The new paper, by a team of scientists from the U.S. Geological Survey (USGS), Woods Hole Oceanographic Institution (WHOI), University of Alaska, University of Maryland, Canadian Wildlife Service and the US Forest Service, refutes point-by-point a widely publicized critique of polar bear population predictions.
The new rebuttal reinforces the reports written by the scientists and accepted by the Department of Interior in its May 2008 decision to list polar bears as a threatened species on the U.S. Endangered Species Act.
“The decision to list the polar bear as threatened was politically charged, and the scientific research on which it was based attracted some criticisms. Our new study shows that the critique is incorrect and based on misconceptions about climate models, the Arctic environment, polar bear biology, and statistical and mathematical methods,” said WHOI biologist Hal Caswell, an author on two of the USGS reports and of the rebuttal.
The rebuttal was published in the journal Interfaces online on April 22, 2009, and will be published in the July-August print edition. The journal recently made the article available for free to the public.
In 2007 when the Department of the Interior was considering listing the polar bear under the Endangered Species Act, it asked the USGS to assemble an international team to analyze information on polar bear populations. The team included Hal Caswell, a mathematical ecologist who specializes in developing population models.
Caswell, along with former WHOI postdoctoral investigator Christine Hunter, and researchers from the USGS and other universities and agencies, developed new models that incorporated USGS-collected information about polar bears’ mortality rates, birth rates, life cycles, and habitats. They coupled these models to projections of Arctic climate changes, especially forecasts of sea ice conditions. They calculated the interplay of all these factors – some 10,000 simulations – to estimate the probabilities of future polar bear population growth or decline. Through their study, Caswell,Hunter, and their colleagues were able to link Arctic sea ice directly to population growth.
The USGS-led group presented its reports in fall 2007, and in May 2008, the Department of Interior listed the polar bear as a threatened species under the US Endangered Species Act.
Following that listing, a critique of the USGS reports was published in the Sept.-Oct. 2008 issue of Interfaces, a journal that specializes in management and operations research. Its lead author, Scott Armstrong, a professor of marketing at the University of Pennsylvania, is a key architect of a set of principles on the science of forecasting, which are intended to provide guidance on which methods to use under different circumstances. The principles were derived from such fields as economics, finance, management, politics, medicine, and weather.
In performing its “audit” of the USGS reports, Armstrong’s group applied its set of forecasting principles and claimed that nearly 70 percent of them had been contravened by the USGS reports. The authors of the forecasting audit include a physicist and two economists but do not include biologists, oceanographers or climate scientists.
“We debated writing something short outlining why we don’t think their criticism are valid,” said Caswell. “After going through their report, however, we decided we needed to do a rebuttal of this, and in the end, we went point by point to refute their criticism.”
Caswell continued: “We began by explaining why the sea ice habitat of polar bears is declining and showing how climate models, outputs from which we used as inputs to our analyses, are reliable for forecasting the future climate. Then we showed how each specific criticism of the Armstrong team was either wrong or misleading. Finally, we took a look at their principles of forecasting, and found they are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations.”
The rebuttal concludes that the audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public policy debate.
In the meantime, the USGS continues to collect data in Alaska and Caswell says he will be involved in further analyses of the polar bear populations based on the new data.
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
WHOI Media Relations | EurekAlert!
Further reports about: > Arctic > Arctic climate changes > Arctic environment > Oceanographic Institution > Polar Bear-Climate Connection > Polar Day > USGS > WHOI > climate models > endangered species > polar bear biology > polar bear populations > polar bears > population growth > sea ice > species
Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)
Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy