Here’s global temperature anomaly (annual averages) since 1951, according to data from NASA (the year 2016 isn’t yet complete, so that value is for the year-to-date):
In addition to the trend there are also plenty of fluctuations, and for some of them we know the cause. In particular, the el Niño southern oscillation (ENSO), volcanic eruptions, and solar variations are known to influence temperature, but only temporarily. As regular readers are aware, I’ve created models of temperature accounting for those exogenous factors, in order to remove their influence as best possible. The model compares to the raw data thus:
The fit of the model is impressive, but what I’d like to draw attention to is the impact of those exogenous factors, which looks like this:
A number of interesting events are plainly visible, like the volcanic eruptions of Mt. Agung in the 1960s, el Chicon in the 1980s, and Mt. Pinatubo in the 1990s, all of which led to temporary global cooling. Then there’s the strong la Niña of the 1970s cooling things off, and there are three especially strong el Niño events which cause warming. The ones in 1998 and 2016 are evident, but the 1983 el Niño is hidden by the fact that it coincides with the el Chicon eruption, so they tended to mask each other.
That leaves the two major el Niño events of 1998 and 2016 as the biggest impacts on annual average global temperature since 1950; they stick out like a pair of sore thumbs.
The reason I’ve drawn your attention to them is that soon after 1998 we started hearing the long drawn-out undead zombie argument from climate deniers about “no global warming for XX years.” It started with “no global warming since 1998,” or sometimes “since 1997” when they could sneak in an extra year because the time span was so short, there wasn’t enough data since then to disprove the claim. Much more data has accumulated since they began this zombie argument, so much that “since 1998” didn’t cut it, so they tried switching to “since 2001” or “since 2002” to shorten the time span again. But there is simply no doubt that the extreme heat of 1998, due to the el Niño, was the start of their malfeasance.
There are always going to be fluctuations. They will always go both ways, hot and cold. Whenever there’s a hot fluctuation followed by a cold fluctuation — something that will happen again and again by the nature of randomness — it will look like there has been a trend change, in spite of being nothing more nor less than the nature of random fluctuations.
That’s why we apply statistics. If you want to claim a trend change, like “no global warming for XX years”, you need to show that the deviation from the existing trend is not just due to fluctuations. Those who have tried to do that with global temperature, have failed. I know; I’ve tried harder than most, maybe even harder than all, and when I published the result is was: no evidence of trend change. No pause, no hiautus, no slowdown.
But climate deniers aren’t much interested in rigorous analysis. Their main desire is to confuse people about the real danger we face, so anything that looks different from steady warming will be seized upon. The fact that random fluctuation so often looks like that doesn’t deter them — it inspires them.
A big spike — an extreme which goes in the direction of global warming even more than usual, is exactly the kind of fluctuation which invites that kind of mistaken conclusion. The 1998 el Niño was exactly that; so much above the trend that it was bound to make what followed look weak.
It doesn’t just happen with temperature data. Witness the recent, truly moronic attemp by David Whitehouse of the so-called “Global Warming Policy Foundation” (their policy: do nothing) which tries to declare a “hiatus” in Arctic sea ice decline. This is because there were two recent years, 2007 and 2012, during which the decline was extreme. Of course we don’t expect subsequent years to be more extreme right away … it takes time for a trend to show its impact. But we might have expected this kind of shenanigans from the GWPF: whenever there’s an extreme in the direction of global warming, the years immediately following probably won’t be so extreme, so you’ll be all set to declare a “trend” which starts at the exteme — just so you can claim the trend isn’t rising as fast as it really is.
So, all you extreme deniers, the next time something goes wild, the kind of thing that makes people sit up and take notice, don’t despair. Just declare a “trend” which starts at the extreme (it’s called “cherry-picking”) and of course it’ll be lower than the real trend. Don’t do it right away, of course! Wait a few years, just long enough for the fluctuations to make some graph look like you want, then … go all in.
And we’ll be here, to expose you.
Update:
By request, the data adjusted for ENSO, Volcanic, and Solar:
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Open Mind 
Would love to see the de-effected line, i.e. with volcanoes, solar and el-ninos subtracted.
[Response: See the update.]
Of course, the trend that counts most is the trend of perception across a large population. Then follows trends of understanding and action. What an easy target for opinion manipulators to attack: The early battlegrounds were policy and governments – the easiest to deflect, delay and mislead – sometimes by misinformation, other times by direct payments. This was a cheap victory for the oil industry… So 30 years of plundering the future. Now the costs and consequences have gone up, so the battleground shifts.
