Parliament does statistical significance

From Hansard:

Climate Change

Questions

Asked by Lord Donoughue

To ask Her Majesty's Government, further to the Written Answer by Baroness Verma on 30 October (WA 114-5) stating that global temperatures have risen less than 1 degree celsius since 1880, on what basis they assert that there has been a long-term upward trend in average global temperatures. [HL3048]

To ask Her Majesty's Government, further to the Written Answer by Baroness Verma on 30 October (WA 114-5) stating that there has been no significant global warming since around 1998, and deeming that period as a shorter timescale, how many years of non-warming they consider would constitute a long-term trend.[HL3049]

To ask Her Majesty's Government, further to the Written Answer by Baroness Verma on 30 October (WA 114-5), whether they consider a rise in global temperature of 0.8 degrees celsius since 1880 to be significant.[HL3050]

The Parliamentary Under-Secretary of State, Department of Energy and Climate Change (Baroness Verma): The assessment that there has been a long-term upward trend in global average near-surface temperatures since the late 19th century is based upon three global temperature records, compiled from observations, by groups in the US and UK. The rate of global temperature rise on different timescales is summarised in table 1 below. The underlying trend over the period from 1880 to 2011 is 0.062 celsius per decade, giving a total change of 0.81 celsius. Such a rate of change has been judged by major scientific assessments to be large and rapid when compared with temperature changes on millennial timescales.

Over this period some parts of the world have warmed at a much faster rate. The land surface average temperature has risen by about 1.1°C and Arctic temperatures have increased by almost twice the global average rate. The consequences of this warming are already seen across the globe. For example, northern hemisphere sea-ice and snow cover have decreased markedly, most glaciers have retreated and the risks of certain extreme weather events occurring have increased.

8 Nov 2012 : Column WA225

Statistical (linear trend) analysis of the HadCRUT4 global near surface temperature dataset compiled by the Met Office and Climatic Research Unit (table 1) shows that the temperature rise since about 1880 is statistically significant.

Time period	Linear trend (°C/decade)	Absolute change in temperature described by linear trend (°C)
1880-2011	0.062±0.009	0.81±0.13
1900-2011	0.074±0.011	0.82±0.13
1950-2011	0.106±0.025	0.66±0.16
1970-2011	0.166 ± 0.038	0.70 ± 0.16

Table 1. Trends fitted to monthly global temperature anomalies for HadCRUT4, with uncertainties describing 95% confidence interval bounds for the combination of measurement, sampling and bias uncertainty and uncertainty in the linear trend fitted to the data. The statistical model used allows for persistence in departures using an autoregressive process (ie that an individual value is not independent of the previous one).

Statistical analyses and modelling of the global temperature record have shown that, because of natural variability in the climate system, a steady warming should not be expected to follow the relatively smooth rise in greenhouse gas concentrations. Over periods of a decade or more, large variations from the average trend are evident in the temperature record and so there is no hard and fast rule as to what minimum period would be appropriate for determining a long-term trend.

Update on Jan 2, 2013 by Bishop Hill

In the comments, Shub notes that the statisticians at DECC (who are presumably advising Verma) are using the IPCC's "new" calculus. Paul Matthews pointed out some years that this is illegitimate and entirely bogus.

Comments

[Billy Liar]

It has yet to dawn on UK (and world) politicians that if the world is not warming we are in serious trouble. The next glaciation will not be as kind to parts of the world as the recent mild warming has been. We will be going back to church, like those in the 17th century, to pray that the advance of the glaciers be halted.

http://academic.emporia.edu/aberjame/ice/lec19/holocene.htm#lia

[TRE]

Hah! You think you have it bad, here in the U.S. our courts ruled in essence "If the EPA has a study which shows that 2+2=5, then it does....."
Good luck slaying THAT dragon!

[Jeremy Shiers]

Baroness Verma's answer assumes that the datasets are correct.

There is ample evidence they are not.

http://www.uoguelph.ca/~rmckitri/research/nvst.html
Ross Mckitrick noticed an "anomaly" around 1990 when about 1/2 the existing weather stations were decomissioned and at that time there was around 1.5C increase in mean temperature.
It is hard to explain this other than measurement error.

