Climate engineering and climate tipping-point scenarios

Many scientists fear that anthropogenic emissions of greenhouse gases have set the Earth on a path of significant, possibly catastrophic, changes. This includes the possibility of exceeding particular thresholds or tipping points in the climate system. In response, governments have proposed emissions reduction targets, but no agreement has been reached. These facts have led some scientists and economists to suggest research into climate engineering. In this paper, we analyze the potential value of one climate engineering technology family, known as solar radiation management (SRM) to manage the risk of differing tipping-point scenarios. We find that adding SRM to a policy of emissions controls may be able to help manage the risk of climate tipping points and that its potential benefits are large. However, the technology does not exist and important indirect costs (e.g., change in precipitation) are not well understood. Thus, we conclude the SRM merits a serious research effort to better understand its efficiency and safety.     

DETERMINANTS OF LANDOWNER'S WILLINGNESS TO PAY FOR FLOOD HAZARD REDUCTION1

ABSTRACT: Estimated benefits of flood control projects are typically limited to avoided property damages. However, the possibility that there are (1) benefits from reduced psychological stress among flood plain occupants, and (2) benefits to the community has long been recognized. A survey of landowners residing in a flood plain in Roanoke, Virginia, found that nonproperty considerations did help explain their expressed willingness to pay for flood control. Of particular importance was the respondents' concern for disruption of the community caused by possible flooding.     

Hot steam transfer through heat protective clothing layers.

The aim of this study was to analyse the transfer of steam through different types of textile layers as a function of sample parameters such as thickness and permeability. In order to simulate the human body, a cylinder releasing defined amounts of moisture was also used. The influence of sweating on heat and mass transfer was assessed. The results show that in general impermeable materials offer better protection against hot steam than semi-permeable ones. The transfer of steam depended on the water vapour permeability of the samples, but also on their thermal insulation and their thickness. Increasing the thickness of the samples with a spacer gave a larger increase in protection with the impermeable samples compared to semi-permeable materials. Measurements with pre-wetted samples showed a reduction in steam protection in any case. On the other hand, the measurements with a sweating cylinder showed a beneficial effect of sweating.     

Diurnal and weekday variations in the source contributions of ozone precursors in California's South Coast Air Basin

For at least 30 years, ozone (O3) levels on weekends in parts of California's South Coast (Los Angeles) Air Basin (SoCAB) have been as high as or higher than on weekdays, even though ambient levels of O3 precursors are lower on weekends than on weekdays. A field study was conducted in the Los Angeles area during fall 2000 to test whether proposed relationships between emission sources and ambient nonmethane hydrocarbon (NMHC) and oxides of nitrogen (NOx) levels can account for observed diurnal and day-of-week variations in the concentration and proportions of precursor pollutants that may affect the efficiency and rate of O3 formation. The contributions to ambient NMHC by motor vehicle exhaust and evaporative emissions, estimated using chemical mass balance (CMB) receptor modeling, ranged from 65 to 85% with minimal day-of-week variation. Ratios of ambient NOx associated with black carbon (BC) to NOx associated with carbon monoxide (CO) were approximately 1.25 +/- 0.22 during weekdays and 0.76 +/- 0.07 and 0.52 +/- 0.07 on Saturday and Sunday, respectively. These results demonstrate that lower NOx emissions from diesel exhaust can be a major factor causing lower NOx mixing ratios and higher NMHC/NOx ratios on weekends. Nonmobile sources showed no significant day-of-week variations in their contributions to NMHC. Greater amounts of gasoline emissions are carried over on Friday and Saturday evenings but are, at most, a minor factor contributing to higher NMHC/NOx ratios on weekend mornings.     

Future directions in air-quality science,policy, and education

On February 12-15, 2001, more than 200 scientists, engineers, decision makers, and educators participated in a conference on the "Future Directions in Air Quality Research: Ecological, Atmospheric, Regulatory/Policy, and Educational Issues." Important perspectives are summarized from the keynote addresses of noted scientists and educators, as well as managers in government, industry, and public interest groups. Observations and recommendations are provided to stimulate further thought about how to increase opportunities to make greater use of scientific knowledge in air-quality decision making and to ensure that decisions are effective, economically viable, health and ecologically sound, and socially acceptable. Recommendations are given regarding ways in which communications between scientists and policy makers should be structured so as to make appropriate and effective use of scientists and the knowledge they can provide in policy-making fora.     

An assessment methodology for successional systems. II. Statistical tests and specific examples

This paper presents a dynamic framework for environmental assessment when the system under study is undergoing successional change. Successional differences between sites for which one wishes to detect a difference because of a treatment are essentially confounding factors. We show how successional changes over the study period or resulting from differences in study site plot ages can be factored out by developing a null model of expected behavior over time. The null model for change in state with time is characterized in terms of a stochastic envelope around a nominal trajectory. Specific tests for the detection of trends associated with succession are described and illustrated on example data. It is concluded that the methods developed work particularly well for laboratory microcosm data.     

The common mussel Mytilus edulis as an indicator of pollution by zinc,cadmium, lead and copper. II. Relationship of metals in the mussel to those discharged by industry

Concentrations of zinc, cadmium, lead and copper were determined in whole soft parts of the common mussel Mytilus edulis (L.) sampled in Port Phillip Bay and Western Port Bay, both in Victoria, Australia. The mussels were sampled according to procedures suggested by previous studies in order to eliminate the effects of natural environmental variables. Results of the analytical studies were compared to data on the quantities of trace metals known to be discharged by industry into the catchments of each Bay. This allowed an evaluation of the indicator ability of the mussel without the need for multiple analyses of water samples. The results suggest that the mussel is capable of acting as an efficient time-integrated indicator of zinc, cadmium and lead over a wide variety of environmental conditions. Although additional variables may remain to be investigated, the mussel is recommended as an alternative to the analysis of water and sediments. With further development this organism may also be useful for monitoring industrial effluent characteristics at the discharge site, allowing rapid, reliable and inexpensive control of water quality. In contrast, the mussel is of doubtful use as an indicator of copper; other indicator types such as macroalgae may be better-suited to the study of this element.     

MANAGEMENT MODEL FOR CONTROLLING NITRATE CONTAMINATION IN THE NEW JERSEY PINE BARRENS AQUIFER1

ABSTRACT: Land use planning in rapidly developing areas can serve as an effective tool for minimizing water quality impacts on ground water supplies. A land use management model applied to Jackson Township of the New Jersey Pine Barrens was developed. The management model consisted of a simulation model for the transport of nitrates from septic tank systems through the aquifer and a multiobjective, goal programming optimization model to determine population density restrictions using 208 areawide planning population projections. Results showed that growth may have to be curtailed in several areas of Jackson Township and that current population projections over the next 30 years may result in unacceptably high nitrate concentrations downgradient of Jackson Township. The management framework provides a flexible approach to land use planning.     

The environment of the mining industry: An industry view

Finance and investment, technological development, government legislation and fiscal policies, public attitudes and aboriginal lands, are among the major issues confronting the Australian minerals industry. Within this context the author discusses the significance of the industry to the Australian economy and assesses its potential.