#paleoclimate

Exciting work studying the chemical bonds in membrane lipids of #archaea (#marine #microbes) which are often used for #paleoclimate reconstructions suggests improvements to #temperature reconstructions.
https://www.sciencedirect.com/science/article/pii/S0012821X25000925

I have released episode 5 of the Raised Beaches Podcast, a podcast about paleoclimate, Earth science and global change! This episode's deep dive is on the greenhouse effect. Get it in the following link or wherever you get your podcasts.

In the intro, I talk about going to watch Sakurajima Volcano erupt, an earthquake I felt in January, my efforts to download data from NOAA and how US government agencies are being shut down, and a commentary on DEI.

I discuss in the deep dive how the greenhouse effect works, and why greenhouse gases are needed to keep the planet inhabitable. In the second part I discuss the history of the discovery of the greenhouse effect and how it got its name, and the greenhouse effect on Venus and Mars.

Finally, I discuss in the papers section a recent paper I am coauthor on, led by Alessio Rovere, about determining past sea level position from a beach ridge in Argentina. I discuss 4 other papers.

#Paleoclimate #ClimateChange #Podcast #SeaLevel #NOAA #Volcano

https://raisedbeaches.buzzsprout.com/2401751/episodes/16758479-episode-5-the-greenhouse-effect

On this #InternationalDayOfWomenAndGirlsInScience, here is a great story presented in two papers led by a #WomanInScience (Jingjing Guo) and last authored by another #WomanInScience (Francien Peterse).

#Scientific #publication #1: https://doi.org/10.5194/cp-21-343-2025
Scientific publication #2: https://doi.org/10.1016/j.orggeochem.2025.104947

#Science
#ScienceMastodon
#AcademicMastodon
#PaleoClimate
#PaleoHydrology
#EastAsianMonsoon
#PaleoTemperature
#OrganicGeochemistry
#GDGTs #brGDGTs
#ClimateProxies #Loess
#IDWGS #IDWGS2025

"The first #Europeans weren’t who you might think." They pretty much were, given what we know about #geography, #paleoclimate, and #human #evolution—but generations of ideologues successfully argued otherwise. Implications for the modern world are left as an exercise for the reader.

https://www.nationalgeographic.com/culture/article/first-europeans-immigrants-genetic-testing-feature

On my way to #utah to make a presentation about research in this and other #caves in the Uinta Mountains. #geology #cave #caving #paleoclimate #earthscience

Warken et al precisely date the Laacher See volcanic eruption (in central Germany) from a speleothem record, which allows them to precisely define when the eruption happened relative to the start of the Younger Dryas. They find that the timing of the eruption (13,008 yr BP) is at least 150 years before the start of the Younger Dryas, precluding any causal relationship between the eruption and the Younger Dryas. The results from the speleothem also show that the cooling in Europe from the Younger Dryas after the AMOC shutdown happened abruptly.

#Paleoclimate #AMOC #YoungerDryas #ClimateChange #Volcano

https://doi.org/10.1126/sciadv.adt4057

#PaperClub is back for the start of 2025, and we're kicking off with Patterson et al (2024), who present a PCP-corrected stalagmite d18O record from Vietnam, spanning 45-4 ka. Interesting paper, and the whole 'PCP impacts on d18O' thing has been getting quite a lot of airtime in recent years. Hopefully without sounding like a hater, I remain a bit skeptical. In this instance, the model assumptions include a feeding stalactite drip rate of 1 drip/second, which seems too high for LGM (where PCP effect on the stal was greatest). For stalactite PCP to be recorded in a stalagmite, there must not be sufficient residence time for re-equilibration to occur. I would love to see a sensitivity test of the drip rate on the model.

Growth rates during the 'peak PCP' period were also extremely low (<5 um/yr), which suggests to me that growth was likely not continuous over the period. d18O vals were high, I assume there was greater opportunity for disequilibrium to drive the signal rather than PCP?

