Shatsky Rise is an oceanic plateau that is located in the Northwest Pacific Ocean off of the coast of Japan. The main goals and objectives of Ocean Drilling Program (ODP) Leg 198 at the Shatsky Rise was to gain a better understanding of abrupt climatic event transitions, “greenhouse” climactic events, and climactic events in general. Shatsky Rise is an excellent location to study such events because it contains sediments of Cretaceous (145.5–65.5 million years ago) and Paleogene (66–23.03 million years ago) ages at relatively shallow burial depths on three distinct highs. Understanding past climatic events such as warming or cooling can play a key role in understanding and predicting similar climatic events in the future.
ODP Leg 198 took place from August 27th, 2001 to October 23rd, 2001. The expedition began at a port located in Yokohama, Japan and ended at a port in Honolulu, Hawaii. The large quantity of sediment cores that were collected on this expedition were helpful in meeting the goals of Leg 198, partially due to the fact that many of the cores contained a clear record of nanno- and microfossils, which are tiny microscopic fossils such as diatoms and foraminifera, that can be an incredibly useful tools to better understand geologic climatic events. Foraminifera, for example, create their shells from ions in the surrounding seawater in which they live, and as such the chemistry of their shells largely reflects the chemistry of the ocean at the time they built their shells. From these fossils and their chemistry, scientists and researchers are able to measure and reconstruct past ocean conditions such as temperature, salinity, and water productivity.
There were three main findings that researchers discovered on Leg 198 that were related to paleomagnetism, climatic transitions, and a cooling event. Paleomagnetism, which is a branch of geophysics, is a field of study that uses rocks or sediment to study the direction and intensity of Earth’s magnetic field at the time of sediment or rock formation. At Site 1208, Leg 198 recovered many mixed siliceous-calcareous Neogene aged (23.03–2.58 million years ago) sediments that were identified to have strong paleomagnetic cycles making them useful for paleoceanographic and paleomagnetic records in the Pacific Ocean during the Neogene (~23-2.58 million yeasr ago). Leg 198 also found climactic transitions related to dysoxic (low-oxygen) or anoxic (no oxygen) environments at the bottom of the seafloor, clear records of nannofossil and planktonic foraminiferal assemblage transformations at the time of major environmental upheavals and transitions, and transitions from paleodepths at the shallower sites that were less sensitive to chemical changes in the deep ocean to those that were at depth ranges highly sensitive to changes. They also found an important deep water cooling event that is related to glaciation in the Antarctic during the Eocene–Oligocene transition (33.9 million years ago), which is important for better understanding the deepening of the calcite compensation depth (CCD), which is the point at which calcium carbonate (CaCO3) is not preserved due to the bottom ocean waters being too acidic. Below the CCD organisms that secrete shells, such as corals, foraminifera, and nannoplankton are not preserved in the sediment.
Bains, S., Corfield, R.M., and Norris, R.D., 1999. Mechanisms of climate warming at the end of the Paleocene. Science, 285:724-727.
Bralower, T.J., Premoli Silva, I., Malone, M.J., et al., 2002 Proceedings of the Ocean Drilling Program, Initial Reports Volume 198
————, 1995. Carbon-isotope stratigraphy and paleoceanographic significance of the Lower Cretaceous shallow-water carbonates of Resolution Guyot, Mid-Pacific Mountains. In Winterer, E.L., Sager, W.W., Firth, J.V., and Sinton, J.M. (Eds.), Proc. ODP, Sci. Results, 143: College Station, TX (Ocean Drilling Program), 99-104.
International Ocean Discovery Program (IODP) Expedition 353 was intended to further the understanding of Indian Monsoon circulation changes. Expedition 353 drilled six sites into key regions around the Bay of Bengal, located off the east coast of India. As low atmospheric pressure over the Indo-Asian continent, and high atmospheric pressure over the southern subtropical Indian Ocean changes, this can lead to different weather patterns that affect precipitation over South Asia, the Bay of Bengal, and southeast China. The drillship R/V JOIDES Resolution had previously undergone many drilling voyages to this region to acquire sediments from areas of monsoon impact, however Expedition 353 was the first expedition to drill sediments from the key region of the northern Bay of Bengal.
The eastern margin of India was a result of the separation of India and the Australia/Antarctica portion of the ancient supercontinent Gondwanaland during the Early Cretaceous at ~130 million years ago (Powell et al., 1988; Scotese et al., 1988). Six key drill sites were identified to target that would allow scientists to reconstruct changes in Indian monsoon circulation since the Miocene (~23 million years ago) to the present. During the 33 days of operation at sea, over 4,280 meters of sediment cores were recovered from the six sites.
Some of the main objectives of this expedition were to establish the sensitivity of changes in monsoon circulation relative to the Sun’s location and angle, heat transfer from the Southern Hemisphere, global ice volume, and greenhouse gas effects. Other objectives included determining how long Indian and East Asian monsoon winds and precipitation affected areas based on the geologic history of the area, understanding the effects of climate change and tectonics on erosion and runoff, and to provide targets for paleoclimate models.
On the northeast Indian margin, Sites U1445 and U1446 records water and salt ratios from precipitation and runoff originating from the Ganges-Brahmaputra river complex and many river basins of peninsular India (Cawthern et al., 2014; Flores et al., 2014). Site U1443 recorded salinity and temperature near the global mean. Sites U1447 and U1448 are located within the Andaman Sea, and as such these sites reveal the precipitation and runoff history from the Irrawaddy and Salween river basins. Future studies of these sediments and oceanic properties can lead to a greater understanding of how this area is affected by the Indian summer monsoon season.
