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An Inconvenient Sequel – the science, history, and politics of climate change

Posted on 15 November 2017 by John Abraham

Al Gore’s new movie ‘An Inconvenient Sequel’ is, in some ways, similar to his groundbreaking Inconvenient Truth project, but different in other ways. Those key differences are why I recommend you watch it.

This movie successfully accomplishes a number of interweaving tasks. First, it gives some of the science of climate change. Gore gets his science right. I remember his first movie, which I thought was more steeped in science and data than this one, so based on my recollection this new picture is somewhat abbreviated. That’s a good thing because the science is settled on climate change. That is, the science is settled that humans are causing current climatic changes and the science is settled that we are observing these changes throughout the natural world. 

Readers of this column who venture into the comments below will likely find people claiming, “science is never settled.” But the people making those comments are not scientists. They don’t work in this field every day, they don’t see the data, and they don’t know what they’re talking about.

The opening of the new film shows a sample of the misguided attacks on Al Gore, exclusively from conservatives in the United States. It was so clear to me, when watching and listening, that these attacks are the same ones that we climate scientists constantly have to endure. Most scientists have not been attacked as consistently or for such a long duration as Mr. Gore, but the types of attacks he has had to handle are close cousins to what my colleagues and I experience on a regular basis. 

Many conservatives, and some progressives too, claim that Al Gore made climate change political. But I now realize he didn’t. Al Gore was simply the first major political figure that took a stand on climate change. He would have loved to have been joined by anyone of any political persuasion. I firmly believe that the denialism we see from conservatives in the USA is partly because they cannot bring themselves to admit he was right. 

In many people’s subconscious, it is better to deny the science and damn the world than admit a liberal former vice president was correct. And that failure is on them. Better people would rise above gut emotions and follow facts faithfully to where they lead. Instead, most US conservatives have tied their legacy to a climate denial movement that is causing and will cause irreparable harm to the planet, its biology, and human societies.

A party that calls itself “conservative” has acted out of accord with its stated values. And this fact should anger true conservatives. How could they allow an entire party to be tarred with this damning legacy? It isn’t Mr. Gore’s fault that conservatives have made climate denial a litmus test for their party. It isn’t Gore’s fault that conservative politicians have been bought by fossil fuel industries who have attacked climate science and climate scientists. It isn’t Al Gore’s fault that the Republican Party has stood in the way of the development of clean renewable fuels in the US. That is on them. It isn’t Mr. Gore’s fault that the very few conservatives who have taken a principled stand have been cast out from their party. The politicization of science is their scar.

With respect to the science, this new movie focuses on actual implications of climate change. Whether Mr. Gore is discussing Greenland’s crumbling ice sheet with scientists Eric Rignot or Konrad Steffen, or conversing with Miami city planners on ways to handle rising waters, the movie brings the implications of a changing climate home. Mr. Gore reminds us of projections for the future. For instance, South Florida may see 7 feet of sea level rise by 2100. City planners are considering ways to raise parts of the city to deal with this. Oh by the way, yes the best evidence shows we really may get 7 feet by 2100.

Later, Gore meets with people who have suffered through terrible and super-charged storms, such as recent typhoons in the Pacific. He lays clear the science that climate change is warming our oceans, providing extra fuel to make storms like Irma, Harvey, Sandy, and Maria more powerful. In these spots, his science is dead on.

This may make you wonder why I recommend people watch this movie. Isn’t it just more doom and gloom? Well, this is the exciting part. While the politics of climate change, at least in the USA (with a President and Congress in full denial mode, not only rolling back progress but sabotaging the science), what reason is there to be hopeful?

First, other countries are taking the lead from the US. I see this in my own work. Not only in basic science but in deployment of renewable energy. This is one area of great potential. Even though, as shown in the movie, fossil fuel companies and some conservative politicians are trying to sabotage clean energy markets, they cannot deny the economics. It just makes sense to use clean and renewable energy.

Do you remember that iconic scene from his first movie, where he followed greenhouse gas data upward using a lift? The gas levels were literally off the screen? Well, that gloomy image is replaced in the new movie by an equally iconic but optimistic animation of how countries are installing clean energy. 

A large part of the story does deal with Al Gore’s personal journey.

