According to highly cited conventional models, cooling and a major drop in sea levels about 34 million years ago should have led to widespread continental erosion and deposited gargantuan amounts of sandy material onto the ocean floor. This was, after all, one of the most drastic climate transitions on Earth since the demise of the dinosaurs.

Yet a new Stanford review of hundreds of studies going back decades contrastingly reports that across the margins of all seven continents, little to no sediment has ever been found dating back to this transition. The discovery of this globally extensive gap in the geologic record was published this week in Earth-Science Reviews.

“The results have left us wondering, ‘where did all the sediment go?'” said study senior author Stephan Graham, the Welton Joseph and Maud L’Anphere Crook Professor in the Stanford Doerr School of Sustainability. “Answering that question will help us get a better fundamental understanding about the functioning of sedimentary systems and how climatic changes imprint on the deep marine sedimentary record.”

The geological gap offers fresh insights into sediment deposition and erosion processes, as well as the broader environmental signals from dramatic climate change, which could help researchers better grasp the global enormity of today’s changing climate.

“For the first time, we’ve taken a global look at an understudied response of the planet’s largest sediment mass-movement systems during the extreme transition of the Eocene-Oligocene,” said study lead author Zack Burton, Ph.D. ’20, who is now an assistant professor of Earth sciences at Montana State University.

Tim McHargue, an adjunct professor of Earth and planetary sciences at Stanford, is also a co-author on the study.

From hothouse to icehouse

During the Eocene-Oligocene period, Earth underwent profound planetary cooling. Giant ice sheets appeared in Antarctica, which was previously ice-free, global sea level plunged, and land and marine life suffered severe die-offs.

Prior to that, in the early part of the Eocene that lasted from about 56 million to 34 million years ago, Earth had the warmest temperatures and highest sea levels since dinosaurs walked the Earth more than 66 million years ago, according to climate-proxy records.

Burton and colleagues initially focused on exploring the effects of early Eocene conditions on deep-sea depositional systems. The resulting study—published in Scientific Reports in 2023—found abundant sand-rich deposits in the ocean basins along Earth’s continental margins.

The research team attributed this deposition increase mainly to intensified climatic and weather conditions boosting erosion from land. Their curiosity piqued, Burton and colleagues then extended the investigation to the late Eocene and early Oligocene, when Earth suddenly went from “hothouse” and “greenhouse” climates to the opposite, an “icehouse” climate.

For the new study, the researchers painstakingly pored over scientific and technical literature documenting ancient sediment up to several kilometers beneath the sea floor, surveying studies published in the past decade to over a century ago. The literature included offshore oil and gas drilling studies, onshore rock outcrop studies, and even interpretations of seismic data to infer Eocene-Oligocene sediment characteristics. In total, just over a hundred geographical sites worldwide were included, outlining every continental landmass.

While the study’s method of literature analysis is not new on its own, the scale of such an approach made possible by vast online databases could prove highly illuminating, Graham said. “There could be other similar events in the geologic past that would bear a closer investigation,” said Graham, “and the way to start that is by doing exactly what we did—a really thorough canvassing of the global geologic literature for certain suspect periods in time.”

“The actual process of reappraising, reinvestigating, and reanalyzing literature that has in some cases been out for decades is challenging, but can be very fruitful,” Burton said. “The method can lead to exciting and unexpected findings, like we were able to make here.”

Wholly unanticipated

As Burton and his colleagues made their way through the compiled data inventory, they grew increasingly perplexed by the apparent sedimentary no-show.

“We didn’t see abundant sand-rich deposition, as in our study of warm climates of the early Eocene,” said Burton. “Instead, we saw that prominent, widespread erosional unconformities—in other words, gaps in the rock record—had developed during the extreme climatic cooling and oceanographic change of the Eocene-Oligocene.”

The researchers offer a few theories about why this lack of deposition occurred. Vigorous ocean bottom currents, driven by temperature and salinity of the waters, may have been triggered or magnified by the major climate shift, potentially eroding the ocean floor and sweeping away sediment that flowed off the continents.

Meanwhile, mechanisms from continental shelves exposed by sea-level fall could have allowed sediments to entirely bypass the closer-in sedimentary basins, sending deposits much farther out onto the abyssal plain of the ocean floor. More regionally restricted processes, like glacial erosion around Antarctica, likely played a part, too.

Whatever mechanisms may have been in play, they collectively created similar scenes of erosion in oceanic basins around every continent. That ubiquity points to what the researchers referred to as global controls—meaning that profound climatic change was felt everywhere, from the tallest landmasses down into the deepest waters.

In this way, the abrupt climatic event at the Eocene-Oligocene boundary and its newly observed, substantial effects along continental margins could help researchers better grasp the global enormity of today’s unfolding climate change. Although the human-caused climate change of the past couple centuries is currently much smaller in overall magnitude compared to the Eocene-Oligocene transition, it is happening at an alarmingly faster pace, the Stanford researchers said.

“Our findings can help inform us of the kinds of radical changes that can happen on the Earth’s surface in the face of rapid climate change,” said Graham. “The geologic past informs the present, and particularly the future.”

In physics, a system composed of two substances can be modeled in accordance with classical mixture theory, which considers the fraction corresponding to each constituent and the interactions among constituents. Examples include the coexistence of high- and low-density phases in supercooled water, and the coexistence of metal puddles in an insulating matrix in the Mott metal-insulator transition.

