Is there any statistical evidence that global temperatures have changed since 1997 ?
Guest post by Clive Best
The UK Met Office seem determined to stand by their claim made in response to the David Rose article in the Mail on Sunday:
‘The linear trend from August 1997 (in the middle of an exceptionally strong El Nino) to August 2012 (coming at the tail end of a double-dip La Nina) is about 0.03°C/decade, amounting to a temperature increase of 0.05°C over that period.’
Several of us have been requesting statistical evidence via their blog that this trend is actually indistinguishable from flat.
Dave Brittan has done a sterling job in replying on behalf of the Met Office, but he eventually crafted a complex answer as to whether the above statement made statistical sense.
“The first is measurement uncertainty associated with basic measurement error and uncertain biases in the observations. These are included in the HadCRUT4 ensemble, and when computing linear trends in global temperatures from August 1997 to August 2012 these give a trend of 0.034 ± 0.011 °C per decade (95% confidence interval) for the observed portion of the earth.”
I questioned this statement because I think their quoted error is actually about a factor 10 less than it should be. After waiting 36 hours with my post still in moderation, and with no other posts being accepted I am now presuming that this is their last word on the matter.
Frustrated by the lack of response, I decided instead to do the analysis myself. – see post here:
http://clivebest.com/blog/?p=4237
I know Gore is sweating, increasingly.
Several of us have been requesting statistical evidence via their blog that this trend is actually indistinguishable from flat.
Irrespective of whether or not there is any statistical distinction between 0.03C per decade and 0, there is absolutely no practical distinction between the two. None.
A global average temp trend of 0.03C per decade is FLAT. Period.
The fact that Global Warming never came up once in the US Presidential debates shows you how far the credibility of Climate Science has fallen.
As more and more facts like these emerge, and the fear/panic of CAGW goes away, my concern is that “Big Oil” will stop our monthly checks. Drat, I was planning on purchasing one more beach front property. Oh well, I’ll have to make do with the four they already bought for me.
On to the next “sky is falling” meme….
So! that and a Euro will get you a cup of what the British call coffee. Anyone who, considers a 0.0 anything on a global average of anything needs a long vacation. I am proposing northern Greenland.
Why can’t they just stick to the science and the data? Is there managerial pressure to produce rising trends when there are non?
Climate changes. Everyone accepts that and part of that change also includes periods of no change.
I think Lucia’s analysis also rejected the zero trend hypothesis. If the Suth is not familiar with her work, I would recommend as a seemingly very honest broker. (see link to The Blackboard blog)
Relevant WoodForTrees graph, from August 1997 to August 2012 inclusive, note in WFT notation that’s 8/1997 to 9/2012 (“From” is inclusive, “To” is exclusive):
http://www.woodfortrees.org/plot/hadcrut4gl/from:1997.67/to:2012.75/plot/hadcrut4gl/from:1997.67/to:2012.75/trend
Click on “Raw data”: Least squares trend line; slope = 0.00340933 per year
Clive,
Your analysis does not correct for autocorrelation, and one standard deviation only points at a 68% CI. Go two wide for ~95%. Correct for both (or perhaps just either), and the error bands will include zero and a swath of cooling territory.
” Least squares trend line; slope = 0.00340933 per year” Right, The CRUT4 data comes with error margins, just because a spread sheet spits out 8 digits after a decimal doesn’t improve the original accuracy of the data. Rose seems to have bated them into a more serious blunder.
So if a strong El Nino swings in late because the sun has been been quieter than usual, and it’s about to become very active peaking within the next 18, should this be cause for alarm? The suns activity warms the planet, and the lack of activity cools it.
Dallas;
baited them, even.
;p
Approximately 2 divided by almost 3 has a pretty good chance of being somewhere between a half and a whole.
It is not 0.667
Hmm. Half of a degree (Aug2012) minus half of a degree (Aug’97) is zero so there is zero actual global warming over this period. There, that wasn’t too hard. Scarf.
But I am sure that answer of zero doesn’t satisfy those at the MetOffice and climatologists worldwide so off they go in search of the statistical global warming over this same period that surly must be hiding within the numbers somewhere. Need I go any further?
Anyone with the least mathematical or scientific mind surely realized buy these two pieces of evidence that this statistical global warming never really exists and is only a man-made constructed math value of no meaning. It can never burn or warm you or anything else and only lives within minds, on charts or graphs. Yet, daily millions of words and thousands of hours of computer time is spent in search of this mythical statistical global warming when actual warming of a period is by a mere subtraction. Simply breathtaking the levels of delusion present today.
Assumptions.
Assumptions.
Assumptions.