Anyway, I'm definitely no expert in d18O kinetics, and I'm looking forward to hearing the opinions of the group, and anyone else who has read the paper :) I am really happy to be wrong about this, as there are lots of clever people on the paper who know more than me about this stuff!

#Paleoclimate #Speleothems #speleology
https://www.nature.com/articles/s41467-024-53422-y

In an ocean of bad news, here's some science excitement - the beyond EPICA team has announced they've drilled an ice core dating continuosly to 1.2 million years ago!! This core will give key information about the transition to the 100-000 year earth - the cycle of glacials and interglacials in which we currently live. So cool (pun intended).

#Antarctica #paleoclimate #IceIceBaby #IceCore #ClimateScience

https://www.awi.de/ueber-uns/service/presse/presse-detailansicht/mehr-als-12-millionen-jahre-altes-eis-erbohrt.html

The third part of episode 4 of the Raised Beaches Podcast, a podcast about paleoclimate and global change, I discuss James Croll's orbital theory of climate change and Charles Darwin's support of it, and Milankovitch Cycles on Mars. #ClimateChange #paleoclimate https://www.youtube.com/watch?v=aJiT2sFcrEI

James et al analyze Holocene speleothem records in Asia in order to test whether or not the 4.2 ka event can be detected. They were unable to detect a coherent signal at this time, and propose that it is unlikely the 4.2 ka event was global in nature. #Paleoclimate #ClimateChange #Holocene https://doi.org/10.1029/2024PA004974

On the deep dive of episode 4 of the Raised Beaches Podcast, a podcast about paleoclimate and global change, I discuss Milankovitch Cycles, and how changes to the Earth's orbital parameters control past climate changes. #Paleoclimate #ClimateChange https://www.youtube.com/watch?v=WuPJGYSn3WY

@DrEvanGowan has released a fine new episode of Raised Beaches podcast, about Milankovich cycles! In recent centuries, industrial CO2 has drowned out Milankovich cycles, but Milankovich cycles were a major factor in climate change during the Pleistocene and Pliocene (and presumably before). Bonus: Mars has Milankovich cycles as well.
https://fediscience.org/@DrEvanGowan/113740539812374781

#paleoclimate
#Milankovich
#cycles
#climate
#iceAge

Episode 4 of the Raised Beaches Podcast, a podcast on paleoclimate and global change is out! The deep dive in this episode is on Milankovitch Cycles. Get it on Buzzsprout or wherever you get your podcasts.

In the intro, I discuss Holocene sea level changes in Okinawa, the Aso Caldera, ammonite fossils, and an overview of my activities in 2024.

For the deep dive, I discuss Milankovitch Cycles, the three types of orbital changes and how they affect climate, as well as the LR04 benthic δ¹⁸O and Chinese speleothem δ¹⁸O proxy records, that demonstrate the orbital control on climate change.

In the further discussion, I discuss how James Croll originally proposed an orbital control on climate change before Milankovitch, why Charles Darwin was a fan, and why Croll's theory was not accepted. I also show how Milankovitch Cycles also affect the climate of Mars.

In the papers section, I discuss one paper by Rubio-Sandoval et al (I am a coauthor) on deducing paleo sea level in Camarones, Argentina. There are four periods of higher-than-present sea level at this location. (link in the next post)

I will be posting the video version of this podcast in the coming days!

