Communicating uncertainty: lessons learned and suggestions for climate change assessment

Assessments of climate change face the task of making information about uncertainty accessible and useful to decision-makers. The literature in behavior economics provides many examples of how people make decisions under conditions of uncertainty relying on inappropriate heuristics, leading to inconsistent and counterproductive choices. Modern risk communication practices recommend a number of methods to overcome these hurdles, which have been recommended for the Intergovernmental Panel on Climate Change (IPCC) assessment reports. This paper evaluates the success of the most recent IPCC approach to uncertainty communication, based on a controlled survey of climate change experts. Evaluating the results from the survey, and from a similar survey recently conducted among university students, the paper suggests that the most recent IPCC approach leaves open the possibility for biased and inconsistent responses to the information. The paper concludes by suggesting ways to improve the approach for future IPCC assessment reports. To cite this article: A. Patt, S. Dessai, C. R. Geoscience 337 (2005).     

Taking the uncertainty in climate-change vulnerability assessment seriously

Climate-change vulnerability assessment has become a frequently employed tool, with the purpose of informing policy-makers attempting to adapt to global change conditions. However, we suggest that there are three reasons to suspect that vulnerability assessment often promises more certainty, and more useful results, than it can deliver. First, the complexity of the system it purports to describe is greater than that described by other types of assessment. Second, it is difficult, if not impossible, to obtain data to test proposed interactions between different vulnerability drivers. Third, the time scale of analysis is too long to be able to make robust projections about future adaptive capacity. We analyze the results from a stakeholder workshop in a European vulnerability assessment, and find evidence to support these arguments. To cite this article: A. Patt et al., C. R. Geoscience 337 (2005).     

IAGC and IAEA Interlaboratory Comparisons of Geothermal Water Chemistry: The Propagation of Uncertainty in the Reservoir pH Calculation

A statistical evaluation of the results of geochemical analyses of geothermal waters during interlaboratory comparison programmes of the International Association of Geochemistry and Cosmochemistry (IAGC) and International Atomic Energy Agency (IAEA) was performed to estimate the uncertainty of measurement of pH, electrical conductivity, Na⁺, K⁺, Ca2⁺, Mg²⁺, Li⁺, Cl^?, HCO₃^?, SO₄^2?, SiO₂ and B. The uncertainty of measurement was found to increase exponentially with decrease in value (concentration) for all the parameters except for pH, electrical conductivity and SiO₂ and was of the same order of magnitude as the concentrations for values of less than 1 μ ml^?1. There was an overall uncertainty of ± 2.5% in the measurement of pH and ± 30% in SiO₂. For all the other chemical species the uncertainty data were modelled by exponential curves. The sample IAEA14 was prepared by dissolving commercial reagents (i.e., represents a solution of known composition). Thus, the calculated values are considered to be the conventional true values for each chemical parameter. The difference between the measured mean of the data submitted by participating laboratories and the conventional true value for each parameter (i.e., bias of submitted measurements) for the species Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^? and SO₄^2? was ‐3.5, ‐1.1, ‐13.3, ‐53.6, ‐12.6 and ‐86.6%, respectively. The observed bias was of the same order of magnitude as statistical fluctuations (1s) for Na⁺ and K⁺, but significantly higher for Ca²⁺, Mg²⁺, Cl^? and SO₄^2?. Two methods, uncertainty interval and GUM (“guide to the expression of uncertainty of measurement”) were used to propagate uncertainty in the pH calculation of geothermal reservoir fluid. The application of the methods is illustrated by considering the IAEA10 and IAEA11 samples analysed in the interlaboratory comparisons as separated geothermal waters at atmospheric pressure.     

Constraints on the ore fluids in the Sando Alcalde AuAg epithermal deposit,southwestern Peru: fluid inclusions and stable isotope data

The Sando Alcalde ore deposit (southwestern Peru) has been studied in order to characterize the physicochemical parameters of the ore fluids and to determine the fluid process (mixing or boiling) which involves the precious metal mineralization. Mineralogy, ${\delta }^{18}{\mathrm{O}}_{\mathrm{quartz}}$ isotopic values and fluid inclusion data give arguments in favour of a boiling phenomenon. This conclusion corroborates fluid inclusion studies previously performed in this area on the low-sulphidation epithermal deposits of Arcata, Orcopampa and Apacheta, where boiling has been described as the main factor for ore deposition. To cite this article: A.-S. André-Mayer et al., C. R. Geoscience 337 (2005).     

Rhinocerotid tooth enamel 18O/16O variability between 23 and 12 Ma in southwestern France

The relationship between the oxygen isotope ratio of mammal tooth enamel and that of drinking water was used to reconstruct changes in the Miocene oxygen isotope ratio of rainfall (meteoric water ${\delta }^{18}$O_MW). These, in turn, are related to climatic parameters (temperature, precipitation and evaporation rate). ${\delta }^{18}$O values of rhinocerotid teeth from the Aquitaine Basin (southwestern France) suggest a significant climatic change between 17 and 12 Ma, characterized by cooling together with precipitation increase, in agreement with other terrestrial and oceanic records. To cite this article: I. Bentaleb et al., C. R. Geoscience 338 (2006).     

Matrix Corrections and Error Analysis in High‐Precision SIMS 18O/16O Measurements of Ca–Mg–Fe Garnet

We report technical and data treatment methods for making accurate, high‐precision measurements of ¹⁸O/¹⁶O in Ca–Mg–Fe garnet utilising the Cameca IMS 1280 multi‐collector ion microprobe. Matrix effects were similar to those shown by previous work, whereby Ca abundance is correlated with instrumental mass fractionation (IMF). After correction for this effect, there appeared to be no significant secondary effect associated with Mg/Fe²⁺ for routine operational conditions. In contrast, investigation of the IMF associated with Mn‐ or Cr‐rich garnet showed that these substitutions are significant and require a more complex calibration scheme. The Ca‐related calibration applied to low‐Cr, low‐Mn garnet was reproducible across different sample mounts and under a range of instrument settings and therefore should be applicable to similar instruments of this type. The repeatability of the measurements was often better than ± 0.2‰ (2s), a precision that is similar to the repeatability of bulk techniques. At this precision, the uncertainties due to spot‐to‐spot repeatability were at the same magnitude as those associated with matrix corrections (± 0.1–0.3‰) and the uncertainties in reference materials (± 0.1–0.2‰). Therefore, it is necessary to accurately estimate and propagate uncertainties associated with these parameters – in some cases, uncertainties in reference materials or matrix corrections dominate the uncertainty budget.