CGRER awarded its fifth set of seed grants in August, 1995, for the period 9/1/95 through 8/31/96. These $15,000 grants are funding the commencement of seven projects (summarized below) related to global change, with the prospect that larger-scale funding will be sought to allow their continuation.

A BRADLEY (Civil and Environmental Engineering, U of I) is attempting to establish whether changes in atmospheric circulation patterns affect the probability of hydrologic extremes (such as Iowa's 1993 floods) in Iowa and surrounding states. By using an innovative regional framework to detect and quantify changes in rainfall extremes, he hopes to find linkages between climate variability and rainfall occurrence probabilities. The results of this work will establish a regional baseline to quantify anomalous events such as the 1993 floods, and help to assess the sensitivity of rainfall extremes to potential climate change.

T-C CHEN (Geological and Atmospheric Sciences, ISU) will be coupling the recently-developed Iowa Global Carbon Model with a global climatic change computer model that was developed at the National Center for Atmospheric Research (NCAR). This will allow combination of the unique features of each: those in the Iowa model that assess interactions of the atmosphere, terrestrial biosphere, and ocean, with the features of the NCAR model which allow assessment of regional variations in the global temperature response to non-uniformly-changing CO2 concentrations.

A ELDERING (Civil and Environmental Engineering, U of I) is interested in the ability of atmospheric particles (pollutants such as sulfate aerosols) to cool the earth's temperature. Such particulates may counteract the global warming potential of the steadily-rising greenhouse gasses. However, calculations about the cooling effects of these particulates are based on several sweeping assumptions about the size composition of the particulate material. Eldering plans to perform numerical studies to quantify the effects of these uncertainties, and thus to better understand the radiative properties of these particles.

L GONZALEZ and S LEIMKUELLER (Geology, U of I) are quantifying and identifying the sources of methane in soils and groundwater in sites in the Upper Midwest. More specifically, they are attempting to develop methods for characterizing and differentiating between methane produced in landfills and the normal background methane - that generated naturally from the loess and till sequences of central Iowa. In addition to defining present-day traits of methane generation, their data will help in the estimation of Holocene carbon fluxes in the Upper Midwest.

G LUDVIGSON, L GONZALEZ, R BRENNER, and B WITZKE (Geology, U of I) are investigating the history and variability of the continental climate during the global greenhouse warming of the Cretaceous Period. By measuring the oxygen isotopic ratios of freshwater carbonate minerals, and dating the non-marine deposits of our mid-continent in which these minerals are contained, they hope to reconstruct air circulation patterns, rainfall patterns, temperature patterns, and other elements of the paleoclimate. Their data will be useful to other investigators who are validating computer models simulating the Cretaceous climate system, which are significant because of the possibility of modern-day global warming.

J RAICH (Botany, ISU) and C POTTER (Cooperative Institute for Research in Integrated Ocean Sciences, California) will be looking at the well-documented seasonal cycle of atmospheric CO2 concentrations: atmospheric CO2 increases in the winter when it is released from the soil, and decreases in the summer when it is being stored in growing plants. These researchers propose to couple, test, and refine existing computer models, so that they can estimate the seasonal and spatial patterns of this exchange of carbon (as CO2) between the atmosphere and terrestrial ecosystems around the globe.

M REAGAN (Geology, U of I) proposes to develop a new radiometric technique for dating oxidation of sulfide minerals. The timing of the growth of iron oxide minerals as they replace sulfides will be determined using uranium-series isotopes. The new technique will be used to investigate the history of the Mississippi River valley, a topic that is poorly understood at present. Reagan hopes to trace the river's downcutting by dating water table levels in mines near the river, and also to date other important geological phenomena such as cave formation and rock weathering rates.