Tag Archives: summer ice minimum

What polar bear habitat could look like in another 5-6 weeks

According to the National Snow and Ice Data Center (NSIDC, Sept. 20 report), the annual sea ice minimum extent was reached on Sept. 13, 2013.

At 5.10 million square kilometers, this year’s low was a whopping 1.69 million square kilometers above the minimum extent for 2012 (which was the lowest since 1979) and well within two standard deviations of the 1979-2010 average. (Two standard deviations: “Measurements that fall far outside of the two standard deviation range or consistently fall outside that range suggest that something unusual is occurring that can’t be explained by normal processes”).

The minimum extent for 2013 is virtually indistinguishable from the minimum for 2009, which was 5.13 million square kilometers. The ice was distributed a bit differently in 2009 – more in the east and less in the west — than it was this year (see Fig. 1 below).

Figure 1. Using the JAXA “Sea ice monitor” feature, I plotted the date the 2013 minimum was reached (September 13, 5.10 million square kilometers, white) with an overlay (purple) for the same date back in 2009 (September 13, 2009, 5.13 million square kilometers), when that year’s minimum was reached (according to the NSIDC report). Areas of overlap are pink.

Figure 1. I used JAXA to plot the date the 2013 minimum was reached (September 13, 5.10 million square kilometers, white) with an overlay (purple) for the same date back in 2009 (September 13, 2009, 5.13 million square kilometers), when that year’s minimum was reached. Areas of overlap are pink.

You’ll know from previous discussions here that the annual minimum reached in late summer has little impact on polar bear health and survival (see excellent summary of the evidence for that here). What matters most to polar bears is the presence of ample ice in spring and early summer (March-June), which is their critical feeding period.

But after the fast that many polar bears endure over the height of the summer, they are eager to get back onto the ice and resume hunting. When in the fall does that become possible?

I wondered what the similarity in extent for 2013 and 2009 might tell us about polar bear habitat development over the next month or so.

In other words, what might polar bears this year expect in the way of sea ice development by say, the end of October? When might they be able to start hunting?

Continue reading

Record sea ice loss in 2007 had no effect on polar bears, Chukchi study confirms

One aspect of the recently published study on Chukchi Sea polar bears (Rode et al.2014 [now in print] 2013; see here and here) has not been stressed enough: their finding that the differences in overall condition between bears in the Chukchi and Southern Beaufort Seas came down to disparities in spring feeding opportunities and therefore, the condition of spring sea ice.

The fact that spring — not summer — is the most critical period for polar bears is something I’ve pointed out before (see here and here, for example) but it’s worth repeating at this time of year, when all eyes are on the annual ice minimum. It is often treated as a given that the decline in extent of summer sea ice in the Arctic since 1979 has been detrimental to polar bears. However, this is an assumption that we can now say is not supported by scientific evidence (see summary of that evidence here).

The results published by Rode et al. (2014 2013) not only add further support to the conclusion that declines in summer sea ice have not harmed polar bears, but should put the matter to rest – unless new evidence to the contrary is produced.

Chukchi bears, the report tells us, had more food available in the spring than Southern Beaufort bears (see map below) and this was the primary reason that bears were doing very well in the Chukchi and not quite as well in the Southern Beaufort. And because the polar bears for this study were captured and measured in mid-March to early May, from 2008 to 2011, they reflect spring-time conditions for 2008-2011 as well as year-round conditions from 2007 through 2010.

This means that the annual low ice extent for 2007 (record-breaking at the time), in the fall before this study began, had no discernible negative effect on either Chukchi or Southern Beaufort polar bears – and neither did similarly low annual minimums in two of the three remaining years of the study (Fig 1).

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in September 2008 and 2010, while 2009 was more like 2013.

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in 2008 and 2010, while 2009 was more like 2013.

Continue reading

How and why great news about Chukchi polar bears has been suppressed

A new peer-reviewed report (Rode et al. 2014 [in print] 2013, accepted), released last month (announced here), documents the fact that polar bears in the Chukchi Sea are doing better than virtually any other population studied, despite significant losses in summer sea ice over the last two decades – even though the Polar Bear Specialist Group (PBSG) said this population was declining (Obbard et al. 2010).

