Progress and Priorities in Ocean Drilling: In Search of Earth's Past and Future (2024)

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1 Introduction This chapter sets the stage for the report by first discussing the importance of scientific ocean drilling in understanding Earth system science and how Earth has evolved over time and behaved during past climate perturbations. The chapter describes the current state of the U.S. scientific ocean drilling program including recent science planning activities to chart out the path forward for the program which provides a segue into the context and rationale behind conducting this study. The chapter ends with a description of the study process and then walks the reader through the report structure. THE IMPORTANCE OF SCIENTIFIC OCEAN DRILLING Astronomers use space telescopes to investigate deep space and look back in time to better understand the nature of galaxies and how they change. Similarly, ocean scientists use vessels equipped with specialized drilling and sampling devices to collect sediment, rocks, and other materials and to leave behind observatories hundreds of meters beneath the seafloor. The data collected using these materials and observatories reveal how Earth, its climate, environment, and life are linked through interconnected processes that operate over a range of temporal and spatial scales. Scientific ocean drilling has enabled critical data, analysis, and insight on how Earth’s oceans, atmosphere, and climate have evolved from hundreds of millions of years ago to the last century, and on regional to global spatial scales. It has led to the innovation of technological tools and analytical methods and the cultivation of a highly skilled scientific and engineering workforce that addresses societally relevant Earth system challenges through research, exploration, graduate and undergraduate education, and training. Over its 56-year history, scientific ocean drilling has brought together a global community of scientists and scholars toward these goals. In so doing, the program has facilitated partnerships among the United States and other nations and established U.S. leadership in ocean exploration and research. Cores drilled from the subseafloor offer a record that extends into Earth’s history three orders of magnitude deeper than do ice cores. Undisturbed by erosion or human development, subseafloor records are gleaned from carefully selected locations, as deep as 1,800 m below the seafloor. These cores are unique and highly valued archives of Earth’s history. The chemical, physical, biological, and geological properties of collected samples have improved understanding of key episodes and tipping points in Earth’s history, such as abrupt warming events—including rates of onset and recovery—and causes of and connections to perturbations in the global carbon cycle, ocean circulation, and sea level, as well as the collapse of ice sheets. These subseafloor samples also reveal the past health and habitability of the ocean, providing insight into periods of widespread ocean acidification, deoxygenation, and fluctuations in nutrient availability, which affect the stability and composition of marine ecosystems. Data on these recorded changes, preserved in subseafloor sediment, are input into predictive Earth models, helping researchers understand how the climate and ocean could change in the future. The subseafloor sedimentary layers and basement rock also provide other unique and valuable information. Instrumented monitoring systems, installed in subseafloor drilling locations where tectonic plates meet, offer valuable opportunities to understand time-dependent natural geohazards, such as earthquakes, tsunamis, and volcanic eruptions. Such monitoring systems can provide unique and timely data (if conveyed in real time) on the mechanisms that control the recurrence, timing, and possible precursors of these geohazards. Moreover, the subseafloor sediment and ocean crust are reservoirs of energy and matter; they are also home to a complex, active, globally spanning ecosystem of microbial life that is only beginning to be explored and understood. Studying the limits and adaptations of life in this deep biosphere may be the best opportunity to understand the possibility of life on other planets, as well as to unlock the potential discovery of novel biological molecules for use in biotechnology and biomedical applications. Prepublication Copy 12 

Introduction These areas of research rely on a well-established scientific ocean drilling domain. Led by the United States, with a history that extends back to 1958, scientific ocean drilling has evolved through different program phases and international collaborations (Figure 1.1). Partnerships forged through scientific ocean drilling activities serve as a model for interpersonal and multinational cooperation. The subseafloor data and materials recovered from past scientific ocean drilling expeditions provide opportunities for scientists around the world to obtain samples and ask new and exciting questions, and for educators to train and mentor the next generation of the science, technology, engineering, and mathematics (STEM) workforce, in order to address existing challenges that lie at the intersection of the Earth’s systems and human society (Box 1.1). FIGURE 1.1 The long history of scientific ocean drilling. NOTES: The United States and its flagship vessel, the JOIDES Resolution, have been the primary drilling platform from the beginning of the Ocean Drilling Program phase. During the Integrated Ocean Drilling Program (IODP-1) and the International Ocean Discovery Program (IODP-2) phases, capabilities expanded by adding international partners operating additional platforms. The current phase of the scientific ocean drilling program is shaded in blue. Cover images of the science plan for the current program phase and a plan guiding future scientific ocean drilling are included. SOURCE: Modified from Gilbert Camoin, ECORD Managing Agency. A CRITICAL JUNCTURE The need to obtain vital records from the subseafloor in carefully selected locations is ongoing and urgent. Scientific ocean drilling is now at a time of consequential transition, which is a result of a confluence of three main factors: 1. The current phase of the drilling program, the International Ocean Discovery Program (IODP-2), ends in 2024. 2. The only dedicated (long-term lease), versatile globally ranging vessel for IODP-2, the aging (45-year-old) research vessel JOIDES Resolution will be out of compliance with modern Prepublication Copy 13 

