Sep 18 2017

Update on Arctic Sea Ice

seaice_trends_chartThe extent of Arctic sea ice is an important marker for global climate change. In the last forty years it also has been unequivocally shrinking. NASA has been tracking Arctic sea ice extent at different times of the year, with the September minimum being an important point of comparison. Like any chaotic system there are going to be short term fluctuations, but the long term trend is crystal clear. Look at the graph and look at the video on the NASA site linked above – the shrinking is clear.

The first estimates for September 2017 are in and they are consistent with the overall trend. Arctic sea ice’s most recent maximum for the September minimum was in 1996 at 7.87 million square km. The minimum minimum was in 2012 at 3.62 million sq km – less than half. This year the minimum is estimated to be 4.7 million sq km, slightly more than 2016. All of the last 10 years are below the average for the previous 30 years.

This past year we had a warm winter, which led to the lowest amount of March Arctic sea ice on record, but a cool summer allowed the Arctic ice to rebound a bit.

All of this adds to the strong scientific consensus that the globe is warming and this trend is largely due to human factors (not natural cycles). But as you probably know, there is a well-financed campaign of denial, ideologically and financially motivated, to muddy the waters and create doubt and confusion about this scientific consensus. This is easy to do with complex scientific questions.

For example – what is the best time frame in which to view the changes in global average temperatures, Arctic sea ice, or some other marker? If you zoom in on the data too closely you see the year-to-year noise. If you back up too far you see natural trends that happen on the scale of tens of thousands or millions of years, and short term changes are lost. If you look at trends in the data over decades and centuries, however, then the noise flattens out and you can see what is happening over a relevant period of time. It’s easy to change your focus, however, to get the view that you ideologically desire.

You can also focus on a different subset of the data. For example, if you just look at Antarctic sea ice, it has been increasing over this same time period. But this needs to be put into context. First, Antarctica is different than the Arctic. The Arctic is all ocean, there is no land mass there. Antarctica is a continent, so it has continental ice and is surrounded by sea ice, so the dynamic is different. We need to look more thoroughly at the overall ice situation to see what is happening.

First, if you look at total sea ice at both poles, that is decreasing. The loss of Arctic sea ice is greater than the increase in Antarctic sea ice. The dynamics in the Antarctic are also different. The water there is isolated by a circumpolar current around the continent. Ice is also fed by fresh water, which freezes more easily, and wind and precipitation coming off the ice shelf.

Further, if you look at the continental ice the Antarctic glaciers are losing mass. However, there was already a general trend toward greater snow fall in the Antarctic, although that trend has slowed. It is still disputed whether the total snow and ice mass in the Antarctic is increasing or decreasing, but the trend is turning down in either case.

If we back up all the way and look at total global ice, which seems like the best measure and avoids any cherry picking, the trend is also clear. Total global ice is decreasing, including glaciers, continental ice shelves, and sea ice.

Is there room for any doubt? Sure, there is always room for doubt in science, it’s built into the process. That is another source of confusion, however. Scientists talk about our level of confidence, and the robustness of the consensus, which is at a fairly high level considering the complexity of the topic. Politicians and those advocating that we do something about climate change, however, may state things in a way that they feel captures the situation, but is not strictly scientific. For example, they may say that climate change is a fact and settled science. Deniers then exploit this to argue that those who accept climate change are trying to shut down debate and are not being scientific.

None of this touches the strong scientific consensus, however. Further, we can simultaneously accommodate the built in doubt and openness required by science and the need to make decisions based on what we do know. The level of consensus, and the level of certainty about the fact that adding large amounts of carbon to the atmosphere is driving a trend of global warming is high enough to justify taking preventive actions.

If a doctor is treating a patient and they are 95% certain they have an infection requiring an antibiotic, and two other doctors are also consulted and they agree with the recommendation, it is probably best to start antibiotics rather than watch the patient die while debating the 5% uncertainty. You have to make a risk vs benefit assessment based on the data and uncertainty that we have.

If we make a risk vs benefit assessment of anthropogenic global climate change, even acknowledging all the uncertainties, it seems obvious to me that the prudent thing to do is to take some rational steps to mitigate climate change. That does not mean ruining our economy, as deniers will claim. It could mean simply accelerating research and developing into carbon neutral energy sources, and encouraging their early adoption.

As I have argued before, burning fossil fuels has multiple costly negative effects, not just climate change, including pollution and adverse health outcomes. The finances are pretty clear at this point – money invested in non-polluting renewable sources of energy is money well spent, and it will save us much more money in the future while improving quality of life.

