“Although there have been jumps and dips, average atmospheric temperatures have risen little since 1998, in seeming defiance of projections of climate models and the ever-increasing emissions of greenhouse gases.” Jeff Tollefson, January 15, 2014, Nature. [open access]
The eminent science journal Nature has finally acknowledged that global average temperatures have not behaved as predicted by climate models over the last 16 years. [h/t A. Watts]
Note that predictions of future sea ice declines and associated predictions of future polar bear declines are totally dependent on these climate models.
Here’s my question: if global temperatures have basically flat-lined since 1998, why has Arctic sea ice continued to decline?
If average global temperatures govern Arctic sea ice behavior, why was 1998 (or the year after) not the lowest September sea ice extent reached over the last 30 years? Oddly, 2012 was the lowest September extent (see graphs below, from NSIDC).
Paradoxically, not only has sea ice continued to decline since 1998 – despite the hiatus in global warming – but since 1998, all but one polar bear populations have either increased in size, not declined, or are doing very well by other measures (see previous summary post, “Polar bears have not been harmed by sea ice declines“).
Sea ice extent graphs for September (which all the hysteria is about) compared to selected months from March, June and November. Ranges given are approximate; note the differences in scale for each graph. NSIDC graphs, colored labels added.
The polar bear biologists and professional activists of the IUCN Polar Bear Specialist Group (PBSG) continue to insist that since 1979 increasingly smaller amounts of Arctic sea ice left at the end of summer (the September ice minimum) have already caused harm to polar bears. They contend that global warming due to CO2 from fossil fuels (“climate warming” in their lexicon) is the cause of this decline in summer ice.
In a recent (2012) paper published in the journal Global Change Biology (“Effects of climate warming on polar bears: a review of the evidence”), long-time Canadian PBSG members Ian Stirling and Andrew Derocher (both of University of Alberta) summarized their position this way:
“Climate warming is causing unidirectional changes to annual patterns of sea ice distribution, structure, and freeze-up. We summarize evidence that documents how loss of sea ice, the primary habitat of polar bears (Ursus maritimus), negatively affects their long-term survival”
I’ve spent the last year examining their evidence of on-going harm, but in addition, I’ve looked at the evidence (much of it not mentioned in the Stirling and Derocher paper1) that polar bears have either not been harmed by less sea ice in summer or have thrived in spite of it.
This is a summary of my findings. I’ve provided links to my original essays on individual topics, which are fully referenced and illustrated. You are encouraged to consult them for complete details. This synopsis (pdf with links preserved, updated; pdf with links as footnotes, updated) complements and updates a previous summary, “Ten good reasons not to worry about polar bears” (pdf with links preserved; pdf with a foreword by Dr. Matt Ridley, with links as footnotes).
Update 8 September 2013: to include links to my post on the recently published Chukchi population report; updated pdfs have been added above.
Update 22 January 2014: added figure comparing March vs. September sea ice extent using the same scale, from NOAA’s “2014 Arctic Report Card,” discussed here.
Posted in Conservation Status, Population, Sea ice habitat, Summary
Tagged Arctic, Barents Sea, Beaufort Sea, body condition, breakup dates, cannibalism, Chukchi, climate change, climate warming, Davis Strait, death spiral, Derocher, global warming, harm to polar bears, heavy sea ice, Hudson Bay, hybridization, ice-free, negative effects, polar bear, polar bear numbers increasing, Polar Bear Specialist Group, Polar Bears International, prolonged ice-free season, ringed seals, sea ice, sea ice decline, September ice minimum, Stirling, summary, summer ice minimum, victim of climate change