Progress and Priorities in Ocean Drilling: In Search of Earth’s Past and Present maritime environmental and safety requirements in 2028. JOIDES Resolution1 is the “workhorse” of international scientific ocean drilling (Table 1.1) and is operated by the United States. 3. The contributed funding from international partners for the operation of JOIDES Resolution has decreased over time, making a sustainable budget model challenging. This is a chronic problem, as noted in a previous report by the National Academies of Sciences, Engineering, and Medicine, Sea Change: 2015-2025 Decadal Survey of Ocean Sciences (NRC, 2015), and is unlikely to be reversed. These factors contributed to the decision by the National Science Foundation (NSF)2 to end the cooperative agreement with Texas A&M University for JOIDES Resolution operations. While no scientific drilling with JOIDES Resolution will be supported, NSF has pledged to support some aspects of drilling-related science until 2028, such as the Gulf Coast Core Repository and data storage, and the necessary management of post-expedition science activities (e.g., publications of expedition reports) through the last IODP-2 expedition (scheduled for 2024). BOX 1.1 Connecting Scientific Ocean Drilling to Other Fields The research enabled by scientific ocean drilling is highly cross-disciplinary and, by design, is often intended to address questions in a wide range of disciplines. Detailed reconstructions of variations in the ocean and climate have contributed significantly to understanding of Earth system dynamics, particularly those systems that have relatively long response times to natural changes. The following are three examples of connections between scientific ocean drilling and other fields. Physical Oceanography: With the development of advanced ocean circulation models capable of simulating the meridional overturning circulation (MOC) (see Figure 1.2), a system of ocean currents carrying water around the globe, it was discovered that with increased freshwater input at high latitudes (such as from the melting of glaciers), the circulation would abruptly transition from one stable state to another (Rahmstorf, 2002; Weijer et al., 2019). The threshold conditions for these transitions became known as tipping points, which were then defined in parallel reconstructions of deep-sea chemical distributions for the last glacial maximum. The paleoceanography reconstructions, based in part on sediment cores recovered by the International Ocean Discovery Program, showed that the MOC operated differently before abruptly transitioning to the present-day circulation pattern (e.g., Böhm et al., 2015; Curry and Oppo, 2005; Roberts et al., 2010). This discovery was particularly timely, as these and similar ocean circulation models, when coupled to atmospheric models and forced by greenhouse gas emission scenarios, have projected a possible future collapse of the MOC with significant impacts on regional climate. Ocean Chemistry: The changes in chemical distributions in the ocean, as reconstructed from sediment cores, contributed to efforts to understand global carbon cycle dynamics, the role of biological diversity, and functional niches in biogeochemical cycles. For example, the observations of the glacial–interglacial changes in ocean chemistry, along with other case studies, have proved critical to elucidating the role of the biological pump (the process by which biologically produced carbon-rich particles sink deep into the ocean interior and sediments) in amplifying the rise and fall of atmospheric CO2 over glacial–interglacial cycles, or the role of carbonate buffering in dampening changes in pH, where ocean acidification, rock weathering, and seafloor carbonate deposition are permanent sinks for anthropogenic CO2. continued 1 “JOIDES” is an acronym for the Joint Oceanographic Institutions for Deep Earth Sampling (see https://joidesresolution.org/about-the-jr). 2 See https://www.nsf.gov/news/news_summ.jsp?cntn_id=306986&org=OCE. Prepublication Copy 14 