Motivated by this kind of consideration, researchers at São Paulo State University (UNESP) in Rio Claro, Brazil, used concepts of condensed matter physics to describe protein compartmentalization in cells and proposed a cellular Griffiths-like phase in direct analogy to the canonical magnetic Griffiths phase.

The study is published in the journal Heliyon. The last author and PI is Mariano de Souza, a professor at the Institute of Geosciences and Exact Sciences (IGCE-UNESP), and the first author is Lucas Squillante, a Ph.D. candidate at the same university.

“In the magnetic Griffiths phase, magnetized or non-magnetized regions emerge in paramagnetic or ferromagnetic matrices respectively, giving rise to a significant reduction in the dynamics of the systems. These so-called ‘rare regions’ emerge in random fashion. In previous work, we explored the electronic Griffiths-like phase at the verge of the Mott metal-insulator transition. In this study we focused on the protein droplets formed inside cells as ‘rare regions,’ in direct analogy with the magnetic Griffiths phase,” Souza said

Production of proteins inside a cell can reach a threshold that gives rise to liquid-liquid phase separation and compartmentalization of proteins in the form of droplets. “Using thermodynamics tools such as the Grüneisen parameter, the Flory-Huggins model and the Avramov-Casalini model, we show that cellular dynamics is dramatically reduced in the vicinity of the binodal line that determines phase separation, and also for an equivalent protein/solvent concentration, giving rise to a Griffiths-like cellular phase,” Souza said.

The study also proposes that the Griffiths-like cellular phase is associated with the origin of life and the emergence of primordial organisms, in accordance with the classical theory formulated by Russian biologist and biochemist Aleksandr Oparin (1894–1980) in the 1930s, since only coacervates (droplets of organic molecules clustering in an aqueous solution) with slow dynamics survived and evolved.

“This in turn may be linked to the fundamental role played by homochirality in the evolution of life,” Souza said. Chirality is the property of an object or molecule which means it cannot be superimposed on its mirror image. Human hands are chiral, for example. Homochirality is the predominance of a single chirality in molecules of a biological system.

The researchers demonstrate in the study that an increase in protein diffusion time occurs concomitantly with a reduction in stochastic fluctuations in the cell, which in turn is key to optimizing gene expression. The study offers an alternative approach to investigating the dynamics of protein compartmentalization, which may also be applicable to other biological systems.

“The fundamental role played by liquid-liquid phase separation in the development and treatment of diseases is widely discussed in the literature, especially with regard to tumorigenesis. The idea is that proteins encoded by genes associated with such diseases can be compartmentalized and that this affects their role in cell mutation,” said Marcos Minicucci, a professor of clinical medicine at UNESP Botucatu and a co-author of the article.

Other examples of the role played by phase separation include cataract (where phase separation in the retina can cause visual impairment), neurodegenerative diseases, and even COVID-19 (where coacervation of the SARS-CoV-2 N protein can suppress the innate immune response to the virus). It has recently been reported that the phase separation associated with ferroptosis suppressing protein 1 (FSP1) can be used in an effective therapeutic intervention against cancer.

“Liquid-liquid phase separation affects each disease differently, and protein droplet formation may or may not be beneficial. The Griffiths-like cellular phase we’re proposing can have a significant impact in managing and even treating diseases,” Minicucci said. The study conducted by Souza’s group demonstrates the importance of interdisciplinarity in fundamental science projects.

The other co-authors besides Squillante, Minicucci and Souza are Antonio Seridonio (UNESP Ilha Solteira), Roberto Lagos-Monaco (UNESP Rio Claro), Aniekan Magnus Ukpong (University of KwaZulu-Natal, Pietermaritzburg, South Africa), Luciano Ricco (University of Iceland), and Isys Mello, a Ph.D. candidate supervised by Souza.

Because small changes in atmospheric and surface conditions can have large, difficult-to-predict effects on future weather, traditional weather forecasts are released only about 10 days in advance. A longer lead time could help communities better prepare for what’s to come, especially extreme events such as the record-breaking June 2021 U.S. Pacific Northwest heat wave, which melted train power lines, destroyed crops, and caused hundreds of deaths.

Meteorologists commonly use adjoint models to determine how sensitive a forecast is to inaccuracies in initial conditions. These models help determine how small changes in temperature or atmospheric water vapor, for example, can affect the accuracy of conditions forecast for a few days later.

Understanding the relationship between the initial conditions and the amount of error in the forecast allows scientists to make changes until they find the set of initial conditions that produces the most accurate forecast.

However, running adjoint models requires significant financial and computing resources, and the models can measure these sensitivities only up to five days in advance. Researchers tested whether a deep learning approach could provide an easier and more accurate way to determine the optimal set of initial conditions for a 10-day forecast.

The findings are published in the journal Geophysical Research Letters.

The researchers created forecasts of the June 2021 Pacific Northwest heat wave using two different models: the GraphCast model, developed by Google DeepMind, and the Pangu-Weather model, developed by Huawei Cloud.

They compared the results to see whether the models behaved similarly, then compared the forecasts to what actually happened during the heat wave. (To avoid influencing the results, data from the heat wave were not included in the dataset used to train the forecasting models.)

The team found that using the deep learning method to identify optimal initial conditions led to a roughly 94% reduction in 10-day forecast errors in the GraphCast model. The approach resulted in a similar reduction in errors when used with the Pangu-Weather model. The team noted that the new approach improved forecasting as far as 23 days in advance.

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.