I did something.
It's about the ColdBlob or SubPolarGyre or AMOC.
Specifically, about finding proxy locations on land for its annual evolution.

Taking SPG average sst in the months DJF and MAM, and computing also their year-on-year growth rate.

Then I computed the growth rate for DJF and MAM in all coordinates on land using Era5-Land 1951-2025.
And when the growthrate matches that of SPG within ±0.5 °C, it gets a ✅ .
6 ✅ per decade gets a 🔵 and counts toward selection.
Some more exclusion criteria applied, and I get a list of 315 locations on land for 🔵matching DJF growthrate, and a whopping additional 11,460 locations for MAM
In a 0.1x0.1 grid.

All DJF locations are in Papua. No proxies I know of have been recovered from Papua yet. I know all speleothems / stalagmites in caves🔴 , and all treerings ever analyzed🟢 , thanks to #NOAA .

But MAM °C has more locations. All of Indonesia basically is THE SPG in terms of growthrate. A few trees and speleothems match, one cave covers the whole #Holocene 🖖🏽
Large patches in Africa also match SPG in MAM. But only 2 short treering studies exist. No caves.
Middle and South America has plenty matching SPG MAM too, and a handful of trees and caves.

Yay.

#AMOC #climateChange #citizenscience #proxy #climateproxies #ColdBlob #SubPolarGyre
#Speleothem #treerings

Towards quantitative reconstruction of past monsoon precipitation based on tetraether membrane lipids in Chinese loess

Abstract. Variations in the oxygen isotope composition (δ18O) of cave speleothems and numerous proxy records from loess–paleosol sequences have revealed past variations in East Asian monsoon (EAM) intensity. However, challenges persist in reconstructing precipitation changes quantitatively. Here, we use the positive relationship between the degree of cyclization (DC) of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in modern surface soils from the Chinese Loess Plateau (CLP) and mean annual precipitation (MAP) to quantify past monsoon precipitation changes on the CLP. We present a new ∼ 130 000-year-long DC-based MAP record for the Yuanbao section on the western edge of the CLP, which closely tracks the orbital- and millennial-scale variations in available records of both speleothem δ18O and the hydrogen isotope composition of plant waxes (δ2Hwax) from the same section. Combing our new data with existing brGDGT records from other CLP sites reveals a spatial gradient in MAP that is most pronounced during glacials, when the western CLP experiences more arid conditions and receives up to ∼ 250 mm less precipitation than in the southeast, whereas MAP is ∼ 850 mm across the CLP during the Holocene optimum. Furthermore, the DC records show that precipitation amount on the CLP varies at both the precession scale and the obliquity scale, as opposed to the primarily precession-scale variations in speleothem δ18O and δ2Hwax at Yuanbao and the 100 kyr cycle in other loess proxies, such as magnetic susceptibility, which rather indicates the relative intensity of the EAM. At the precession scale, the DC record is in phase with δ2Hwax from the same section and the speleothem δ18O record, which supports the hypothesis that monsoon precipitation is driven by Northern Hemisphere summer insolation.

Let me explain in the following #thread why the (auto-)citation of Davtian et al. (2018) Organic Geochemistry—my second first-authored #PhD #scientific #publication—by De Jonge et al. (2024) Geochemistry, Geophysics, Geosystems matters to me and my current CEREGE colleagues at CEREGE
https://doi.org/10.1016/j.orggeochem.2018.01.007 👇🏻 (1/9)
#Science
#ScienceMastodon #AcademicMastodon
#Paper
#GDGTs #isoGDGTs #brGDGTs
#Index #Indices #ClimateProxies
#LiquidChromatography #MassSpectrometry
https://mastodon.world/@nina_davtian/113364848478272072
The importance of mass accuracy in selected ion monitoring analysis of branched and isoprenoid tetraethers

Among the new proxies based on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs), the BIT index (Branched and Isoprenoid Tetraether in…

#Halloween is soon and so is the beginning of a new #chapter of my #academic #career!
For this reason, I reintroduce one of my most significant first-authored #research articles (Davtian et al., 2021 #Paleoceanography and #Paleoclimatology):
https://doi.org/10.1029/2020PA004077
More details in the #thread below: (1/15)