In conclusion, IODP Expedition 353 helped develop an understanding of the Indian monsoon circulation changes through time. It is important to understand how these monsoonal changes have affected the area through paleo reconstructions of geologic history. This study of the subtropical Indian Ocean helped scientists understand how precipitation changes over South Asia, the Bay of Bengal, and southeast China will change in the future. Understanding what these areas have experienced throughout time during warming and cooling periods can lead us to predictions as to how the area will be affected during increased warming scenarios in the future.
Cawthern, T., Johnson, J.E., Giosan, L., Flores, J.A., Rose, K., and Solomon, E., 2014. A late Miocene–early Pliocene biogenic silica crash in the Andaman Sea and Bay of Bengal. Marine and Petroleum Geology, 58(Part A):490– 501. http://dx.doi.org/10.1016/j.marpetgeo.2014.07.026
Clemens, S.C., Kuhnt, W., and LeVay, L.J., 2014. iMonsoon: Indian monsoon rainfall in the core convective region. International Ocean Discovery Program Scientific Prospectus, 353. http://dx.doi.org/10.14379/iodp.sp.353.2014
Flores, J.A., Johnson, J.E., Mejía-Molina, A.E., Álverez, M.C., Sierro, F.J., Singh, S.D., Mahanti, S., and Giosan, L., 2014. Sedimentation rates from calcareous nannofossil and planktonic foraminifera biostratigraphy in the Andaman Sea, northern Bay of Bengal, and eastern Arabian Sea. Marine and Petroleum Geology, 58(Part A):425–437. http://dx.doi.org/10.1016/j.marpetgeo.2014.08.011
Johnson, J.E., Phillips, S.C., Torres, M.E., Piñero, E., Rose, K.K., and Giosan, L., 2014. Influence of total organic carbon deposition on the inventory of gas hydrate in the Indian continental margins. Marine and Petroleum Geology, 58(Part A):406–424. http://dx.doi.org/10.1016/j.marpetgeo.2014.08.021
Ponton, C., Giosan, L., Eglinton, T.I., Fuller, D.Q., Johnson, J.E., Kumar, P., and Collett, T.S., 2012. Holocene aridification of India. Geophysical Research Letters, 39(3):L3407. http://dx.doi.org/10.1029/2011GL050722
Powell, C.McA., Roots, S.R., and Veevers, J.J., 1988. Pre-breakup continental extension in East Gondwanaland and the early opening of the eastern Indian Ocean. Tectonophysics, 155(1–4):261–283. http://dx.doi.org/10.1016/0040-1951(88)90269-7
While the South Pole is covered by a glacier today, the South Pole was not always a frozen wasteland. Glaciation only started about 34 million years ago. As global temperatures changed throughout geologic history, the amount of ice covering Antarctica changed with it. As carbon dioxide (a greenhouse gas) amounts have increased and decreased in the atmosphere throughout history, the amount of ice has also fluctuated, so understanding ice flow through geologic time provides a picture of the impact of changing temperatures. It is particularly important to understand how anthropogenic warming has affected rapid ice melting in polar regions. Global carbon dioxide levels are increasing today in amounts not seen in the geologic past . The most recent time interval that had comparable atmospheric carbon dioxide levels occurred 17–15 million years ago, when the earth last warmed. Thus to best understand the future, it is imperative to understand the past and how Earth systems behaved or responded to increased greenhouse gasses in the atmosphere.
Integrated Ocean Drilling Program Expedition 318 focused on the Wilkes Land Ice Shelf, located on the eastern half of the Antarctic continent. The purpose of the expedition was to drill into the ice sheet to understand how much ice melt occurred, and the rate at which it occurred throughout the past 34 million years. In understanding the rate of ice melt it becomes possible to correlate carbon dioxide levels and accompanying temperature increases in the recent past with ice melt and growth. Additionally, another objective of the mission was to understand how phytoplankton (marine photosynthesizers) have changed through the Holocene (~117 thousand years ago to today). Understanding these changes can provide some insight into how biologic life has changed throughout recent geologic history, particularly in response to changes in the glacial ice.
Results from this expedition were found to be quite alarming. Scientists found that global ice amounts increase and decrease with global carbon dioxide concentrations respectively. This conclusion supported the hypothesis made by scientists that the amount of carbon dioxide in the atmosphere is tightly correlated with the amount of ice melt that is occurring into ocean waters. However, most alarmingly the rate of ice melt exceeded predictions, showing that global sea level rise may occur faster than previously expected.
Gulick, S., Shevenell, A., Montelli, A. et al. Initiation and long-term instability of the East Antarctic Ice Sheet. Nature 552, 225–229 (2017). https://doi.org/10.1038/nature25026
Expedition 318 Scientists, 2011. Expedition 318 summary. In Escutia, C., Brinkhuis, H., Klaus, A., and the Expedition 318 Scientists, Proc. IODP, 318: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.318.101.2011
The Chicxulub impact crater, located on the Yucatán Peninsula of México, is best known for being the location of a massive meteor impact causing the Cretaceous/Paleocene (K-Pg) mass extinction event. This is a major mass extinction that led to the extinction of 75% of species on Earth (Gulick et al., 2017). The site has been the subject of debate for many years surrounding the extent of the impact and the environmental fallout of the area since.
Such debates led to a need for further studies and additional information. The main goal of the International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Leg 364 was to drill sediments within the impact site to study the peak rings that formed during impact, and how the meteor impact affected the surrounding area. Other expedition objectives included the nature and extent of post-impact hydrothermal circulation, the recovery of life in a sterile zone, and recovery of sediments through the Paleocene/Eocene Thermal Maximum (PETM; Gulick et al., 2017), an event that took place approximately 55 million years ago and was characterized by the Earth heating up by 5–8°C.
