EFFECTS OF DIVERSIONS ON THE NORTH AMERICAN GREAT LAKES1

ABSTRACT: Water level fluctuations of the Great Lakes often have created regional controversies among the states and Canadian provinces that share this vast resource. Even though the 100-year range of their water levels is only four to five feet, episodes of high and low Great Lakes water levels have been a recurring problem throughout the twentieth century. The possibility of increased diversion and consumptive use has exacerbated the existing conflicts over how to manage this water resource. A research project evaluated the effects of interbasin diversion on the Great Lakes system and on the industries that depend on the maintenance of historical water levels, namely hydropower and commercial navigation. The simulation approach employed in this research and some of the important findings are presented. The approach is similar to that used in recent government studies of Great Lakes water level regulation. Several significant modifications were made specifically addressing the diversion issue. Aggregate annual impacts to hydropower and shipping resulting from a diversion of 10,000 cubic feet per second were found to vary from 60 to 100 million dollars. Increases in impacts as a function of diversion rate are nonlinear for the navigation industry.     

Biomineralization in plants as a long-term carbon sink

Carbon sequestration in the global carbon cycle is almost always attributed to organic carbon storage alone, while soil mineral carbon is generally neglected. However, due to the longer residence time of mineral carbon in soils (10²–10⁶ years), if stored in large quantities it represents a potentially more efficient sink. The aim of this study is to estimate the mineral carbon accumulation due to the tropical iroko tree (Milicia excelsa) in Ivory Coast. The iroko tree has the ability to accumulate mineral carbon as calcium carbonate (CaCO₃) in ferralitic soils, where CaCO₃ is not expected to precipitate. An estimate of this accumulation was made by titrating carbonate from two characteristic soil profiles in the iroko environment and by identifying calcium (Ca) sources. The system is considered as a net carbon sink because carbonate accumulation involves only atmospheric CO₂ and Ca from Ca-carbonate-free sources. Around one ton of mineral carbon was found in and around an 80-year-old iroko stump, proving the existence of a mineral carbon sink related to the iroko ecosystem. Conservation of iroko trees and the many other biomineralizing plant species is crucial to the maintenance of this mineral carbon sink.     

The end of the fat dodo? A new mass estimate for <Emphasis Type="Italic">Raphus cucullatus</Emphasis>

A new mass estimate for the dodo (Raphus cucullatus), based on the lengths of the femur, tibiotarsus and tarsometatarsus, is attempted. The obtained mean mass is 10.2 kg, which is less than previous estimates based on other methods, which ranged from 10.6 to 21.1 kg, and much lower than the 50 lbs reported by a seventeenth-century eyewitness. The new estimated mass, which is similar to that of a large wild turkey, seems more realistic than previous ones and supports the hypothesis that contemporary illustrations of extremely fat dodos were either exaggerations, or based on overfed specimens. Pictures of “fat” dodos may also have been based on individuals exhibiting a display behaviour with puffed out feathers.     

Managing the cost of emissions for durable,carbon-containing products

We recognize that carbon-containing products do not decay and release CO₂ to the atmosphere instantaneously, but release that carbon over extended periods of time. For an initial production of a stock of carbon-containing product, we can treat the release as a probability distribution covering the time over which that release occurs. The probability distribution that models the carbon release predicts the amount of carbon that is released as a function of time. The use of a probability distribution in accounting for the release of carbon to the atmosphere realizes a fundamental shift from the idea that all carbon-containing products contribute to a single pool that decays in proportion to the size of the stock. Viewing the release of carbon as a continuous probabilistic process introduces some theoretical opportunities not available in the former paradigm by taking advantage of other fields where the use of probability distributions has been prevalent for many decades. In particular, theories developed in the life insurance industry can guide the development of pricing and payment structures for dealing with the costs associated with the oxidation and release of carbon. These costs can arise from a number of proposed policies (cap and trade, carbon tax, social cost of carbon, etc), but in the end they all result in there being a cost to releasing carbon to the atmosphere. If there is a cost to the emitter for CO₂ emissions, payment for that cost will depend on both when the emissions actually occur and how payment is made. Here we outline some of the pricing and payment structures that are possible which result from analogous theories in the life insurance industry. This development not only provides useful constructs for valuing sequestered carbon, but highlights additional motivations for employing a probability distribution approach to unify accounting methodologies for stocks of carbon containing products.     

Evaluating The National Land Cover Database Tree Canopy and Impervious Cover Estimates Across the Conterminous United States: A Comparison with Photo-Interpreted Estimates

The 2001 National Land Cover Database (NLCD) provides 30-m resolution estimates of percentage tree canopy and percentage impervious cover for the conterminous United States. Previous estimates that compared NLCD tree canopy and impervious cover estimates with photo-interpreted cover estimates within selected counties and places revealed that NLCD underestimates tree and impervious cover. Based on these previous results, a wall-to-wall comprehensive national analysis was conducted to determine if and how NLCD derived estimates of tree and impervious cover varies from photo-interpreted values across the conterminous United States. Results of this analysis reveal that NLCD significantly underestimates tree cover in 64 of the 65 zones used to create the NCLD cover maps, with a national average underestimation of 9.7% (standard error (SE) = 1.0%) and a maximum underestimation of 28.4% in mapping zone 3. Impervious cover was also underestimated in 44 zones with an average underestimation of 1.4% (SE = 0.4%) and a maximum underestimation of 5.7% in mapping zone 56. Understanding the degree of underestimation by mapping zone can lead to better estimates of tree and impervious cover and a better understanding of the potential limitations associated with NLCD cover estimates.