Gavin's Twitter Trick

NS,
I don’t think you understand. Ninos and Ninas are anomalous events and they should appear as outliers against a background of predictable changes. If the uncertainty boundaries are doing their job properly, showing the extremes of natural variability, then the anomalous events should be pushing those boundaries.

i think nick does understand. as reality edges ever further away from modeled “projections” i think nick along with many others will become more obtuse. either that or admit they are wrong. ten years from now the amo will make many so called experts look like the snake oil salesmen they really are. i don’t doubt they believe their own hype ,but belief never trumps reality.

Kurt September 27, 2017 at 3:17 pm
“Hansen’s projections for CO2 were as follows for 2016: Scenario A: 405.5; Scenario B: 400.5; Scenario C: 367.8 – Actual global annual average: 402.8
So the CO2 projection fell between A and B, not bad agreement after 30 years.”
There is no agreement to be had; Hansen’s prediction, even on how much CO2 would be in the atmosphere was way off.
No it was not, as shown above A was about 3ppm above actual and B was about 2ppm below actual.
I don’t know where you came up with those numbers – they certainly weren’t in Hansen’s 1988 paper, so I suspect that they were put out post hoc as some sort of deceitful statistical trick.
Clearly you don’t know, so you make up your own conspiracy theory, they are from the file containing the projected concentrations released by Hansen in 1989, the same source as used by McIntyre when he plotted the data in 2008.
But let’s assume for a second that you have accurately correlated each of Hansen’s emissions scenarios with a 1998 prediction of CO2 atmospheric concentrations in 2016 at each of those scenarios.
Let’s not because that’s not what I or McIntyre did!
With respect to CO2 emissions, Hansen’s scenario A assumed that CO2 emissions would only grow at a 1.5% rate.
No it did not, it assumed that from 1981 onwards (after the end of Keeling’s observations) the ‘annual increment’ in CO2 would grow at 1.5% yr-1, i.e. it is the second derivative not the first as you have erroneously supposed. Since the annual increment in 1981 was 1.4ppm, 36 years of 1.5% growth in that increment would mean that it would now be growing at 2.3ppm yr-1.
The world blew through that rate throughout the 1990s and 2000s, and even after the stall in CO2 emissions growth over the last several years, growth since 1998 still average around 2% a year – well above Hansen’s 1.5% growth rate for emissions scenario A (33% off), and his scenario B assumed that growth rates would drop to 1.0% in 1990, 0.5% in 2000 and 0% in 2005. Needless to say, scenario B didn’t happen.
Wrong of course because of your mistake, scenario B assumed that the second derivative would be 0 in 2010 and explicitly stated that the growth rate in CO2 at that time would be a constant 1.9ppm yr-1. The actual values in 2009, 2010 and 2011 were 1.62, 2.44 and 1.68.
So what you’re trying to say is that Hansen should be viewed as some kind of a prophet because the actual CO2 concentrations in 2016 correspond to something between Hansen’s emission scenario A and emissions scenario B, when in the real world emissions exceeded scenario A by a large margin and made scenario B look ridiculously optimistic.
No I’m saying that the scenarios he chose were a good description of what happened over the next 30 years, CO2 just over B, CH4 ~C, CFCs below C, and that you made an error in your interpretation of Hansen’s paper.