Introduction BOX 1.1 continued FIGURE 1.2 Schematic circulation of surface currents (solid curves) and deep currents (dashed curves) that form portions of the Atlantic meridional overturing circulation (MOC). NOTES: Analysis of core samples and data from scientific ocean drilling expeditions has informed models of MOC operations during different climate states. SOURCE: William Curry, Woods Hole Oceanographic Institution/ Science/ USGCRP, permission for use via Creative Commons 3.0. Astrobiology: A growing understanding of the deep-subseafloor biosphere and the conditions under which such life exists is contributing to the field of astrobiology, particularly as it pertains to the search for habitable planets. Such planets could host conditions similar to the deep biosphere, allowing for both biotic and abiotic organic synthesis. These planets would likely have oceans and active tectonics with the energy to drive life-sustaining chemical reactions within or near the seafloor. The exploration of life in Earth’s subseafloor biosphere permits experimentation with the basic constituents that enable living things to emerge. This also allows the development of instruments and apertures necessary to explore and discover life in planets with habitable zones. Synergistic activities between planetary science researchers and scientific ocean drilling researchers aim to explore such possibilities.a This collaborative science aligns with a memorandum of understanding between the National Aeronautics and Space Administration and the National Science Foundation on the achievement of mutual research activities to advance space, Earth, and biological sciences.b a See https://www.hou.usra.edu/meetings/oceandrilling2024. b See https://www.hou.usra.edu/meetings/oceandrilling2024/emrc=b5475f. Prepublication Copy 15 

Progress and Priorities in Ocean Drilling: In Search of Earth’s Past and Present TABLE 1.1 Expedition Statistics for the International Ocean Discovery Program (2013–2024) Program JOIDES Resolution Mission-Specific Platforms Chikyu Total or (United States) (European Consortium) (Japan) Record Expeditions 46 (81%) 6 (10%) 5 (9%) 57 Completed Sites Visited 193 (85%) 28 (12%) 6 (3%) 227 Holes Drilled 530 (84%) 80 (13%) 18 (3%) 628 Deepest Hole 1,807 Penetrated a 1,807 1,335 1,180 (max) (m below seafloor) Shallowest Water 87 20 1,939 20 (min) Depth (m) Deepest Water 8,023 5,012 8,023 4,776 Depth (m) (max) Core Recovery (m) 78,067 (95%) 3,373 (4%) 1,085 (1%) 82,525 a The deepest hole drilled for all of scientific ocean drilling history was 3,262.5 m below seafloor at Site C0002 using the Chikyu. Coring at this site occurred during multiple expeditions across two phases of the program; most of the coring occurred during Expeditions 326, 338, and 348 (reaching a depth of 3,058.5 m). The hole depth was extended during Expedition 358 (Tobin et al., 2020). NOTES: Data through Expedition 399, June 2023. Percentages of total per category provided where appropriate. SOURCE: Updated by Mitch Malone, modified from IODP, 2023d. JOIDES Resolution photograph by Bill Crawford. In addition, the international landscape for scientific ocean drilling is changing rapidly. The European Consortium for Ocean Research Drilling and Japan—which are the primary operational partners with the United States for the current phase of the scientific ocean drilling program—have released a joint vision for future scientific ocean drilling, known as IODP3 (Camoin and Eguchi, 2023; Kinkel, 2023). The new vision would be a partnership between these ECORD and Japan and potentially other countries currently in IODP-2, and would include the combination of European-led ocean drilling operations of mission-specific platforms (MSPs), as during IODP-1 and IODP-2, which contracts vessels and other platforms on an expedition-by-expedition basis, and the operation of the very large, specialized, Japanese drilling vessel, Chikyu, specifically designed for drilling very deep into ocean sediments and rocks in and near Japanese waters. Currently, the United States has not joined IODP3, nor is there a dedicated globally ranging drilling vessel that can take on the activities that will be lost with the decommissioning of the JOIDES Resolution. A further change to the international landscape is that China is independently developing a plan for its future leadership in scientific ocean drilling, centered around a new drilling vessel and using existing smaller platforms. The new Chinese flagship deep-sea drilling vessel, the Mengxiang, was launched for sea trials in December 2023. China plans to make berths available to the developing nations that are part of their Belt and Road initiative (Yand and Shumei, 2024). Given these national and international factors, scientific ocean drilling is at a critical juncture, and the future of U.S. operational and scientific leadership and participation in scientific ocean drilling research is at risk (Figure 1.3). Prepublication Copy 16 