#Podcast #ClimateChange #Paleoclimate https://www.buzzsprout.com/2401751/episodes/16354340-episode-4-milankovitch-cycles

Lundine and Trembanis investigate the genesis of Carolina Bays, shallow elliptical depressions commonly found in unglaciated areas of the eastern United States. They propose that the initial formation was caused by wind erosion as the region dried out during the beginning of the last glacial cycle, and a large proportion may have formed as the Laurentide Ice Sheet reached a maximum extent between 45 and 18 thousand years ago. Their shapes were reinforced from repeated filling and emptying, and the rims are paleoshorelines from when they were ponds. Their analysis allows them to conclude that an extraterrestrial impact origin hypothesis, which has propagated recently, is unviable. #Paleoclimate #Geomorphology https://doi.org/10.1016/j.margeo.2024.107449

Wakasa et al investigate the age of a tectonically uplifted terraces in Sanriku, northeastern Japan, using cosmogenic burial dating. They conclude that one of the terraces likely formed in Marine Isotope Stage (MIS) 5c, and another in MIS 7. #SeaLevel #Paleoclimate #Tectonics #Japan https://doi.org/10.1016/j.geomorph.2024.109497

Singh et al investigate biomarkers in Arctic Ocean sediment cores, and conclude that drifting sea ice continued to exist during Marine Isotope Stages 2 and 3. There was no Arctic Ocean ice shelf during this time. #Paleoclimate #ArcticOcean #SeaIce https://doi.org/10.1016/j.orggeochem.2024.104920

Lucia et al investigate the strength of the Central American monsoon system over the past 140,000 years, using speleothem δ¹⁸O records from caves in Guatemala. The combined proxy record shows that the strength of the monsoon is correlated with the strength of the Atlantic Meridional Overturning Circulation (AMOC). It is also likely there is an influence from the size of the Northern Hemisphere ice sheets and tropical Atlantic sea surface temperature. The relationship with the AMOC is demonstrated by the close timing of a strengthening of the monsoon during the Bølling-Allerød, and a weakening during the Younger Dryas. However, the record lacks an impact from Dansgaard–Oeschger events, so this differentiates it from the climate in other North Atlantic regions.

The interesting part of this is that most other monsoon systems respond closely to Northern Hemisphere summer insolation, which changes due to Milankovitch Cycles. This makes sense, since the position of global wind patterns that drive the monsoon is related to the temperature gradient between the tropical regions and the poles. That the Central American monsoon responds more to AMOC means that if the predictions of a global warming induced shutdown in the AMOC come true, that will make Central America drier.

#Paleoclimate #ClimateChange #Monsoon #CentralAmerica #AMOC

https://doi.org/10.1038/s41467-024-54856-0

Ottesen et al use 3D seismic data to infer the history of the filling of the North Sea basin by sediments transported by Quaternary ice sheets. They find that the ice sheets did not advance over the central North Sea until after 1.1 million years ago. #paleoclimate #IceSheets https://doi.org/10.1126/sciadv.adq6089

Gao and Turton investigate the δ¹⁸O of Tyrrell Sea sediments at the Victor diamond mine in Northern Ontario. The Tyrrell Sea was precursor of Hudson Bay, which formed after the collapse of the Laurentide Ice Sheet about 8000 years ago. They find that the study site likely deglaciated after the final drainage of Lake Agassiz-Ojibway after the collapse of the Laurentide Ice Sheet, since there were no freshwater sediments. The δ¹⁸O fluctuations implies periods of freshwater input, possibly from the melting of glacial ice. The site was above sea level by about 6100 years ago. From their data, they hypothesize that the 8.2 ka event, which is generally thought to be caused by the sudden drainage of Lake Agassiz-Ojibway, might not have been caused by this, as there were long periods of freshwater input afterwards.

#SeaLevel #Paleoclimate https://doi.org/10.1016/j.quascirev.2024.109134

Grant et al provide an estimate of sea level fluctuations in the Early Pleistocene from grain size variations in a sedimentary basin in New Zealand. They find that fluctuations on the order of 45 m happened, paced by obliquity. This implies that even though it might be possible for the North Hemisphere ice sheets to have had large extent comparable to the last glacial cycle, the volume must have been a lot less. It also implies that the benthic δ¹⁸O also overestimates ice volume during this time. #SeaLevel #Paleoclimate https://doi.org/10.1016/j.quascirev.2024.109096