from: Tim Osborn <t.osbornatXYZxyz.ac.uk>
subject: recently submitted paper abstract
we decided a while ago that when papers are submitted we should email
around a copy of the abstract to everyone in CRU so we can keep up
with forthcoming work and not be taken by surprise when some relevant
work gets published. I keep forgetting to do this (as do
others)! But, in case anyone out there has an interest in polar
bears, this has just been submitted....
O'Neill SJ, Osborn TJ, Hulme M, Lorenzoni I, Watkinson AR (2007)
Expert assessment of the uncertainties of polar bear population
dynamics under climate change. Submitted to Journal of Applied Ecology.
Polar bear population dynamics under climate change has become a
controversial topic. A survey of expert opinion (the first ever
undertaken for a particular species) based on modelled sea-ice data
was performed in order to quantify the trends and variance
surrounding possible impacts of climate change on polar bear populations.
1. Polar bears Ursus maritimus have become an iconic species in the
communication of climate change, with media coverage implying a rapid
population decline. This contrasts with scientific research, which
indicates that most populations are currently stable or growing.
Negative impacts of climatic warming on polar bears have been
suggested, but cannot be quantified as no models yet exist to analyse
the relationship between polar bear population dynamics and climate change.
2. Ten polar bear experts participated in an expert opinion survey,
quantifying the trends and variance surrounding possible impacts of
climate change on polar bear populations. The experts were provided
with maps and time series of sea-ice extent and duration to 2050,
simulated under mid-range emissions scenario SRES A1B. Expert
responses for future polar bear habitat range and population size
across the Arctic, and for population size in five regions, were
obtained. Experts were asked to define 'best conservation practice',
and to re-evaluate the total Arctic population projection if this
best practice was implemented.
3. Most experts project a substantial decline in polar bear range and
population across the Arctic, and in population across each region.
Expert best estimates for total Arctic polar bear population size lie
from no change to a 70% decrease relative to today; with half the
experts projecting at least a 30% decrease. The median best estimates
show the Barents Sea, Hudson Bay and the Chukchi Sea populations
experiencing the greatest population decline under this scenario.
There is much uncertainty both within and between expert responses,
especially in little-researched regions such as the Chukchi Sea.
4. Synthesis and Applications. The responses of experts suggest polar
bear populations will undergo significant declines by 2050, even
implementing best management practices, under the scenario of
climatic warming outlined here. In order to minimise population
decline many experts believed that a precautionary approach to
hunting is needed. However, unless conservation management of polar
bears is teamed with global mitigation efforts there is little
prospect of preventing significant population declines.
Dr Timothy J Osborn, Academic Fellow
Climatic Research Unit
School of Environmental Sciences
University of East Anglia
Norwich NR4 7TJ, UK