Introduction Permission pending FIGURE 1.3 A critical juncture in the future of U.S. and international scientific ocean drilling. NOTES: ECORD = European Consortium for Ocean Research Drilling; IODP = International Ocean Discovery Program SOURCES: Information compiled from slide 3; ECORD, 2023; IODP, 2023b; Camoin and Eguchi, 2022, slides 4–5; Yand and Shumei, 2024. PREPARING FOR THE NEXT STAGE OF SCIENTIFIC OCEAN DRILLING With the current phase of the program scheduled to conclude in 2024, the U.S. and international communities have been planning for the future of scientific ocean drilling. Efforts began in 2018 with a series of workshops to conceptualize a new scientific ocean drilling program, with emphasis on identifying priority science areas, strategic infrastructure, and collaborations. Approximately 650 scientists participated in six planning workshops held in the United States, Japan, India, Europe, Australia and New Zealand, and China.3 The convergence of the community-wide perspectives from these planning workshops ultimately led to the development of the 2050 Science Framework: Exploring Earth by Scientific Ocean Drilling (Koppers and Coggon, 2020), referred to hereafter as the 2050 Framework. 2050 Science Framework: Exploring Earth by Scientific Ocean Drilling The purpose of the 2050 Framework is to guide multidisciplinary subseafloor research on the interconnected processes that characterize the complex Earth system and shape the planet’s future. With a 3 Workshop reports of four of the planning workshops can be accessed at https://www.iodp.org/iodp- future/planning-workshop-outcomes. Prepublication Copy 17 

Progress and Priorities in Ocean Drilling: In Search of Earth’s Past and Present 25-year outlook, it serves as a community-developed science plan subsequent to the 2013-2023 IODP Science Plan, which was extended to 2024 (IODP, 2011). The 2050 Framework identifies a series of strategic objectives as well as a set of long-term initiatives. The seven strategic objectives focus on understanding the interconnections within the Earth system (Figure 1.4). The initiatives (referred to in the report as flagship initiatives) are multidisciplinary research endeavors that combine goals from multiple strategic objectives; these are summarized in Box 1.2. Additionally, four “enabling elements” were defined for enhancing scientific output and impact. These include education and outreach; collaborative research with continental drilling programs (e.g., International Continental Scientific Drilling Program, U.S. Continental Scientific Drilling Facility), collaborative research with space agencies (e.g., National Aeronautics and Space Administration); and advancing technological developments and big data analytics. FIGURE 1.4 The seven strategic objectives of the 2050 Science Framework are broad areas of scientific inquiry that focus on understanding the interconnected Earth system. SOURCE: Ellen Kappel, Geo-Prose, modified from Koppers and Coggon, 2020. Prepublication Copy 18 

Introduction BOX 1.2 2050 Science Framework Flagship Initiatives In 2020, a group of scientists representing 23 countries published a guide on global-scale, interdisciplinary, societally relevant research priorities for the next 30 years of scientific ocean drilling, titled the 2050 Science Framework: Exploring Earth by Scientific Ocean Drilling (Koppers and Coggon, 2020). From the 2050 Science Framework derivative a pamphlet: The 2050 Science Framework guides scientists on important research frontiers that scientific ocean drilling should pursue. It focuses on the many ways in which scientific ocean drilling will increase understanding of the fundamental connections among Earth system components while addressing a range of natural and human-caused environmental challenges facing society. The Flagship Initiatives comprise long-term, multidisciplinary research endeavors that aim to test scientific paradigms and hypotheses that inform issues of relevance or interest to society. They typically combine research goals from multiple strategic objectives. Their implementation will be shaped by proposals from the scientific community that develop coordinated strategies that include long-term planning, technology development, and innovative applications of existing and new scientific ocean drilling data products. Ground Truthing Future Climate Change. By collecting the robust data required for reconstructing global climate evolution over extended geologic time periods, scientific ocean drilling will provide information that is critical for improving climate model performance. Probing the Deep Earth. By penetrating deep within oceanic crust, scientific ocean drilling will lead to a better understanding of Earth’s formation and evolution and the connections between tectonics, earthquake and volcanic hazards, climate, and the planet’s habitability. Assessing Earthquake and Tsunami Hazards. By acquiring samples and deploying instruments in offshore and nearshore fault zones, scientific ocean drilling will enable more reliable assessments of the risks posed by major earthquakes and tsunamis and will facilitate improved hazard preparedness and response. Diagnosing Ocean Health. By retrieving sedimentary records that preserve key information about past responses of biological activity to natural cycles and catastrophic events, scientific ocean drilling will enable a more informed assessment of the expected rates, duration, and magnitudes of future ocean health deterioration. Exploring Life and Its Origins. Scientific ocean drilling and monitoring in borehole observatories will advance research into the distribution and limits of deep microbial life, novel microbes and their biotechnological applications, the emergence and evolution of life on Earth, and the possibility of life on other worlds. a See https://www.iodp.org/docs/iodp-future/1087-2050-science-framework-pamphlet/file. Community-Identified Science Mission Requirements In 2022, following the publication of the 2050 Science Framework, and recognizing that the JOIDES Resolution was approaching the end of its operational utility, NSF requested that the U.S. science community provide further input on U.S. science priorities and regional foci for subseafloor drilling, and define necessary vessel design requirements to meet these priorities. In response, U.S. community input Prepublication Copy 19 

