Scientists: The Arctic Was Sea-Ice-Free, 19°C Warmer 4 Million Years Ago — And Yet Polar Bears Somehow Survived

“Whether polar bears are 350,000 years old or 6 million years old, unless we take action to curb greenhouse gas emissions, they face a future where the climate will continue to warm. And this warming will be unlike anything polar bears have survived before.”  —  Polar Bears International


Image: NoTricksZone

During the Pliocene, or from about 3 to 5 million years ago, subarctic regions of the Northern Hemisphere (Norway, Iceland, Canada) were up to 10°C warmer than they are now,  and the Arctic region itself was as much as 19°C warmer than now, with sea-ice-free summers and no permafrost.  All this warmth occurred while CO2 concentrations were well below today’s levels.  Polar bears somehow managed to survive in these balmy Arctic and subarctic climates.

Robinson, 2010

“Pollen from three subarctic sites in the Norwegian Sea, northern Iceland and Labrador Sea indicate that mid-Pliocene January temperatures in Norway, Iceland and southeastern Canada were 4 to 10°C warmer than today (Willard 1994). … Evidence of both mixed deciduous/coniferous and coniferous forests places mean July temperatures 10°C warmer than today [in Arctic Canada] (Vincent 1990). In addition, northwestern Alaska air and sea temperatures during peak Pliocene interglacials were considerably warmer than present, by 7 to 8°C, with no permafrost, and absent or severely limited sea ice (Carter et al. 1986; Kaufman and Brigham-Grette 1993).”

From the press release, Robinson states that Arctic summer sea surface temperatures were about 10-18°C (50 – 64°F) on average 4 million years ago, compared to 0°C (and lower) during summers today.

“The U.S. Geological Survey found that summer sea-surface temperatures in the Arctic were between 10 to 18°C (50 to 64°F) during the mid-Pliocene, while current temperatures are around or below 0°C (32°F).”

Ballantyne et al., 2010

“The consensus among these proxies suggests that Arctic temperatures were 19 °C warmer during the Pliocene than at present, while atmospheric CO2 concentrations were ∼390 ppmv.”

Cronin and Cronin, 2015

“Pliocene Arctic Ocean summer SSTs were appreciably warmer than modern and seasonally sea-ice free conditions existed in some regions. … At Lake El’gygytgyn (Lake ‘‘E’’) in Siberia summer temperatures were 8°C warmer than modern and at Ellesmere Island, Canada, summer and MAT [mean annual temperatures] were 11.8°C and 18.3°C higher than today.”

[A] seasonally ice-free marginal and central Arctic Ocean was common … regionally during the early Holocene [6,000 to 10,000 years ago]. … Some species thought to be dependent on summer sea ice (e.g., polar bears) survived through these periods.” 

Arctic Also Much Warmer A Few Thousand Years Ago, With Sea-Ice-Free Summers

Although far less pronounced, the Arctic climate was also much warmer than now (by 2° to 3°C) throughout significant portions of the last 10,000 years, warm enough to elicit sea-ice-free summers (or far less sea ice than exists presently).  Somehow, polar bears survived during these warmer climates.

Spolaor et al., 2016

“We report bromine enrichment in the Northwest Greenland Eemian NEEM ice core since the end of the Eemian interglacial 120,000 years ago, finding the maximum extension of first-year sea ice occurred approximately 9,000 years ago during the Holocene climate optimum, when Greenland temperatures were 2 to 3 °C above present values.”

(press release): “Researchers have found that 8000 years ago the Arctic climate was 2 to 3 degrees warmer than now, and that there was also less summertime Arctic sea ice than today.”

Jakobsson et al., 2010

“The combined sea ice data suggest that the seasonal Arctic sea ice cover was strongly reduced during most of the early Holocene and there appear to have been periods of ice free summers in the central Arctic Ocean.”

Williamson, 1975

Between 1000 and 1300 average summer temperatures were about 1°C higher than today, with the mean annual temperature higher by perhaps 4°C in a largely ice-free Arctic.”