Click here to read the rest

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Comments 1 to 38:

  1. From the 8th paragraph of the article - 

    For instance, South Florida may see 7 feet of sea level rise by 2100. City planners are considering ways to raise parts of the city to deal with this. Oh by the way, yes the best evidence shows we really may get 7 feet by 2100.

    7 feet equals 2,134mm.  In order to reach 2,134mm in 84, the annual rate of sea level rise needs to be 26mm per year.  The current rate of sea level rise is only 3mm per year. 

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    Moderator Response:

    [DB]  And yet evidence exists that recent SLR is exponential.

    Recent SLR

  2. Tom 13@1

    "The current rate of sea level rise (in Florida) is only 3mm per year."

    No in parts of  Florida its currently approx. 8.4mm year:

    This is caused by a combination of factors including climate change, some localised change in the North Atlantic Ocean cycle which may be natural variability, or climate change related, and some land subsidence as well.

    The climate change components are modelled to accelerate particularly after 2050,  due to increasing rates of ice loss in Greenland etc. Put all those causal factors together and Florida could well have two metres of sea level rise by 2100. This is within our childrens lifetimes so is rapid, and the  implications are severe. 

    Sea level rise in Florida is not all caused by climate change, but climate change is a major factor, and something that can be addressed. 

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  3. DB] And yet evidence exists that recent SLR is exponential.

    There is also evidence that the large increase in the rate circa 1990-2015 is an artifact of the change in method of measurement from tide gauges to satellite.  Keep in mind that rate of sea level rise based on tide gauges doesnt reflect the same exponential rate of rise.

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    Moderator Response:

    [DB] "There is also evidence that the large increase in the rate circa 1990-2015 is an artifact of the change in method of measurement from tide gauges to satellite"

    Citation, please.

  4. Good  article. So conservatives claim Al Gore politicised the issue. Yet his book An Inconvenient Truth discussed science, and didn't mention politics or even the key denialist arguments.

    In all fairness and honesty he did write a book criticial of republican attitudes to science but this was a separte sort of thing coming well after an Inconvenient Truth. Gore has his faults, but IMO is mostly making the effort to be on the right side of science, and future well being of humanity. I have no right to expect more.

    I think it's actually the Republicans and many conservative leaning people that tend to politicise climate change. Listen to their rhetoric and its some variation on liberal scam, a chinese conspiracy, a socialist scam, big government, nanny state, secret tax scheme, evil agenda 21, in a long predictable political rant mostly free of scientific awareness. Their claims are also nonsensical and unproven.

    Sometimes its more subtle but the message is the same. But what is all that if its not politicising the issue?

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  5. Tom13@3, you are  forgetting that the basic physics would expect an acceleration. 

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  6. Tom13@3,

    "There is also evidence that the large increase in the rate circa 1990-2015 is an artifact of the change in method of measurement from tide gauges to satellite. Keep in mind that rate of sea level rise based on tide gauges doesnt reflect the same exponential rate of rise."

    The graph of sea level rise posted by moderator appears to have curve fitted showing acceleration over period  1990 - 2016. Please note change from tide gauges to satellite data happened about 1995 so might explain a sudden change around 1995, but it  can't explain curve  acceleration over the full period in the graph.

    Satellite data is more accurate than tide gauges.

    To repeat, the physics would also expect acceleration.

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  7. Does anybody know how much rate of sea level rise is affected by the increasing amount of water vapour in the atmosphere? If all the water vapour in the atmospere was to suddenly be returned to the ocean would this be negligible or noticeable?

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  8. That SLR graph shows that the rate of SLR is supralinear. But I would not say it is yet evidence for an exponential rise.

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  9. Sidd @8 , your point about the difference between "supralinear" versus "exponential" is a very obscure point (at least, to me — and I suspect, to many other readers as well).

    Please clarify what you intend.   In colloquial English [rather than in strict mathematical jargon] the term "exponential" seems a fair approximation for the increasing rate of sea-level rise which is occurring at present & in the coming decades.

    Obviously, there is only a finite tonnage of ice-sheets, so the long-term sea-level rise cannot be truly exponential for millennia.   Much of the East Antarctica Ice Sheet will persist for 1000+ years.   But the melting of Greenland ice & WAIS . . . could produce a general sea-level rise of about 50 feet by year 2200.   And possibly the rise would be higher.   All rather uncertain, of course.   But none of it looks "good for us".