In 2016 the Vessel L/B Myrtle began its voyage for the Yucatán continental shelf. A single borehole (Hole M0077A) was drilled into the Chicxulub impact crater and 828.99 meters of cored sediments and rock was recovered from below the seafloor. The recovered sediments and rocks allowed scientists to achieve many of the scientific goals that were established for this expedition.
One of the main goals of the expedition, to core sediments from the peak ring, was successful. Peak rings were formed during the large impact on the Earth’s surface causing the underlying rocks to fracture and overturn onto the impact site. The recovered rocks and sediments allowed scientists to determine that the peak ring is formed from uplifted, shocked, and fractured granitic rocks that overlie older sedimentary rocks. This supported the hypothesis made by Morgan et al. (2016), stating that the dynamic collapse model for peak-ring formation is accurate, and also supported the hypothesis that the rocks are highly porous and fractured from the impact (Gulick et al., 2013). Shipboard studies of microfossils recovered from the sediments indicated that the PETM interval is present in the core sediments, which will allow for the sediments to be studied in greater detail.
Another objective of the expedition was to understand the hydrothermal system surrounding impacts on Earth. Many scientists hypothesize that microbial life starts on Earth at impact sites. Scientists wanted to study this area for signs of early microbial life. Directly after impact Chicxulub was considered to be a sterile zone, as the impact was so sudden, the area around the impact became super heated and all life in the region was instantly wiped out. Scientists have recently found evidence that cyanobacteria may have bloomed a few months after impact (Schaefer et al., 2020). Small trace fossils and other forms of microbes are believed to have come back within a year after the impact.
In conclusion, this drilling expedition is considered to be a great success. Many of the predetermined objectives for the expedition were completed, and lots of other promising data was collected for future studies. Drilling into the impact point of the meteor that caused the Cretaceous/Paleocene (K-Pg) mass extinction was a monumental finding for scientists all over the world. This expedition gave scientists evidence for the formation of peak rings, and allowed for the unique study of how life recovers from such an event.
Collins, G.S., Melosh, H.J., Morgan, J.V., and Warner, M.R., 2002. Hydrocode simulations of Chicxulub crater collapse and peak-ring formation. Icarus, 157(1):24–33. https://doi.org/10.1006/icar.2002.6822
Gulick, S. P., Morgan, J. V., Mellett, C. L., Green, S. L., & Kring, D. A. (2017). Expedition 364 summary. International Ocean Discovery Program.
Gulick, S. P. S., Christeson, G. L., Barton, P. J., Grieve, R. A. F., Morgan, J. V., & Urrutia‐Fucugauchi, J. (2013). Geophysical characterization of the Chicxulub impact crater. Reviews of Geophysics, 51(1), 31-52.
The Strait of Gibraltar is a significant gateway that currently connects the Atlantic Ocean to the Mediterranean Sea. From November 2011 to January 2012, the Integrated Ocean Drilling Program (IODP) Expedition 339 science team drilled a total of seven sites, consisting of five sites in the Gulf of Cadiz (GC) and two sites off the West Iberian margin (Table 1 & Figure 1). The major objective of this drilling expedition was to study what happened when the Strait of Gibraltar opened about 5 million years ago, causing warm and salty water to flow into the North Atlantic Ocean. Scientists chose to drill in this region because it is an important spot to study the movement of Mediterranean Outflow Water (MOW) through the Strait of Gibraltar and how it affects the world’s ocean currents and weather patterns. It is also an area of interest for understanding the effects of tectonic activity on the evolution of the Strait of Gibraltar and how sediments collect around the continents. Climate plays a huge role in influencing the changes in the MOW and ocean currents over time. From about 6 million years ago, when the connections between the Atlantic Ocean and the Mediterranean Sea in Spain and Morocco closed off, to 5.3 million years ago when the Strait of Gibraltar opened back up, the way the Earth’s tectonic plates moved had an even bigger impact on how sediment built up and how the ocean currents changed.
Some of the Expedition 339 crew members had the opportunity to watch the International Space Station (ISS) pass overhead on the night of Dec 4th, 2011, even though it appeared as a tiny moving dot in the sky. As reported by Helder Pereira, while drilling at Site U1386, the Joides Resolution (JR) research vessel was spotted by the ISS as it was orbiting the Earth! Interestingly, while they were watching, the ISS was also observing them and took a beautiful picture of the Iberian Peninsula. Can you spot the JR inside the orange circle located a few miles southeast of Faro (Algarve, Portugal) in the lower bottom right of Figure 3?
Expedition 339 had five broad scientific objectives, which are summarized below:
Understand the opening of the Strait of Gibraltar gateway and when the Mediterranean Outflow Water (MOW) began. Many scientists have different hypotheses on how the Strait of Gibraltar opened around 5 million years ago. Some believe it was due to tectonic changes, while others think it was caused by erosion of the land. The reopening ended the isolation of the Mediterranean Sea and the global effects of the Messinian Salinity Crisis (this was a time in which the Mediterranean Sea was isolated from the Atlantic Ocean, and drying up of the sea left behind major salt deposits and highly saline waters). It took some time for the deep MOW to flow out, and the exact timing of such outflow is relatively unknown. The first objective of Expedition 339 was to drill through sediment layers on the seafloor to determine the age of those sediments in the Gulf of Cádiz. Scientists also wanted to examine changes in contourite deposits, or sediment deposits that happen offshore, and MOW bottom water changes (temperature, salinity) during the geologic period from the end of the Miocene Period (~5 million years ago) to the early to middle Pliocene Period (~3 million years ago).
