polar bear politics a case study in forecasting anna whelan, orkney islands council forecasting and...
TRANSCRIPT
Polar Bear PoliticsA case study in forecasting
Anna Whelan, Orkney Islands Council
Forecasting and Projections Workshop Analysts Network, 1 July 2010
The Sunday Times, December 18, 2005Polar bears drown as ice shelf melts
Daily Mail, 01 February 2007 Global warming sees polar bears stranded on melting ice
Daily Telegraph, 15 Sep 2008 Polar bears 'could become extinct' because of melting ice, scientists claim
Al Gore, March 22, 2007
“Their habitat is melting… beautiful animals, literally being forced off the planet. They’re in trouble, got nowhere else to go.”
Should polar bears be listed under the US Endangered Species Act?
• Nine administrative reports were commissioned by the US Geological Survey in 2007 to “…Support U.S. Fish and Wildlife Service Polar Bear Listing Decision.”
• Listing decisions are made on the basis of long-term population forecasts
• The reports contained forecasts of polar bear populations for 2045, 2075 and 2100
Forecast methodology
• Forecasts used IPCC (Inter-governmental Panel on Climate Change) GCM (general circulation model) projections of the extent of sea ice in the Arctic
• GCM assumes that Arctic ice melt in recent years results from global warming
• Sea ice forecasts used as one of several variables in population variability analysis (PVA)
http://scienceandpublicpolicy.org/videos/armstrong_testimony.html
J. Scott Armstrong, Kesten Green & WillieSoon
Polar Bear Population Forecasts: A Public-Policy Forecasting Audit
Interfaces Vol 38 no. 5 Sep-Oct 2008
To make policy recommendations based on forecasts, the following assumptions are necessary:
(1) Global warming will occur and will reduce the amount of summer sea ice;
(2) Polar bears will not adapt; thus, they will obtain less food than they do now by hunting from the sea ice platform;
(3) Listing polar bears as a threatened or endangered species will result in policies that will solve the problem without serious detrimental effects; and
(4) Other policies would be inferior to those that depend on an Endangered Species Act listing.
How valid were the assumptions?
• No scientific evidence for global warming forecasts
• IPCC GCM sea ice forecasts are inaccurate from 1990 to present day
• Sea ice has decreased in the northern hemisphere and increased in the southern hemisphere
• NASA research indicates cause of Arctic ice melt to be a change in wind patterns
Armstrong principles cited
• Make forecasts independent of organizational politics
• Use all relevant data• Use the most recent data• Use simple forecasting methods• Be conservative in situations of high
uncertainty • Match the forecasting method(s) to the
situation
Expert forecasts are of no value in complex and uncertain situations, because of:
(1) Complexity: People cannot assess complex relationships through unaided observations.
(2) Coincidence: People confuse correlation with causation.
(3) Feedback: People making judgmental predictions typically do not receive unambiguous feedback that they can use to improve their forecasting.
(4) Bias: People have difficulty in obtaining or using evidence that contradicts their initial beliefs. This problem is especially serious among people who view themselves as experts.
BBC “Five live” Interview with Scott Armstrong during the International Conference on ClimateChange on March 9, 2009
Host: So what did your research actually say?...Professor: Well people aren’t sure how many polar bears there are but there seems to be a consensus… that they’ve been growing in numbers over the past few decades...Host: We’ve got a guy here, a very esteemed TV broadcaster and zoologist, David Attenborough. I don’t know if you know him, Scott. He put out this most heart wrenching documentary on the TV on national telly about a month ago showing the polar bears starving to death, the ice slopes melting, they can’t get to the seals anymore, population’s in decline. So David Attenborough wouldn’t be lying to us, would he?
Polar bear populations
• 19 delineated polar bear sub-populations
• 5 are declining
• 5 are stable
• 2 are increasing
• 7 have insufficient data to observe a trend
• Estimated total population 20-25,000
The Daily Telegraph, 27 Jun 2009
Polar bear expert barred by global warmists Top of the agenda at a meeting of the Polar Bear Specialist Group … will be the need to produce a suitably scary report on how polar bears are being threatened with extinction by man-made global warming…But one of the world's leading experts on polar bears has been told to stay away from this week's meeting, specifically because his views on global warming do not accord with those of the rest of the group.
