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Is there such a thing as a 'global temperature'? How is it calculated?

Isn't it wonderful to see us under a positive anomaly for a change? What are the chances of that happening in July I wonder?

To ensure that our forcasts remain on record I post the predictions made at the start of the year


Met Office +0.44
SmokingDeepThroat +0.39
quake +0.36
ukpahonta +0.35
Gadgetfriend +0.30
NeilHamp +0.27
QuaesoVeritas +0.25 (revised)
millinia +0.24
Joe Bastardi +0.2
Ken Sharples +0.18
LabMunkey +0.18
nibor25 +0.15

As Paul says RSS is showing +0.1
If HadCRUT3 follows RSS we can expect at least +0.4 for April
The La Nina is showing some signs of returning to neutral conditions
The next few months will be critical

# NeilHamp wrote:
"As Paul says RSS is showing +0.1
If HadCRUT3 follows RSS we can expect at least +0.4 for April"
Actually, I make it about 0.26c, based on adjusting RSS to1961-90, by adding 0.147c.
However, the 12 month mean unadjusted RSS to March was 0.347c and HadCRUT3
was 0.412c, so that differential would make HadCRUT3 about 0.175c.
Just out of curiosity, how did you arrive at 0.4c? Was it based on the March
differential, which seemed to be unusually high? There doesn't seem to be
a consistent relationship between monthly RSS and HadCRUT3.

#1 - Devonseaglass-on the shore wrote:
"Is there such a thing as a 'global temperature'? How is it calculated?"
In simple terms, by measuring the temperature at a number of points on the planet and averaging them. It sounds simple, but in practice, it's a lot more complicated.
There are several different sources of global temperature, (UKMO, CRU, NASA/GISS, NOAA/NCDC, RSS and UAH, to name the main ones. The temperature is usually expressed in terms of "anomalies", i.e. the difference between the current temperature and a "normal" period. One problem is that the different bodies all use different periods as the "normal" period. Another is that they all use different methods and locations, and some use satellite measurements. A good starting point for finding out about this is the Climate4you website:


My advice however, if you wish to stay sane, is not to bother!

My estimate for HadCRUT3 for April was based upon a crude up-scaling of the March figure.
If your estimate is right QuaesoVeritas then the mean to date for 2011 will be +0.26

"Is there such a thing as a 'global temperature'? How is it calculated?"

It's a bit similar to taking an average temperature of all points in your kitchen, including of course the kettle and the freezer. It's only usefulness is in keeping a load of Mann-made-up warmist scientists on the gravy train.

Hmm! Looking back at previous El Nino / La Nina events of 1998/1999 and 2007/2008

HadCRUT3 1999 global average was +0.263
HadCRUT3 2008 global average was +0.312

2011 looks as though it may be a little warmer than 2008
My money is on quake and ukpahonta as likely forecast winners

We have a PDO switching to cold in recent years, so more of a bias to La Nina than El Nino for the next 30 years. I suppose this could be the big test, if we match these previous temperatures with larger negative influences it will be telling. However I'm sticking to my +0.24 by taking that larger negative influence into account.
All the extreme weather of the last few months certainly points to a greater influence of cold, with the latest Mississippi floods being a combination of deep and long lasting snow cover finally melting out (late) and the big storms created by the clash between still cold northern air and warm moist Gulf air.
May is usually the worst month in the US for violent weather (barring tropical cyclones), so there could be a lot worse to come. One thing for certain, no amount of CO2 output restriction will stop it happening again - these floods happened in 1927 and likely have been at least as severe on many occasions when European settlers were not around to to record. The Mississippi is a huge river with a very wide flood plain, which is why that part of the US is so fertile.

#6. - NeilHamp wrote:
"My estimate for HadCRUT3 for April was based upon a crude up-scaling of the March figure.
If your estimate is right QuaesoVeritas then the mean to date for 2011 will be +0.26"
I'm not saying your wrong, it's just that the differential for March was unusually high, but being the most recent, it may be the most accurate.

#7 - PingoSan wrote:
"It's a bit similar to taking an average temperature of all points in your kitchen, including of course the kettle and the freezer. It's only usefulness is in keeping a load of Mann-made-up warmist scientists on the gravy train."
A good analogy - I wish I had thought of it!