Progress and Priorities in Ocean Drilling: In Search of Earth’s Past and Present was gathered via online surveys and a series of workshops, resulting in the report Science Mission Requirements for a Globally Ranging, Riserless Drilling Vessel for U.S. Scientific Ocean Drilling (hereafter referred to as the SMR report) (Robinson et al., 2022). The science priorities described in the report include the themes of: • climate change; • life on Earth; • natural hazards; and • the cycling of tectonic plates, energy, and matter. The geographic areas of interest identified in the SMR report (Robinson et al., 2022) span the global ocean, including all ocean basins, with special emphasis on high-latitude settings. Other special settings include continental shelves and slopes, glaciated margins, ocean ridges, and subduction zones and trenches. The SMR report concluded that prioritization should go toward working in unexplored locations (geographic and geologic record gaps) and recovering cores that are representative of the target geology and microbiome, with an emphasis on characteristically difficult settings (e.g., unconsolidated sediments, glaciomarine sediments, fractured formations, young oceanic crust). The report also identified as a priority obtaining petrophysics logs of drilled holes, especially drilling the upper 50–100 m below the seafloor, which is not achievable in the current phase of the program. Technological advancements envisioned in the report include installing more observatories and implementing a greater range of tools for in situ measurements of subseafloor conditions (e.g., fluid flow, slip rates). The SMR report (Robinson et al., 2022) described two categories of vessel design characteristics necessary for meeting the identified science priorities: foundational requirements, which are the minimum criteria for a future riserless drilling vessel,4 and more robust design features. The eight foundational requirements are interrelated (Figure 1.5). The report concluded that a vessel—supported by highly trained technical and scientific personnel—that can provide access to sites globally, operate in diverse subseafloor settings, and control specific aspects of the downhole conditions is essential for accessing key geological and biological environments, collecting high-quality cores, and establishing subseafloor observatories. FIGURE 1.5 Dependencies and relationships of the foundational science mission vessel requirements. SOURCE: Robinson et al., 2022. 4 Specific drilling terminology is described in Box 2.1 in Chapter 2. Prepublication Copy 20 