Interesting times.
The updated data, adjusted for ENSO, Volcanic, and Solar, is starting to look slightly non-linear.
[Response: That’s because it starts way back in 1950. From around 1975 on it’s indistinguishable from linear+noise.]
and once Arctic Ocean becomes free of ice, it’ll look slightly more non-linear.
We still hear the “no warming for x years” mantra from many deniers. The problem is that deniers can simply lie about the science, the facts; countering them has to rely on the science, the facts. And it can be tedious in the extreme to respond to every lie (using reality takes more effort than simply lying), especially when exactly the same lie comes out, again and again. Lying has no limit.
Thanks for this.
PS I was reminded of Michael Mann’s brief twitter response about your “no slowdown” post after a recent paper (co-authored by Mann) talked about the slowdown as though it was real. It came across a little as denial (something like “Tamino is entitled to his opinion”).
[Response: I wouldn’t call it denial at all. It’s a difference of opinion, probably combined with different definitions for important terms.
Most important is the fact that he (both of us, I hope) can actually be *persuaded* by evidence. That doesn’t mean instantaneous agreement, but it does mean “listen to reason.”]
Re. Mann and others. It has been my long experience with physicists that they really, really do not like the notion of unexplained error. This is probably a good thing in a physicist. But the approach brings its own problems when measurements and theory cannot possibly make predictions at the level of detail required to explain every bit of error.
In my experience with extreme denialists, which is limited to online interactions, the ones who still tout the “no global warming since…” nonsense do so based on the lower troposphere satellite data rather than the surface data, as they believe the surface data to be doctored. IIRC Ted Cruz did the same thing.
Speaking of the satellite data, does anyone know when RSS is going to release TLT V4.0? I’ve been looking forward to that one.
Yes, Texas Cruz cherry-picked the RSS data, which was the only one to show a flat linear trend since 1998. We now know, of course, just why that was… I, too, am looking forward to the new TLT.
“Texas”??? “Ted,” of course. Damn autocorrect. And tiny phone keyboards.
As typos go Texas Cruz is a nice one. One commenter wanted to call him Babbling Cruz (after one of his evidence-free speeches) and it came out Bubbling Cruz, which then led people to riff off the Beverly Hillbillies song line “shootin’ for some food when up from the ground came Bubblin’ Cruz”.
akanaja:
It is going to take me a long time to get that ear worm out of my head! “The first thing you know, old Ted’s a millionaire…”
Well, we can certainly hope he listens to the ‘kinfolk’ and moves to California. I can just imagine how that would boost his political career!
Regarding the release of a new RSS TLT v4, there shouldn’t be any problems/delays with that, unless TMT limb views need a special kind of diurnal drift correction.
Maybe RSS is abandoning the old TLT concept, since it has some inherent problems with central views and limb views (used to subtract cold stratosphere) being from different locations.
I believe that RSS TTT V4 is a good replacement for old TLT. It is also possible ( for everyone) to make a new RSS TLT product with the UAH v6 TLT recipe, or with channel data from NOAA STAR.
Btw, STAR has a new version 4 using Po Chedley (2015) methods for drift correction. It is still beta, hidden in the ftp directories, but the TMT and TTT trends (If one makes a TTT) are slightly larger than corresponding trends of RSS v4.
A question on the history… I don’t remember any serious “no warming since 1997/1998” claims until after 2005. And even then, they did not really get serious until the David Rose article in 2012, and the Hansen paper in 2013.
The “no global warming since 1998” claims ramped up when they had the fig leaf that allowed them to get away with saying “no global warming for a decade”. So that would have been in 2008. I recall some denialists ramped up these claims after the La Nina early in 2008.
Here’s my article on the topic:
http://hubpages.com/politics/When-Did-Global-Warming-Stop
There was indeed a lot of ‘warming cessationism’ around 2007-2010.
Reblogged this on Don't look now.
It looks like, even with so much understood noise subtracted, one can still go down the up escalator.
Quite a while back I did a quick and nasty graph of the number of prior years required to determine, for any year in the last several decades and with 95% confidence, a warming signal:
http://www.skepticalscience.com/argument.php?p=5&t=237&&a=11#89115
I’d be curious to see Tamino tackle this with more appropriate statistical handling, because the visual representation give an immediate impression (-> understanding?!) of the inherent nose superimposing on the warming signal.