Rode and Regehr 2010_Chukchi_report2010_Fig1_triplets_labelled

Rather than this good news being shouted far and wide, what we’ve seen so far is a mere whisper. The strategy for suppressing the information appears to have several parts: make it hard to find; don’t actively publicize it; down-play the spectacularly good nature of the news; minimize how wrong they were; keep the focus on the future.

Something similar happened with the newly-published paper on Davis Strait bears (Peacock et al. 2013, discussed here and here) but the news there wasn’t quite so shockingly different from expected. The suppression of good news stands in marked contrast to anything with a hint of bad news, which gets reported around the world — for example, Andrew Derocher and colleagues and their prepare now to save polar bears” policy paper in February, 2013.

US Fish & Wildlife biologist Eric Regehr, co-investigator of the Chukchi study and co-author of the newly-published report, wrote an announcement about the paper. It wasn’t a real press release, since it was not actually sent to media outlets. It was a statement, with a brief summary of the paper, posted on a regional US Fish & Wildlife website, with no mention of lead author Karyn Rode. Not surprisingly, lack of active promotion = no media coverage.

The posted announcement also down-played how well the Chukchi bears are doing. In fact, the news documented in the paper is much better than any of them let on: Chukchi polar bears are doing better than virtually all other populations studied.

But Regehr also had to do some damage control to counter the evidence this paper contains of how wrong they had all been — not only about the Chukchi population today but about their predictions for polar bears in the future.

After all, the computer models used to predict a dire future for polar bears combined the Chukchi Sea with the Southern Beaufort, as having similar ice habitats (“ice ecoregions”). The published paper and Regehr’s statement now say these two regions are very different and that polar bear response to loss of sea ice is “complex” rather than a simple matter of less summer ice = harm to polar bears. Regehr goes on to say that polar bear scientists expected this would happen. I call total BS on this one, which I explain in full later (with a map).

Finally, Regehr’s statement emphasizes that good news for 1 subpopulation out of 19 today should not be celebrated because the overall future for polar bears — prophesied by computerized crystal balls — is bleak. Focus on the future, they say. Did they forget that for years they’ve been telling us that polar bears are already being harmed and that this foreshadows what’s to come? Now we have the results of yet another peer-reviewed study showing bears not being harmed by declines in summer ice (see the full list here).

So, in the end, all of this double-talk and contradiction is not just about suppressing this particular paper. There’s much more at stake.

The Rode et al. Chukchi paper is strong evidence that their predictions of a grim future for polar bears – based on theoretical responses to summer sea ice declines that should already be apparent – have been refuted by their own studies. It’s no wonder they want to keep the media away from this story.

Details below.  [Update September 11, 2013: another news outlet picks up the story, see Point 2 below]

Continue reading

Tracking polar bears in the Beaufort Sea: August map

Here is the follow-up I promised to my post on the July track map for polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice. See that post for methods and other background on this topic, and some track maps from 2012.

The track map for August was posted on the USGS website on September 4th and is copied here below (Figure 1). The ice moved a bit further offshore during August but not nearly as far as it did in 2012. The ten bears from July were down to eight – their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died (the researchers don’t say which).

 Figure 1. “Movements of 8 satellite-tagged polar bears for the month of August, 2013. Polar bears were tagged in 2013 on the spring-time sea ice of the southern Beaufort Sea. All 8 of these bears have satellite collar transmitters [i.e., all are females]. Polar bear satellite telemetry data are shown with Ice Analysis charts from 26 August, 2013. Ice Analysis charts are made available by the National Ice Center. The land cover is made available by Natural Earth. Click on the above image to enlarge.”[Note that the dots with the polar bear icons are the end points (end August), while the other end of the string is their position in early August. The yellow dot is behind the purple dot, on shore; two of the bears present in July (see Fig. 2 below) are no longer being tracked - their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died. The researchers don’t say.]


