By Paul Homewood
In an attempt to downplay the recent halt in global warming, the IPCC have claimed in their Summary for Policymakers that:
As one example, the rate of warming over the past 15 years (1998–2012; 0.05 °C per decade), which begins with a strong El Niño, is smaller than the rate calculated since 1951 (1951–2012; 0.12 °C per decade.)
Simply translated, this means that warming has slowed down to just under half what it was before. This message has been quickly picked up by the media, which, of course, was the main intention.
The dreadful Geoffrey Lean comments in the Telegraph:
The IPCC did, however, address a much more substantial sceptical point, that the temperature increase at the Earth’s surface has slowed down since 1998 to about 40 per cent of its average rate since 1951 – something it accepts it didn’t predict. One reason is that 1998, the year invariably chosen by sceptics, was one of the warmest ever.
So, at a stroke, the “pause” has become a “slowdown, but still significant” in the public’s eyes. But look deeper, and you will see this is a piece of devious trickery.
Is 1998 the best place to start?
First, let’s get rid of the 1998 red herring. The implication is that you can only get this “slowdown” by picking 1998 as the start year. The reality is that temperatures have been flat since 2001, which was a neutral ENSO year, and therefore comparable to this year. The Wood For Trees graph below shows this well.
Figure 1
They could also have mentioned that RSS satellite data actually shows a drop in temperature since 1998, not the small (and statistically insignificant) amount shown by HADCRUT4.
Figure 2
http://www.woodfortrees.org/plot/rss/from:1998/to:2013/trend/plot/rss/from:1998/to:2013
Longer term trends
But much more important than this attempt to deflect attention form the pause, is the way the IPCC have totally misrepresented the longer term trends. Figure 3 shows HADCRUT4 numbers going back to 1941.
Figure 3
Spot what they have done? Their base period of 1951-2013, against which they have measured post 1998 trends, includes:-
- 28 years of cooling – 1951-79
- 22 years of warming – 1979-2001
- 12 years of cooling again – 2001-2013
So, in total, during 40 out of the 62 years there has been a cooling trend. They are comparing a statistically insignificant amount of warming since 1998, with three decades of cooling. The result is to make this small trend sound much more significant than it is.
It would surely have been more honest to have compared the post 1998 trend with the 1979-98 period. If they had have done this, of course, most people would realised that the much trumpeted global warming really had stopped for the time being. And, in the IPCC’s eyes, that was not the message they wanted people to hear.
By this dodgy use of statistics and the 1998 red herring, they have also tried to distract attention from the clear fact that temperatures really have flatlined since 2001.
How temporary is the “temporary pause”?
It is commonly argued that a short pause in warming, of a decade or so, is not unexpected, amidst all the natural variability.. Back in 2010, the UK Met Office commented:
Recent Met Office research investigated how often decades with a stable or even negative warming trend appeared in computer-modelled climate change simulations.
Jeff Knight, lead author on the research, says: “We found one in every eight decades has near-zero or negative global temperature trends in simulations. Given that we have seen fairly consistent warming since the 1970s, the odds of one in eight suggest the observed slowdown was due to happen.”
But, if you go back to 1941, you have actually got 50 years of near zero or negative trends, and only 22 years of warming.
So which is the norm, and which is the rarity?
Footnote
It appears that the IPCC’s Thomas Stocker now claims that climatic trends should not be considered in periods of less than 30 years.
I don’t remember the IPCC suggesting that after just a decade of warming, when they wrote their first report.
richardscourtney says: September 30, 2013 at 1:33 am
“You did not SAY the FAR SPM suggested there could be a halt to warming “for a decade or more”, but in context you SUGGESTED that.”
Nonsense. My contention weas very simple. The head post said:
“I don’t remember the IPCC suggesting that after just a decade of warming, when they wrote their first report.”
and I quoted what the IPCC actually said in 1990. They in fact had a record of 14 years warming, not 10, but they said, that’s not enough to be unequivocal; we’d need at least another decade of warming to say that. That is, we need at least 24 years – Stocker prefers 30.