Then there is Urban Heat effect. Michael Palmer posted at WUWT showing there was a very slight FALL in temperature during 20th century at those stations which were rural and in operation for at least 90% of the time.
http://wattsupwiththat.com/2011/10/24/unadjusted-data-of-long-period-stations-in-giss-show-a-virtually-flat-century-scale-trend/

Clive Best, also at WUWT, has questioned the reliabillity of global temperature anomalies
http://wattsupwiththat.com/2012/02/07/how-reliable-are-global-temperature-anomalies/
Raising, among other things, the changing distribution of weather stations, the difference in pattern of temperatures in southern hemisphere compared to north.

Finally there is Steven Goddard who posts tirelessly about temperature records.
Firstly people have saved a snapshot of GISS at different times of the last 10 years or so. When the earlier datasets are compared with later it can be seen the temperatures at the beginning of 20thcentury are lower in the later versions. I.e. they have been adjusted downwards to produce a rise.

http://stevengoddard.wordpress.com/2012/12/11/hansen-caught-cheating-again/
http://stevengoddard.wordpress.com/2012/12/10/twenty-years-later-climate-science-is-still-populated-by-morons/
http://stevengoddard.wordpress.com/2012/11/30/verifying-john-dalys-data-capture/
diff between giss around 1999 and now for beginning of 20th century

http://stevengoddard.wordpress.com/2011/02/15/data-corruption-at-giss/

Secondly the "raw" dataset is not actually raw - it has been adjusted.
http://stevengoddard.wordpress.com/2012/12/07/ushcn-sets-new-record-for-adjusting-raw-data/

Thirdly past newspapers carry weather reports. Google and others have obliging scanned these. Apparently past record temperatures are not reflected in current temperature datasets.
(Steve has plenty of posts on this you can search for yourself).

So if the data is wrong things derived from it will be meaningless.

Baroness Verma might as well have read out the phone directory
backwards.

http://stevengoddard.wordpress.com/2012/11/26/1950-shock-news-strange-atmospheric-events-causing-floods-droughts-polar-melting-global-warming/

it's nice to see the alarm stories have always been with us!

[oldtimer]

@Jeremy Shiers Jan 3, 2013 at 9:18 AM

You are correct, the land based temperature data sets have been constantly changing. EM Smith at
http://chiefio.wordpress.com/category/dtdt/
performed an epic analysis of the published data sets. Among other things his method identified the fact that only c200 of the 1200 post 1990 temperature station records were common with c6000 available pre 1990. He also noted that all stations at any significant altitude above sea level were eliminated, and that there was a distinct shift in location away from the poles towards the equator. To date there has been no satisfactory analysis of the effect this change had on the temperature records used for official purposes - it was explicitly dodged by the Mir Russell enquiry.

The global historic record seems OK as a rough and ready description, but it has been deemed, in official quarters, to possess a precision that it does not deserve.

[John Peter]

"In the Parliamentary reply it was stated that [t]he underlying trend over the period from 1880 to 2011 is 0.062 celsius per decade, giving a total change of 0.81 celsius. Such a rate of change has been judged by major scientific assessments to be large and rapid when compared with temperature changes on millennial timescales." So how are we going to get to IPCC's middle temperature increase of 3 degrees C by 2100 at a "rapid" decadel temperature increase of 0.062 C? Where is the acceleration? This is what it is all about ACCELERATION (or lack of same). There is no acceleration and the longer temperatures remain static the stronger acceleration is required for the remaining period. CAGW looks like a dreamworld to me.

[Jeremy Shiers]

@oldtimer at Jan 3, 2013 at 11:29 AM

Thanks enormously for the link to EM Smiths blog which I was previously unaware of. It has important information which should be widely publicised (your grace???).

In this post http://chiefio.wordpress.com/2009/10/09/how-long-is-a-long-temperature-history/

EM Smith talks about the cycles and spikes in the temperature record

AND in particular there was a dip after 1880.

How convenient the Baroness' temperature record starts from there - all the better to distort the record.

I am a big fan of Peter Taylor's book Chill. In the book Peter talks about

Trends
Cycles
Pulses

Trends are the preferred instrument of climate change mob, as they go on and on. Most people ignore cycles and just about everyone ignores pulses. But pulses are a part of nature e.g. the 1998 El Nino. What would the linear trend be if the influence of this event was removed - flat??