Research – Zachos Research Group

The Paleocene-Eocene Thermal Maximum: A Deep-Dive into Climate History

Climate models are used to predict the impacts of anthropogenic carbon emissions on future climate, and scientists enhance their accuracy by testing and comparing these models with paleoclimate data. Such comparisons are crucial for testing climate theory. Researchers studying ancient climates (paleoclimate) examine sediments from the Earth’s past to reconstruct the key characteristics of these climates, with a particular focus on periods of extreme warmth. One such period is the transition from the Paleocene to Eocene epochs—a time characterized by significant global warming. This event was driven by a rapid rise in greenhouse gas levels and thus has served as an invaluable natural experiment for testing theory (models) on greenhouse forcing and ocean acidification. Zachos’s research group has investigated and constrained many aspects of this event, from the magnitude of ocean warming to the total emissions of carbon. At present, they are mainly focused on how such extreme warming impacted the hydroclimate on global and regional scales. They are also involved in a major collaborative effort to reconcile the role of feedbacks (i.e., carbon cycle) that could have potentially amplified the rate and magnitude of warming.

The Ocean Drilling Program’s (ODP) Leg 208 photo archive offers an in-depth visual account of a scientific drilling expedition in the South Atlantic, one that was designed to test the hypothesis of massive carbon release as the primary cause of the Paleocene-Eocene Thermal Maximum. The photos capture the process of deep-sea drilling operations, from drilling to the examination of core samples in the lab, showcasing the equipment, the retrieved core samples, and the scientists in action. These visuals are key for illustrating the logistical and scientific efforts involved in marine geological research, ensuring that the methods and results of the Leg 208 expedition are transparent and widely accessible.

Color-coded bathymetric map of Walvis Ridge highlighting depth variations and key geological survey sites

Map showcasing the RV Meteor's seismic grid lines and drilling sites for the ODP 208 study on a bathymetric backdrop. Various zones are marked with red and yellow lines indicating different survey areas on the ocean floor. The depths are color-coded, ranging from shallow green to deep blue. Labels indicate specific site numbers like 1264, 1265, and 1267. An inset in the bottom left corner places the study area in the context of the South Atlantic Ocean, highlighting the Walvis Ridge's location relative to the African and South American continents. — This map illustrates the RV Meteor seismic grid utilized during the Ocean Drilling Program (ODP) Leg 208. It depicts a defined area of the ocean floor with marked seismic lines, survey sites, and zones of interest. Each line and site is clearly labeled, showing the systematic approach taken in the survey to study the Earth’s subsurface. The color gradations represent different depths of the seabed, and the inset map situates the grid in the larger context of the South Atlantic Ocean, highlighting the location of the Walvis Ridge in relation to Africa and South America.

Three-dimensional bathymetric model showing the terrain of Ocean Drilling Program Leg 208 sites along a depth transect. The vertical legend displays water depth, with colors ranging from red for shallower areas to violet for deeper regions. Drilling sites are marked with red dots and numbered for identification. Below the 3D model, a corresponding two-dimensional map outlines the same locations, providing a clear reference for the topology and drilling site positions. The model is oriented with north at the top, aiding in geographical context. — D topographic representation of Ocean Drilling Program Leg 208 sites along a depth transect, with marked drilling locations such as 1262, 1263, and others. The vertical scale indicates bathymetry in meters, ranging from shallow (red) to deep (blue). The underlying 2D map provides a reference for the 3D model, with site numbers positioned accurately. This visualization aids in understanding the seabed variations and the geological structure of the surveyed area.

Comparative seismic profiles from ODP Site 1262, with left panel showing a GI gun profile and right panel a high-resolution watergun profile. Both profiles illustrate a notable debris flow or slump feature at Site 1262, amidst a complex pattern of sedimentary layers. The profiles exhibit varying geological formations, with the left panel displaying detailed layering and the right panel offering a broader perspective. Each profile includes a depth scale on the left with a vertical exaggeration of 16 times to accentuate the subsurface features.

The photo captures a scene on a research vessel where a team is engaged in geological investigation, searching for a specific boundary clay layer. The deck is lined with core samples, carefully arranged in trays for examination. Professor Zachos crouches closely, scrutinizing a section, while others stand.
The photo shows active scientific collaboration, with tools of the trade like notebooks and measuring instruments visible.
Safety is a priority, indicated by the helmets and safety signage like "Crane Signals."
This moment represents the hands-on aspect of geological fieldwork aboard a research vessel, where every sample holds potential clues to Earth's history. — The photo captures a scene on the JOIDES Resolution where a core recovered from below the sea floor at 4500 meters water depth has just been brought on deck, possibly capturing the Paleocene-Eocene boundary clay layer. The cores are sectioned, split, and brought into the lab for examination This moment represents the hands-on aspect of geological fieldwork aboard a research vessel, where every sample holds potential clues to Earth’s history.

The photo shows a team of researchers onboard a scientific research vessel processing geological core samples. A male researcher, labeled "TIMMY" on his helmet, is carefully handling a section of the core, while two female colleagues assist with the examination and documentation of other samples. They are focused on their tasks, wearing gloves for protection, and surrounded by equipment and tools for core analysis. The deck is well-organized, with core sections laid out in trays for easy access, indicating a systematic approach to their scientific investigation. The setting is outdoors, in daylight, suggesting that the work is being conducted in real-time following core retrieval. — Marine technicians carefully handle an ocean sediment core on the deck of a scientific drilling ship, uncovering secrets from beneath the sea floor..

A group of sedimentologists examines geological core samples aboard a research vessel. Three of the scientists, two men and one woman, are engaged in analyzing and discussing the layered sediment cores laid out on the table, while another man listens intently. The laboratory is well-equipped with books, equipment, and fluorescent lighting, setting the scene for scientific discovery. — Sedimentologists describing a freshly extracted core, piecing together Earth’s history layer by layer. From left to right – A. Sluijs, S. Schellenberg, C. Riesselman, K.C. Lohmann

This photo shows a close-up view of a geological sample displaying a lithologic contact between carbonate ooze and clay, which is an indicator of a chemical erosion process. A ruler is placed across the sample for scale, marked in centimeters. The left side of the sample is rough and textured, characteristic of carbonate ooze, while the right side is smoother and more homogeneous, indicative of clay material. The transition between these two materials is captured right at the center of the image, showcasing the distinct boundary. Two circular boreholes are visible on each side of the contact, likely for taking smaller samples or for analysis purposes. Yellow and blue stickers with handwritten text are placed on the ruler, presumably for labeling or identifying the specific sections of the sample. — This photo shows a close-up view of a geological sample displaying a lithologic contact between carbonate ooze and clay, which is an indicator of a chemical erosion process.

A collection of elongated core samples laid out on a wooden table, representing the Paleocene-Eocene boundary. The lighter-colored clay sections are indicative of the PETM event, providing evidence of past ocean acidification. Each core is segmented and encased in black protective liners, with blue and yellow labels visible at the ends, possibly for identification and cataloging purposes. — Core samples displaying the Paleocene-Eocene Thermal Maximum (PETM) boundary clay, marking a significant shift linked to ancient ocean acidification events.

Graphical plots representing sediment core samples from various depths, illustrating a transect of the dissolution horizon. The graphs show the percentage of calcium carbonate (CaCO3) at different depths, indicating how ocean chemistry affected sediment composition. Each core sample is accompanied by a visual strip log on the left, correlating the data points to the physical appearance of the sediment layers — Graphical representation of a depth transect showing the dissolution horizon across different sediment core samples, with variations in CaCO3 content highlighting changes in ocean chemistry.