Phil:
I think you’re missing my point. Hansen’s 2008 paper made predictions on what temperatures were like for three different scenarios – A, B, and C – where those scenarios were explicitly described as alternative paths of “emissions.” Hansen stated, verbatim, that “Scenario A assumes that growth rates of trace gas emissions . . . will continue indefinitely.” Note that he didn’t say “concentrations.” He further states:
“Scenario A, since it is exponential, must eventually be on the high side of reality in view of finite resource constraints and environmental concerns, even though the growth of emissions in Scenario A is (~1.5% per year) is less than the rate typical of the past century (~4% per year). Scenario C is a more drastic curtailment of emissions than has generally been imagined; it represents elimination of chloroflourocarbon (CFC) emissions by 2000 and a reduction of CO2 and other trace gas emissions to a level such that the annual growth rates are zero (i.e. the sources just balance the sinks) by the year 2000. Scenario B is perhaps the most plausible of the three cases.”
This latter quote is about a clear as it can be – Hansen is using his model to make a prediction of what temperatures would result from three different hypothesized courses of action, each specifying how much greenhouse gasses we choose to pump into the atmosphere. Thus, when Hansen says that “Scenario B is perhaps the most plausible” he means that scenario B best represents the emissions reductions the world might be willing to implement. Hansen then used this paper and his model to go on a very public crusade to advocate for emissions reductions based on the scary results of scenario A, which he indicated were his predicted consequences of simply doing nothing.
Eliminating all doubt on this subject, Hansen brought this paper up in a Congressional hearing specifically investigating the issue of what kind of emissions reductions would be desired in view of the global warming hypothesis, and Hansen characterized scenario A as “business as usual” which plainly expresses the assertion that the temperatures shown in scenario A are what Hansen is predicting will occur if we keep increasing our emissions, even at the conservative exponential rate assumed. After all, the climate system doesn’t have a “business.” People do.
When, decades later after the real world results came in and he got called on that failed forecast, Hansen’s felt the need to dissemble. He not only took his “high side of reality” quote entirely out of context but he also falsely said that Scenario A was presented as a “worst case” scenario and that it assumed “rapid” exponential growth of GHGs, even though his actual paper specifically noted that the 1.5% growth rate was much lower than the recent historical rate of growth in emissions. If, as you say, Hansen’s predictions were right on target, why did Hansen have to lie like this?
Hansen assumed without any data or reasoning to back it up, that there was a 1-1 relationship between emissions and the measured increase in GHG concentrations. In other words, his prediction was premised on an understanding of the climate system where that system would not react to remove any portion of the amount emissions that we sent up into the air, hence to Hansen in 1988, emissions and forcing were for practical purposes the same thing. Accordingly, he assumed that past incremental increases of CO2 measured in the atmosphere was a measurement of past annual GHG emissions. In some cases, however, he used industrial data of emissions (see appendix B as it pertains to CFCs) and assumed that those emissions would continue, to construct his emission scenarios.
But I don’t care about what kinds of assumptions went into how Hansen got from point 1 (emission scenarios) to point 2 (temperature response to emissions scenarios), or even whether his numerical model differentiated emissions from concentrations. I’m judging Hansen’s predictions the same way my engineering professors judged my answers to the problems they gave me on an exam with specified starting conditions. If my answer was wrong, they weren’t interested in any after-the-fact excuses as to what information I didn’t know, what parts of my analysis were sound, or sophistries about what my numbers really represented, after I had already learned the right answer and how to approach the problem.
Hansen’s predicted relationship between emissions and temperature was wrong, and it was wrong because Hansen didn’t understand the climate system well enough to make that prediction. Having failed, his recourse was to start over with a new prediction about the future and see if it is right, not to retroactively adjust the old prediction by taking only those subparts of his prediction that in hindsight turned out to have not been invalidated (perhaps by sheer coincidence; since his model has a feedback factor of over 3, as long as the forcing is low, any variations between the three projected temperature curves are going to be impossible to distinguish over background variation for a really long time).
I know full well what an exponential rate of growth is. It’s just that I’m observing that our actual emissions into the air exceeded Hansen’s 1.5% growth rate, because that is the relevant metric to his actual prediction. You want to be able to remove Hansen’s assumptions about the relationship between emissions growth and trace gas concentration growth in the atmosphere from his prediction, and pretend that in 1988 he was just forecasting bland scenarios on different, arbitrarily selected atmospheric GHG concentrations, as if he had picked them by throwing darts at a board.
That increases in GHG concentrations didn’t follow in lockstep with emissions took Hansen by surprise.
We know this because in 1998, when temperatures weren’t rising fast enough in the last decade, and his preferred policy changes were accordingly not being adopted, he put out a new paper with new data assembled from “personal communications” to try to explain why temperatures weren’t rising: https://pubs.giss.nasa.gov/abs/ha01100t.html. Only after temperature didn’t follow scenario A did Hansen see the need to investigate what portion of emissions remains in the atmosphere, and after finding out that there really wasn’t much of a relationship, he decided to retroactively pretend that the scenarios of his 1988 paper should be judged against W/m^2 forcing calculated from atmospheric GHG concentrations, and not emissions.
And even in that paper he couldn’t bring himself to actually show the graph of changes in emissions against changes in GHG concentrations, instead hiding that information by converting it to a useless (and vaguely described) chart of the “fraction” of CO2 in the atmosphere relative to emissions, smoothing the curve, and serenely remarking that the smoothed fraction “remained at about 0.6” even though the annual variations ranged between 0.3 and 0.98, the smoothed curve ranged between 0.4 and 0.7 and the 30-year trend was downwards.

That still misses the point. I understand full well that with CO2 and methane (but not CFCs) Hansen is using measurements to determine what future emissions to assume as his scenarios. And I also understand that Hansen is likely taking those assumed emission scenarios (not all of which are based on measurements) and using them directly to increment future GHG concentrations, and having the model use his k-means clustering method on those concentrations to produce his delta T (called forcing) and then applying feedback to get his final temperature graph.
But the prediction being offered was of what would happen under various “emission” scenarios. That 1.5% figure was arbitrary. Given that the past emissions rates were disclosed to be about 4%, Hansen could have picked that value for post-1981 emissions. He could have picked 2%. All of those would have been based on measured CO2 atmospheric concentrations. But whatever value he picked was stated to represent an “emissions” scenario because the point of this paper was to present choices to politicians showing what consequences were associated with what policies they might adopt..