PingoSan wrote:

". It's only usefulness is in keeping a load of Mann-made-up warmist scientists on the gravy train."

And of course determining if the globe is warming like it should do on average if the concentration of green house gases increases according to basic and long established physics.

Why is GISS consistently the warmest?

"And of course determining if the globe is warming like it should do on average if the concentration of green house gases increases according to basic and long established physics."

We'd be better using ocean temperatures. Oh wait, those show cooling, we can't use those!!

"Why is GISS consistently the warmest?"

James Hansen. Invented data for the Arctic.

The April UAH figure is a bit higher than I had expected based on it's normal relationship with the AQUA CH5 anomaly, but the latter figures were missing for the end of the month. According to my calculations it is equivalent to a HadCRUT3 figure of about 0.37c, whereas RSS was equivalent to about 0.26c. However, I don't necessarily think we will see a HadCRUT3 figure as high as those.
The increase seems to due to the NH anomaly, which jumbed from -0.073c to +0.199c before adjustment.

#13. At 18:55pm 10th May 2011, openside50 wrote:
"Why is GISS consistently the warmest?"

It isn't!
After the figures have been adjusted to the same time base that is.
At the end of March 2011, the HadCRUT3 10 year mean was 0.432c and the adjusted GISS 10 year mean, was 0.436c.
The adjusted GISS 10 year mean was below HadCRUT3 between about 1968 and 2010. Based on monthly anomaly figures.

>>>It's a bit similar to taking an average temperature of all points in your kitchen, including of course the kettle and the freezer. It's only usefulness is in keeping a load of Mann-made-up warmist scientists on the gravy train.>>>

I prefer one thermometer in the middle of the kitchen, with a reading taken at 0100 when there are no appliances on, the sun isn't shining and the cat is asleep.

Hmm!
AMSU-A Temperature Trends (Ch.05 v2) have just risen above the average for the first time this year



The last La Nina year 2008, as well as the average, is a good comparison year for 2011.
Looks like the La Nina is beginning to subside

#18. - NeilHamp wrote:
"Hmm!
AMSU-A Temperature Trends (Ch.05 v2) have just risen above the average for the first time this year"
Not strictly true, it went over the average for a few days in January, and again in April, actually by more than it is currently. The cumulative figure for any month is above average for the first time, but that is probably because it has happened so early in the month. The cumulative figure for the year is still well below average and I am not convinced that this period of above average anomalies is any different to the earlier ones. Of course, I may be wrong.
Incidentally, I believe that Prof. Jones has now "interpolated" some figures for the missing last few days of April and May 1st. As a result of the additional April figures, I make the final April CH5 anomaly about -0.089, equivalent to a UAH of about +0.46c, still a bit lower than the actual UAH figure.
It appears that even Prof. Jones thinks the official number is a bit higher than he would expect from the CH5 figure, and is trying to find out why that is.

"It appears that even Prof. Jones thinks the official number is a bit higher than he would expect from the CH5 figure, and is trying to find out why that is."

I'm sure he'll find a reason, and then not show you his working because he's spent 24 hours on it and why should he show you his working when your intention is to find something wrong with it?

Spoken like a true scientist.

At 14:37pm 11th May 2011, You wrote:
#20. At 13:25pm 11th May 2011, PingoSan wrote:
"I'm sure he'll find a reason, and then not show you his working because he's spent 24 hours on it and why should he show you his working when your intention is to find something wrong with it?
Spoken like a true scientist."

I have mislead you by saying Prof. Jones instead of Dr. Spencer!!!!
I really don't know why I would get those two mixed up.
Just to clarify, it is Dr. RoyW. Spencer, who produces the UAH anomaly figures
who is checking the April figures.
SORRY!!!!

According to Dr. Spencer, the difference between the AQUA CH5 data and UAH is the result of a switch from a westerly Quasi-Biennial Oscillation to an Easterly one, resulting in strong lower stratospheric cooling in the tropics, which influenced CH5.
I don't pretend to understand this, but there didn't seem to be any evidence of cooling in the CH5 figures and in fact, the anomalies were lower in March.