Determine the ancient circulation pattern of MOW and how such different circulation changes might affect global climate: Today, warm and salty (more than 300,000 tons of excess salt) water flows into the North Atlantic from the Mediterranean Sea through the Strait of Gibraltar gateway every second! A density increase in North Atlantic Deep Water could affect the ocean’s thermohaline circulation (circulation of deep waters driven by density differences in those waters) and could have implications for climate change. To better understand these processes, researchers are actively studying the millennial to long-term changes of Mediterranean outflow and its effects on thermohaline circulation. The second objective was to date the unconformities (where there is missing time in the sedimentary record) and discontinuities identified on seismic records. Such identification can help to assess the sedimentary record’s link to past circulation variation and events and understand the forces driving bottom water circulation changes over different timescales.
Establish a marine reference section of Pleistocene (2.58–0.017 million years ago) climate (rapid climate change): This objective intersects with the principal objective of Site U1385 [APL-763] which was to drill into the Iberian margin, offshore Portugal to recover a sediment record that could be studied to infer Pleistocene climate changes. In turn, this sediment record can be correlated with polar ice cores and terrestrial sediments and other climate records to better understand climate change during the past ~2.58 million years.
Identify external controls on the sediments from the Gulf of Cádiz contourites and West Iberian margin: The fourth objective of this expedition was to study how sea level change and the size of the Strait of Gibraltar impacted sediment deposits in the Gulf of Cádiz and the West Iberian margin. This will help to distinguish between regional changes caused by climate and sea level, and to develop a better understanding of the sediments and under what conditions they were deposited in the area. The researchers plan to drill and analyze sediment cores, date them, and correlate them to create a pattern of the sediments and the hiatuses, or times of no sediment deposition, between them. They also want to evaluate how the Mediterranean Outflow Water flux and how global sea level changes affected the Gibraltar sill, as well as the circulation of the North Atlantic. By analyzing the composition of sediments and how fast they accumulated through time, scientists hope to better understand the sediment supply and flux for the sediment deposits in the gulf.
Investigate the tectonic activity in the region, and how it controlled the deposition of sediments in the region: This objective relates to using the sediments that were drilled to infer the age of tectonic events and the changes that resulted from this events in the Gulf of Cadiz and Iberian margin. The scientists also wanted to investigate diapirs, or the movement of low-density rocks such as salts, into older, more dense rocks.
The expedition successfully met all five of the scientific objectives, and recovered about 5447 meters (3.38 miles!) of cores. The region was drilled for the first time for scientific purposes and the results confirmed some pre-expedition hypotheses and also provided new information and ideas not initially anticipated. For instance, the scientists discovered a larger-than-anticipated petroleum system with huge hydrocarbon potential, presenting a new and significant opportunity to explore oil and gas reserves in the region!
Results from Expedition 339 opened the door for even more post-expedition research. Some studies focused on the reconstruction of the Mediterranean-Atlantic water exchange after the opening of the Gibraltar Strait 5.3 million years ago to understand the behavior of the Mediterranean Outflow Water during this period (Bahr et al., 2014) and to study the past ocean conditions (García-Gallardo et al., 2017). Studies published using the recovered sediments observed that MOW varied in strength and location during different historical periods, and that MOW resembles water from the Levantine Basin in the Eastern Mediterranean (Kaboth et al., 2016). A new detailed record from 416,000 years ago reveals that changes in MOW strength and depth during the Late Pleistocene age (~0.12–0.017 million years ago) were caused by the climate; the main factor controlling these changes being the rainfall pattern around the Mediterranean region (Nichols et al., 2020). Also, pollen and biomarker data from Site U1385 (Figure 1) was used to study the unique climate during Marine Isotope Stage (MIS) 13, a period around 533,000 to 478,000 years ago, when the climate was cool and humid, resulting in forest expansion in the Iberian Peninsula (Oliveira et al., 2022).
Bahr, A., Jiménez-Espejo, F.J., Kolasinac, N., Grunert, P., Hernández-Molina, F.J., Röhl, U., Voelker, A.H.L., Escutia, C., Stow, D.A.V., Hodell, D., and Alvarez-Zarikian, C.A., 2014. Deciphering bottom current velocity and paleoclimate signals from contourite deposits in the Gulf of Cádiz during the last 140 kyr: an inorganic geochemical approach. Geochemistry, Geophysics, Geosystems, 15(8):3145–3160. https://doi.org/10.1002/2014GC005356
García-Gallardo, Á., Grunert, P., Van der Schee, M., Sierro, F.J., Jiménez-Espejo, F.J., Alvarez Zarikian, C.A., and Piller, W.E., 2017. Benthic foraminifera-based reconstruction of the first Mediterranean-Atlantic exchange in the early Pliocene Gulf of Cadiz. Palaeogeography, Palaeoclimatology, Palaeoecology, 472:93–107. https://doi.org/10.1016/j.palaeo.2017.02.009
Kaboth, S., Bahr, A., Reichart, G.-J., Jacobs, B., and Lourens, L.J., 2016. New insights into upper MOW variability over the last 150 kyr from IODP 339 Site U1386 in the Gulf of Cadiz. Marine Geology, 377:136–145. https://doi.org/10.1016/j.margeo.2015.08.014
Nichols, M.D., Xuan, C., Crowhurst, S., Hodell, D.A., Richter, C., Acton, G.D., and Wilson, P.A., 2020. Climate-induced variability in Mediterranean Outflow to the North Atlantic Ocean during the late Pleistocene. Paleoceanography and Paleoclimatology, 35(9):e2020PA003947. https://doi.org/10.1029/2020PA003947
Oliveira, D., Desprat, S., Yin, Q., Rodrigues, T., Naughton, F., Trigo, R.M., Su, Q., Grimalt, J.O., Alonso-Garcia, M., Voelker, A.H.L., Abrantes, F., and Sánchez Goñi, M.F., 2020. Combination of insolation and ice-sheet forcing drive enhanced humidity in northern subtropical regions during MIS 13. Quaternary Science Reviews, 247:106573. https://doi.org/10.1016/j.quascirev.2020.106573
Expedition 374 took place from 4 January to 8 March 2018, during which five sites were drilled in the eastern Ross Sea of Antarctica, ranging from the outer continental shelf to the continental slope and rise (Fig. 1). Three sites (U1521, U1522, and U1523) were on the continental shelf, while U1524 and U1525 were from the continental rise and slope, respectively (Fig. 1).