The great sadness with people like Geoffrey Lean is that they don’t want to recognise that warming isn’t happening as they would like it. When did we last hear any warmist say, l “let us hope that the sceptics are correct and that we might not have anything to worry about after all”? For reasons best known to them, they seem to hope and pray that catastrophic warming will happen, and want to fight to the bitter end in order to persuade a gullible public that catastrophe for the world is just round the corner. Perhaps it’s all about their potential loss of income coupled with their reputations as scientists that they consider more important than admitting they have been barking up the wrong tree for so long.
Nick Stokes:
re your post at September 30, 2013 at 2:08 am.
Having been shown to be disingenuous in your previous two posts, you now resort to a flat out lie.
The IPCC First Assessment Report (1990) did NOT say they needed 24 years to determine “The unequivocal detection of the enhanced greenhouse effect from observations”. They then said the “unequivocal detection” would probably require “a decade or more” FROM THEN.
Your interpretation of why they said that has no relevance to anything.
The previous IPCC Report (i.e. AR4) made a prediction (n.b. prediction and not ‘projection’ for “the first two decades of the 21st century” of “0.2°C per decade”.
(ref. IPCC AR4 (2007) Chapter 10.7 which can be read at
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-7.html )
The halt to global warming has refuted that prediction in the AR4, and that refutation by reality is the reason why the AR5 has introduced the 30-year period to assess climate.
Richard
Ooops my intended bolding has become a spurious block quote. Sorry. Richard
Scute
There is only one word applicable at present. It is a halt.
Yes, you are right.My use of the word “pause” was not intended to convey that warming would resume, merely that it seems to be the word that is in common currency now.
Perhaps we all ought to agree on a new word!
richardscourtney says: September 30, 2013 at 2:51 am
“They then said the “unequivocal detection” would probably require “a decade or more” FROM THEN.”
This gets tiresome. Yes, that’s what they said. And they had observed 14 years of warming. I pointed out the obvious arithmetic.
The big La Nina drop in temperatures which occurred immediately after the 1998 El Nino, almost cancels out the effect of this el Nino spike on the overall temperature trend. Indeed one could choose 1999 as the start date in order to try to salvage a warming trend up to the present (but it would still not quite succeed).
If temperatures maintain even a weak upward trend to the end of the year, then there could be a steep drop in temperatures in the start of 2014. If you look at el Nino and La Nina events, large temperature drops after an el Nino always start in Jan-Feb, and significantly reduce global temperatures. By contrast, the temperature falls after peaks in summer are always weaker (and form part of a rising trend). We are not of course in an el Nino, nor really La Nina – the ENSO status (Nina 3.4 index) has persisted around zero for an unusually long time. But if a temperature drop is going to take place, the most likely time for this to begin, for synchrony with the normal annual phase-locked ENSO cycling, is after the new year.
Nick Stokes:
At September 30, 2013 at 3:26 am you at last say something I can agree; viz.
YES!
And the tiresome thing is that you tried to mislead and you have been using any method you can think of to avoid admitting you tried to mislead.
The IPCC did not say, suggest or imply that a 30-year period was needed to assess climate in any to its Reports until the AR5. Indeed, the IPCC AR4 made a 20-year prediction that has proven to be wrong. But in response to a comment saying
Your post at September 29, 2013 at 11:34 pm claimed
and you quoted from the FAR.
Your quotation and nothing else in that or any other IPCC Report prior to AR5 says anything like you claimed.
Admit that you were wrong or simply shut up, but don’t think I am going to stop pointing out your egregious and tiresome behaviour until you do admit you were wrong or simply shut up.
Richard
The MET office “research’ is dishonest and damage control to say consistent warming since 1970 without mentioning AMO pattern and contribution.
I cannot for the life of me understand why any skeptic is even using the loony notion of linear trends at all in such noisy data as is evident from the silly conversation being passed off as debate on the matte. The ‘trend’ quantum and even sign is significantly dependent of the start/stop point of the linear ‘fit’ and frankly the ‘fit’ seems more epileptic than statistical to me. Once you apply a filter to the data, even a 2, 3 or 5 year filter what results is something with obvious cyclical components visible in the sample period and the clear suggestion of longer period components being just as possible contenders as underlying monotone increasing ones.
