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Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History

Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and pr...

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Autores principales: Cunningham, Susan J., Kruger, Andries C., Nxumalo, Mthobisi P., Hockey, Philip A. R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3861557/
https://www.ncbi.nlm.nih.gov/pubmed/24349296
http://dx.doi.org/10.1371/journal.pone.0082492
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author Cunningham, Susan J.
Kruger, Andries C.
Nxumalo, Mthobisi P.
Hockey, Philip A. R.
author_facet Cunningham, Susan J.
Kruger, Andries C.
Nxumalo, Mthobisi P.
Hockey, Philip A. R.
author_sort Cunningham, Susan J.
collection PubMed
description Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (T(thresh)) above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using T(thresh) values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (T(thresh) = 35.5°C) and the common fiscal Lanius collaris (T(thresh) = 33°C). We used these T(thresh) values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > T(thresh)), in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance) of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the T(thresh) technique as a conservation tool.
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spelling pubmed-38615572013-12-17 Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History Cunningham, Susan J. Kruger, Andries C. Nxumalo, Mthobisi P. Hockey, Philip A. R. PLoS One Research Article Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (T(thresh)) above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using T(thresh) values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (T(thresh) = 35.5°C) and the common fiscal Lanius collaris (T(thresh) = 33°C). We used these T(thresh) values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > T(thresh)), in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance) of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the T(thresh) technique as a conservation tool. Public Library of Science 2013-12-04 /pmc/articles/PMC3861557/ /pubmed/24349296 http://dx.doi.org/10.1371/journal.pone.0082492 Text en © 2013 Cunningham et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Cunningham, Susan J.
Kruger, Andries C.
Nxumalo, Mthobisi P.
Hockey, Philip A. R.
Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title_full Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title_fullStr Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title_full_unstemmed Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title_short Identifying Biologically Meaningful Hot-Weather Events Using Threshold Temperatures That Affect Life-History
title_sort identifying biologically meaningful hot-weather events using threshold temperatures that affect life-history
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3861557/
https://www.ncbi.nlm.nih.gov/pubmed/24349296
http://dx.doi.org/10.1371/journal.pone.0082492
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