Basic Earth Science and Society - Basic Research Opportunities in Earth Science - page 15

used to infer the extent of glaciers and ice sheets, as well as the temperature and
composition of the oceans. The abundance and range of species, the nature of the
land cover, and the position of shorelines can be inferred from analysis of
terrestrial sediments, soils, and fossils. Such research provides important
constraints on climate models, which are extending increasingly into the
geological past.
National Defense and Global Security
Earth science has found significant applications in the arenas of national
defense and global security. A range of technologies based on Earth science are
essential components in the global monitoring and verification of nuclear test
bans, nuclear nonproliferation treaties, and other arms control measures. From the
first multinational discussions in Geneva in the late 1950s, it has been recognized
that reliable identification of small underground nuclear explosions is the primary
technical issue confronting the verification of a comprehensive nuclear test ban
treaty (CTBT). The resulting U.S. program in nuclear explosion seismology
stimulated basic as well as applied research. To improve seismological detection
and location capabilities, for example, the Department of Defense developed a
120-station World Wide Standardized Seismographic Network (WWSSN). The
WWSSN sharpened the images of global seismicity, which played a significant
role in the discovery of plate tectonics and yielded much better models of deep-
Earth structure that in turn resulted in a better understanding of the Earth's
composition and internal dynamics.
After decades of negotiations, the CTBT was opened for signature on
September 24, 1996, and has thus far been endorsed by 154 nations. Adherence to
the treaty will be verified by the International Monitoring System (IMS). The IMS
is a worldwide distribution of permanent stations designed to detect clandestine
nuclear explosions by measuring wind-transported radionuclides and waves
transmitted through the atmosphere (infrasound), oceans (hydroacoustic), and
solid Earth (seismic). Basic research related to the hydroacoustic and infrasound
networks will open new avenues of research in the Earth sciences (e.g., the
infrasound network can be used to count meteorites). EAR-sponsored research
related to the CTBT focuses primarily on seismology, although radionuclide and
other geochemistry studies are also critical for verification of the CTBT and the
Chemical Weapons Convention of 1993. Recent advances in particulate and
isotopic analyses have considerable potential for improving the capabilities in
radionuclide monitoring.
Earth science contributes to national security in a number of other ways.
Precise geodetic measurements of the Earth's topography, gravity field, and