Slightly OT but are our politicians slowly getting the message? - Bravo Vince Cable.

/news/uk-politics-13343055

The more each day passes, the less I buy into the Global warming myth by man. I personally think it is a distortion of the truth, no matter how people try to portray it. Until we consider the temperature of the sun and earths orbit around the sun, the whole truth will not be known.

The setting of Carbon emissions to me, is totally pointless. Any business, should always consider carrying out its actions in as efficient way as possible, to ensure maximum profitibility. But then if you are a government organisation, who spends money that you don't generate, you are most likely to be one of the biggest culprits.

Margaret Thatchers desire to close down pits and her investment in science that proofed Global warming, brought out into the open by Nigel Lawson on the TV and in his book, says it all for me. We are still suffering from Margaret Thatcher 30 years later and I am no socialist.

timawells,
While I disagree strongly with your comments re M. Thatcher (we are all socialists now), I do agree regarding carbon emissions and AGW.
Unfortunately, "climate change" propaganda has been so successful that it is now assumed that the climate is changing, when there is little evidence for that, apart from the fact that average temperatures have risen slightly over the last century.
I heard the chairman of Waitrose, Mark Price, cite "climate change" as one of the reasons for rising food prices, without giving any examples. A few years ago, he would have used the term "adverse weather", but he used "climate change", because it is now assumed that is the cause of all bad weather. He also mentioned the increase in the demand for food due to world population growth, which is a much more likely cause. Incidentally, I also heard a commodities trader in the U.S. say that we face a crisis on food supply much sooner than we face one on fossil fuels.
Regarding the U.K. carbon emissions, we have apparently already missed our 2010 targets, despite the fact that we have "exported" a large part of our industry to China, so setting even lower targets does seem futile:

I think it is ironic that one of the reasons that carbon emissions increased in 2010, despite the recession, were the cold winters of 2009/10 and 2010/11, which of course, if we believe the AGW propaganda, shouldn't have happened.

Even Watchdog was complaining about greenwashing tonight, so it must be bad.

The stupid decisions we are making regarding energy in the UK is far more worrying that what the weather is going to be in 50 years. Fuel poverty is going to become endemic in the UK, yet shale gas will probably mean many parts of the world are awash with energy. What is it about the UK that makes us continually strive to make the most cloth-headed decisions and waste billions of pounds time and time and time again?
To the man in the street with common sense and no scientific background it must all look fishy, but they have no argument against the "intellectuals" and yet have to bear the greatest pain when these decisions invariably are shown to be wrong.
Regarding food, again it is all so much hogwash bandied about to keep us scared. Food production has risen to meet the growing population, and with 50% of food production in the developing world and 30% in the developed world wasted before it gets to the table we already have the capacity to feed 9 billion - we just have to learn to do it better. Whether we can do it with animal protein is another question altogether, a more varied diet for all of us would do no harm.

Have to repost this outburst from Mr Bastardi - . It's the cooling stoopid!

#26 - millennia wrote:

"To the man in the street with common sense and no scientific background it must all look fishy, but they have no argument against the "intellectuals" and yet have to bear the greatest pain when these decisions invariably are shown to be wrong."
I have noticed a tendency for scientists, when challenged by non-scientists, to revert to scientific and statistical jargon, possibly to bamboozle their opponents,
knowing that most people won't understand what they are saying or be in a position to challenge it, because in general, people don't want to look stupid by asking more questions.

"Regarding food, again it is all so much hogwash bandied about to keep us scared. Food production has risen to meet the growing population, and with 50% of food production in the developing world and 30% in the developed world wasted before it gets to the table we already have the capacity to feed 9 billion - we just have to learn to do it better. Whether we can do it with animal protein is another question altogether, a more varied diet for all of us would do no harm."
Surely you mean less varied, since we will all be eating the protein we would have been feeding to the animals.?

Quaesoveritas. I think that Margaret Thatcher has much to do with todays problems even though she has been gone for quite a few years. As far as I am concerned H&S and political correctness madness started under her, there was only one opinion and that was hers. I think Global warming was started by her investing in scientific research to proof it. I was a Conservative at the time, but have seen the error of my ways, but don't swing to the opposite polarity of Labour.