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  10. Phil @7,  According to the USGS if all the water in the atmosphere were to rain out at once, it would cover the earth with about an inch of water.

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  11. Thank you RickG that is very interesting. So the increase of water vapour to date through global warming may have reduced potential sea level rise by a few mm's. 

    Thanks for link also.

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    NOAA is only 2.39mm MSL rise for miami beach, 2.32mm MSL rise per year for Daytona beach, FL.

    Nigelj is citing 8.4mm per year.  

    The NOAA data should be a better gauge of whether a jump to per year is even remotely likely.  keep in mind that in order to reach 7 feet, the rate of sea level increase has to be 26mm per year for 82 years straight.  Can someone provide a credible estimate as to when 26mm per year will be reached - with the emphasis on credible. 

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  13. Tom13 @12

    "NOAA is only 2.39mm MSL rise for miami beach, 2.32mm MSL rise per year for Daytona beach, FL."

    This data is an average for last 40 years! The source I quoted is over last decade where rate has increased to about 8.4mm year. The article I posted quite clearly had graph of data.

    "Can someone provide a credible estimate as to when 26mm per year will be reached - with the emphasis on credible."

    The last IPCC report predicted global average sea level rise will increase to approx. 1 metre by 2100, worse case with increasing emissions, following quadratic curve. 

    Please note IPCC estimates are conservative, with some science now suggesting more than 1 metre is very feasible as global average.

    Florida is possibly extreme case, as sea level rise adds to local conditions and land subsidence etc to make 2 meters possible.

    I have no interest in whether your gut feeling on this is "credible" or not, only whether you provide solid evidence otherwise.

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  14. It is well known and undeniable that, repeatedly, when CO2 levels fell to 100ppm below pre-industrial (i.e. from 280ppm to 180ppm), sea level was 200 feet below present.  How hard is it to fathom that going from pre-industrial (280ppm) to 500ppm or higher will raise sea level by 10 feet or so?  (the actual estimate is ~75 feet, eventually).  Someone needs to tell me how sea level can be so sensitive to CO2 in the past but so completely insensitive today.  Did we melt all the ice caps in the last interglacial transition?  If we didn't, then expect sea levels to rise today.  A lot.  This is not rocket science.

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  15. I seldom post comments but was moved to do so today after reading this article.  Many thanks to John Abraham for such an excellent review.

    Last night our Swanpool Landcare group funded a free screening of 'An Inconvenient Sequel' at the Swanpool Cinema (Vic, Australia).  We were pleased with the attendance and the lively discussions over supper which followed.  The same AMSL graph as in the Moderator's Response was used in our opening slides and accompanying short film clips before the main feature reflected the current Australian political response (or lack thereof), with an emphasis on sea level rise.

    There is a considerable amount of debate about what the mean sea level rise might be by 2100 but I choose to look at it another way.  With CO2 levels still rising inexorably a two metre or more rise is inevitable and it is just the timing that is uncertain.  The Greenland icecap footage in the film just supports this view.  Should our response be any different if a two metre rise occurs a few years earlier or later than 2100?

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  16. nigelj: "This data is an average for last 40 years!"

    Actually, nigel, that statement is not quite correct. I looked at Tom13's link and saw the numbers, and did quite a bit of searching to try to find out what time period was being used. It's not easy to find.

    If you click on the Home/Map link on the left side of Tom's page (just under "Sea Level Trends"), you get to this URL:

    If you zoom in on the map to S Florida, you can click on Miami and get details. A balloon pops up with the following text:

    The mean sea level trend is 2.39 mm/year with a 95% confidence interval of +/- 0.43 mm/year based on monthly mean sea level data from 1931 to 1981 which is equivalent to a change of 0.78 feet in 100 years.

    (Bolding added.)

    You're right about it being over a period of 40 years, but the period ended almost 40 years ago.

    I think I can tell where the true credibility gap lies.

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  17. RickG @10.

    Interesting factoid.Thanks for bringing it up.

    Water in the atmosphere can be in two forms: vapour, or clouds (liquid or ice). The vapour portion is often referred to as "precipitable water" - the total amount from the surface to the top of the atmosphere, expressed as a depth of liquid water (i.e., how much rain would fall if it all condensed and rained out).

