Temperatures increased extremely rapidly, and the perturbation of the carbon cycle led to ocean acidification and a mass extinction of benthic foraminifera. The warming event occurred suddenly, geologically speaking, perhaps in as little as 10,000 years[12], making it one the most rapid warming events detected in the Phanerozoic. The extreme warmth of the PETM lasted less than 220,000 years before returning to "normal" Eocene levels. The rapid warming warming associated with the PETM makes it a good analogue to current warming, so I think it would be helpful to cover this event as well as provide a bibliography for further reading on the subject. The PETM is also one among many examples in geologic history where it is clear that GHGs were driving global warming. CO2 led (and drove) the warmin...

Note: 1/15/2024. Graphs are updated to include 2024 when available. You sometimes hear that, at least on certain time scales, CO2 and global temperature (GMST) don't correlate very well or even that the two go in opposite directions. The implication drawn from this is that CO2 can't be the primary driver of climate changes. What I want to show here is that this claim is categorically false. On virtually all time scales in the Phanerozoic, CO2 and GMST correlate very well, especially when taking into consideration that GMST correlates with the log of CO2.  The best way for me to demonstrate this point is to simply show the correlation. Where I can, I convert CO2 to forcings (using RF = 5.35*ln(CO2/280)) and and plot CO2 forcings on the x-axis and GMST on the y-axis. This gives us two advantages: first, it allows us to calculate the r^2 for that correlation, and second, the slope of the correlation gives us an indication of sensitivity - that is, the temperature response to chang...

Along with the publication of Emily Judd's reconstruction[1] of global temperatures, she and her team compiled an up-to-date reconstruction of CO2 concentrations from proxy data. I shared in a previous post how this new reconstructions shows a CO2 and GMST as well-correlated on geologic time scales, with GMST increasing by ~8 C for 2xCO2. Her CO2 reconstruction is another step forward for paleoclimate because it makes use of a growing database of proxy evidence, much of which is being compiled at the Paleo CO2 project . For the Paleozoic and Mesozoic, Judd's reconstruction followed Foster et al 2017 [2] pretty closely, especially during the Paleozoic, but she also included additional data from Witkowski et al 2018[4][3]. Differences between Judd's and Foster's reconstruction had to do with different ways of site and time averaging and updates from Witkowski's study. During the Cenozoic, she followed more recent work by Rae et al 2021 [5] which agrees closely with t...

In January, I blogged about a lecture I watched from Jessica Tierney, a geologist who has done some fascinating work in paleoclimate, in which she described the research behind a new paper that was at the time still undergoing peer review. You can watch the video and see my previous thoughts about this here . Ever since I watched this lecture, I have been anticipating the publication of the paper and hoping that the text wouldn't be behind a pay wall so I could learn more about what Tierney shared in her lecture. Well, late last week, both of my hopes became a reality. The paper is published and the full version is available. The lead author is Emily Judd[1], and this appears to be a remarkable paper. The tl;dr for this paper is that Emily Judd and her colleagues put together a data analysis (PhanDA) reconstruction of global temperatures and CO2 for the last 485 million years (most of the Phanerozoic), and they found that GMST varied greatly on geologic time scales, ranging from ...

CO2 Coalition 's " fact #1 " is an excellent example of I consider contrarian alarmism. The claim here is essentially that the overall trend over the last 140-million years shows that we are on a long-term trend towards a climate apocalypse until we were saved by carbon emissions from the fossil fuel industry. In fact, while contrarians frequently call those who accurately present the scientific evidence as "alarmist," this so-called "fact" actually qualifies as an alarmist claim. In the graph above, the CO2 Coalition claims that CO2 levels have been steadily decreasing for 140 million years, such that "CO2 levels fell precipitously & steadily to within about 30 ppm of the 150 ppm 'line of death' below which plants can’t survive. Both the relatively short-term data from ice cores and much longer-term data going back 140 million years... show an alarming downward trend toward CO2 starvation." The data they use comes from Berner 20...

WA07 Demonstrating Verification Failure of M&M This is part 3 of a 3 part series on M&M's accusations of "tricks" on the part of MBH and the hockey stick. Part 1 is here and Part 2 is here . Stephen McIntyre is reporting another "Nature Trick" on his ClimateAudit blog. The post is from Nov 24, 2023. As I've pointed out before, the MBH98/99 hockey stick have been replicated so many times that it's really old news. In 2007, Wahl and Amman were able to emulate the MBH98/99 hockey stick reconstruction and verify that it was robust to statistical method. But there were some slight differences between the two, and it seems some people won't be happy until they emulate it exactly.  An "Audit" of MBH98/99 In 2021, Hampus Söderqvist apparently succeeded in reproducing MBH98/99 exactly, but in the process of doing so, he discovered some minor errors from the infilling of grid box temperatures in Jones & Briffa 1992 that affected MBH98/99...

Cenozoic CO2 and Temperature A new paper was published this month that I think will produce some exciting new insights for those interested in historical geology and paleoclimate studies. The paper is a product of the Cenozoic Carbon dioxide Proxy Integration Project (CenCO2PIP) Consortium, and it looks to reconstruct the proxy evidence for CO2 levels during the Cenozoic (the last 66 million years). The Cenozoic began after the asteroid impact (and/or volcanism) at the Cretaceous-Tertiary (K-T) boundary that caused the mass-extinction that included the extinction of non-avian dinosaurs. The value of this kind of work will have significant benefits for scientists as they seek to constrain estimates for long-term climate sensitivity (ESS). We can think of "sensitivity" on roughly three time scales:  TCR : On a near-immediate time scale, GMST increases with increasing CO2 in what is called transient climatic response (TCR), which generally speaking tells you how quickly temperat...