#29. - timawells
I don't really want to start a discussion about M.T. here, as it is considerably off topic.
All I will say is that she is like Marmite, you either love her or hate her.
In my opinion, she was one of the best PMs of the 20th century, and she laid down the foundations for a modern U.K., whether or not you think that is a good thing or a bad thing. Without her, we would still be living in a country with a state owned telephone service, with a waiting list for a state approved telephone, state owned gas and electricity suppliers, a state owned car manufacturer and a state owned mining industry which could hold the nation to ransom every now and again. And of course, many more failed state owned industries.
Prior to M.T. we effectively lived in a Communist country, now we only live in a socialist one, and even with privatisation even her Governments were socialist, as has every Government since. O.K. things haven't worked out perfectly for the privatised industries, but we couldn't go on the way we were. If anything, our current problems with these industries is due to a lack of competition, rather than too much.
I am also sure that someone once posted a comment here to the effect that she was also sceptical about climate change, according to her autobiography, which I haven't read.
I am sure that you will wish to respond to the above, but I will resist the temptation to reply, since as I say, it is off topic. I blame the lack of any more temperature data for this digression into politics!

According to Essex, McKitrick and Andresen, in a paper 'Does a Global Temperature Exist?' published in 2006 in the Journal of Non-Equilibrium Thermodynamics This spurious temperature does not exist so the calculation of such a thing is a waste of time. the paper runs to some 24 pages.

Read it and weep Paul.

QV @ 28
"Surely you mean less varied, since we will all be eating the protein we would have been feeding to the animals.?"
Long time since my biology 'O' level but I suspect that the digestible proteins and fats available through meat consumption are significantly different to those available in arable crop production. So on the one hand, yes, more variety with meat. However, it is generally assumed that with the meat and two veg approach, the meat replaces what would otherwise be alternative veg - enhancing the variety of nutrients. Unless of course, like my wife, you're more than happy to live on mash potato.

Also on food production, let's not forget the effect of biomass crops. Stupid, stupid, stupid! Using productive land to raise crops for burning at power stations is quite frankly, immoral.

lateintheday,
I agree.
There is also the idiocy of building on prime agricultural land, so as the UK population increases, there is less farm land to grow crops on to feed the population. It appears that at last, someone has woken up to this problem in Parliament, but she seems to be a lone voice.
/iplayer/episode/b010xvwl/Farming_Today_12_05_2011/

I did mean more varied, adding more vegetables to a diet that since the war has included far more meat than we need. As ever a balanced diet is the best, and less meat consumption will help meet increased demand. I wouldn't advocate going completely veggie, it is not the easiest thing to do to get everthing you need from a diet, were are genetically omnivorous after all. It is the input of meat that helped the human brain to develop because of the concentration of energy per kg it gives.
Only technology has allowed the modern day human veggie to survive their diet, and it was the meat eaters that developed the technology. If we had stayed vegetarian we would still be fighting Gorillas for bed space.

Millennia @26
"To the man in the street with common sense and no scientific background it must all look fishy, but they have no argument against the "intellectuals" and yet have to bear the greatest pain when these decisions invariably are shown to be wrong."

I am that man. You're spot on with this comment.

Two examples if I may (from WUWT). . .
Firstly, Hansen states in a recent presentation that our current position in the Milankovic cycle should be having a 'cooling' effect.
One of the comments (sounded like he knew what he was on about), was that Hansen had got it badly wrong. Specifically, that the Sun - Earth distance was a neglible forcing when compared to axial tilt or inclination (can't remember which). Moreover, the Northern Hemisphere was not only receiving more direct (angle of incidence) sunlight, but also for longer. The summer in the NH now being 7 or 8 days longer than in the SH.

Secondly, the recent sea level 'adjustment' (add 0.3mm) to data points. Under April 2011 Warmist since . . topic, my comment/question @92 to John Marshall. Simply re-stated, some say this adjustment makes no difference to the trend, others say it does. My maths are as rusty as my biology, so it's tough to spot who is right. I'm still left wondering so if anybody can clear that up for me, I'd appreciate it.

