I think the question is not if it’s going to get colder (cooler?) but how much. There’s an underlying upward trend but there is also this cycle (which I’m assuming is related to the PDO). How big an effect that has I don’t know, but I think it’s a real problem for the modelers if they haven’t taken that into account. If the models don’t show that cycle in the output then they’re going to be off when the PDO goes negative (which is seems to be doing). The PDO is also going to bias any long term trend if you’re only catching part of a cycle.

There is a 60 yr cycle in the trends of the historical data and we are at the peak of a cycle. The trends are going to go down for the next 30 yrs before starting back up if historical observations hold true. If we are to get to 2C/Century the average rate has to get to that value. So if you believe that the rate is going to go well above .2C/decade for the last four decades great, but at 2060 the trends should be starting down again.

I’m not arguing that the temperatures will continue going down or the rise stop, just that the projection of 2C, or even close to it, doesn’t seem to be reasonable. The average rate, on the other hand, may reach that but not anytime soon.

Did the IPCC say that the trend for last Century was 2C/Century?

I have no idea what substantive point you are trying to make or what specific statement you are trying to rebut.

But to answer your question– which I suspect you intended as rhetorical: Read the the next blog post. It shows the 20 year trends based on IPCC projected during the period of we are discussing which includes portions of the 2C/century.

As I said in this post:

In closing, do note: While these sorts of eyeball methods aren’t very useful for discriminating whether the IPCC projection of “about 2C/century” from the AR4 is on track or not, we can see all 20 year trends ending after 2005 fall below that 2C/century.

I could have added “and fall below the 20year trends based on projections based on models including volcanic eruptions since at least 1979.”

Feel free to say “So what?” In this post, I’m just decribing the data.

More to the point: “you can’t get there from here”. Only taking trends 20 yrs or shorter do you see trends above 2C/century, even using all of the Hadley data (ref Comment#12790).

Well it looked like you were implying it as you are saying if the trend is below 0.2C/decade (on your graph) then it is below the 2C/ Century.

I am not “unhappy” about it. I think it’s kind of comic actually.
So what if the trend to 2008 doesn’t fit the 2C/Century trend? The Century has barely started.
Why is it important that the trend to 2008 doesn’t fit?

o assume that the IPCC trend of 2C/Century means that the decadal trend will always be 0.2C/decade is… dumb

Who here assumed this? Not me.

As for long and short trends: You are unhappy if I note the smoothed, long term trends fall below the IPCC “about 2C/century”. You are unhappy if I show the IPCC “about 2C/century” is not consistent with the short term trend. If you are blond, can I ask, “Goldilocks, what length trend is just right? “

To assume that the IPCC trend of 2C/Century means that the decadal trend will always be 0.2C/decade is… dumb.

“Why should anyone try to gain understanding of what’s going on using smoothed graphs (i.e. 20 year averages) when it’s well understood that smoothing reduces the information in the original noisy graphs?”
What? So if you want to find a long term signal, you use the shortest term data you can find?

AGW’ers have jumped on the upswing that global temperatures experienced from the mid-70’s to 1998, without ever noting that the preceding downswing was almost as severe. With all the arbitrary “adjustments” (“bi-linear” homogeneity, bucket, etc. ) they never truly adjust for UHI. This produces an UHI and adjustment-corrupted surface record that conceals the preceding downswing. That’s why satellite measurements are so important! Alas, they’re still too short to discern true climate trends.

So, this is a plot of a large collections of trends fit to a graph that is not shown here.

But I’d expect that to produce a single line through the data. The graph does not show a single line, which contradicts that expectation. Also the phrasing suggests one trend per year, and I’m not seeing the many expected lines (1988-2008, 1987-2007, 1986-2006). My hypothetical meanings are not matching the results.

# tendency: a general direction in which something tends to move; “the shoreward tendency of the current”; “the trend of the stock market”
# course: general line of orientation; “the river takes a southern course”; “the northeastern trend of the coast”
# drift: a general tendency to change (as of opinion); “not openly liberal but that is the trend of the book”; “a broad movement of the electorate to the right”
# swerve: turn sharply; change direction abruptly; “The car cut to the left at the intersection”; “The motorbike veered to the right”
# vogue: the popular taste at a given time; “leather is the latest vogue”; “he followed current trends”; “the 1920s had a style of their own”

The common usage of the word “trend” permits us to refer to these lines as “trends” for those specific periods.

But, global temperature seems be very non-linear on nearly every time scale.

Applying standard statistical tests (of, for example, confidence intervals) makes implicit assumptions regarding the temperature data. The assumptions may be true or false.

Thus, the use of straight line trends to reach defensible conclusions in the case of AGW need more than “statistical” justification — they need “scientific” justification — i.e. their applicability should be proven empirically.

Then, there is the issue of published temperature data quality. In the current context, historical thermometer data is suspect. And, satellite data is calibrated to thermometer data to an extent.

None of this is news to most people here. These thoughts run through my mind when people debate AGW on the basis of straight line trends.

What I like about this site though, is that Lucia is mathematically objective and many posters attempt objective agreements and rebuttals. Consequently, in my mind, this site adds value to the discussion of AGW. And, I visit often.

link

So teh issue is not the size of an trend but the capability of teh current models in matching an observed trend.

I have a feeling that I am stating the obvious here but eh disucssion seeems to be all about trends and not about model accuracy.