U.S.-supported scientific ocean drilling has a long and illustrious history—from its earliest roles in the confirmation of plate tectonics to more recent contributions in paleoclimate and global sea level reconstructions. As the current phase of scientific ocean drilling draws to a close in 2013, the National Science Foundation (NSF) requested that an ad hoc National Research Council committee review the scientific accomplishments of U.S.-supported scientific ocean drilling over the past four decades. The committee evaluated how the programs (Deep Sea Drilling Project [DSDP], 1968-1983, Ocean Drilling Program [ODP], 1984-2003, and Integrated Ocean Drilling Program [IODP], 2003-2013) have shaped understanding of Earth systems and Earth history and assessed the role of scientific ocean drilling in enabling new fields of inquiry. The committee also assessed the potential for transformative discoveries1 resulting from implementation of the science plan for the next proposed phase of scientific ocean drilling, which is scheduled to run from 2013 to 2023 if funding is approved by NSF.
The committee found that the U.S.-supported scientific ocean drilling programs (DSDP, ODP, and IODP) have been very successful, contributing significantly to a broad range of scientific accomplishments in a number of Earth science disciplines. In addition, the programs’ technological innovations have strongly influenced these scientific advances. To a large extent, the success of IODP and prior scientific ocean drilling programs has been a result of strong international collaboration. Following the broad themes in the IODP Initial Science Plan (2001), the committee identified three general areas in which there have been significant accomplishments: solid Earth cycles; fluids, flow, and life in the subseafloor; and Earth’s climate history. Several of the scientific achievements that could not have been accomplished without scientific ocean drilling are listed in Box S.1.
Scientific ocean drilling fundamentally advanced the fields of plate tectonics, paleomagnetism, geomagnetism, and geochronology. It has been critical to understanding connections between subseafloor fluid flow, microbial communities, and massive sulfide deposits. Technology pioneered by scientific ocean drilling enabled the recovery of intact gas hydrates, strongly influencing the understanding of gas hydrate distribution for economic and geohazard objectives. DSDP and ODP were integral to the study of continental breakup, in conjunction with onshore and offshore geophysical and geologic exploration and geodynamic modeling. Scientific ocean drilling has contributed to increased understanding of lithospheric formation and structure, and to connecting the occurrence of submarine large igneous provinces with volcanic eruption-related climate change. It also played a central role in deciphering the relationship between atmospheric carbon dioxide and global surface temperatures, glacial-interglacial cycles, global sea level change, ocean anoxia events, and the discovery of large climate excursions and abrupt climate change. In addition, scientific ocean drilling lent credence to the meteorite impact hypothesis as a paradigm for global extinction processes, a mainstay of modern Earth science education.
Since their earliest days, scientific ocean drilling programs have actively engaged in educating graduate students
1NSF’s definition of transformative research is: “Transformative research involves ideas, discoveries, or tools that radically change our understanding of an important existing scientific or engineering concept or educational practice or leads to the creation of a new paradigm or field of science, engineering, or education. Such research challenges current understanding or provides pathways to new frontiers.” See http://www.nsf.gov/about/transformative_research/definition.jsp; accessed August 2011.
Scientific Accomplishments That
Could Not Have Been Achieved Without
Scientific Ocean Drilling
Solid Earth Cycles
• Verification of the seafloor spreading hypothesis and plate tectonic theory
• Development of an accurate geological time scale for the past 150 myr
• Confirmation that the structure of oceanic lithosphere is related to spreading rate
• Exploration of the emplacement history of submarine large igneous provinces
• Contribution to a new paradigm for continental breakup due to studies of rifted margins
• Definition of subduction zone inputs and confirmation of subduction erosion
Fluids, Flow, and Life in the Subseafloor
• In situ investigation of fluid flow processes, perÂmeability, and porosity in ocean sediments and basement rocks
• Characterization of the sediment- and rockÂhosted subseafloor microbial biosphere
• Study of subseafloor water-rock interactions and the formation of seafloor massive sulfide deposits in active hydrothermal systems
• Examination of the distribution and dynamics of gas hydrates in ocean sediments
Earth’s Climate History
• Reconstruction of global climate history for the past 65 myr, based on ocean sediments
• Development and refinement of the Astronomical Geomagnetic Polarity Timescale
• Documentation of the pervasive nature of orbital forcing on global climate variability
• Recognition of past geological analogs (for example, the Paleocene-Eocene Thermal Maximum) for Earth’s response to increases in atmoÂspheric carbon dioxide
• Discovery of the history of polar ice sheet initiaÂtion, growth and variability, and their influence on fluctuations in global sea level
in the Earth sciences. During ODP, informal activities aimed at undergraduates, K-12, and community outreach were initiated. More structured and extensive programs during IODP included a vigorous education initiative aimed at K-12, undergraduate, graduate, and informal science educators. The education, outreach, and capacity-building programs are of significant value, but evaluations of each of them would enable a better understanding of the impacts of these activities on different groups and would demonstrate the broader impacts of scientific ocean drilling.
RECOMMENDATION: Formal evaluation of education, outreach, and capacity-building activities should be implemented to demonstrate the broader impacts of scientific ocean drilling.
The committee also assessed the potential for future transformative scientific discoveries envisioned in Illuminating Earth’s Past, Present, and Future: The International Ocean Discovery Program Science Plan for 2013-2023, which was released in June 2011 by Integrated Ocean Drilling Program Management International. The science plan is divided into four research themes: climate and ocean change, biosphere frontiers, Earth connections (deep Earth processes), and Earth in motion (direct time series observations on human scales). There are 14 scientific challenges within these four themes, which the committee evaluated individually for potential for transformative discovery, synergy between science plan challenges and themes, and linkages to NSF-supported and other research programs. Each of the four themes within the science plan identifies compelling challenges with potential for transformative science that can only be addressed by scientific ocean drilling. Some challenges within these themes appear to have greater potential for transformative science than others.
The committee was particularly positive about the potential for transformative discoveries resulting from subseafloor biosphere exploration and for continuing paleoclimate investigations to provide constraints on projected climate change. It also noted the need for data in under-represented regions such as high latitudes and for deeper sampling into intact ocean crust. The themes and challenges identified in the science plan were well-justified and timely, although there was a lack of guidance as to which challenges were most important.
RECOMMENDATION: The scientific ocean drilling community should establish a mechanism to prioritize the challenges outlined in the science plan in a manner that complements the existing peer-review process.
The scientific ocean drilling programs have a history of making excellent use of legacy samples and data that have helped to quickly advance new areas of research. Using legacy data and samples to their maximum capabilities will continue to increase the scientific value of the scientific ocean drilling programs. Expanded use of legacy materials could help, for example, with prioritization of drilling objectives in the next phase of scientific ocean drilling.
There are several natural areas of synergy between the challenges and themes, and more detailed examination of potential integration would be valuable in lending strength to the overall program. Integration of scientific ocean drilling
objectives is currently done in an ad hoc fashion during the expedition planning process.
RECOMMENDATION: From the earliest stages of proposal development and evaluation, possibilities for increasing program efficiency through integration of multiple objectives into single expeditions should be considered by proponents and panels.
Transformative discoveries are critically dependent on technological breakthroughs, and it is essential for future scientific ocean drilling programs to continue to advance a technological agenda. This is an area where prior programs have demonstrated great strength.
RECOMMENDATION: Pathways for innovations in technology should be encouraged. In addition, setting aside some resources specifically to promote technological research and development could increase the potential for transformative science.