    A quick search for "precipitable water global map" led me to this nice page:

    which includes a nice map of NOAA origin:

    Global precipitable water map

    To get a larger version, go to the link above. I think the numbers are consistent with RickG's source.

    One thing that is very apparent is that the amount of water vapour in the atmosphere is a strong function of temperature. I'll need to keep such a map in mind next time I am trying to point out that water vapour can't act as a forcing on climate - just a feedback.

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  18. Bob Loblaw @16, thanks. I struggled to find time periods as well. I clicked on the trend data for the gulf of mexico area, and it said data was for 40 years. I just assumed it was last 40 years. Not the clearest of websites.

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  19. The movie "An Inconvenient Truth" did certainly politicise the issue — not just because Al Gore was a former politician.  It discussed the details of how he lost the presidential election.  Even though I think he should have won the election, those interludes made me cringe.  Those who think he deserved to lose would have been outraged by them and distracted from the key message.

    If the election had been fought on the issue of climate change, then the political comments would have been justified, although possibly unwise.  However, public awareness of climate change was low until An Inconvenient Truth itself was released, and so I don't see how it could have been a major election issue (though I wasn't there).

    The movie also focused more on Al Gore himself than was necessary.  I remember there were scenes discussing the fact that his parents were tobacco farmers.  So what?  He may have been making a subtle point about the need to change industries, or similarities between the tobacco industry and the fossil fuel industry, but it isn't central to the issue and creates an impression of self-aggrandisement.

    I haven't read the book, and so perhaps these criticisms don't apply to it — but applying to the movie is enough to justify the claims that he politicised the issue.


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  20. I forgot to add that my comment #19 doesn't mean that I think the Republicans aren't also politicising climate change.  They're doing it deliberately and unscrupulously, whereas I think Gore did it carelessly at worst.

    Also, I'm not saying that the harm done by politicisng the issue outweighs the good he did by raising awareness.  I don't know enough to have even an opinion on that.

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  21. Bob Loblaw @16: Well done finding tht data.

    You talk of "where the credibility gap lies", but I don't think you can blame Tom13.  The NOAA is a reputable source, and the data sets for most of the Florida points finish at 2016 (also spanning 4-10 decades), and give rates of change in the same ball-park as the old Miami data.  It doesn't look to me like he was deliberately cherry-picking — just misled by an unclear site, and being genuinely skeptical as this site encourages :)

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  22. Lachlan @19

    I have not seen the "Incovenient Truth" movie. From what you say it does politicise the issue, which is unfortunate. However the material on Gores personal background may have been inserted to add human interest aspect.

    I just can't recall the book politicising the issue. I dont think it mentioned Gores background, and it was a relatively short book and large parts  were illustrations. 

    However few writers are going to be politically totally neutral people. Most people have some political leaning. I just wish people would just look at what Gores says, and forget that he is a Democrat. I'm happy to listen to Conservatives views on climate change, and I might disagree, but not because they are "conservatives". 

    You said you wonder if the movie did more harm than good. I haven't seen any study on this. However I suggest it probably did more good than harm at outside America, because wouldn't really care about Gores statements on his political and personal background.

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  23. Lachlan @21. The NOAA data on sea level rise in Florida is hard to follow.  

    This is a peer reviewed study specifically on Miami beach Florida: It was hyperlinked in the original article I posted if you looked carefully.

    Ocean & Coastal Management Volume 126, June 2016, Pages 1-8
    Ocean & Coastal Management. Increasing flooding hazard in coastal communities due to rising sea level: Case study of Miami Beach, FloridaAuthor links open overlay panelShimonWdowinskiaRonaldBrayaBen P.KirtmanaZhaohuaWub


    Flooding frequency in Miami Beach increased significantly since 2006, mostly due to high tide events.

    The average rate of sea level rise in Southeast Florida increased from 3 ± 2 mm/yr prior to 2006 to 9 ± 4 mm/yr after 2006.

    Increasing sea level in the Miami area correlates with weakening of the entire Gulf Stream system (decrease in kinetic energy).

    Engineering solutions to SLR should rely on regional sea level rise rate projections and not only on the commonly used global SLR projections.