The study of western Antarctica and the Ross Sea region is crucial because computer models have shown this area is highly sensitive to changes in ocean temperature and sea level. The West Antarctic Ice Sheet (WAIS) contains a vast amount of ice, and its complete melting could result in a 4.3 meter rise in global sea level (Patterson et al., 2012). Therefore, by understanding how the ice sheet in this region has changed in the past, researchers can predict how it may change in the future under different climate conditions, which can better prepare societies for the inevitable future (McKay et al., 2019).
The primary objective of Expedition 374 was to comprehend how the evolution of the WAIS during the Neogene (23–2.58 million years ago) and Quaternary (2.58 million years ago to Recent) geologic periods relates to changes in climate and oceanic conditions. Scientists wanted to determine the contribution of West Antarctica to overall ice volume and sea level rise, comprehend past polar temperature changes and causes of such changes in temperatures, understand the effect of changes in ocean temperature and sea level on the stability of the Antarctic Ice Sheet, determine how the Earth’s position in its orbit influences the stability of the Antarctic Ice Sheet under different climate conditions, and analyze the relationship between seafloor geometry in the eastern Ross Sea and the stability of the ice sheet and global climate.
Despite challenges such as drifting sea ice and mechanical vessel failure during drilling at Site U1524, the team managed to retrieve significant recoveries. Although about 39% of operational days at sea were lost, making it challenging to achieve all the proposed goals of Expedition 374. Regardless, the recovered samples can still be effectively compared with those from other sites, such as U1522, U1525, and sites from similar projects like the Antarctic Geological Drilling Project (ANDRILL). The goal is to create a continental shelf to rise transect of the Pliocene (5.33–2.58 million years ago) to the Pleistocene (2.58–0.017 million years ago) periods, which is an essential component of the expedition’s overall objectives.
During Expedition 374, 1292.70 meters of cores were recovered from five drill sites spanning the early Miocene (~15 million years ago) to late Quaternary (Recent). The sediments in the Ross Sea near Antarctica were studied by several scientists to gain insights into the history of the West Antarctic Ice Sheet (WAIS). A study by King et al., (2022) focused on how ice and ocean currents interacted during past ice ages (about 2.4 million years ago) to estimate the future extent of the ice sheets and help improve future models of the ice sheet. The study also fostered an understanding of how the ice sheet formed and grew under different oceanographic conditions. Also, findings from Expedition 374 inspired a new WAIS drilling project that will predict how the ice sheet will respond to future global warming scenarios, including how melting of the ice could contribute to sea-level rise, based on how the ice sheet responded to warming scenarios in the geologic past (Patterson et al., 2012).
In 2022, a study by Lelieveld analyzed sediments from Expedition 374 to investigate how the Antarctic Ice Sheets impacted sea level variations and vegetation changes during the Miocene Period (23–5.33 million years ago) in the Ross Sea. The Miocene Period is a time when atmospheric carbon dioxide levels were much higher than today, and reached levels projected for the coming decades. As such, the Miocene Period is a good geologic analogue for how Earth systems behave and change under increased greenhouse gasses and increased warming. The study found that despite the climate being conducive to higher-order plants, the region’s vegetation was dominated by shrubs and tundra due to the reduced land available for plant growth caused by erosion resulting from glacial advances of the West and East Antarctic Ice Sheets. Another study presented geological evidence of large WAIS expansions from sediment samples obtained during Expedition 374 (Marschalek et al., 2021). The findings from Marschalek et al. (2021) supported the hypothesis that during the intensely warm Miocene Period , East Antarctica experienced significant ice loss, which contradicted the view of other scientists who suggested that the ice in East Antarctica mostly remained intact during this period of time.
Expedition 374 also contributed to providing valuable information on the history of a volcano! A study by Di Roberto et al., (2021) examined a layer of volcanic ash, known as tephra, found in marine sediments in Antarctica’s Ross Sea (Figure 2). The tephra was estimated to be around 1.3 million years old and matched a deposit discovered at Chang Peak volcano, located 1,300 km away from the study site. This discovery adds a new reference point for dating and correlating early Pleistocene records in West Antarctica.
