How biomarkers can record and reconstruct climate trends
Nestled within sediments that accumulate in marine environments, a certain class of molecule-sized fossils (biomarkers) sneakily record surface-water temperature changes over time. For almost two decades, scientists have used these molecules, found in cell membranes of organisms and called glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), to reconstruct climate trends experienced over both regional and local marine environments. These microorganisms optimize cell membrane fluidity by adjusting the chemical composition and number of cell membrane lipids collectively known as TEX86 in response to environmental temperature changes fairly reliably: Relatively more lipids with a greater number of carbon rings are thought to be produced at higher temperatures. But a mystery remained: No one fully underderstood the mechanisms by which the complex membrane-spanning GDGTs encoded information about temperature, or which organisms actually contributed to the sedimentary GDGT signals. That's now set to change, thanks to scientists associated with the MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS). Former...