Figure 1. “Movements of 8 satellite-tagged polar bears for the month of August, 2013. Polar bears were tagged in 2013 on the spring-time sea ice of the southern Beaufort Sea. All 8 of these bears have satellite collar transmitters [i.e., all are females]. Polar bear satellite telemetry data are shown with Ice Analysis charts from 26 August, 2013. Ice Analysis charts are made available by the National Ice Center. The land cover is made available by Natural Earth. Click on the above image to enlarge.” [Note that the dots with the polar bear icons are the end points (end August), while the other end of the string is their position in early August. The yellow dot is behind the purple dot, on shore; two of the bears present in July (see Fig. 2 below) are no longer being tracked – their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died. The researchers don’t say.]

So, of the eight polar bears still being followed by USGS researchers in August, three were on shore and five were on the ice. Only time will tell if the three females on shore are pregnant and preparing maternity dens for the winter, but this seems the likely reason they are not on the ice with the others.

I’ll post the track map for September when it is available in early October at the USGS website.

The map for July 2013 is below, for comparison: Continue reading

Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice

PB_male on ice_Regehr USFWS_March 2010_labeledTracking Beaufort Sea polar bears over the summer — what can it tell us about how important the position of summer sea ice relative to the shoreline in this region is to these bears? Do Beaufort Sea bears get stranded on shore like the polar bears in Davis Strait and Hudson Bay?

Polar bear biologist Eric Regehr (with the US Fish & Wildlife Service, or FWS) has a team working with US Geological Survey researchers (USGS) in the southern Beaufort tracking where adult female polar bears go throughout the year. This is part of on-going research in the Beaufort and Chukchi Sea (see previous post here; see also Fish & Wildlife 2009; Polar Bear News 2010 and 2013; Rode and Regehr 2010, pdfs below; and just out, the “accepted” version of the Rode et al. paper discussed here, and announced in my last post here).

The researchers have been posting a summary map at the end of each month on the USGS website showing the tracks of the females they fitted with radio collars the previous spring — for 2013, and back to 2010. They can’t put collars on male bears because their necks are larger around than their heads, so a collar would just slip off.

I’ve posted the July 2013 track map below, which shows all ten bears out on the ice, and the previous month (June 2013) to compare it to (the August map should be out shortly). I’ve included a few maps from 2012 to allow you to compare this year’s results to the situation last summer.

The August tracks should be available after the Labour Day weekend – check back next week to see where the bears have been this month. I’ll post the map here or you can go to the USGS website directly. [UPDATE Sept 4, 2013: The August map is up, posted here.]

Continue reading

Polar bears have not been harmed by sea ice declines in summer – the evidence

PB  logo colouredThe 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.
Continue reading

Biologists spreading misinformation: hybridization with grizzlies not due to polar bears moving inland

A paper published last week in the journal Science, written by a team of biologists and atmospheric scientists, expounds on a possible dire future for a range of Arctic animals. It’s called, “Ecological consequences of sea-ice decline” and surprisingly, polar bears are discussed only briefly.

However, with the inclusion of one short sentence, the paper manages to perpetuate misinformation on grizzly/polar bear hybridization that first appeared in a commentary essay three years ago in Nature  (Kelly et al. 2010)1. The Post et al. 2013 missive contains this astonishing statement (repeated by a Canadian Press news report):

Hybridization between polar bears and grizzly bears may be the result of increasing inland presence of polar bears as a result of a prolonged ice-free season.

Lead author of the paper, Professor of Biology Eric Post, is quoted extensively in the press release issued by his employer (Penn State University, pdf here). In it, Post re-states the above sentence in simpler terms, removing any doubt of its intended interpretation:

“… polar and grizzly bears already have been observed to have hybridized because polar bears now are spending more time on land, where they have contact with grizzlies.

Both statements are patently false. All recent hybridization events documented (2006-2013) occurred because a few male grizzlies traveled over the sea ice into polar bear territory and found themselves a polar bear female to impregnate (see news items here and here, Fig. 1 below). These events did not occur on land during the ice-free season (which is late summer/early fall), but on the sea ice in spring (March-May).

Grizzlies have been documented wandering over the sea ice of the western Arctic since at least 1885 (Doupe et al. 2007; Fig. 2, below) and the presence in this region of hybrid grizzly/polar bear offspring is not an indicator of declining summer sea ice, whether due to global warming or natural causes, or some combination thereof.

Continue reading