Jakobsson et al., 2014

“Several studies suggest that the Early Holocene (∼6000–10,000 years BP [before present]) experienced less summer-sea ice than at present. …. [S]ea ice during the Early Holocene potentially could have moved over to a seasonal regime with sea ice-free summers due to the insolation [solar radiation] maxima the Earth experienced at that time.”

Funder et al., 2011

“Arctic Sea Ice extent during the Holocene Thermal Maximum 8,000 years ago was less than half of the record low 2007 level. … Multiyear sea ice reached a minimum between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position.”

Arctic Sea Ice Cover Also Lower Than Now During 18th, 19th, Early 20th Centuries

According to scientists, not only was Arctic sea ice extent much lower than it has been in recent decades a few thousand years ago, it was lower during the 1700s, 1800s, and early 1900s too, when CO2 levels were still quite “safe” at about 300 ppm and less.  In fact, during the 1880s to 1940s period, when Arctic temperatures were warmer than they have been recently, the Arctic’s sea ice cover began forming more than one month later than it has in recent decades (or melted more than one month earlier than it has been) (Durantou et al., 2012).   And somehow polar bears survived these Arctic conditions.

Durantou et al., 2012

Sea surface temperature [Arctic Ocean, Canada] between AD 1885–1935 are warmer by up to 3°C with respect to the average modern temperature at the coring site. For the period ∼ AD 1887–1945, reconstructed sea ice cover values are on average 8.3 months per year which is 1.1 months per year lower than the modern values.”


[T]he series of climatic oscillations affecting the northern hemisphere are linked through a teleconnection sequence between the oceans and the atmosphere called “stadium wave” (Wyatt et al., 2011). This teleconnection plays a crucial role in climatic changes, notably in exchanges of heat fluxes within the Arctic through the Bering Strait (Woodgate et al., 2005). According to our results, the PDO pattern is closely linked with most of the sea-surface condition variability in the study area through upwelling events of Pacific origin.”

According to Zhang and co-authors (2015), sea ice extent in recent decades has followed the patterns of the AMOC and hovered around the average of the last 3500+ years, with many periods (for example, during the mid-1700s) having much lower sea ice extent anomalies than during the last few decades of human influence — or when polar bears have been classified as endangered.

Zhang, 2015

Observations reveal multidecadal variations in Arctic surface air temperature (SAT), and amplified Arctic warming similar to that observed in recent decades also occurred during 1930–1940. Both observations and climate modeling results suggest that the reduced Arctic sea ice is crucial for the early twentieth century Arctic warming, and internal variability is a very likely cause for that event.”


The estimated increase in the Atlantic heat transport into the Arctic since 1979 is consistent with the strengthening of AMOC since the mid 1970s implied by indirect evidence such as the AMOC fingerprints, and could have contributed substantially to the observed summer Arctic SIE decline.”

Polar Bears Survived The Arctic’s Warmer Past, And They’re Thriving Now

Somehow, polar bears survived an Arctic climate that was as much as 19°C warmer than now a few million years ago, with balmy (66°F), sea-ice-free summers.

Currently, polar bears are not only surviving, their numbers are growing, leading scientists to conclude that they cannot find support for the perspective that polar bears “are currently in any sort of climate crisis.”

York et al., 2016   

“Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on mark–recapture estimates of population numbers and vital rates, and harvest statistics using population viability analyses (PVA). … Considering both TEK [traditional ecological knowledge] and scientific information, we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis.”

Because of the tendentious preference to ignore observational and paleoclimate evidence that would not appear to portend their demise, polar bears will continue to be classified as an “endangered” species.  That’s what the concocted narrative of human-caused climate alarm dictates.

25 responses to “Scientists: The Arctic Was Sea-Ice-Free, 19°C Warmer 4 Million Years Ago — And Yet Polar Bears Somehow Survived”

  1. tom0mason

    The polar bear is a niche predator, preferring to live and hunt in the icy north, away from competition with other predators.
    That is not to say it can not live on land it can, as the Russian and Canadians know. But living on the land means that the bears are now in competition with other predatory animals, and humans(!) something that is not normal for them.
    They can adapt…they can easily survive…go ask the Canadians or Russians.

