skierinvermont

The "back to 1870" project that the author of that blog post references hoping they will show less ice 1920-1940 than the early 2000s was completed recently. It did not live up to the author's expectations. It did increase the variability somewhat, but the lowest years of the 1930s is similar to the 1980s. The study produced was titled " A database for depicting Arctic sea icevariations back to 1850. " and was published earlier this year in the journal Geogrpahical Review. https://www.carbonbrief.org/wp-content/uploads/2016/08/Walsh-et-al.-2016-Fig8.png http://cires.colorado.edu/news/reconstructing-arctic-history

I read through most of that article and the comments and am fairly unimpressed. It's a stew of anecdotes (no saying how cherrypicked they might be) without any objective data compilation and analysis.

I would be greatly interested in such evidence. I hope you are not referring to anecdotal reports of submarines surfacing at the north poll etc. Studies that actually compiled airplane recon and ship data come to a very different conclusion. The highest years of the early 80s might have been similar to the lowest years of the 40s: Also I don't want to hear the same old dismissal of these studies because they look too "flat". As you go back farther on the graph the data is smoothed because there is less data and more uncertainty. To reduce uncertainty they combine data from multiple years. Thus it represents the multi-year average well, but doesn't capture all the annual variability. The data is smoothed. That doesn't make it "wrong" or "suspicious" as you and others have suggested.

Well I wouldn't say that. But as the climate warms we're going to see more and more extreme anomalies like this. We're so far below even the modern average for the date. And what so often gets forgot in discussions of sea ice is that 1980-2000 is not "average" or normal for sea ice. There's strong evidence that there was lots more sea ice earlier in the century. The highest years of the early 1980s might be a little closer to an early 20th century normal.

Given this decline has been persistent and today's value is 160k lower than the value 3 days ago it's not due to cloud cover or measurement error. If we saw a 100k blip down and then it went right back up the next day then a big portion of the dip could have been measurement error. But when the measurement is consistent across 3 days, and in fact just keeps getting lower, it's not measurement error. A calving event or ice shelf breaking off would have no effect on sea ice area. If anything land ice or ice shelves calving would increase sea ice area because previously land bound ice would now be afloat and thus newly within the sea ice boundary area. Nor does an area of sea ice separating from (IE getting blown away from) the rest of the sea ice pack, decrease sea ice area. The resolution of the satellites measurements is such that this separated ice would still be included in the total. Obviously small icebergs would go unnoticed. But 100,000 sq km is several orders of magnitude bigger than what might go unnoticed. Sea ice decreases this time of year are probably largely due to wind compaction. We could also be seeing newly formed ice from the last week or two melting. When it first freezes it would be very thin and then if the weather changes it might melt again. Normally any compaction would be compensated for by the rapid freezing going on elsewhere. The ice area and volume should be exploding this time of year. So what we're really likely seeing is a general arctic-wide lack of rapid freezing combined with either compaction and/or melting of newly formed ice.

troll

troll

You're right it doesn't exaggerate it as much as I thought. But I think it does still exaggerate it somewhat. The area of Russia is 6.6 million square miles. The area of the arctic ocean including the Kara, Barents, Hudson and the seas on either side of Greenland is 5.4 million. Probably around 4 million if looking just at the high arctic ocean.

It's also worth mentioning that square depictions of the earth from the north pole (sorry don't know the cartography term) greatly exaggerate the size of arctic ocean relative to the lower latitudes. Those negative anomalies over Asia encompass an area several times the arctic ocean.

It seems like you are confused about what you are trying to say. You say one thing and then 2 posts later say you didn't say it.

OK let's try it again. What exactly are you trying to say? So far all I've heard is talk of previous "fall peaks" (IE back to historical averages) and "record fast re-freezes" (an inherent result of the faster decline in summer) and I have no idea what they have to do with the current 3+ standard deviation record and how people dismissed this (allegedly) positive data but are hypocritically not dismissing this negative record. And those are quotes.

Nobody has ever claimed that. I do remember people including myself saying that the trend in summer is more significant than the trend in winter because global warming is expected to cause greater declines in summer sea ice. But that's different. And you did reference "record fastest refreeze" or "high point in the fall" in relation to their significance vs a record low summer min. One is irrelevant and the other is a an apples to orange comparison.