Taylor, Mitchell and Dowsley, Martha
Demographic and Ecological Perspectives on the Status of Polar Bears
Science & Public Policy Institute, March 2008
Taylor and Dowsley
“The concern that polar bears will decline if the climate continues to warm is valid. However, the assertion that polar bears will become extinct unless immediate measures are taken to curb greenhouse gas emissions is irrational because it is inconsistent with the long-term persistence of polar bears through previous periods of warming and cooling…Currently polar bears are abundant and in no danger of extinction…”
Taylor and Dowsley contd
“Observations of natural mortality, intra-specific aggression, poor condition and even healthy bears in good condition on ice floes have been cited as evidence of population impacts on polar bears due to declining sea ice…
Anecdotal information, although useful and interesting, is not equivalent to scientific information based on valid statistical analysis of sample data.”
Taylor and Dowsley contd
“…traditional ecological knowledge (TEK) from Inuit has been largely ignored because TEK is mostly oral, and because TEK generally does not support the assertion that polar bear populations are in general, or even local decline.”
Taylor and Dowsley contd
“The popular notion that polar bears are declining…has been initiated and perpetuated by environmental organisations and individuals who apparently believe that current subpopulation numbers and trends are an insufficient basis for an appropriate status determination.”
Taylor and Dowsley contd
“Neither the demographic nor ecological perspectives suggest any conservation benefit from a premature decision to list polar bears as a “threatened species”. “The negative conservation implications from a premature up-listing include loss of scientific credibility, loss of support from aboriginal harvesters, and perhaps even reduced support for the Endangered Species Act as conservation legislation.”
Forecasting methods
• Quantitative forecasting: information is recorded externally and used explicitly
• Judgemental forecasting: information is recorded in human memory and used intuitively or implicitly
Quantitative bias
• Quantitative methods are objective and involve the identification and extrapolation of established patterns or existing relationships.
• Simple regression equation:Actual = α + β [forecast] + error
• Coefficients α and β are a measure of the bias observed in the forecasts compared with the actual values
How valid were the assumptions?
• No scientific evidence for global warming forecasts
• IPCC GCM sea ice forecasts are inaccurate from 1990 to present day
• Sea ice has decreased in the northern hemisphere and increased in the southern hemisphere
• NASA research indicates cause of Arctic ice melt to be a change in wind patterns
Long term quantitative forecasts
Three phenomena in particular affect accuracy at longer lead times:
1. many patterns are irregular and contain a high level of randomness
2. regular patterns may change over time
3. the forecasts themselves may influence the future
Evaluation is difficult because changes may occur post-forecast in the situation under review.
Henry Mintzberg
“Long-range [quantitative] forecasting (two years or longer) is notoriously inaccurate.”
It works only under limited conditions:1 When the world is stable or the trends are favourable2 When the world is under the control of the planning organisation3 When the policy adopted is one of scenario building followed by contingency planning – provided that the number of possible options is known and limited
In all other circumstances “the predetermination assumption of planning proves to be a fallacy”
Judgemental forecasting
• Requires no past data
• Can take into account future events (both known and anticipated
• Be aware of the “framing problem” – is the forecaster trying to
- predict the outcome precisely
- set an aspirational target
- err on the side of caution?
Judgemental bias
It ain’t so much the things we don’t know that gets us into trouble. It’s the things we know that ain’t so.
Artemus Ward (1834-1867)
Judgemental bias
• Belief bias – tendency to generate forecasts which confirm to prior beliefs and to be more critical of conclusions which conflict with beliefs
• Confirmation bias – tendency to test hypotheses in a manner likely to minimise rather than maximise their chance of falsification
• Illusory correlation – tendency to see correlations which are not statistically present but which are expected to occur on the basis on theories held
Nah, min; I don’t really buy intae the argument that wir winters ere gettan warse and warse…
Photographer was Amanda Byrd, a marine biology student on a field trip to Alaska in 2004
“The time of year was August, summer.
“Dan Crosbie gave the image to the Canadian Ice Service, who gave the image to Environment Canada, who distributed the image to 7 media agencies including Associated Press.
“They did not appear to be in danger…I did not see the bears get on the ice, and I did not see them get off. I cannot say either way if they were stranded or not.
“I take neither stand, I simply took the photos...If I released the image myself, it would have been as a striking image. Nothing more.”
Email from Amanda Byrd to ABC Television, Australia
http://www.nationalcenter.org/PolarBear.html
For discussion
• Have you ever been asked to produce forecasts to back up a policy decision? What happens if the forecasts don’t match the policy?
• How is the framing problem affecting forecasts of the effects of public sector funding cuts?
• Why might various parties want to over- or under-estimate population forecasts? To which forms of bias might they be susceptible?