US National Snow and Ice Data Center says the Arctic maximum extent for this winter peaked at 14.88 mkm2 on 25 February, but in fact this amount of ice coverage lasted for at least two weeks (22 February – 8 March), with very slight variation. Just a little something they all left out of their announcements, for some reason.
Comments Off on Arctic sea ice maximum extent was present for at least two weeks at about 14.9 million km2
Posted in Sea ice habitat
Tagged habitat, maximum extent, NSIDC, peak, polar bear, sea ice, winter
The most positive thing that US National Snow and Ice Data Center sea ice experts could say about this year’s winter sea ice maximum was that it wasn’t a record breaker. But it provides ample polar bear habitat when the bears need it most: just before the critical spring feeding season.
In fact, they said: “The 2020 maximum sea ice extent is the eleventh lowest in the 42-year satellite record, but the highest since 2013.” All that winter ice is essential polar bear habitat just before the critical spring feeding season (Crockford 2019, 2020) and it’s one of the reasons that polar bears are thriving.
Comments Off on Winter sea ice maximum extent on March 5 was the highest since 2013
Posted in Life History, Sea ice habitat
Tagged habitat, NSIDC, polar bear, sea ice, spring feeding, video, winter
We’ve hit the seasonal Arctic sea ice minimum for this year, called this morning by US NSIDC for 19th and 23rd of Septmeber: 4.59 mkm2, the same extent as 2008 and 2010. This is not a “ho-hum” year for polar bears: it means that since 2007, they have triumphed through 10 or 11 years1 with summer ice coverage below 5.0 mkm2 — levels that in 2007 were expected to cause catastrophic declines in numbers.
Summer sea ice below 5.0 mkm2 were not expected to occur until about 2050, according to 2005/2006 sea ice models and polar bear specialists at the US Geological Survey (USGS). Polar bear survival models predicted 2/3 of the world’s polar bears would disappear when ice levels reached this threshold for 8 out of 10 years (Amstrup et al. 2007, 2008; Hunter 2007) but polar bears have been more resilient than expected (Crockford 2017, 2018; Crockford and Geist 2018). In fact, in many areas (like the Chukchi Sea, Barents Sea and Foxe Basin) polar bears are thriving despite dramatic declines in summer sea ice coverage (Aars et al. 2017; ACSWG 2018; Peacock et al. 2013; Regehr et al. 2016; Stapleton et al. 2016).
The sea ice models used to support the addition of polar bears to the US Endangered Species List as ‘threatened’ with extinction suggested sea ice levels from 3-5 mkm2 would not occur unti mid-century, yet they dropped before the ink was dry on the 2007 USGS Reports (ACIA 2005; Hassol 2004; Holland et al. 2006; Solomon et al. 2007; Zhang and Walsh 2006).
The ice extent charts from the University of Bremen (below) show ice that’s 50% concentration or greater at the date of the seasonal minimum (19th September): what polar bear specialists define as preferred habitat (Amstrup et al. 2007).
Compare the minimum shown above to the coverage predicted for 2050 and to coverage at the minimum in 2012 (the NSIDC image is here):
Comments Off on Now at least 10 years with sea ice at 2050-like levels yet polar bears are still abundant
Posted in Conservation Status, Sea ice habitat
Tagged failed predictions, global warming, icon, NSIDC, polar bears, sea ice, sea ice minimum, September, statistic, summer, USGS
According to NSIDC daily sea ice interactive graph, there was ever so slightly more ice on 31 Dec 2016 than on that date in 2010. However, the corresponding ice maps show just how differently that ice was distributed.
Recall that in 2010, there was no huge die-off of polar bears attributed to reduced amounts of sea ice in the fall (or to reduced ice in summer, for that matter) because there was no catastrophic die-off at all.
Comments Off on Polar bear habitat message for the year end: 2016 Arctic ice extent same as 2010
Posted in Sea ice habitat
Tagged Barents Sea, extent, habitat, MASIE, NSIDC, polar bear, population decline, sea ice, Svalbard
Arctic sea ice is spreading out quickly from its central basin summer refuge – according to this NSIDC Masie ice chart, it has already grown more than 2 mkm2 beyond the annual minimum reached in early September. Ice is already pushing south into the eastern Beaufort and the archipelago of Franz Josef Land in the Barents Sea.
