A simple Bayesian method of inferring extinction : comment

Author Posting. © Ecological Society of America, 2016. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 97 (2016): 796–798, doi:10.1890/15-0336.1

River dolphins can act as population trend indicators in degraded freshwater systems : comment

Author Posting. © Ecological Society of America, 2015. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 96 (2015): 2027-2028, doi:10.1890/14-1900.1

An ENSO shift revisited

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 33 (2006): L22602, doi:10.1029/2006GL027632.An influential 1996 paper presented a statistical analysis showing that the prolonged ENSO warm event of the early 1990's was inconsistent with the historical pattern of ENSO variability and therefore concluded that there had been a shift in ENSO behavior possibly connected to global warming. A fundamental problem with this earlier analysis is that the data used to test for a shift in ENSO behavior were not independent of the data used to identify the hypothetical shift. A new analysis is presented that avoids this problem by using more recent data. The results raise a question about the earlier finding.This work was supported by NSF grant DEB-0515639

Characterizing the error in the estimated age-depth relationship

Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2003. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 45 (2003): 501-509.It is common practice to estimate the age of undated material extracted from a sediment core from radiocarbon or other radiometric dates of samples taken above and below the extracted material. This paper presents a simple expression for the variance of this estimated age. This variance accounts for both 14C dating error and error due to bioturbation

A nonparametric test for change in variability using a proxy record with an application to ENSO

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L19708, doi:10.1029/2008GL035400.A common problem in climate science is determining whether the pattern of variability in a particular process or variable has changed over time. When the modern observational record is short, this problem can be addressed by comparing its variability to that of an historical proxy record. In doing so, it is important to recognize that the statistical properties of the modern and proxy records are different. Here, a nonparametric test for a change in variability in this situation is described that accounts for this difference. The method is illustrated by testing for a change in ENSO variability using a record of an ENSO index over the period 1871–2007 and oxygen isotope records extracted from corals at Palmyra Island that cover four different periods spanning the past millennium. The results are mixed.Partial funding for this work was provided by NSF Grant DEB-0515639

Method for reconstructing climate from fossil beetle assemblages

Author Posting. © Royal Society, 2004. This article is posted here by permission of Royal Society for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society of London B 271 (2004): 1125-1128, doi:10.1098/rspb.2004.2706.Fossil beetle remains have been used to reconstruct temperatures. One method by which these reconstructions are made--the Mutual Climatic Range method--is based on the overlap of the observed modern climatic ranges of the beetles present in a fossil sample. A limitation of this method is that it does not exploit variations in the rate of occurrence of a species within its climatic range. We present an alternative method that uses observed variations in this rate in modern data for climate reconstruction. The method is shown to perform well in an experiment using modern data from North America

On the incompleteness of the historical record of North Atlantic tropical cyclones

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L11803, doi:10.1029/2008GL033546.There is some question as to whether the historical record of observed North Atlantic tropical cyclones prior to the advent of satellite coverage is complete. This question is central to understanding the historical trend in tropical cyclone activity and the effect of environmental factors on it. To address this question, a statistical model of the relationship between annual cyclone counts between 1870 and 2004 and sea surface temperature and the state of the Southern Oscillation is extended to allow for non-decreasing observation probability prior to 1966. The estimated observation probabilities increase from 0.72 in 1870 to 1 in 1964. Allowing for record incompleteness reduces the estimated effect of sea surface temperature on annual tropical cyclone activity.This work was supported by NOAA Grant NA17RJ1223

On predicting abundance from occupancy

Author Posting. © University of Chicago, 2010. This article is posted here by permission of University of Chicago for personal use, not for redistribution. The definitive version was published in American Naturalist 176 (2010): 96-98, doi:10.1086/653077.There is growing interest in predicting the abundance of a species in a region from the occupancy of cells in a uniform grid overlaid on the region. When the number of individuals in each cell follows a negative binomial distribution, prediction is in general not possible from the number of unoccupied cells alone. A prediction method based on the number of unoccupied cells and the number containing a single individual is described and shown to work well on simulated and real data

Inferring functional extinction based on sighting records

© The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biological Conservation 199 (2016): 84-87, doi:10.1016/j.biocon.2016.04.034.The term functional extinction is used to describe a permanent failure of reproduction or recruitment in a population. Functional extinction results in a truncation of the age distribution, but this can be very difficult to detect in poorly studied populations. Here, we describe a novel statistical method for detecting functional extinction based on a sighting record of individuals of known or estimated ages. The method is based on a simple population dynamics model and simulation results show that it works well even with limited data. The method is illustrated using a sighting record of the ship sturgeon (Acipenser nudiventris) in the Danube River. The results indicate that this population is functionally extinct, most likely by 2002. Management implications of this finding are discussed.The authors also acknowledge the sponsorship provided by the Alexander von Humboldt Foundation and the Federal German Ministry for Education and Research, as well as the support by the Project No. 173045, funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia.2017-05-1

On the attribution of a single event to climate change

Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 27 (2014): 8297–8301, doi:10.1175/JCLI-D-14-00399.1.There is growing interest in assessing the role of climate change in observed extreme weather events. Recent work in this area has focused on estimating a measure called attributable risk. A statistical formulation of this problem is described and used to construct a confidence interval for attributable risk. The resulting confidence is shown to be surprisingly wide even in the case where the event of interest is unprecedented in the historical record.GH acknowledges funding from the Federal Ministry for Education and Research. MA acknowledges partial support from the Giannini Foundation.2015-05-1