Millennia @35
funnily enough, my wife is a veggie and yes, I have to fight for my share of bed space (or at least some of the duvet) most nights.

"Fuel poverty is going to become endemic in the UK, yet shale gas will probably mean many parts of the world are awash with energy."

That may be a price worth paying. There are shades of the financial crisis here. The question is are we going to tackle the mounting debt by making cuts and tolerate the cost, or are we going to keep spending and drive the debt higher? For mounting debt read rising CO2 levels. Many governments, businesses and citizens would rather just keep with the good times and think short-term and put the debt issue on the backburner. Of course the spending can't go on forever so we are effectively passing the buck to a later generation to deal with it. More importantly we are assuming they can. Afterall the previous generation ran on such an assumption about ours.

@28

"I have noticed a tendency for scientists, when challenged by non-scientists, to revert to scientific and statistical jargon, possibly to bamboozle their opponents,
knowing that most people won't understand what they are saying or be in a position to challenge it, because in general, people don't want to look stupid by asking more questions."
This works both ways. Watch any Moncton lecture to see a whole host of 'facts' thrown out to the room. Any counter argument can take much longer as each fact requires a proper scientific answer.

Also when scientists try to use analogies they get quickly accused of treating the public like idiots. Use correct scientific terms and they accused of baffling the public.

#36. - lateintheday wrote:
"Secondly, the recent sea level 'adjustment' (add 0.3mm) to data points. Under April 2011 Warmist since . . topic, my comment/question @92 to John Marshall. Simply re-stated, some say this adjustment makes no difference to the trend, others say it does. My maths are as rusty as my biology, so it's tough to spot who is right. I'm still left wondering so if anybody can clear that up for me, I'd appreciate it."
I, for one, haven't forgotten about that. I had intended to look at this and thought it would be easy to decide, but I only became more confused. It isn't helped by the fact that the figures seem to keep changing.

QV - thanks for that.
I was hoping that you or possibly Quake, might have a sniff at this. While you stand on different sides of the fence on many things, you both seem to have an excellent grasp of maths and often come to some agreement over numbers.
I'm becoming something of a regular here, so I'll keep a look out in case the answer is on a future thread.

Quake says . .
"Of course the spending can't go on forever so we are effectively passing the buck to a later generation to deal with it."

This analogy (spending - read CO2) is to my mind, more accurate when not viewed as an analogy. The countless £billions already spent on CO2 alarmism may well turn out to be wasted money. The 'later generations' have already got their name on this very real £bill. I find the whole thing more comparable to the very topical, banks mis-selling of insurance policies.

The NASA/GISS anomaly for April has just been published:
Global anomaly = 0.55c, compared to 0.57c in March. The April figure is equivalent
to 0.44c relative to the HadCRUT3 base period.
NH anomaly = 0.72c, compared to 0.86c in March, equivalent to a HadCRUT3 of 0.66c.
SH anomaly = 0.38c, compared to 0.27c in March, equivalent to a HadCRUT3 of 0.24c.
It's worth remembering that last month, NASA/GISS was the highest of the main anomalies and it seems to have fallen to nearer this months UAH and RSS, although it is still slightly higher. The fall is due to a lower NH anomaly, partially offset by a rise in the SH. Personally I think this points to very little change in the HadCRUT3 figure since last month. It also leads me to suspect that it was last month's UAH and RSS anomalies which were "out of step".
As a result of this month's fall, the NASA/GISS 10 year linear trend has fallen to 0.38c/century, from 0.45c/century last month, which means it has resumed it's downward trend which started around April 2007.

John Cogger @39
I agree to some extent. Its a big ask to convince joe public of the science when the science is so complex. Like a jury, we are only left with our sense of smell when it comes to deciding how to weigh the witness' evidence. Since the consensus climatologists have shredded their own credibility over recent years, it is of no surprise that CAGW skepticism is on the rise. If the consensus prove to be right in the long run, they need look no further than their own actions when it comes to laying blame for delay in getting the message across.