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  24. All the NOAA sea level data on Tom13's link (broken for me today) are least squares fits to all the data that exists for that location.  If you look carefully some of the locations are short term and others are longer.  Key West has a complete 100 year record, most of the others are shorter and sometimes end before 2017.

    Since NOAA fits a linear trend to an increasing curve they underestimate all current rates.  The actual rate is higher than NOAA states.  Nijelj's data is recent and is the actual current rate.  Search Taminos blog for details of NOAA sea level graphs.

    Tom13 is not familiar with the NOAA site and incorrectly thinks that they measure current sea level rise instead of the average over the enitre data set. On denier sites they use the NOAA fits to claim sea level is not rising at the rate it is actually increasing.

    The state of Florida will be in a lot of trouble soon if the rate continues at 9 mm/yr.

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  25. Michael, should we expect Florida's sea level rise to continue at well above world average?

    There must be a definite upper limit to the effect of Gulf Stream slowing.  And land subsidence rate would continue slowly and steadily.  Would not the general SLR increase from Global Warming be the big factor in coming decades and centuries?

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  26. Eclectic:

    The Gulf Stream is currently not as strong as it was 20 years ago.  An article on Climate Central quotes Dr. Tal Ezer:

    "“[The Gulf Stream] keeps coastal sea level [on the US East Coast] a meter or a meter and a half lower than the rest of the ocean,"

    The amount of rise varies over the US East Coast.  It is not clear to me how much of that rise has been seen to date, although it is a positive value.  Scientists are not sure if the current slowing of the Gulf Stream is permanent or just decadal variation.  Models predict less slowing than has been observed.

    About land subsidence in Miami Beach, this poster states:

    "Preliminary InSAR results detected localized subsidence, up to -3 mm/yr, mainly in reclaimed land located along the western side of Miami Beach.
    • Although the detected subsidence velocities are quite low, their effect on the flooding hazard is significant, because houses originally built on higher ground have subsided since the city was built, about 80 years ago, by 16-24 cm down to flooding hazard zones."

    Add in 25 cm of sea level rise and you start to see more flooding.

    In addition, melt from the Antarctic causes more than average sea level rise in North America because of gravity effects.  The effect of Greenland melt in North America is close to average.  Currently this effect is small but measurable.


    It is my understanding that 400 ppm of CO2 is expected to cause 20-25 feet of sea level rise.  Most scientists currently think that it would take 500 or more years to rise that much.  If all the ice melted it would be about 75 feet. 

    You are correct, there is less ice in the world today than 20,000 years ago so the possible total sea level rise is less now than it was in the past.  As scientists understand the great ice sheets in Greenland and the Antarctic better the estimations of how long it takes to melt have changed a lot (generally melting faster). 

    Also, since temperature rise is proportional to log[CO2], as concentration increases the effect on temperature rise is less for each new 100 ppm.

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  27. Michael Sweet @26 , thanks for that info on the Gulf Stream & Florida.

    I was innocently [=ignorantly] supposing that the Gulf Stream effect on the local sea level was a matter of a few centimetres in total, rather than a metre.

    An article in RealClimate 4th January 2017 discussed the shotgun spread of model projections for future Gulf Stream developments.   Clearly a difficult area to get some sort of handle on.   Maybe 100 — 300 years until Stream shutdown (if that's its eventual fate).   Interesting times, at a global level.

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  28. [JH] Recommended supplemental reading:

    Does NASA Data Show That Global Warming Isn’t Causing a Sea Level Rise? by Alex Kasprak, Snopes, Aug 1, 2017

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  29. Lachlan @21:

    You are much more charitable that I with respect to Tom13's presentation of data. He started in comment 1 by saying " The current rate of sea level rise is only 3mm per year."

    NIgelj immediately responded with "No in parts of Florida its currently approx. 8.4mm year." and provided a link to a site that includes a graph of how sea level has varied since 1950 (and how rates of rise have varied).

    Tom13 countered (@12) with the link to the NOAA data, and made the following statement:

    "The NOAA data should be a better gauge of whether a jump to per year is even remotely likely. keep in mind that in order to reach 7 feet, the rate of sea level increase has to be 26mm per year for 82 years straight.

