Sentences with word «alkenone»

New methods using alkenones in marine sediments and coral studies are also described.

The new paper uses alkenones from the Svalbard islands and is among the first studies that present Arctic summer temperature change over the period from the end of the last Ice Age some 12000 years ago.

One approach to answer these important questions is the investigation of paleoclimate data like the ancient alkenones analyzed by van der Bilt and colleagues.

By measuring the bonds of prehistoric alkenones preserved in ancient layers of lake sediment, the team opened a window on Arctic temperature change since the end of the last Ice Age.

To construct a long - term temperature record for the Horn of Africa, the researchers analyzed the sediment layers for chemicals called alkenones made by a particular kind of marine algae.

The ratio of the different alkenones indicates the sea surface temperature when the algae were alive and also reflects regional temperatures, Tierney said.

By simply manipulating specific paleo proxy ending dates, Marcott et al. were able to fabricate the imaginary hockey stick representation (see black curve in above alkenone - proxy chart) versus the original thesis non-hockey stick representation based on the actual paleo - dataset's beginning and ending dates (see red curve)

The one other thing I would add is that the Mg / Ca and alkenone unsaturation records show quite clearly in the time domain that systematic glacial cooling occurred throughout the Pleistocene.

«In this study, the last glacial — deglacial — Holocene variability in SST [sea surface temperature] and sea - ice cover are reconstructed using alkenone - based SST [sea surface temperature] and sea - ice IP25 and PIP25 proxies in sediment cores from the Bering Sea [Arctic Ocean] and the subarctic Pacific.

Alkenones, fats produced by a specific class of aquatic algae, manage to retain a stable viscosity under changing temperatures by building or breaking chemical bonds.

The algae change the composition of the alkenones depending on the water temperature.

As for the geochemical data, it is based on Mg / Ca in foraminifera, alkenone unsaturation in sediments and some sparse data from other techniques such as Ca isotopes, clumped isotopes and TEX86.

That ¹ s a big change in ECS, and there is substantial evidence from two of the SST proxies — Mg / Ca, where a lot of my own work has focused, and alkenone unsaturation — for LGM cooling of ~ 3 deg.

S1; Table S1): alkenone (n = 31), planktonic foraminifera Mg / Ca 24 (n = 19), TEX86 (n = 4), fossil chironomid transfer function (n = 4), fossil pollenmodern analog 25 technique (MAT)(n = 4), ice - core stable isotopes (n = 5), other microfossil assemblages (MAT and 26 Transfer Function)(n = 5), and Methylation index of Branched Tetraethers (MBT)(n = 1).

If, on the other hand, you switch from recalibrated to originally published ages, and push data which is beyond 1940 back in time or maybe extend the reconstruction beyond 1940 (when there aren't nearly enough proxies no matter how you slice it), and limit only to alkenones, and do whatever else you need to get what you want... then you can flood the internet with innuendo and sneering.]

Evidence for past temperatures [edit] Our evidence for past temperatures comes mainly from isotopic considerations (especially δ18O); the Mg / Ca ratio of foram tests, and alkenones, are also useful.

CBT = cyclization ratio of branched tetraethers; MBT = methylation index of branched tetraethers; TEX86 = tetraether index of tetraethers consisting of 86 carbon atoms; Uk37 = 37, alkenone unsaturation index.