Plot the residuals. They don’t meet the (unspoken & unwritten) assumptions about the model error term, so statistical inference produces meaningless p-values &/or confidence intervals.
Good Stat 101 students know this, but sensible comments about statistical inference in the climate discussion (in both alarmist & nonalarmist circles) are – to be frank – nearly nonexistent. Everyone just pretends untenable assumptions aren’t a problem and this ignorance is absolutely wrong at the level of fundamentals.
“from August 1997 to August 2012 these give a trend of 0.034 ± 0.011 °C per decade (95% confidence interval) for the observed portion of the earth.” So in other words, at 0.034/decade, we can be 95% confident that warming is occurring? But in Phil Jones’ interview from February 2010:
“B – Do you agree that from 1995 to the present there has been no statistically-significant global warming
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level.”
Can both statements be true for equally long 15 year periods?
With the Hadcrut4 anomaly for August at 0.526, the average for the first eight months of the year is (0.288 + 0.209 + 0.339 + 0.514 + 0.516 + 0.501 + 0.469 + 0.526)/8 = 0.420. If the average stayed this way for the rest of the year, its ranking would be 11th. 2010 was the warmest at 0.54. The highest ever monthly anomaly was in January of 2007 when it reached 0.818. With the 2011 anomaly at 0.399 in 12th place and the 2008 anomaly of 0.383 in 14th place, if things stay as they are, then 3 of the last 5 years are not even in the top 10 in Hadcrut4.
Hadcrut4 has a slope of 0 (-0.00018 per year to be exact) since November 2000 or 11 years, 10 months (goes to August.)
P.S. My earlier graph estimating Hadcrut4 using GISS was off by only one month as the flat line started in December 2000 in the estimation.
See: http://www.woodfortrees.org/plot/hadcrut4gl/from:2000.8/plot/hadcrut4gl/from:2000.8/trend
I think this has something to do with science, even though it is OT, so I decided to post it.
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We already have a collective hive mind.
You know it’s there, but you can’t touch it with your hand.
You can get in contact with it, especially through your keyboard, but you can’t grasp the whole of it’s collective conciseness.
The Universal Collective Hive Mind knows nearly everything knowable.
It’s really there.
It’s like the collective conciseness above us, almost but not quite.
It’s called the Internet.
Michael;
INTERNET Hive Mind calling. Either I exist, or you do. Choose.
The Met Office are determined to factor in their global warming models into their supercomputer, despite all evidence to the contrary.
What results from this is as follows:
1) Forecast of an Indian Summer in October 2012! Did not happen.
2) Forecast of BBQ Summers for this year and last year! Wettest Summers ever!
3) Forecast for the last four years, summer drought! We had hosepipe bans, followed by floods (in the same areas that the Met office said would be dry.
4) 2010, would be the mildest winter on record, thanks to AGW! In actual fact we had the worst winter for many years.
Met office, will you please cast your bigotry aside and reprogram your computers!
The global temperature trend over 1997 to now is negative, not positive at all, in RSS satellite data, slightly negative but negative nonetheless:
http://www.woodfortrees.org/plot/rss/from:1997/plot/rss/from:1997/trend
Over 1998 to now in contrast, it is substantially negative, with a linear trend line fit being cooling at a rate of around 0.5 degrees Celsius per decade:
http://www.woodfortrees.org/plot/rss/from:1998/plot/rss/from:1998/trend
The exact trend depends on the start point. 1998 could seem arbitrary. However, 1998 corresponded to the key change from a warming regime to a cooling regime. A surge of warmth built in the oceans up through earlier in the 1990s was released into the atmosphere by the El Nino then. There will not be as strong warming from such a El Nino again for decades to come, and a trendline like 1998 -> 2020 will show greater cooling than 1998 -> 2012 now.
——————————–
History is explained well if one sees what unfortunately even few skeptics ever have, part of the big picture visible by combining enough data not too adjusted by the CAGW movement:
http://s10.postimage.org/l9gokvp09/composite.jpg
(click to enlarge and scroll)
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1997/plot/hadcrut4gl/from:1997
HadCRUT4 has miraculously created warming where was none before. How on Earth could 2006 El Nino suddenly overtook the 1998 one? Which are the areas, which in retrospection suddenly increased Earth temperature by 0.2 deg C globally?
I never use HadCRUT4 in any analysis.
Typo correction to my prior comment: I wrote 0.5 degrees when I meant 0.05 degrees.
Brian H says:
October 25, 2012 at 9:28 pm
“Michael;
INTERNET Hive Mind calling. Either I exist, or you do. Choose.”
We both exist.
You can’t erase information from history. It is stored in universal consciousness. It has something to do with photons and DNA.