    Clearly, Tom is arguing from a standpoint where the 2.39 mm/yr is the current rate at Miami, making the year 2100 as 82 years from now.

    Tom13 is just plain wrong about the current rates. I see two possibilities:

    1. Tom13 did not know what period the 2.39mm/yr applied to, but chose to assume that it was current rate and presented it as such. (This would apply whether Tom13 spent no time or a lot of time trying to find out the data period used.)
    2. Tom13 did know the time period for the 2.39mm/yr, but chose to misrepresent it as current in order to make an argument.

    I am charitable enough to accept that #1 is quite likely. It is for this reason that I followed Tom13's link to look at the source of data and try to determine more about the quoted rate. It took a bit of time, but I was able to find it. And when I found it, I discovered the information, I was able to determine that Tom13's quoted rate is a very poor choice for examining current Miami rates of sea level rise. (I will admit that until now I did not check Tom's quoted rate for Daytona Beach. Tom's 2.32mm/yr is correct, but it applies to the period 1925 to 1983. It is no more useful than the MIami data.)

    You further state "It doesn't look to me like he was deliberately cherry-picking — just misled by an unclear site, and being genuinely skeptical as this site encourages."

    I strongly disagree.

    • A genuine skeptic looks at the two different rates (NOAA,as quoted by Tom13, and the graph linked to by nigel) and asks "why are they different?"
    • A genuine skeptic then tries to determine the reason for the difference.
      • In this case, the reason is simple: different time periods. And anyone with a smidgeon of knowledge of climate issues should know that time periods are very important in comparing data.
      • Note that the graph nigel linked to starts in 1950.
      • Note that from 1950 to 1980, the rate of sea level rise was about 2mm/yr.
      • Note that this is entirely consitent with the NOAA value.
      • Note that there is really no difference to explain.
    • ...and if a genuine skeptic cannot determine a reason for the difference, she will not present the data as if it is conclusive proof of a counterpoint. A genuine skeptic will include the caveat that there is uncertainty in the results, and perhaps ask if anyone can explain the difference before making statements such as "Can someone provide a credible estimate..." and immediately doubling down with the statement "...with the emphasis on credible. "
      • The graph nigel linked to already shows credible evidence that rates are increasing since the time period of the NOAA data.

    Tom13's behaviour does not look like "being genuinely skeptical" to me. And yes, I blame Tom13 for Tom13's behaviour.

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  30. nigelj:

    I have not seen the "Incovenient Truth" movie. From what you say it does politicise the issue, which is unfortunate. However the material on Gores personal background may have been inserted to add human interest aspect.

    AGW is a political issue, whatever other kind of issue it is. Al Gore has mastered the basics of climate science well enough, but he's a politician first and foremost, from highly personal motives. Why else would he talk so much about AGW?

    The peer community of climate science specialists has reached a lopsided consensus. IOW, the consensus case is settled science. The current POTUS, nevertheless, has publicly said AGW a hoax. You'd think he'd recognize that three may keep a secret if two are dead, yet he's accusing generations of climate scientists of enlisting, with mysterious though implausibly unified purpose, in a 200-year-long conspiracy to deceive the public. How polarizing is that (especially if you're a climate scientist)?

    'Market oriented' economists agree that AGW is a drama of the commons, requiring collective intervention in the 'free' market to avert tragedy for ever more millions of people. That much is settled economics.  Any collective decision will create relative winners and losers, but the sooner the US economy is decarbonized, the lower the net aggregate cost will be. Perhaps coincidentally, the people with the most to lose are fossil fuel billionaires. In the event, the offical position of the dominant US political party, whose leaders are apparently unclear on the whole 'commons' concept, is that decarbonizing our economy will cost too much.  How politicizing is that?

    A sufficient plurality of US voters must be assembled to enact something like Carbon Fee and Dividend with Border Adjustment Tax. Yet a regrettably large number of Americans reject responsibility for the marginal climate-change costs of their private comfort and convenience. They're happy to socialize as much of ther private costs as they can get away with. How politicized is that? 

    AGW has always been politicized. If it wasn't, the US economy would be well on its way to carbon-neutrality by now, 30 years after Jim Hansen's Congressional testimony, and Al Gore would be talking about something else.

