Scientists within the Geosciences Research Division (GRD) address a wide range of topics in the earth, ocean, and atmospheric sciences. GRD researchers study the physical, chemical, and geobiological processes of Earth's mantle, crust, ocean, and atmosphere. They carry out detailed investigations in marine geology, petrology, paleomagnetism, tectonics, geophysics, isotope geology, geochemistry, mantle and crustal evolution, and paleontology.

David Hilton's three-year study of subduction zone activity in the western Pacific's Mariana Islands and Japan received a fortuitous kick-off in May when one of the Mariana's volcanic islands, Anatahan, erupted for the first time in recorded history.

Hilton and colleague Tobias Fischer from University of New Mexico arrived at the island within two weeks of the eruption and measured how much sulfur dioxide the volcano emitted in its ash plume. The readings will help Hilton estimate the output of volatiles along the entire Izu-Bonin-Marianas (IBM) volcanic arc system that includes Anatahan.

The work is part of Hilton's study of subduction zone dynamics in the IBM chain of volcanoes, which was created by the Pacific tectonic plate moving beneath the Philippine plate. His science party will analyze those dynamics by sampling by-products like gases and rocks ejected by the volcanoes.

Kathy Barbeau hopes to understand how phytoplankton communities in the Southern Ocean interact with iron, a nutrient trace metal.

Barbeau and colleagues, led by Scripps biological oceanographer Greg Mitchell, are visiting a site in the southern Drake Passage between Antarctica and the southern tip of South America. There, a transition from low to high phytoplankton quantities takes place, possibly due to iron additions. Potential sources of iron range from wind-blown dust to land runoff to upwelling from the deep ocean. The researchers want to determine which source is most important and also to understand how plankton respond to changes in iron supply.

Barbeau said researchers favor the Southern Ocean as a study site because iron addition can predictably enhance phytoplankton growth and, potentially, carbon dioxide sequestration. Artificial "seeding" of the oceans with iron to enhance that sequestration has been offered as one way to diminish concentrations of harmful greenhouse gases in the atmosphere.

Until about two decades ago, little was understood about methane hydrate distribution in the ocean. Scientists now know that the substance has a profound influence on how the planet stores methane, a greenhouse gas, and in how undersea masses of methane hydrate remain intact.

Methane hydrate is a compound that consists of methane and water. It exists in ocean sediment and on the seafloor under great pressures and in cold temperatures in a solid form resembling ice. Recent discoveries of warming trends in the oceans have led to inquiries about what happens when the hydrates melt and release the methane into the oceanic environment or even into the atmosphere. Miriam Kastner was one of the first researchers to study methane hydrates and is now engaged in projects offshore of Oregon and in the Gulf of Mexico to understand more about the characteristics of the hydrates.

Scenarios associated with warming oceans could include landslides involving sections of continental slopes for which the hydrates act as a kind of cement that maintains stability. Sudden influxes of large amounts of methane into the world's oceans could deplete oxygen from the waters, causing profound ecological changes. If methane gases pass into the atmosphere, they could exacerbate the concentration of greenhouse gases, to which global warming trends are partially attributed.