First of all, the rate is really not relevant at all. Since the decline is expected/predicted (by climate models) and observed to be fastest in summer, the rate of ice growth in fall will continue to grow. That's why I'm sure when you've mentioned it, I and others have dismissed you. Second, we've never had a real "high point in the fall" anytime recently. Some years have been higher than others which I suppose has some very slight immeasurable benefit in slowing the decline. But none have been 3SD above the mean, as we are currently 3+ SD below the mean. You're comparing apples to oranges. You're comparing a "high point" (which is really just a temporary return to average) to a 3+ standard deviation drop below the mean. Plus the fact that sea ice extent is a much less comprehensive metric than volume. And we've never had a meaningful volume recovery. Extent has to be taken in the context of near perpetually decreasing volume. I don't remember anybody saying "what happens in winter is not as important as summer." If we actually saw some serious volume growth in winter, that would be significant. We've had some recent years with better volume in winter than others. And that has been discussed extensively. Anyways, I'm done. I don't really have an interest in debating the "significance" of individual extent days. The trend is clear.

As I said before, the main problem is part of your previous post was simply false. There has not been record high sea ice extent in the fall anytime recently. There have been many record lows, including this fall. If there had been, that would be significant, but it still wouldn't mean much of anything in the big picture. Likewise, I don't think anybody here is saying a record low min on 11/4/2016 means much of anything in the big picture, but the trend certainly does. It seems, as usual, you are more interested in semantics and playing "gotcha" than the actual issue.

I don't believe we have ever reached a record high sea ice extent in fall in the last 10 years. That is false. What's impressive is not the rate of refreeze but the fact that we are now well below the previous record for the date. The slow rate of re-freeze would not be all that impressive were we starting at a more normal minimum. But we started at a near-record low minimum and followed it with slow re-freeze to produce a record low extent for this date that is far below the previous record. In other words, highly anomalous. So no, there is no inconsistency. Your post kind of comes off like you are looking for one where there isn't anything.

It probably doesn't help to have such warm temps the last month or two, but there's lots of other more important factors at play.

I didn't disagree.. just skeptical given that we *do* hear it every year (a broken clock is right twice a day) and it would have been a near record early min.

We hear this every year..

Just put the CO2 back in the atmosphere... we're pretty good at that already without even trying.

I know. The most common geoengineering involves blocking the sun or sequestering CO2... both of which would have minimal impact unless done on a massive scale and sequestration is pretty reversible. I think the bigger issue with geoengineering is the side effects.

Be pretty tough to get a degree of cooling w CO2 at 400ppm. You'd have to take out a crap ton of CO2 or block a lot of sunlight....

If you read the article, it says that an organism "exists" not that said organism is widespread or actually breaks down most plastics in nature. The idea is we could breed this organism and spray it all around the world to dissolve plastics. This is easily proven by the fact that the oceans are full of plastic.

I don't think you understood him. He's saying since so much oil seeps NATURALLY it doesn't matter when humans spill a few million gallons. I'm not sure if he even read his own links though. The second one says that plastics take forever to degrade in the oceans and plastics building up in the ocean are major environmental problem...

Even if every other natural factor aligned for cooling we'd stay well above pre-industrial temperatures. The only exception would maybe be a temporary 5-10 year cold spell by a 1 in 10,000+ year volcanic eruption. Even if the earth's axis and orbit aligned for an ice age, we probably wouldn't cool very much if CO2 were pegged @400ppm. Much of the cooling in ice ages comes from a declining CO2 concentration feedback loop and without it, the cooling would be much less. It might just cause us to stop warming instead of continuing to warm. You have to understand that even if CO2 stopped rising, the earth is still gaining unimaginable quantities of thermal energy every second and surface temperatures would continue to rise for some decades (until surface temperatures are high enough that outgoing LW radiation is in balance with incoming SW radiation). But if the factors aligned strongly enough, we probably would see some cooling. But nothing like any ice age. I don't think there has ever been an ice age with CO2 at 400ppm.

While science has not, and probably will not ever, precisely pin down GHG contribution. It is very likely between 75-125%. The earth would likely have cooled due to human aerosol pollution which is literally dimming the sun (this is why some areas with high levels of pollution have seen less warming). GHG warming has more than countered this cooling and created the observed warming. The sun has had a minimal effect since the sun has always had a minimal effect and is currently in a weak period of solar output. We also know that every doubling of CO2 produces 1.1C of surface warming. The uncertainty is in the feed-backs, not CO2. The feed-backs are very likely positive. We should have seen .5C of warming based on CO2 alone without feedbacks. With feedbacks, probably .8-1.5C. The reason we have seen on the low end of that is aerosol pollution and the fact that the earth is still warming (even if we stopped emitting CO2 the earth would warm significantly more).