Introduction Workshops: Envisioning Science Communication and Outreach In addition to science and infrastructure planning meetings and reports, the U.S. scientific ocean drilling community also held a series of workshops in 2022 designed to inform science communication and outreach for future scientific ocean drilling. The workshops focused on three areas: engaging the public (White et al., 2021), informing policy makers (Cotterill et al., 2021a), and preparing the next generation of scientists (Cotterill et al., 2021b). Key premises of these workshops were that (1) robust science communication, outreach, and education are important enabling elements for the future of U.S. scientific ocean drilling, and that (2) consideration of diversity, equity, and inclusion provides an important lens through which to consider these topics. Findings were wide ranging, but included the recognition that there is a need to build greater awareness of the important contributions of scientific ocean drilling to issues that affect science policy and society, and that there is great value in utilizing approaches that capture public imagination and interest and provide new understanding of Earth. Findings also identified the value of utilizing core samples and data in course-based research experiences for undergraduate students and in short courses and workshops for graduate students and early-career researchers; such opportunities can help develop critical scientific and transdisciplinary skills that contribute to building the STEM workforce. STUDY ORIGIN AND PURPOSE In addition to efforts underway by the U.S. and international scientific ocean drilling communities to prepare for the demobilization of the JOIDES Resolution, the conclusion of the current drilling program, and the transition to a new phase of ocean drilling, NSF also asked for input from the broader U.S. ocean science community. In response, the National Academies formed the Committee on the 2025–2035 Decadal Survey of Ocean Sciences for the National Science Foundation. The goal of the present study, an interim report for the Decadal Survey of Ocean Sciences (DSOS), is to provide a broader perspective on high-priority science needs that require ocean drilling, and the resources and infrastructure needed to accomplish such important research. The committee’s task for the interim report is presented in Box 1.3 (the full DSOS statement of task is included in Appendix A). In consultation with NSF, the committee has chosen to address the statement of task by highlighting high-priority science themes (i.e., areas, topics), rather than specific scientific questions. Because scientific ocean drilling is at a time-sensitive juncture, NSF requested that the committee produce an interim report focused solely on scientific ocean drilling ahead of the DSOS final report (Appendix A). This report therefore aims to fulfill the two tasks listed in Box 1.3 and does not include recommendations to NSF, which fall outside the scope of this report. Over the next year, as the committee continues work on the final DSOS report, the findings and conclusions from this study will inform the committee’s recommendations on the broader ocean science research and infrastructure portfolio for NSF. BOX 1.3 Statement of Task The Committee will produce an interim report to provide advice to NSF OCE on the resources and infrastructure available to address high priority research questions requiring scientific ocean drilling. The interim report will cover the following: 1. Based on previous reports, assess progress on addressing high priority science questions that require scientific ocean drilling and identify new, if any, equally compelling science questions that would also require scientific ocean drilling. 2. Of the unanswered scientific questions, which could be addressed through the use of existing scientific drilling assets including sediment or rock core archives and existing platforms, and which questions would require new infrastructure or sampling investments? Prepublication Copy 21 

Progress and Priorities in Ocean Drilling: In Search of Earth’s Past and Present STUDY APPROACH The committee’s deliberations and resulting conclusions were informed by its collective expertise; review of scientific literature; and several mechanisms for hearing directly from the broad scientific ocean drilling community, including public meetings and a virtual town hall. The main public information gathering (see Appendix B for agenda and participant list) consisted of a 2-day meeting on scientific ocean drilling program research priorities and required infrastructure. Thirty guests at all career stages—representing three subcategories of scientific ocean drilling: solid Earth dynamics, climate and environment, and health and habitability—were invited to participate in person. Virtual participation was open to anyone who registered, and roughly an additional 150 individuals participated online. The committee also opened a virtual town hall for the community to submit their thoughts on ocean science research priorities broadly, as well as those relevant to scientific ocean drilling. The virtual town hall remained open for 2 months and collected input from 94 participants representing voices from early-, mid-, and late-career scientists and practitioners. Roughly 50 percent of respondents were in the late-career stage, and the remaining were split evenly between the early- and mid-career stages. In addition to solicited outreach, the committee received emails, letters, and public feedback submitted through the project website, including input specifically from early-career scientists and international scientific ocean drilling programs. All information shared with the committee was considered in report deliberations. The process for information gathering, deliberations, report writing, and publication occurred over a relatively short period of time. The findings and conclusions from this study are interim; they will be incorporated and referenced in the full report as appropriate, and as a component of the larger ocean sciences priority research portfolio. REPORT ORGANIZATION Chapter 1 provides the context for this study. An overview or “primer” of scientific ocean drilling is provided in Chapter 2, including an overview of how the program works, a history of scientific ocean drilling and a historical summary of the major accomplishments achieved using scientific ocean drilling over the decades. An assessment of progress made in scientific ocean drilling over the last decade and questions remaining for the future is summarized in Chapter 3. Chapter 4 then examines the priorities in the context of what can and cannot be accomplished with available infrastructure. The committee’s main findings are presented throughout the text and conclusions follow the text supporting them. Prepublication Copy 22