Over the next couple of weeks, shorefast ice will start forming along the coasts of North America and Eurasia (see the first bits off Alaska in the 21 October CIS map below), which will eventually meet the expanding Arctic Basin pack to fill the Basin and Canadian Arctic Archipelago with ice – as it has done for eons.
The evidence from the last decade or so suggests that by the end of October, most of the Arctic north of the 79th parallel (see map below) will be filled with ice – although the Chukchi Sea (north of the Bering Strait) may not fill until sometime in November:
Polar bears usually resume hunting as soon as sea ice conditions permit in the fall, since it’s their last chance to top up their fat reserves before the dark and cold of winter when hunting may become next to impossible.
I’ve copied ice charts from the Masie archives for some previous years at 31 October below.
Comments Off on Fall Arctic ice growth often differs regionally: 2016 compared to other years
Posted in Life History, Sea ice habitat
Tagged 79th parallel, Arctic, Barents Sea, Beaufort Sea, Canadian Arctic Archipelago, Chukchi Sea, fall ice growth, hunting, MASIE, NSIDC, platform, polar bears
The annual Arctic sea ice minimum for 2016 is imminent and the hand-wringing about polar bear survival has already begun. While this year is shaping up to be another very low sea ice minimum in the Arctic – not as low as 2012 but lower than as low as 2007 (previously the 2nd lowest since 1979) – contrary to predictions, several recent studies show that such low sea ice coverage in summer has had no (or very limited) negative effects on polar bear health and survival. In fact, for polar bears in some areas low summer sea ice has been quite beneficial (although these are not the populations that polar bear specialists predicted would do better).
Since low summer extents of recent magnitude (3.0 – 5.0 mkm2) are clearly not any sort of threat to polar bears, it seems improbable that even an ice-free (≤ 1.0 mkm2) summer (e.g. Wang and Overland 2015) would be devastating to the species [don’t forget Cronin and Cronin 2016: they’ve survived such conditions before] – as long as conditions in spring allow for the necessary concentrated feeding on young seals.
Above: Top, minimum at 2012 (16 Sept, 3.41 mkm2, lowest since 1979); Center, 2007 (18 Sept, 4.17 mkm2); Bottom, 2015 (9 Sept, 4.50 mkm2), from NSIDC. Below: sea ice at 10 Sept 2016, 4.137 mkm2 – minimum not yet called).
Recall that in 2006, the IUCN Polar Bear Specialist Group based their conservation status of ‘vulnerable’ (likely to become threatened within the next 45 years due to reduced habitat) on the predictions of sea ice specialists (see 2008 update here).
Sea ice experts in 2005 predicted such low summer sea ice extents as polar bears have endured since 2007 (3.0 – 5.0 mkm2) would not happen until 2040-2070, at which time PBSG biologists said that >30% of the world’s bears would be gone.
Evidence to the contrary comes from polar bear specialists working in the Chukchi, Beaufort, and Barents Seas – and in Southern Hudson Bay – since 2007. Overall, the latest IUCN Red Book assessment (2015) put the global population size at 22,000-31,000 (or about 26,500).
All of this means that those polar bear experts were wrong: polar bears are more resilient to low summer sea ice conditions than they assumed.
UPDATE 2 January 2017: I’ve added some quotes from the original USGS reports that explicitly state their dire predictions for 2050 that differ from the predictions made by the IUCN Polar Bear Specialist Group.
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Comments Off on Recent studies show Sept ice of 3-5 mkm2 did not kill polar bears off as predicted
Posted in Conservation Status, Population, Sea ice habitat
Tagged ACIA, arctic sea ice, Barents Sea, bearded seals, Beaufort Sea, body condition, Chukchi Sea, endangered, extinction, extirpation, facts, IUCN Polar Bear Specialist Group, NSIDC, polar bear, population size, predictions, productivity, ringed seals, sea ice, Southern Hudson Bay, summer ice minimum, survival, threatened
Only three females with collars are still being tracked by USGS researchers in the Beaufort Sea and all of them spent August 2016 on the sea ice in the eastern portion, off the coast of Banks Island.