    1. DirkH

      Well and scientists shoot any Pizzly, Polar Bear-Grizzly bastards.
      Before there were scientists they must have freely mixed – which they are not allowed to do today. Scientists should learn about Mendel; and the re emergence of hidden phenotypes by genetic recombination.

  2. tom0mason


    Will your system lose this comment with no response?

  3. tom0mason

    Hey guys, you now have 4 identical comments from me somewhere.

    1. P Gosselin

      Pls be patient. All comments have to go through the moderating process and so will not always appear immediately.

      1. John F. Hultquist

        Often, here, when I click submit I get thrown to the top with no message. I’m now used to it.
        On Euan Mearns site, Energy Matters, when I hit submit I get a message that “It looks like you have already said that.” I get a memory flash:

        Some one had blunder’d:
        Theirs not to make reply,
        Theirs not to reason why,
        Theirs but to do & die,
        Into the valley of Death

        Then I go away for a few hours and come back to find my comment.
        Cheers, to all.

      2. tom0mason

        It is not going into moderation for which I am notified about, but the utter lack of info. I’m just thrown back to the top of the article with no means of knowing if the comments have vaporized or what.

        Probably nothing that you can do anything about Pierre, it is just the usual effect with modern computer systems programmers whims, deciding to hide the essential informational feedback from the user.

  4. Ric Werme

    I’m in the camp that says PBs went extinct during the Medieval Warm Period. And before that during the Roman Warm Period. And really went extinct during the Holocene Climatic Optimum.

  5. Doug Proctor

    4 million years is a long evolutionary time. Polar bears need not have been while or the same back then, perhaps more a variety of grizzly. So would they still be polar bears?

    Nature adapts. Big deal. It is vanity to say the “appropriate” situation is a particular current one.

    1. Kenneth Richard

      Actually, the Arctic was much warmer, with sea-ice-free summers as recently as a few thousand years ago too. There was even less sea ice coverage than now as recently as a few *hundred* years ago.

  6. Rud Istvan

    See essay polar bears. They evolved from grizzlies (brown bears). The most recent dna comparisons suggest the majority of the split was about 650,000 years ago during the ice ages. So there were’t polar bears in the Arctic when it was last ice free. And, polars and browns can still interbreed and produce fertile offspring (pizzlies and grolars), so the speciation is not yet complete– same as with coyotes, wolves, and coywolves.

    1. Kenneth Richard
      “Polar bears diverged 4 to 5 million years ago, but interbred with brown bears”
      “New DNA studies suggest that polar bears evolved into a distinct species as many as 4-5 million years ago.”

      1. nightspore

        Yes, it’s now pretty well agreed that closely related species can sometimes interbreed and produce viable offspring, for example in hybrid zones. So just because polar bears and brown bears can interbreed doesn’t mean they are not yet different species.

        1. DirkH

          “So just because polar bears and brown bears can interbreed doesn’t mean they are not yet different species.”

          Says who? The UN High Commissioner for words? Polar Bears are just bleached Grizzlies. Just like Neandertals were just bleached humans.

          1. wert

            Well, no. There is no good definition for subspecies, but polar bears are not “just” grizzlies.

          2. DirkH

            And Neandertals had bigger skulls than humans. Sophistry. Species is as undefined as subspecies. Nature doesn’t care.

          3. yonason


            A few articles on species you might enjoy.

            Darwin on the difficulty of defining “species.”

            More on Darwin’s “species” problem.

            “In the ‘Glossary of the Principle Scientific Terms Used in the Present Volume’, … , surprizingly, neither ‘species’ nor ‘natural selection’, the key terms of the book, are defined in the Glossary.”

            The problem hasn’t gone away, as we see from reading to the end.

