No, I can not deny that temperatures are trending below scenario C. I would say that climatology is is better understood now than when Hansen made his predictions, just as in the days of Svante Arrhenius, it was better understood than in the days of Joseph Fourier. And in the days of Gilbert Plass, it was better understood than in the days of Svante Arrhenius. And it was better understood in the days when James Hansen made his projections than in the days of Gilbert Plass. And it will be better understood in 50 years than it is today.

In addition, no one knew what the Sun would do and all three scenarios were based on constant solar output. Hansen predicted that an increase in solar output would lead to more waming and a decrease in solar output would lead to less warming than would changes in carbon dioxide alone. He also overestimated the amount of carbon dioxide which we would put into the atmosphere under scenario B as well as scenario A.

Well, let me answer with a thought experiment.

Suppose I spend several years studying the traffic patterns on a Friday evening between city A and city B. I begin to understand the general mechanics and dynamics, develop a model of the traffic patterns, and use this model to predict how long it will take you to complete a journey between city A and city B next Friday. When the Friday comes, we attach a GPS tracker to your car, you set off from city A and I start my stopwatch.

For the first 50 miles or so, we find that where you are and the time elapsed pretty much match my prediction. But then you get caught in traffic and there is a deviation ... you've not progressed as fast as my model predicted. Ten minutes go by and you're 10 miles behind where my model said you'd be.

Now at this point, we have two options. You could stop the experiment and declare my model a failure. But would my model really be a failure? After all, it predicted your progress accurately for 50 miles. That would suggest it wasn't completely wrong and that maybe there was some factor I hadn't taken into account properly. I could say that, actually, my model might be incomplete, and needs a bit of tweaking based on the data we obtained. Which is, after all, how science progresses.

But, of course, if you'd continued the experiment, maybe the road would have cleared and you'd have begun to catch up with my model. We'd never really know if my model was generally correct or not if you just stopped and turned around home.

So, back to Hansen. That model did a pretty good job of predicting future climate trends. It wasn't perfect, and we know that, but then science operates by making improvements based on additional knowledge. Will the temperature continue to trend in the manner you state - well, that's like turning around when the model doesn't match, so if we continue the journey we'll get a better idea.

For a detailed description have a look at

http://www.realclimate.org/index.php/arc...

Ian I'm surprised that you would post something like this; I thought that you, having pulled me up a couple of times for inadvertently posting misleading graphs, were more reasonable than the many on your side that happily peddle this kind of thing.

From your criticisms of my postings, it is clear that you know that you don't determine a temperature trend simply by drawing a line between the start and end points, yet that is exactly how the 0.22C temperature rise has been arrived at. The figures for the three Hansen scenarios have been determined in a similar way and from the same starting point.

So I would say, and I hope we can agree, that neither the actual trend nor any of the Hansen trends are reliably portrayed by your graph.

I've had a quick look at the whatsupwiththat site; not my usual reference, but I found this, which I think is a fairer graph for your question. I would say from eyeballing this that the trend lies somewhere between Hansen's B and C scenarios.

http://wattsupwiththat.files.wordpress.c...

That all depends on ones interpretation of the word 'trending'.

And no, Ian, it does not mean 'they are currently at' as Ira Glickstein wants you to believe with his highly modified original Realclimate graph. He's plastered the graph with so much additional (nonsensical) info that the original trend-lines are hardly visible anymore.

Were you to argue here that Hansen's 1988 Scenario C for 2012 has turned out to be too high, you would have a point. But that is not what you are doing with this question because here you specifically refer to 'trending'.

And why on earth would someone referring to 'trending' post a graph with the trendlines almost completely obscured from view with (convenient?) thick red lines and circles splattered all over the most important pieces of info?

Here's the original Reaclimate graph with the trendlines fully visible:

http://www.realclimate.org/images/hansen...

Edit @ Ian:

<>

Then why use a highly-modified graph with most if not all of the trend data obscured? I think you blatantly misunderstood what the WUWT/Glickstein modified graph tried to get across (and which has nothing to do with trends).

<>

Isn't that bleeding obvious?

Original graph: http://www.realclimate.org/images/hansen...

The one you used:

http://wattsupwiththat.files.wordpress.com/2013/03/hansen88.jpg

Wow did I just hear right, an alarmist admitting the sun might have some effect after all.

The important point to consider is that if Hansens A,B and as looks like C is over exaggerated, then the Earth is not going burn up soon and disaster is not likely for some time.

Isn't it time for the world government to sit back and consider what to do long term, rather than rush headlong with crazy schemes that might cause as much harm than good, shouldn't we be looking at a hundred year energy policy, not crazy firefighting.

Or is it all politics, just thinking about the next term in office.

James Hansen was too busy participating in left wing demonstrations to carefully check his figures.

James Hansen's eyes were too teary over Obama's inauguration speech to accurately see the data.

James Hansen didn't know the difference of the figures between the true data and his corrupted data.

James Hansen is a distant relative of Michael Mann, so you have to forgive him.

I am sure they are willing to forgive Hansen because he was simply exaggerating for the cause and it is a cause they believe in. I suspect they feel we can't dwell on the past (now that they are proved wrong). It is time to focus on the future and we need to redraw the line (again) and continue to rid the world of that evil liquid, petroleum. If we have to exaggerate here and there, it is worth it, and we can still pin the science badge on our chests.

http://wattsupwiththat.files.wordpress.com/2013/03/hansen88.jpg

I will give Best Answer to the alarmist that can best refute that temps are trending below Hansen's scenario C.

I will NOT accept typical alarmist answers of "You lie" ("Watts lies", "You can't trust Watts", etc...) or "You don't understand science".

To help you out you can build on:

----When Hansen made that prediction, Climatology wasn't well understood. Now we have it on lockdown.

----Hansen was 100% correct. It's just that reality didn't cooperate.

----We're still finding out reasons that current temperatures need to be adjusted upwards. Just give it a few more years.

----Who are you going to believe, Hansen or your own lying eyes?