#Science
#ScienceMastodon #AcademicMastodon
#Paper #Scientific #Publication
#PaleoClimate #ClimateChange
#ClimateProxies #SeaSurfaceTemperature
#NorthAtlantic #AtlanticOcean #Atlantic #Ocean

I am honored to co-author the new #scientific #publication first-authored by Petter Hällberg! This time, it is the use of #levoglucosan rather than #GDGTs—as #paleohydrology rather than #paleotemperature #ClimateProxies this time!—which granted me this #collaboration and co-authorship!
https://doi.org/10.1016/j.quascirev.2024.108948
More information in the following thread: 👇🏻 (1/6)
#Science
#ScienceMastodon #AcademicMastodon
#Paper #OpenAccess #OpenAccessWeek #OpenAccessWeek24 #OpenAccessWeek2024
#isoGDGTs #brGDGTs
Disentangling seasonal and annual precipitation signals in the tropics over the Holocene: Insights from δD, alkanes and GDGTs

Rainfall seasonality in the tropics has a substantial impact on both ecosystems and human livelihoods. Yet, reconstructions of past rainfall variabili…

What if celebrate #IWD2023 by featuring two recent #scientific #publications with female first authors and involving some of the #molecular #fossils that I studied during my #PhDThesis?

Robles et al. (https://doi.org/10.5194/cp-19-493-2023) and Barhoumi et al. (https://doi.org/10.1016/j.quascirev.2023.108014) reconstructed past #temperatures using #pollen and bacterial membrane lipids named #brGDGTs.

Indeed, membrane plasticity adjustments to #environmental changes also yield complementary #ClimateProxies.

#InternationalWomensDay

Climate changes during the Late Glacial in southern Europe: new insights based on pollen and brGDGTs of Lake Matese in Italy

Abstract. The Late Glacial (14 700–11 700 cal BP) is a key climate period marked by rapid but contrasted changes in the Northern Hemisphere. Indeed, regional climate differences have been evidenced during the Late Glacial in Europe and the northern Mediterranean. However, past climate patterns are still debated since temperature and precipitation changes are poorly investigated towards the lower European latitudes. Lake Matese in southern Italy is a key site in the central Mediterranean to investigate climate patterns during the Late Glacial. This study aims to reconstruct climate changes and their impacts at Matese using a multi-proxy approach including magnetic susceptibility, geochemistry (XRF core scanning), pollen data and molecular biomarkers like branched glycerol dialkyl glycerol tetraethers (brGDGTs). Paleotemperatures and paleo-precipitation patterns are quantitatively inferred from pollen assemblages (multi-method approach: modern analogue technique, weighted averaging partial least-squares regression, random forest and boosted regression trees) and brGDGT calibrations. The results are compared to a latitudinal selection of regional climate reconstructions in Italy to better understand climate processes in Europe and in the circum-Mediterranean region. A warm Bølling–Allerød and a marked cold Younger Dryas are revealed in all climate reconstructions inferred from various proxies (chironomids, ostracods, speleothems, pollen, brGDGTs), showing no latitudinal differences in terms of temperatures across Italy. During the Bølling–Allerød, no significant changes in terms of precipitation are recorded; however, a contrasted pattern is visible during the Younger Dryas. Slightly wetter conditions are recorded south of 42∘ N, whereas dry conditions are recorded north of 42∘ N. During the Younger Dryas, cold conditions can be attributed to the southward position of North Atlantic sea ice and of the polar frontal jet stream, whereas the increase in precipitation in southern Italy seems to be linked to relocation of Atlantic storm tracks into the Mediterranean, induced by the Fennoscandian ice sheet and the North European Plain. By contrast, warm conditions during the Bølling–Allerød can be linked to the northward position of North Atlantic sea ice and of the polar frontal jet stream.

#introduction

Happy #EarthDay everyone!

I am a #paleoclimate #scientist who also is an expert on #biomarkers as #ClimateProxies. In other words, I study past #climate using #molecular #fossils.

I am currently a @CNRS_INSU researcher at the Centre de Recherche et d'Enseignement en Géosciences de l'Environnement (CEREGE, France).

In addition to boosting toots of interest, I will essentially toot my new #scientific #publications and other #scientific content.

#ECR #WomenInSTEM 👩‍🔬