Meanwhile, as Arctic sea ice nears the annual low, NSIDC predicts that 2016 will likely not set a new record but may bottom-out below 2007 (the second-lowest since 1979). The impact of low September sea ice on polar bear health and survival, based on recent research reports, will be the topic of an upcoming post.
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Comments Off on Tracking polar bears in the Beaufort Sea during August 2016
Posted in Life History, Sea ice habitat
Tagged Beaufort Sea, females, NSIDC, polar bear, satellite collars, sea ice, September minimum, summer, tracking, USGS
Never mind that the sea ice maximum this year came almost a month later than last year (and close to latest since 1979) – and was lower by only .02 – the US National Sea Ice Data Center (NSIDC) today trumpeted a new record low. What this means to polar bears, if anything, remains to be seen.
2015: maximum set February 25 (day 56), at 14.54 mkm2
2016: maximum set March 24 (day 84), at 14.52 mkm2
[The difference in area? Smaller than the Islands of the Bahamas]
Latest maximum extent (since 1979) occurred in 2010 on April 2 (Day 92).
The average date for maximum extent is March 12.
I note, however, that given the lateness of the winter sea ice surge meant that the amount of ice present at 24 March 2016 (see NSIDC Interactive) was more than was present on the same date in 2006, 2007 and 2015.
Clearly, there was plenty enough sea ice in the spring of those years for most polar bears to hunt seals successfully and put on the weight they needed to survive the summer fast ahead. I see no reason to expect 2016 to be different.
Comments Off on 2016 record low maximum will make headlines but unlikely to affect polar bears
Posted in Sea ice habitat
Tagged extent, habitat, MASIE, maximum, NSIDC, polar bears, sea ice, spring ice conditions, winter
Using sea ice maps issued by the National Sea Ice Data Center (NSIDC), it’s interesting to compare these two years with respect to polar bear health and survival (keeping in mind that no polar bears live in what I like to call the armpits of the Arctic – the Sea of Okhotsk, the Baltic Sea or in the Gulf of St. Lawrence)1:
22 January 2016
Comments Off on Polar bear survival: habitat 2013 vs. 2016 for 22 January
Posted in Conservation Status, Sea ice habitat
Tagged Arctic, Baltic Sea, Barents Sea, darkness, Derocher, facts, feeding, Gulf of St. Lawrence, habitat, NSIDC, polar bear, sea ice extent, Sea of Okhotsk, spring, starving, survival, Svalbard, winter
Polar bear habitat in the Arctic Basin this year appears to have reached its apex days earlier than average. As of 12 September, freeze-up of Arctic sea ice had begun. Unless something dramatic happens over the next few days, this will make 2015 the earliest September minimum since at least 2007, using NSIDC data.1
The two lowest September ice extents (2007 and 2012) were also both later than average; this year’s minimum is the fourth lowest (see chart below).
Of course, all this fuss about how low the September minimum gets is irrelevant to polar bears: they are either on land or in the Arctic Basin, and virtually all are living off stored fat no matter where they are (see Arctic Basin bear here). What matters is when the refrozen ice reaches pregnant females that have preferred denning spots onshore (like in Svalbard) or for bears onshore waiting to return to the ice to hunt (like Davis Strait, and Western and Southern Hudson Bay bears). We won’t know that until October (for Svalbard) or November (for E. Canada).
Again, no sea ice death spiral or polar bears in peril because of it.
UPDATE 15 September 2015, 11:00 am PDT: Just published at the NSIDC website, 2015 minimum has been (tentatively) called at 4.41 mkm2, confirming my figure taken from their interactive graph (see below). However, despite the fact that their own data show that sea ice extent stayed at that value for three days, NSIDC has chosen the last day of that 3-day period rather than the first to represent the 2015 minimum. Go figure. That makes 2015 tied with 2011 for the earliest date for their official records, which seems more than a little self-serving and means I’m not changing the title of my post. NSIDC have also modified slightly some of the official extent figures for past minimums (added below) but it doesn’t really change anything.
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Comments Off on September minimum 2015 looks like the earliest end of Arctic melt season since 2007
Posted in Sea ice habitat
Tagged Arctic, death spiral, fast, freeze-up, habitat, MASIE, melt, minimum, NSIDC, polar bear, sea ice, September, summer
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