Renewable energy sources are the technology of the future, can lead to energy independence, reduced pollution, and improved health. Even if you don’t mention climate change, it is still advantageous to switch to renewables. That is a point worth driving home. And if we prevent a climate disaster, that’s good too.

19 responses so far

19 thoughts on “Update on Arctic Sea Ice”

  1. Lobsterbash says:

    “Even if you don’t mention climate change, it is still advantageous to switch to renewables.”

    This has been my thinking more and more lately. We should really be focusing on aggressively expanding renewable energy, efficiency, and related tech and make it loud and clear that it’s for economic reasons. Even if that’s only part of our actual motivation.

    Unfortunately, talk of climate change is often quickly dismissed (unless it is something big and obvious) as liberal rallying cries. In the narrative, it’s bundled together with a perception of general overreaction for things (e.g. sexism, racism, bigotry, and the latest one being authoritarianism). I observe it definitely being a turn off for a lot of people.

  2. praktik says:

    Is anyone else getting fatalistic about all this?

    Im starting to greet the constant spectre of denialism with a Devil May Care approach and almost a bit of a “Well y’know, the greater this denialism is, the steeper the price is we will pay for our actions, the greater chance we will adopt change”

    The price needs to be big enough to really exact a cost on the people currently enjoying the extraordinary benefits that accrue to the extraction and distribution of carbon intensive fuels – and the rest of us – such that they themselves or everyone else is incentivized to change their ways.

    Is anyone else kind of entering this defeatist perversion or is it just me?

    I guess I’ve read a bit about the stuff that happens north of 450ppm and 4+ degrees and wondering where the threshold is between and

  3. praktik says:

    huh – somehow comment got edited cause of my syntax, meant to close with

    I guess I’ve read a bit about the stuff that happens north of 450ppm and 4+ degrees and wondering where the threshold is between (Pain sufficient to mend our ways) and (Pain so high and toll so terrible no recovery is possible)

  4. Lobsterbash says:

    praktik – In my opinion, your reasoning there is understandable because it’s exasperating and exhausting to change people’s minds. It’s easy to throw your hands in the air and say “fuck it” because climate change is real, so people will have to change their minds as boxes on the checklist of climate change predictions get checked. Right?

    I’d say… wrong. The best case scenario with a “fuck it” approach is that the scales get tipped just enough among leaders and consumers before it’s too late. The change of heart will never be rapid and it will never be complete. There will always be holdouts denying everything, even after the most dire outcomes possible come to pass. Some people would be huddled in their shacks, sand dunes piling up outside, starving, most of the biodiversity gone, and would still hold fast to the “this is natural cycle” denial. We could only hope that this group becomes an impotent, marginalized minority, and soon.

  5. banyan says:

    @praktik: Unfortunately, the costs will not be distributed evenly or proportionately. The countries most responsible are among the least vulnerable. Probably the biggest impact on the United States, for example, will be increased migration and refugee crises, and the results of the last election suggest that Americans will be more interested in addressing that by walling ourselves off. There were the hurricanes this year, but I’ve been disappointed by how little talk I’m hearing of the role of climate change in making hurricanes more severe.

  6. banyan says:

    Meant to add this link, to a group that approximates and maps where climate change is likely to be the most (and least) disruptive:

  7. Lobsterbash says:

    Banyan, that map looks indistinguishable from a map of general poverty. The situation with struggling states being kicked while they are down with climate change seems like a reasonable analogy to the US and its income inequality/social mobility issues: Prosper from favorable circumstances and proclaim inferiority of those struggling with unfavorable circumstances. Self-fulfilling prophecies for everyone!

  8. carbonUnit says:

    praktik, the way things are now, the people most enjoying the benefits (fossil fuel industry) will be dead before the real costs become apparent. Going into old age in a world becoming increasingly destabilized by climate is rather scary too.

  9. praktik says:

    I agree carbonUnit, the human organism’s response to stress is also a factor you don’t read in climate science as much as you read it in pentagon and political reports that use climate as an input to models of human and political behaviour.

    This is something that will kick in much stronger than people imagine, especially if you consider the maps shared in comments above.

    Events in the periphery, so to speak, may seem to affect us little. But politically we are more vulnerable than you’d think. Consider 9/11 and the Bronze Age Collapse, chain reactions can originate from areas under acute climate pressure and deliver blowback to areas under less of that pressure.