Climatologists - reminds me of that old Maureen Lipman ad. You've got an 'ology', then you're a scientist my boy.

There were a couple of pertinent items on today's "More or Less", on R4 today.
One related to the findings of Jonah Lehrer that many scientific results tend to fade over time, which cast doubt on the validity of "peer reviewed" scientific papers, and the other asked whether science was now too complicated to be left to scientists and the call for all supporting data related to scientific papers to be made available for scrutiny. No mention of "climate change", but there are obvious implications.
/iplayer/episode/b010xzs5/More_or_Less_13_05_2011/

45. QuaesoVeritas wrote:

"...the other asked whether science was now too complicated to be left to scientists..."

Sorry QV, but does this mean that we just hand it over to the bloggers?

Scientists don't (yet) know what the answer to 'this or that' is, so whoever wants to can just fill in the gaps with whatever notion takes their fancy?

That's not what 'you' think, surely?

44. lateintheday wrote:

"Climatologists - reminds me of that old Maureen Lipman ad. You've got an 'ology', then you're a scientist my boy."

That rests on the supposition that there is some generic course run somewhere for green-tinged hippy-types called 'Climatology' (and there may be somewhere these days).

But the scientists at the leading edge of climate science these days are men and women who have cut their teeth in the normal way - studying the natural sciences; physics, chemistry, biology; geology, etc.

Did you know that Michael Mann for instance (of 'hockey stick' fame) has the following qualifications?:

A.B. applied mathematics and physics (1989), MS physics (1991), MPhil physics (1991), MPhil geology (1993), PhD geology & geophysics (1998) ( )

The guy is not exactly a lightweight in many scientific fields.

That's not an 'argument from authority' in these circumstances, I would argue. You have more or less implied that climate scientists are a bunch of dopes who rely on fancy-sounding, perhaps 'new age', credentials to back up their arguments.

Nothing could be further from the truth.

43. At 15:21pm 13th May 2011, QuaesoVeritas wrote:

"As a result of this month's fall, the NASA/GISS 10 year linear trend has fallen to 0.38c/century, from 0.45c/century last month, which means it has resumed it's downward trend which started around April 2007."

Can you explain how you arrived at that conclusion please?

Just to develop on the above, the linear trend from April 2007 to the present on the NASA series is upward:

newdwr54 @47
just my sense of humour - sorry if I offended your gods.

Michael Mann is bright - incredibly bright, of that I have no doubt. He is also ambitious, incredibly ambitious - equally no doubt. That reminds me, has Phil Jones returned the favour regarding the APU Fellowship application yet?

#49 - newdwr54 wrote:
"Just to develop on the above, the linear trend from April 2007 to the present on the NASA series is upward:
What this is is the linear trend between 2007 and 2011. Yes, the linear trend is still positive, but it is less positive than it was in 2007.
What I am talking about is how the 10 year linear trend has changed since 2007.
In April 2007, the 10 year linear trend (actually 120 month) was about +2.05c per century. At the end of April 2011, the 10 year linear trend was +0.38c per century.
In order to see this, you have to calculate the rolling 10 year linear trend over each 120 month period since April 2007, not just the linear trend between 2007 and 2011. This approach shows long and short term patterns in the linear trend. I'm not sure, but I don't think the woodfortrees site would be capable of doing that.
In fact, the NASA/GISS 10 year linear trend last reached a peak of about +4c per century in June 2002 and it has been generally falling since. If you do these calculations for the entire NASA/GISS dataset, you will see how the trend has changed over the years. Actually the patterns of all of the main datasets are very similar, after adjustment to the same base period.

#46 - newdwr54 wrote:
""...the other asked whether science was now too complicated to be left to scientists..."
"Sorry QV, but does this mean that we just hand it over to the bloggers? "
I was only quoting from the summary of the programme contents, NOT expressing an opinion. You have to listen to the programme to understand the argument. I think that what was being suggested is that scientists should make available all of the methods and data used in academic papers, to allow scrutiny and replication of the results by other scientists and the general public.
Please listen to the programme before it goes. The item on the "decline effect" is also relevant in relation to "climate change".