Di Roberto, A., Scateni, B., Di Vincenzo, G., Petrelli, M., Fisauli, G., Barker, S.J., Del Carlo, P., Colleoni, F., Kulhanek, D.K., McKay, R., De Santis, L., and the IODP Expedition 374 Scientific Party, 2021. Tephrochronology and provenance of an early Pleistocene (Calabrian) tephra from IODP Expedition 374 Site U1524, Ross Sea (Antarctica). Geochemistry, Geophysics, Geosystems, 22(8):e2021GC009739. https://doi.org/10.1029/2021GC009739
King, M.V., Gales, J.A., Laberg, J.S., McKay, R.M., De Santis, L., Kulhanek, D.K., Hosegood, P.J., and Morris, A., 2022. Pleistocene depositional environments and links to cryosphere-ocean interactions on the eastern Ross Sea continental slope, Antarctica (IODP Hole U1525A). Marine Geology, 443:106674. https://doi.org/10.1016/j.margeo.2021.106674
Ocean Drilling Program Leg 113: Weddell Sea, Antarctica
Ocean Drilling Program (ODP)Leg 113 drilled sites in the Weddell Sea, which is surrounded on nearly three sides by Antarctica. Some of the sites were drilled from Maud Rise, which is an underwater plateau, representing an area that stands above the deeper seafloor crust which surrounds it. Maud Rise was formed as part of a large igneous province (LIP), which is a large extrusion of lava that erupted (non-violently) in the ocean or on land. Maud Rise was formed approximately 140 to 122 million years ago, in the Cretaceous Period.
ODP Leg 113 had several objectives. The first was to determine when Antarctic ice sheets first began to form, and if they had been permanent since their formation. The second objective was to monitor the development of Antarctic Bottom Water, a very cold and very dense water mass that flows along the bottom of the ocean floor, and forms near Antarctica. Using sediments recovered from Leg 113, scientists also wanted to determine how this very cold water mass responded to ancient warming and cooling events through time. The third and fourth objectives were related to marine organisms that live in the waters surrounding Antarctica, in the Weddell Sea. How did they live in such cold conditions, and did different species respond to such warming and cooling events through time? These objectives, in part, were addressed by drilling a transect of sites across the Weddell Sea, in shallower to progressively deeper waters, to obtain sediments from shallow- to deep-water masses.
Leg 113 recovered sediments that dated back to the Cretaceous, the time the dinosaurs were alive. Several sedimentary sections were recovered that contained the end-Cretaceous Mass Extinction that occurred 66 million years ago, the extinction event that led to the demise of non-avian dinosaurs. The sediments were used to determine the history of Antarctica through the entire Cenozoic, or the last 66 million years of Earth’s history. The earliest Cenozoic sediments from the Weddell Sea indicate that the region was warm and semi-arid (Barker et al., 1988). Within the Oligocene (~25 million years ago), the sediments were used to determine the approximate size of the Antarctic ice sheet that formed during this time, and was relatively stable (Escutia et al., 2019). Around the Middle Miocene (~15 million years ago), another expansion of Antarctic ice was found to occur (Barker et al., 1988).
Leg 113 was the first expedition to recover sediments from the Paleocene-Eocene Thermal Maximum (PETM), which was a short-lived but intense warming event that occurred around 55.5 million years ago. The PETM section recovered from Site 690 is one of the most expanded sections of the PETM ever to be drilled (Röhl et al., 2007), and as such, it is the site that is most intensively studied for this event. The PETM lasted only about 20,000–50,000 years, but within this short time frame, the Earth warmed by 5–8°C. The PETM is often studied as an analogue for future climate change, as warming happened rapidly during this event.
Most of the sediments drilled from the Weddell Sea contained microfossils, tiny fossils that can only be seen with the help of microscopes. Using these microfossils from Antarctic sediments, paleontologists were able to determine when different species of microorganisms evolved and went extinct (e.g., Harwood & Gersonde, 1990; Leckie, 1990; Funakawa & Nishi, 2005), and in turn use different species to help reconstruct the ancient environments around Antarctica.
Barker, P. F., Kennett, J. P., O’Connell, S., Berkowitz, S., Bryant, W. R., Burckle, L. H., … & Wise, S. W. (1988). Proceedings of the Ocean Drilling Program, Initial Reports, Vol. 113. Weddell Sea, Antarctica. Covering Leg 113 of the cruises of the drilling vessel JOIDES Resolution, Valparaiso, Chile, to East Cove, Falkland Islands, Sites 689-697, 25 December 1986-11 March 1987. Ocean Drilling Program.
Escutia, C., DeConto, R. M., Dunbar, R., Santis, L. D., Shevenell, A., & Naish, T. (2019). Keeping an eye on Antarctic Ice Sheet stability. Oceanography, 32(1), 32-46.
Funakawa, S., & Nishi, H. (2005). Late middle Eocene to late Oligocene radiolarian biostratigraphy in the Southern Ocean (maud rise, ODP Leg 113, site 689). Marine Micropaleontology, 54(3-4), 213-247.
Harwood, D. M., & Gersonde, R. (1990). 26. LOWER CRETACEOUS DIATOMS FROM ODP LEG 113 SITE 693 (WEDDELL SEA). PART 2: RESTING SPORES, CHRYSOPHYCEAN CYSTS, AN ENDOSKELETAL DINOFLAGELLATE, AND NOTES ON THE ORIGIN OF DIATOMS1. In Proceedings of the Ocean Drilling Program, scientific results (Vol. 113, pp. 403-425).
Leckie, M. R. (1990). Middle Cretaceous planktonic foraminifers of the Antarctic margin: hole 693A, ODP LEG 1131. In Proceedings of the Ocean Drilling Program, Scientific Results (Vol. 113, pp. 319-324).
Röhl, U., Westerhold, T., Bralower, T. J., & Zachos, J. C. (2007). On the duration of the Paleocene‐Eocene thermal maximum (PETM). Geochemistry, Geophysics, Geosystems, 8(12).