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  31. Mal Adapted @30, yes all fair comments. The whole thing is horribly politicised in America, especially by denialists but also large part of the public, but  Gore shouldnt make it worse, and was a bit unwise to include material in his movie about the election etc. This may have alienated a lot of republicans.

    But his book and I presume the movie was very good scientifically and he is passionate, and I think it probably had positive impact in rest of the world outside America, who wouldnt really care so much about his politics. 

    We have talked about the market economics tragedy of the commons issue elswehere. I find myself coming back to it again and again, that people are just going to have to accept it. This may require dragging Republicans kicking and screaming somehow! 

    I like Americans and strong rule of law etc, but their constitution puts huge emphasis on individual freedom, which I think is used as a convenient excuse sometimes to say no to anything they dont like. The basic principle is sound, as a protection against excessive coercive power,  but it can be taken to absurd extremes that I doubt the writers really meant.

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  32. There's nothing wrong with Gore making it political: everything is politics and he is a politician... what do the rest of us do for a living that makes us so much better?

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  33. Re: supralinear and exponential.Supralinear means a faster than linear increase, that the dependent variable y, (the rate of sea level rise ) is increasing as some power of t (time), like t^n where n is greater than 1. The graphs support this, and the first nonlinear term can be fitted as t^2. which gives a constant acceleration in the rate of sea level rise. This is not to be confused with the far faster exponential exp(t) where the acceleration of the rate of sea level rise is also exponential, in fact all derivatives are also exponential. The data do not allow one to say that the rate is exponential, but they do allow one to say that the rate is increasing. There is justification for a t^2 term but not higher powers, and certainly not an exponential.

    That said, paleo data show step like change, but we cannot yet say that we are seeing any more than a t^2 term from current data.


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  34. I realize i was asked to give a colloquial discussion of the difference between supralinear and exponential without resort to mathematical language, and i failed badly. So i post a link to a picture. The curves go from linear (invisible on this scale) through quadratic(x^2), cubic (x^3), quartic(X^4) and exponential. Observe how exponential outruns all in the long run.

    In any event, to decree a process exponential requires data for several doublings of the rate in question. So when the rate of sea level rise over the last century of 2 mm/yr hit 4 mm/yr in 20 yrs and hypothetically 8 mm/yr in another 20 yr we have reason to believe the increase is exponential with the doubling time of twenty year. But as of now we have perhaps seen one doubling which can be fitted just as well with a quadratic as any other larger power or even an exponential. But quadratic is already troubling.

    Waiting for it to become obviously exponential is ridiculous. When it hits 8 mm/yr we all screwed. So the evidence of a quadratic (y^2) term is already troubling.And long before we see a cubic term we need to be migrating away from coastline quick.

    Is that better ?


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  35. Sidd @34 , the real underlying point is that the next 100 years will likely show a sea level rise which is "above linear".

    Warmer air will affect Northern Hemisphere ice and warmer seawater will affect Antarctic ice, in a complex way.   All a matter of physical processes -— likely to have nett accelerations & slowings which won't fit well with basic algebraic formulae.

    During the initial decades, SLR predictions will probably require frequent adjustments as observations & understanding continue to grow.   Recent SLR has accelerated and we can expect even faster melting of ice sheets, since little has been done to counter the underlying cause of global warming.

    For myself, I have never been able to empathize with the strange "reality-rejecting" mentality which views the very obvious global warming & higher sea level as being something which could be blamed on left-wing/right-wing political factions (including the "Gore" himself).

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  36. A regular doubling period is of course impossible to achieve.

    It is of course what the stockholder demands...

    Jevons paradox rules the world hence blood for oil wars!

    Eclectic thinks warmer air will melt the arctic sea ice but my understanding was that the atmosphere was chiefly responsible for heat distribution at the equator but the ocean took over the dominant role toward the poles!

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  37. Bozzza @36 , my reference was not to arctic sea ice — which would not affect SLR, of course.   Rather, to NH ice such as the Himalayas and Greenland.   The latter case involves "warming air" gaining some of its heat from the nearby ocean, true.

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  38. Sidd, what you say makes sense.

    Graph of sea level rise projections for my country New Zealand here, out to 2100.

    This is a quadratic curve. I can't see how it would ever become exponential and why melting would do this, melting is not like  population growth! A quadratic curve is more than bad enough to worry about.

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