51. QuaesoVeritas:

That's fair enough, but bear in mind that what it shows is a decline in the 'rate' of temperature rise since 2002, not a decline in 'temperatures', which have continued to rise, albeit more slowly. We still need an explanation for this temperature rise.

52. QuaesoVeritas:

I listened to the show, which was very interesting. However I think Lehrer's case re the 'decline effect' is overstated. There are several phenomena that explain why strong-looking early results tend to fade over time. E.g. regression to the mean - as more data points become available the closer the range of average values gets to the true average value. In the long term we have to expect that science will correct itself.

Re the data issue; as far as I know most research papers do now provide good access to core data. Some is subject to intellectual property rights, etc and has to be paid for (for instance RSS, as far as I know, is a commercial operation).

#53 - newdwr54 wrote:
"That's fair enough, but bear in mind that what it shows is a decline in the 'rate' of temperature rise since 2002, not a decline in 'temperatures', which have continued to rise, albeit more slowly. We still need an explanation for this temperature rise."
Sorry, I could have phrased it better in the original post. I have to keep reminding myself that this reflects a decline in the rate of temperature rise. However, I think you are missing something if you ignore this completely. At some stage, a decline in the rate of increase does imply a decline in actual temperatures. The calculation of rolling trends over longer periods also points to an average temperature increase which is less than it appears.
For example, based on you knowledge of the pattern of temperatures over the last 100 years, what would you EXPECT a rolling 50 year linear trend to look like if graphed? Please think about this before you read further.
Personally I had expected it to show a steady increase over time, or at the least, a steady increase with the odd flattening or slight decline. I was therefore very surprised that when I graphed the rolling 50 year trend in HadCRUT3, (and other series), to find a pattern of rises and equal falls, in an apparently cyclical pattern with a period of approximately 60 years. If this pattern is projected forward, based on a sine curve, which correlates very closely (>0.99) to the pattern so far, it is possible to estimate the actual temperatures which would result in that cyclical pattern, and that points to a general decline in actual temperatures over the next 30 years, which ties in with what some people are forecasting. Of course, this is entirely dependant on the cyclical pattern repeating and getting the precise timing correct. Based on the estimated future temperatures, I expect that the 10 year linear trend of all of the anomaly series will become negative during the course of the next few months and will stay negative for some time. If you want to see the 50 year rolling linear trend for HadCRUT3, go to the climate4you website and look under Global Temperatures/Cyclic air temperature changes.

#54 - newdwr54 wrote:
"I listened to the show, which was very interesting. However I think Lehrer's case re the 'decline effect' is overstated. There are several phenomena that explain why strong-looking early results tend to fade over time. E.g. regression to the mean - as more data points become available the closer the range of average values gets to the true average value. In the long term we have to expect that science will correct itself. "
But will it?
Personally, I believe that we are about to see this pattern repeated in the case of "climate change". The evidence is starting to appear if you look for it with an open mind.

55. QuaesoVeritas:

"...based on you knowledge of the pattern of temperatures over the last 100 years, what would you EXPECT a rolling 50 year linear trend to look like if graphed? Please think about this before you read further."

I don't honestly know what I would expect to see. Since what we are tracking using this system is 'rates' of temperature change as opposed to temperature changes themselves, then I don't know whether I'd expect to see any clear picture over the past 100 years.

I've done it now with HadRCRUT3 and NCDC and find that both give the sine wave pattern you describe, but that a linear trend passed through the data shows an upward incline. So whilst there appears to be a cyclical pattern, it is on an upward slope, so to speak.

If we are about to fall into a trough in this pattern, it must be remembered that this pattern just describes 'rates' of temperature change, not real world temperature changes. It is by no means clear that a downturn in the rate of temperature change equates to downward real world temperatures.

For instance, using the HadCRUT3 series (and assuming I've calculated it correctly!) the last trough in the 50 year trend cycle started around 1950 and ended around 1980. Despite an overall reduction in the 'rate' of temperature rise, 'actual' temperatures rose over time throughout that period with about a 95% correlation significance.

So I'm sticking with the view that temperatures following the passing of the La Nina will resume their upward clime, whether or not the rate of climb falls.