Ocean Drilling Program Leg 130: Ontong Java Plateau
Ontong Java Plateau (OJP) is an oceanic plateau or region of elevated ocean crust that rises up higher than the surrounding ocean crust. The OJP was formed around 120 million years ago during the Cretaceous Period, and when it was first formed from volcanic processes, mainly the eruption of basalt (a volcanic rock) on the seafloor. Today, the OJP remains the largest oceanic plateau on Earth.
The main objective of Ocean Drilling Program (ODP) Leg 130 was to drill a series of sediment cores from atop OJP, with the recovery of sediments aged from the late Cretaceous Period to the Recent. As OJP is a shallower-water region, shells of marine plankton, which are single-celled organisms, collect in great quantities in warm, shallow-water regions. Using properties of the sediments, the fossils themselves, and the chemical signatures from the shells of fossil plankton through time, scientists aimed to reconstruct the ancient climate in this region through time using the sediments recovered from OJP. The secondary objective of Leg 130 was to drill into the seafloor basalts on OJP to better understand the origin and development of the oceanic plateau.
Leg 130 drilled a total of 5889 meters (3.65 miles!) of sediment and basalt, which amounted to a total of 639 cores. The recovered sediments were full of microfossils – tiny fossils that can only be viewed with the help of a microscope. Using these fossil-laden sediments, scientists were able to conduct studies related to evolution of marine plankton, and use the chemistry of fossil tests (shells), along with other properties of the sediments, to reconstruct ancient climate conditions.
Some studies focused on how evolution of marine plankton occurs at sea (Hull & Norris, 2009) and when certain species evolved and went extinct from 23 million years ago to the Recent (Chaisson & Leckie, 1993). Scientists were also able to reconstruct atmospheric carbon dioxide (CO2; a greenhouse gas) levels for the past 20 million years of Earth’s history (Tripati et al., 2009, 2011). The early Pliocene (4.5–3.0 million years ago) was a time in Earth’s history when CO2 was at or near present-day conditions, and as such this time period is useful to investigate Earth systems processes and how they behave under elevated greenhouse gas concentrations. Across this time interval, scientists used chemical methods from Leg 130 cores to reconstruct of western equatorial Pacific sea surface temperatures (Wara et al., 2005). The sea surface temperature data from Leg 130 sites was compared with sea surface temperatures from eastern equatorial Pacific sites. Scientists found that during the early Pliocene, the equatorial Pacific Ocean had a reduced east to west temperature gradient, which resembles El Niño states today. Reconstruction of atmospheric circulation patterns from Leg 130 sediments indicated atmospheric circulation and wind patterns began to resemble modern-day patterns around 900,000 years ago (McClymont & Rosell-Melé, 2005).
Chaisson, W.P., and Leckie, R.M., 1993. High-resolution Neogene planktonic foraminifer biostratigraphy of Site 806, Ontong Java Plateau (western equatorial Pacific). In Berger, W.H., Kroenke, L.W., Mayer, L.A., et al., Proc. ODP, Sci. Results, 130: College Station, TX (Ocean Drilling Program), 137–178. doi:10.2973/odp.proc.sr.130.010.1993
Hull, P.M., and Norris, R.D., 2009. Evidence for abrupt speciation in a classic case of gradual evolution. Proc. Natl. Acad. Sci. U. S. A., 106(50):21224–21229. doi:10.1073/pnas.0902887106
McClymont, E.L., and Rosell-Melé, A., 2005. Links between the onset of modern Walker circulation and the mid-Pleistocene climate transition. Geology, 33(5):389–392. doi:10.1130/G21292.1
Tripati, A.K., Roberts, C.D., and Eagle, R.A., 2009. Coupling of CO2 and ice sheet stability over major climate transitions of the last 20 million years. Science, 326(5958):1394–1397. doi:10.1126/science.1178296
Tripati, A.K., Roberts, C.D., Eagle, R.A., and Li, G., 2011. A 20 million year record of planktic foraminiferal B/Ca ratios: systematics and uncertainties in pCO2 reconstructions. Geochim. Cosmochim. Acta, 75(10):2582–2610. doi:10.1016/j.gca.2011.01.018
Wara, M. W., Ravelo, A. C., & Delaney, M. L. (2005). Permanent El Niño-like conditions during the Pliocene warm period. Science, 309(5735), 758-761.
Hi! My name is Charlotte and I am currently a graduate student from Long Island, NY pursuing an accelerated masters degree in biology at Binghamton University in NY. I am also a recent graduate and earned my bachelors in biology in May of 2022 at Binghamton. I love exercising and being active and some of my favorite activities are taking spin classes, practicing yoga, and I recently got into hiking over the summer. When I’m not in the lab I also enjoy going to museums, listening to music, spending time with my friends and family, and going to the beach and swimming in the ocean.
What kind of scientist are you, and what do you do?
The research that I am currently doing as a graduate student for my master’s thesis project is to reconstruct future climate warming scenarios using past climates. I use stable isotopic data from two species of thermocline-dwelling planktic foraminifera found in deep ocean sediments that date back to ~3-3.35 million years ago during the Pliocene era. More specifically I am trying to reconstruct ocean behavior in the Kuroshio Current Extension (KCE) off of the coast of Japan during the mid-Piacenzian Warm Period (mPWP) which is often regarded as an analogue to future climate warming scenarios. The calcium carbonate shells of foraminifera can be used as a proxy to reconstruct past climates because they collect the chemical signature of the water around them through isotopes of carbon and oxygen. From this data I am able to understand ocean characteristics such as salinity, temperature, and water productivity from over millions of years ago. Climate change is an incredibly important topic that I am extremely passionate about and using the past as a tool to understand the future can be one method to understand how to solve the problem.
What is your favorite part about being a scientist, and how did you get interested in science?