It is in this swamp of fundamental irrationality that the AGW case is floundering around like the French knights at Agincourt and the band of skeptical brothers can so easily pick off these self important fools mounted on their trusty sinecures . Who needs to venture down into the swamp and start swinging a rhetorical sword by even using the language of the fools?
Plateau.
Samurai
Could someone please post a link to the latest HADCRUT4 anomaly?
From the attached graph, it looks like the latest temperature anomaly is around 0.1C, which I don’t think is correct. I thought the latest HADCRUT4 temperature anomaly was around 0.5C.
The Woodfortrees system is slightly misleading. Where it says “To 2013”, it actually cuts off at Dec 2012, when the anomaly was 0.268C. It is currently 0.514C.
For UnfrozenCaveman & Others
Don’t get me wrong, my skeptical credentials are above reproach, but the breakdown of the temperature anomaly record into chunks of differing linear trends is a little dishonest if the gaps between linear segments invariably contain discreet upward jumps.
Please note that my only purpose in showing these trends was to highlight the periods of cooling/flatlining, and not to detract from the warming that did take place between 1979 and 1998.
I generally do not refer to the pause or hiatus. I reference the change in the PDO around 2005 and show that hadcru4, GISS and RSS all show cooling from that point. Hence, I state the planet is now cooling. That really gets the true believers goat.
Also, if the alarmist are going to claim 1998 is cherry picking just show them that 1951 started as a La Niña and 2010 was an El Niño. The entire IPCC report is cherry picking a cool start point and warm end point. That is the only way they get .12C/decade.
***
CRS, DrPH says:
September 29, 2013 at 5:40 pm
Can anyone explain the physics of hiding heat deep in the ocean to me?
***
There is no significant mechanism for it. Just the opposite — the deep ocean is a store for cold water. The water there being well below the avg earth temp is proof.
I love how any cooling is always explained as natural variability, but all warming is due to human use of fossil fuels liberating CO2. Warming is never due to natural variability.
I am sure I made a comment here
cannot remember what is was about
but I can not think of any reason why it was not published?
[Reply: I believe that may have been my mistake. In deleting more than a hundred spam comments, I may have overlooked a legitimate one. My apologies if that’s what happened. Best to keep a copy until you see it published. — mod.]
philjourdan says:September 30, 2013 at 1:50 pm
” a “decade or more” is nowhere near “no less than 30 years”!!!! “
The IPCC in 1990 had observed warming for 14 years. They said a further decade or more was required to make a an unequivocal assessment.
@Nick Stokes – so you cut the margin of error in half. It still does not say the same thing. Not even closing one eye and winking at it will make it say the same thing.
If this warm period is to be named, please stay away from words like recent, current, etc. They will only lead to confusion in the future (e.g., ‘contemporary’ style homes in the US refers to a style that was popular fifty or so years ago. They are no longer contemporary). How about just calling it a very boring name like, the Late Twentieth Century Warming, or LTCW? That would also emphasize that it ended before the start of this century.
I consider 2001 as an honest start year of the hiatus. Using 1998 appears to me as using the El Nino to overstate one’s case. Smoothed global temperature trends continued rising past 1998 and largely leveled off in 2001.
As for Figure 3: Consider that 1941 was a warm time in the cyclic pattern of global temperature that shows up in HadCRUT3. Also, I would use a choice of borderline years and slope determining means that makes the line segments connect – as opposed to having upward vertical jumps from one to the next. Supporting an argument that a majority of the time it has been cooling appears to me as overstating the case of how low the manmade extent of global warming is.
….my apologies to Mssr. Jules Verne!
http://www.online-literature.com/verne/
All of the heating they have been documenting is likely caused by the direct heating of the earth by burning fossil fuels.
For example if I burn 1 log on the fireplace in my house every night, my house is a little warmer at night.
If I burn 10 logs on the fireplace in my house every night, my house gets a lot warmer.
Silly stuff.
Jtom says: @ur momisugly September 30, 2013 at 6:08 pm
….. How about just calling it a very boring name like, the Late Twentieth Century Warming, or LTCW? That would also emphasize that it ended before the start of this century.
>>>>>>>>>>>>>>>>>>>
Sounds good.