IUCN Polar Bear Specialist Group says its global population estimate was “a qualified guess” !
“As part of past status reports, the PBSG has traditionally estimated a range for the total number of polar bears in the circumpolar Arctic. Since 2005, this range has been 20-25,000. It is important to realize that this range never has been an estimate of total abundance in a scientific sense, but simply a qualified guess given to satisfy public demand. It is also important to note that even though we have scientifically valid estimates for a majority of the subpopulations, some are dated. Furthermore, there are no abundance estimates for the Arctic Basin, East Greenland, and the Russian subpopulations. Consequently, there is either no, or only rudimentary, knowledge to support guesses about the possible abundance of polar bears in approximately half the areas they occupy. Thus, the range given for total global population should be viewed with great caution as it cannot be used to assess population trend over the long term.”