Damage Functions and the Social Cost of Carbon: Addressing Uncertainty in Estimating the Economic Consequences of Mitigating Climate Change.

Mitigating the effects of human-induced climate change requires the reduction of greenhouse gases. Policymakers must balance the need for mitigation with the need to sustain and develop the economy. To make informed decisions regarding mitigation strategies, policymakers rely on estimates of the social cost of carbon (SCC), which represents the marginal damage from increased emissions; the SCC must be greater than the marginal abatement cost for mitigation to be economically desirable. To determine the SCC, damage functions translate projections of carbon and temperature into economic losses. We examine the impact that four damage functions commonly employed in the literature have on the SCC. Rather than using an economic growth model, we convert the CO2 pathways from the Representative Concentration Pathways (RCPs) into temperature projections using a three-layer, energy balance model and subsequently estimate damages under each RCP using the damage functions. We estimate marginal damages for 2020-2100, finding significant variability in SCC estimates between damage functions. Despite the uncertainty in choosing a specific damage function, comparing the SCC estimates to estimates of marginal abatement costs from the Shared Socioeconomic Pathways (SSPs) indicates that reducing emissions beyond RCP6.0 is economically beneficial under all scenarios. Reducing emissions beyond RCP4.5 is also likely to be economically desirable under certain damage functions and SSP scenarios. However, future work must resolve the uncertainty surrounding the form of damage function and the SSP estimates of marginal abatement costs to better estimate the economic impacts of climate change and the benefits of mitigating it.

Serological and Molecular Detection of Anaplasma spp. in Blood From Healthy Horses: A Preliminary Study of Horses in East Texas.

Anaplasmosis is a disease caused by the bacterium Anaplasma phagocytophilum, which is spread by infected ticks. In horses, A. phagocytophilum generally causes transient infection characterized by fever, lethargy, inappetence, ventral edema, petechiae, icterus, ataxia, recumbency, muscle stiffness, and, in severe cases, death. Following natural infection, horses retain antibodies for approximately 2 years, which can be detected through an immunofluorescence antibody assay. Current infections are determined through PCR assay of white blood cell DNA. For this study, whole blood was collected from apparently healthy horses located in East Texas (n = 70), west Texas (n = 3), New York (n = 49), and New Jersey (n = 11) for the determination of serum antibodies and PCR testing of bacterial DNA. Of the 133 horses, 24 tested positive for DNA presence of A. phagocytophilum, and 107 tested positive for serum antibodies. Of the 24 horses testing positive for A. phagocytophilum, 16 were positive for serum antibody presence and 8 were negative. Twenty of the msp2 positive horses were located in East Texas and 4 resided in New York. For serum antibodies, 100% of New York and New Jersey horses tested positive, while only 66% of Texas horses tested positive. This study provides evidence that a large number of horses are exposed to A. phagocytophilum and that this bacterium is present in East Texas. No Texas horse owners reported treatment for anaplasmosis, and the currently infected horses were not demonstrating signs of illness at the time of sample collection. Further research to understand the differences in disease severity amongst equine populations is warranted.