One question that’s unresolved for me is the minimum time span for completely averaging out weather noise. IPCC uses 30 years, but Gavin Schmidt of RealClimate has said that 15 years is sufficient for global temperatures (although not for smaller regions). I keep meaning to ask him about this, but never remember.

This may help:
http://julesandjames.blogspot.com/2009/02/decadal-prediction-cage-fight.html#comments

http://initforthegold.blogspot.com/2007/03/why-truth-is-losing-ground.html

See if you recognize our interaction in that description, eh? If so we can both do better.

W.F. Ruddiman’s “Plows, Plagues and Petroleum”
David Archer’s “The Long Thaw”
W.F. Ruddiman’s “Earth’s Climate: Past and Future”
“The Discovery of Global Warming” by Spencer Weart:

http://www.aip.org/history/climate/index.html

Review of above:

http://query.nytimes.com/gst/fullpage.html?res=9F04E7DF153DF936A35753C1A9659C8B63

[Response: Don't be too harsh on Hank, he's capable of excellent "knowledge harvesting" and is usually very even-tempered. Most of us have been assaulted by (sometimes very rude, sometimes "too stupid") denialists so often that we get irritated. Probably, too easily. Maybe that's their strategy.

Do you have kids? Grandkids maybe? If so, consider their future well-being: the greatest threat to them is Global warming. It's likely to create a crisis in basic needs (food and water are as basic as it gets) that'll make the current economic crisis seem like a Sunday-school picnic. But the "disease" progresses slowly, so it's critically important to "quit smoking" now.]

There is no magical threshold number. Volcanic eruptions cool for a year or two, El Ninos and La Ninas create spikes in the global temperature time series, and you got lots of other stuff going on. For instance, in situations where you can force deep, cold ocean water up to the surface you will see a “delay” in the long-term signal, but since the planet as a whole is taking in excess energy eventually you’ll see that warming realized.

Climate prediction involves accurate radiative transfer modeling since that is the key factor which serves to define the basic boundary conditions at the top of the atmosphere which constrain the global climate. Fully acconting for the time evolution of the global climate involves the physics of ocean-atmosphere heat exchange and their respective heat capacities.

On the other hand, the natural variability will swamp short-term “trends” since the trend is comparatively small. No matter how much the globe warms there is still going to be weather fluctuations and intra and inter-annual variability; you’ll have to get used to the fact that these weather fluctuations and even the long-term trend are not simply a function of CO2 increase.

As such, your question is not reducible to “we see the trend in 2012, but not 2011!!” The issue involves the time-evolution of the climate change signal and the degree of variability inherent in the climate system (as well as other external forcings such as volcanic eruptions and solar output). It is not self-evident that the current climate should not be more variable (as it seemed to be in glacial times) so if the “noise level” were to increase, detection would be a bit more difficult and would require a stronger signal or a longer time to detect it.

CO2 and other greenhouse gases are the only external forcings which are expected to rise significantly over the coming century. That is why there is concern over climate change, but you cannot define this change by looking at a handful of arbitrary years and seeing if “it happens” (wahtever that means).

C

It’s the assumption that science proves or disproves, truth or falsehood, that’s wrong.
You’re starting from a lack of information.
Very basic information. And you’re starting with assumptions that concern people who know they are wrong — concern people very much, because they’re very often fed to people to confuse them about what science can do.

Either you invented the mistake, or you caught it somewhere. It’s really basic stuff, it was taught when I was in grade school, I don’t know when or where it gets taught now. But people do miss out on it. Often because they’re misled.

This one:

> It’s simply a matter of projecting the trend
> and the range of noise around it

That’s wrong.

> seeing in what year the plateau would
> leave the potential range of noise.

That’s wrong. Know why? What’s the potential range of noise that might happen in any particular future year? How likely is that potential to happen in that year? How much of this can you tell in advance?

So when does the black line leave the gray area?

Look at the past. Can you find any period when you could be sure that you knew you had a trend? In the past the forcings were all natural variation.

Now we have added one known forcing to the mix. How much will it stand out from the rest?
Well, how much do we know about all the rest?
Do you know the level of likelihood for any of the other forcings?

> Can the author provide that year, please?

That’s “must be a pony here somewhere.”
We can express great concern that you were misunderstood, and ask how you came to the wrong assumption. But why bother? If you can’t recover from this, you need to look at the advice about asking smart questions.

Try this. It’s really helpful:

How To Ask Questions The Smart Way
Guide to teach how to ask technical questions in a way more likely to get a satisfactory answer.

http://www.catb.org/~esr/faqs/smart-questions.html

The author pointed out in his analysis that the so-called ‘plateau’ is not yet indicative of anything because it’s still within an acceptable range of noise around his equation. I simply asked how many years would it have to continue before it’s outside of that range.

And you guys wonder why the public is apathetic? Jesus Christ, someone comes along, who doesn’t spend every waking hour thinking and posting about this issue, sees an interesting article and decides to ask some questions. Here was a chance to win over someone and, instead of that, you tell him his questions are stupid. Now just how do you think that will be effective?

You know, I, like most people, have limited free time – I can spend it with my family, maybe try reading some books, maybe catch up with some friends. So it’s not easy to get all the facts on Global Warming, the Stimulus bill, new tax rules, new licensing requirements for my business, etc., etc. I decided to take some time to understand better Global Warming and all I get is a bunch of screaming people on both sides.

You guys may know a lot about this subject. Congrats. But when it comes to conveying that information to the public, actually trying to get people interested in understanding what’s going on, you are complete knuckleheads. Too bad.

[Response: I suspect some of the cold shoulder may be due to the fact that the question you asked gets asked a lot, usually by someone who has an agenda: to deny the reality of global warming. I'm not saying that's your intention -- just explaining why some people might view the question in that way.

In any case, there's not really any valid evidence that global warming has stopped, or even slowed. By 2015 or thereabouts, we'll know more about the situation. But the science behind global warming is so solid, the consequences so severe, the forces of misinformation so adamant, and time so short, that it's inadvisable to adopt a "wait-and-see" policy.]