            See also here…

            …where we read.
            “Contrary to expectations following the discovery of DNA, genetics has failed to define any species”

            Regardless of what one might think of his religious conclusions, one cannot legitimately argue that his evidence isn’t sound, or that it doesn’t show that Darwinism cannot provide the scientific explanation for why there are different species.

            So, if you want to say a polar bear is just an albino grizzly that can swim, with an appetite for seal as opposed to salmon, who are they to say you’re wrong?

      2. yonason

        @Kennith Richard (& anyone else interested)

        You might enjoy these very thoughtful comments on the topic

        There’s lots more on her excellent website.

  7. Don B

    Matt Ridley:

    “Would it matter if it did all melt one year? Here’s the point everybody seems to be missing: the Arctic Ocean’s ice has indeed disappeared during summer in the past, routinely. The evidence comes from various sources, such as beach ridges in northern Greenland, never unfrozen today, which show evidence of wave action in the past. One Danish team concluded in 2012 that 8,500 years ago the ice extent was “less than half of the record low 2007 level”. A Swedish team, in a paper published in 2014, went further: between 10,000 years ago and 6,000 years ago, the Arctic experienced a “regime dominated by seasonal ice, ie, ice-free summers”.”

  8. John F. Hultquist

    A few years ago I made a comment on a Jo Nova post** to insert a link to a paper titled
    Historical Aspects of the Northern Canadian Treeline,
    by Harvey Nichols

    “. . . northernmost dwarf spruces of the tundra and parts of the forest-tundra boundary may be relicts from times of prior warmth, . . .

    includes maps, photo, and references

    **Here is the link to Jo Nova**

  9. Eric Gisin

    The reason polar bears split from brown bears is they occupied a colder climate with little vegetation. The reason they turned white is they were hunting on snow or sea ice. This could not happen before the ice age, which is 2M years old.

  10. Brad

    “All this warmth occurred while CO2 concentrations were well below today’s levels.”

    Incorrect. From the study that you quoted: “Recent proxy estimates that are better constrained indicate Pliocene atmospheric CO2 levels of ∼390 ppmv (Pagani et al., 2010), which are comparable to today’s levels (∼385 ppmv).”

    In other words, CO2 levels were about the same as today during the Pliocene, and, if the estimates are correct, were actually slightly higher.

    The study also points out that, “widespread Northern Hemisphere glaciation did not occur until 2.75 Ma,” which was just at the very end of the Pliocene, which according to the study is defined as ending 2.6 Ma.

    Just because the earth lacked polar glaciation 2.75 million years ago does not mean that ice caps melting now is not dangerous. Rising sea levels are incredibly dangerous to shore towns.

    1. Kenneth Richard

      “Just because the earth lacked polar glaciation 2.75 million years ago does not mean that ice caps melting now is not dangerous. Rising sea levels are incredibly dangerous to shore towns.”
      According to scientists (see above link), the net gains in shoreline land mass have exceeded the gains in sea level in recent decades, such that there is more land area along the world’s coasts today than there was in the 1980s. Can you explain why you believe that *more* shoreline land area is “dangerous”?

      Also, according to scientists, the estimates for the sea level rise contribution from the melting of polar ice caps (Greenland and Antarctica) occurred at a rate of about 2 inches per century (0.59 mm/yr) between 1992 and now (Shepherd et al., 2012). Again, can you explain why you believe 2 inches per century of ice sheet melt contribution is dangerous? After all, the glacier melt contribution to sea level rise was much higher during the 1930s and 1940s, when CO2 concentrations were “safe” at around 310 ppm and human CO2 emissions were annually about 1/10th of what they are now. So what drove the early 20th century glacier melt, since it wasn’t CO2?

    2. AndyG55

      “Rising sea levels are incredibly dangerous to shore towns.”


      around 1.5mm/year from tide gauges, or even a HORRENDOUS 3mm/year from “adjusted” satellite data

      SCARY !!!!!

    3. AndyG55

      Arctic sea ice melt..

      oh NO…… PANIC because of massive sea level rise ! 😉