    Think of the boat people and the helicopter gunships in 1984 and you may not be far off a near future imagining of our proximate future

  10. BillyJoe7 says:

    Has the pendulum swung?

    Normally a post like this would attract a barrage criticism.
    But not a single appearance from any of our regular climate deniers.
    Perhaps deniaism is becoming increasingly difficult to defend.

  11. Gingerbaker says:

    Don’t mistake sea ice extent (what your graph shows) for how much ice is really there, which is mass. Most experts have been saying for several years now that Antarctica is losing mass, just like the Arctic.

  12. Sarah says:

    I’ve been convinced that the deniers have basically won most of their objectives for years. They have steadfastly blocked everything of worth. At best, we’ve kept them from total victory by blocking their most extreme measures.

    The economic success of renewables is all we can hope for now.

  13. Lobsterbash says:

    Sarah, that is true. With the incredible representation climate deniers have with our presidential administration AND congress, all they need to seal the deal is organize and direct their leadership. Efforts to deal with climate change in the US from the top will be stalled for a long time to come. The market is where it’s at now.

  14. BillyJoe7 says:


    “The market is where it’s at now”

    And the market is talking and making climate denying politicians look stupid.

  15. amosrf says:

    What is generally referred to as ‘climate denial’ is not. The majority of skeptics are not skeptical of global warming or of the fact that humans are responsible for much if not most of the recent warming (50-60 years.) We are skeptical that it poses or will pose a serious, much less catastrophic problem. CO2 (and methane, etc.,) by itself will not cause much warming, perhaps another 1/2 a degree, on this even most alarmists are in agreement. The problem, they say, will come as a result of collateral effects, primarily melting icecaps (reduced albedo) and increased water vapor in the atmosphere. The problem with this theory is that, if accurate, the effects should be exponential, that is, the rate of increase in global temperatures should accelerate the world warms, regardless of the cause. Observational evidence (so far) does not reflect this, even after Karl, et. al. went in and changed the recent numbers. The world has been warming for over 100 years (the rapid warming from 1910 to 1940 is rarely mentioned by the alarmists) so we should by now be in and exponential death spiral. But clearly we are not. While the ‘collateral effects’ theory has not yet been completely disproved (climate is too complicated for quick conclusions,) it is becoming more and more difficult to support, which is reflected in the increasingly desperate measures taken by the enormous community whose jobs and funding rely on its validity.

  16. Lobsterbash says:

    BillyJoe7, that is awesome. It’s totally possible that within industries that are energy-hungry, the forward-thinking, science-aware companies that invest in their own renewable energy will stomp competition in the future. And if there is ever another fossil fuel crisis, game over for the unprepared. As a US citizen, it’s such a depressing shame to see my country essentially discard the renewable opportunity that’s being handed to it on a silver platter. We could be a global leader with state-of-the-art solutions almost overnight, if we weren’t so intellectually diseased.

  17. Lobsterbash says:

    amosrf, there’s so much more to the perils of accelerated climate change than melting ice and a water cycle on steroids. Just read about the destruction of marine ecosystems directly caused by warming water and water acidification. Read about biodiversity loss as habitats continue to change at a rate that far outpaces what is possible for natural selection. The future of life on the planet is a future of generalists, just a fraction of the diversity we even have today. This is just one of many consequences of climate change.

  18. BillyJoe7 says:


    We are supporting the consensus view of the world’s experts on climate science here, so it’s no good propping up your climate deniaism by ranting against the other extreme, climate alarmism.

  19. bachfiend says:


    What makes you think that global warming should be exponential if AGW is going to have deleterious effects?

    There are negative feedbacks, as well as positive feedbacks. And cycles too. The Palaeocene-Eocene Thermal Maximum, 55 mya, due to a natural release of greenhouse gases of similar magnitude to that we’d achieve if we burn all known reserves of fossil fuels, but over 25,000 years instead of centuries, led to global warming of around 7 degrees. And the carbon cycle resulted in the added atmospheric CO2 being removed from the atmosphere – increased temperatures, led to increased precipitation, with the rain being more acid due to the increased CO2 levels, causing more weathering of rocks, and increased precipitation of sedimentary carbonate rock, reducing atmospheric CO2 levels, causing cooling.

    All climate science 101.

    Greenhouse gases aren’t the only driver of climate. Being able to point to, or suggest, that global warming may have occurred at other times for other reasons doesn’t mean that AGW is false.

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