I honestly came into my first year of undergrad as an undeclared major. In high school I never excelled in science or math and never thought I could make it through undergrad majoring in science because of this. This however, changed when I felt more confident in myself as a scientist after joining Binghamton’s First Year Research Immersion program in the biogeochemistry research stream where I worked in a group on a geology based project reconstructing the environmental conditions of the oldest known forest located in Cairo, NY. I was so lucky to be supported by an incredible mentor and a great group of peers that made me feel more comfortable about majoring in science. My first few years of undergrad were tough but I was able to get through it and get exactly where I needed to be. From that experience I was able to meet my current mentor and current research advisor Dr. Adriane Lam who I’ve been so grateful to be working with since 2020. My current research interests include paleoclimatology, paleoceanography, and anything related to foraminifera. After my masters graduation next May I hope to enter the industry working on corporate sustainability projects. Last summer I interned at Pfizer with the Global Environmental Health and Safety Group and I worked on some projects regulating the company’s environmental impacts. My research background has made me more passionate about climate change and I really want to make a difference in the corporate industry one day. My favorite part about being a scientist is definitely working with other amazing and bright scientists and I have met so many inspiring mentors, labmates, classmates, and lifelong friends.
What advice do you have for up and coming scientists?
There are so many things I wish I knew but my biggest piece of advice is to not get discouraged. Being a scientist can be extremely difficult but it is also extremely rewarding at the same time. Try not to compare yourself to others because everyone is on a different path and do not give in to imposter syndrome. Nobody truly ever has it figured out but if you work hard and do your best you will end up exactly where you need to be. I also think it is important to take every opportunity as an opportunity to grow and never to be afraid to ask others for help and advice.
Hello! My name is Ella Halbert (she/her/hers) and I’m from Nashville, Tennessee. I am a fourth year Biology and Hispanic Studies major at Oberlin College in Oberlin, OH. I’m interested in disease ecology, epidemiology, and human health. Outside of academics, I love doing anything outdoors, particularly playing sand volleyball and going on hikes. I also sing in an a cappella group and am part of a traditional Japanese Taiko drumming group.
My favorite part about being a scientist is getting to explore questions that interest me. I’m a very hands-on learner, so research has been a great way for me to learn about the world. My most recent research began in the summer of 2022 with a National Science Foundation funded Research Experience for Undergraduates (REU) at Mountain Lake Biological Station (MLBS) in Pembroke, VA. I was drawn to Dr. Chloé Lahondère’s work with mosquito thermal biology and interactions with plants and herpetofauna because of the wide possibility for projects. I joined a project that examines the interaction between Culex territans, a mosquito species present throughout the Northern Hemisphere, and its amphibian hosts. That’s right, this mosquito species feeds exclusively on amphibians (and the occasional reptile), and it couldn’t care less about humans!
More specifically, I studied the interactions between Cx. territans mosquitoes and their frog hosts to determine what diseases they vector in that environment. So far, my work has focused on their potential as vectors of the Batrachochytrium dendrobatidis (Bd) fungus, which causes chytridiomycosis, a deadly disease, in amphibians. The chytrid fungus is responsible for the decline of amphibian populations around the globe, so understanding how this disease is spread in the environment is critical. There is evidence that suggests that when a Cx. territans mosquito lands on a frog, it has the capability to pick up Bd spores and transfer them to its next host. By swabbing the frog population and testing the mosquito population in the same habitat, I was able to compare rates of Bd infection among species and get a better picture of how Bd is spreading in that habitat.
I’ve always loved science, even before I knew what it was. When I was in elementary school, I wanted to know everything there was to know about dinosaurs, and I was curious about why we lost those species 65 million years ago. I loved bugs, and asked for Eyewitness books for my birthday. Over the years, as I was formally introduced to science, I developed a strong desire to know more and to discover how the natural world works.
In high school, I participated in a program called the School for Science and Math at Vanderbilt (SSMV). One day each week, instead of attending my high school courses, I attended lectures and participated in hands-on science projects with my cohort at Vanderbilt University. This four-year long experience opened my eyes to the stunning variety that exists within STEM, and through this program I participated in several summer sessions that emphasized research. The SSMV solidified my interest in science and gave me a platform to engage with subjects that had fascinated me for so long.
I matriculated into Oberlin College in 2019 and declared my Biology major, eager to continue my exploration of the natural world. In the summer of 2021, I joined Professor Mary Garvin’s research lab at Oberlin. I investigated the role of nest mites in overwintering Eastern Equine Encephalitis Virus in Northeast Ohio. With the team, I worked to elucidate the mechanism that allows this disease to persist through the cold, harsh winters of Ohio using DNA and RNA extraction techniques. This experience made me more curious about how ecology and diseases interact and steered my interests towards a summer research internship in the summer of 2022.
My current research is part of an ongoing project at MLBS that seeks to understand how Culex territans, a mosquito species that feeds on cold-blooded hosts, locates and interacts with its hosts. This mosquito’s preference for cold-blooded hosts is intriguing and poorly understood, and by learning how Cx. territans interacts with its hosts, we can provide insight into how mosquito host-seeking behavior evolved. This will ultimately inform current-day disease control strategies regarding mosquito-borne pathogens.
My advice for up and coming scientists is to seek out mentors! Having an experienced scientist in your corner makes a world of difference, and the best research experiences I’ve had were all facilitated by incredible mentors who really took the time to teach me what they knew. The strong interpersonal connections I’ve made in science are what keep me going when an experiment fails or I lose a bunch of data, both of which are annoyingly common occurrences in science! So my best advice is to find people who will support you on the best and worst days of your journey in research!