#57. - newdwr54 wrote:
"I've done it now with HadRCRUT3 and NCDC and find that both give the sine wave pattern you describe, but that a linear trend passed through the data shows an upward incline. So whilst there appears to be a cyclical pattern, it is on an upward slope, so to speak."
Thanks for doing that.
The upward slope is only about 0.8c per century, so I think that is the most we can say temperatures are rising in the long term.

"For instance, using the HadCRUT3 series (and assuming I've calculated it correctly!) the last trough in the 50 year trend cycle started around 1950 and ended around 1980. Despite an overall reduction in the 'rate' of temperature rise, 'actual' temperatures rose over time throughout that period with about a 95% correlation significance."
That sounds about right, so your calculations seem to be o.k. As a check, the 50 year linear trend should have been about 1.395c/century at March 2011. It is still rising, but the rate of increase is slowing down. If you graph the monthly change in the trend, you will see that also seems to be cyclical and we are currently at about the same place we were in the early 1950's.
I agree that this only reflects a decline in the rate of temperature rise, but it does imply a fall in actual temperatures over the next 10 years or so, and critically, no huge rise as predicted by the IPCC models over the next 20 years. Based on projections I have done, average temperatures will be well below IPCC predictions by 2030. Also, if the curve pattern is repeated, the next big rise in temperatures will not occur until about 2040.
"So I'm sticking with the view that temperatures following the passing of the La Nina will resume their upward clime, whether or not the rate of climb falls."
The accuracy of the cyclical pattern depends on the precise timing of other influences, which of course, may not be regular. According to millennia's post in the latest topic, La Nina may be returning later this year, so that could cool temperatures again!

58. QuaesoVeritas wrote:

"The upward slope is only about 0.8c per century, so I think that is the most we can say temperatures are rising in the long term."

Hi CV,

Since what we are measuring with this graph is a 'rate of rise', then any linear increase in it over time represents an increase in the 'rate' of rise; i.e. it indicates that temperatures rise has accelerated over the period of measurement.

A rate of rise of 0.8 C per century is approximately what the IPCC estimated for the 20th century. As we have discussed recently, the decadal trend of all the main temperature providers is currently centred around 0.15 C, equating to around 1.5 C per century, but as the longer term trend shows, this rate is accelerating over time (although admittedly this acceleration has slowed lately).

#59 - newdwr54 wrote:
"Since what we are measuring with this graph is a 'rate of rise', then any linear increase in it over time represents an increase in the 'rate' of rise; i.e. it indicates that temperatures rise has accelerated over the period of measurement."

You are correct, of course, but that doesn't alter my predictions for actual temperature anomalies in the future, since they have been calculated on the basis of what would be required to match the projected increase in the cyclical trend.
Otherwise, the growth in the trend is consistent with approx. zero growth in temperatures over the next 20 years, which is not what the IPCC models show.

The NCDC/NOAA global anomaly for April was 0.585c, up from 0.510c in March, although that March figure has itself been revised upwards from the
previously published figure of 0.483c. After adjustment to 1961-90, the April figure is equivalent to a HadCRUT3 figure of about 0.447c.
HOWEVER, it appears that ALL of the previous monthly anomaly figures have been adjusted retrospectively, so it is quite possible that the figure I am using
to adjust the NCDC/NOAA anomaly to 1961-90 requires revision.
In general, the monthly anomaly figures appear to have been increased between 1880 and 1900, reduced between 1900 and 1955 and increased again between 1955 and the present day. The most recent increases are of the order of 0.02c per month. NCDC/NOAA seem to have a habit of retrospectively revising the monthly anomaly figures and it is very confusing. They made some similar adjustments between October and November 2010, which was apparently due to a change in the base period for the land based grid points. I haven't yet found any explanation for the latest adjustments on the website.
After adjustment, the latest NCDC/NOAA anomaly is almost identical to the adjusted NASA/GISS anomaly.
I haven't had a chance to look at the Hemispheric anomaly figures yet, but no doubt they will have revised those too!

All the databases revise their figures. All data is published 'provisionally'. That applies the same to UAH as it does to CRU, NOAA or NASA.