Micropaleontology and ocean surface climate

The interpretation of micropaleontological data based on the fossil remains of planktonic organisms requires an appropriate reference frame. The environmental changes that the plankton experience are a combination of geographic and seasonal factors, correlated by the average drift trajectories. Appropriate methods have been developed to study two drifts in the North Atlantic, one form the west-central Sargasso Sea to the Norwegian Sea and another around the subtropical Sargasso Gyre. The data on planktonic foraminifera from core tops can be used to relate the relative species distribution to the characteristics of the present sea surface. At any one location, the fossil assembly results from a superposition of plankton that have had varied time-temperature histories. To interpret the climatic and geologic history from downcore data will require an iterative technique. One assumes a surface climatology, determines the fossil record this would produce, and then compares this inference with available core data. The climatological assumptions are then modified until a satisfactory agreement is reached.     

Ocean science. Enhanced: internal tides and ocean mixing

Recent satellite and in situ observations have shown that at ocean ridges and other seafloor topographic features, a substantial amount of energy is transferred from the main ocean tides into "internal tides." In his Perspective, Garrett explains how these internal waves with tidal periods propagate through the density-stratified deep ocean and eventually break down into turbulence. The resulting mixing affects ocean stratification and ocean circulation. It thus influences climate as well as biological production. The energy for the internal tides is derived from the rotational energy of the Earth-Moon system changes of the length of the day and the distance to the Moon.     

Global climate change and intensification of coastal ocean upwelling

A mechanism exists whereby global greenhouse warning could, by intensifying the alongshore wind stress on the ocean surface, lead to acceleration of coastal upwelling. Evidence from several different regions suggests that the major coastal upwelling systems of the world have been growing in upwelling intensity as greenhouse gases have accumulated in the earth's atmosphere. Thus the cool foggy summer conditions that typify the coastlands of northern California and other similar upwelling regions might, under global warming, become even more pronounced. Effects of enhanced upwelling on the marine ecosystem are uncertain but potentially dramatic.     

Coral reefs under rapid climate change and ocean acidification

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2 degrees C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.     

Topography, albedo-temperature feedback, and climate sensitivity

Numerical experiments with an energy balance model of the earth's climate suggest an enhancement of albedo-temperature feedback caused by the presence of a high middle-latitude plateau in the zonally averaged Northern Hemisphere topography. The increased climate sensitivity arises from the increased rate of change of snow cover produced by the advance or retreat of the winter snow line over the north slope of this topographic feature.     

Noise-induced reduction of inner-ear microphonic response: dependence on body temperature

The rate of reduction of chinchilla cochlear microphonic response with exposure to steady noise is less at lower body temperatures and greater at higher body temperatures. Before exposure to noise, this auditory response is invariant within the range of temperatures employed. The mechanism of reduction of cochlear response appears to involve processes sensitive to body temperature.     

Global iron connections between desert dust, ocean biogeochemistry, and climate

The environmental conditions of Earth, including the climate, are determined by physical, chemical, biological, and human interactions that transform and transport materials and energy. This is the "Earth system": a highly complex entity characterized by multiple nonlinear responses and thresholds, with linkages between disparate components. One important part of this system is the iron cycle, in which iron-containing soil dust is transported from land through the atmosphere to the oceans, affecting ocean biogeochemistry and hence having feedback effects on climate and dust production. Here we review the key components of this cycle, identifying critical uncertainties and priorities for future research.