Global Warming Stopped 16 Years Ago

Source:  Global Warming Policy Foundation

by David Whitehouse

In response to an article in the Mail On Sunday that points out the absence of a recent temperature rise in the Met Office’s newly released Hadcrut4 global temperature database the UK Met Office released a statement that is misleading.

The Mail On Sunday article uses the Met Office’s Hadcrut4 database that was updated from 2010 to the present day last week.

We live in the warmest decade of the instrumental era (post-1850), and most of the warmest years have occurred in the past decade, but what the Met Office ignores to say is that, at present, we live on a temperature plateau – there is no recent upward trend in global temperature.

The Met Office says that the world has warmed by 0.03 deg C per decade since 1997 based on their calculation of the gradient in the Hadcrut4 dataset. But what the Met Office doesn’t say is that this is statistically insignificant. The gradient of the trendline in Hadcrut4 is very sensitive to the start and end dates used as temperatures vary significantly month-to-month, so the Met Office is being misleading in quoting trendlines for a particular start and end date without taking into account how the scatter of the data, the errors in the temperature measurements, and short-term changes affect the statistical confidence in the resulting trendline.

Trendlines from 1997 to August 2012 vary between 0.04 to 0.02 deg C per decade with an associated error of 0.04 deg C per decade. This has to be considered along with the error in annual global temperature measurements of 0.1 deg C. Hence there is no case to be made for a statistically significant increase in global temperatures as given in the Hadcrut4 dataset between 1997 and August 2012.

Quoting trendlines without errors can mislead. For instance the trendline between January 2002 and August 2012 in Hadcrut4 is negative, being minus 0.04 deg C per decade: Between January 2003 and August 2012 it is minus 0.05 deg C per decade – that is global cooling. Would the Met Office be happy to quote such figures in the same way they have for 1997 onwards and state that the world has cooled in the past decade? Only when the errors are incorporated, which the Met Office did not do, can these be seen to be statistically insignificant.

The Met Office also says that if they were to calculate a linear trend from 1998 (a strong El Nino year) to August 2012 it would show a warming more substantial that 0.03 deg C per decade. Actually the warming since 1998 is the same – 0.03 deg C per decade – and again statistically insignificant.

The year 1997 – roughly the start of the recent temperature standstill – is not cherrypicked. Before that year there is a statistically significant increase to 2012, after 1997 there is not.

The Met Office says the 15-year standstill is not unusual. This is true but again the Met Office is being economical with the truth. The IPCC concluded that the period 1960-80 marked the start of mankind’s domination of the Earth’s climate via greenhouse gas forcing. The period before 1960-80 the IPCC regarded as being solely due to natural factors. In the pre 1960-80 period there was a standstill between 1940-80. In the post 1960-80 period there was warming between 1980 – 96 and a standstill thereafter. The mankind-dominated era has only one standstill, which is becoming the dominant global climatic feature of this era.

Only a few years ago the Met Office said that temperature standstills of a decade were common (about one in eight decades), but that temperature standstills of 15 years were not supported by their climate models. They appear to have altered their view as the observed temperature standstill lengthens. The Met Office’s track record in predicting global temperature changes has been dismal.

The Met Office says that climate change can only be detected in multi-decadal timescales. In the three decades since the IPCC said that mankind dominated the Earth’s climate there has been equal timespans of warming and temperature standstills. Which one do they consider to be more significant?

It is disappointing, if not misleading, that when the Hadcrut4 data was announced in March, with data only available to 2010 (a warm El Nino year), the Met Office promoted it with a press release and briefings to journalists. They told Louise Grey of the Daily Telegraph that the Hadcrut4 data showed that the world had warmed even more than expected in the past ten years and that the warming between 1998 – 2010 was 0.1 deg C.

When the full dataset was available, in the past week, showing global temperatures to August 2012, and telling a very different story, no press release was produced.

MORE:

CCNet –  15 October 2012
The Climate Policy Network

Global Warming Stopped 16 Years Ago

Met Office Quietly Releases Missing Data 

The world stopped getting warmer almost 16 years ago, according to new data released last week. The figures, which have triggered debate among climate scientists, reveal that from the beginning of 1997 until August 2012, there was no discernible rise in aggregate global temperatures. The new data, compiled from more than 3,000 measuring points on land and sea, was issued quietly on the internet, without any media fanfare, and, until today, it has not been reported. This stands in sharp contrast to the release of the previous figures six months ago, which went only to the end of 2010 – a very warm year. –David Rose, Mail on Sunday, 14 October 2012

Global warming stopped 15 years ago and the average temperature has not risen at all since 1997, the Met Office said last night. But critics said the Met Office had released the figures onto the internet without publicity – in contrast to the attention it gave to those released six months ago that reinforced the case for global warming. Those figures went up to 2010 – the hottest year on record – and showed a continuing warming trend. Dr Benny Peiser of Lord Lawson’s Global Warming Policy Foundation said: “It is quite scandalous that the Met Office is misleading the public. The latest data proves beyond any doubt that there has been no warming [trend] over the past 16 years.” –John Ingham, Daily Express, 15 October 2012

The data confirms the existence of a ‘pause’ in the warming. The impact of this pause within the climate dynamic community has been to focus increased attention on the impact of natural variability, particularly the impact of internal multi-decadal oscillations in the ocean.  The new climate model calculations for the AR5 have focused on trying to assess what it would take to accurately simulate these multi-decadal ocean oscillations and how predictable they might be.  These new observations and climate modeling results will hopefully impact the the IPCC AR5 deliberations so that we do not see the same overly confident consensus statements that we saw in the AR4.  –Judith Curry, Georgia Tech University, 14 October 2012

The Met Office says that the world has warmed by 0.03 deg C per decade since 1997 based on their calculation of the gradient in the Hadcrut4 dataset. But what the Met Office doesn’t say is that this is statistically insignificant. There is no case to be made for a statistically significant increase in global temperatures as given in the Hadcrut4 dataset between 1997 and August 2012. The Met Office says the 15-year standstill is not unusual. This is true but again the Met Office is being economical with the truth. –David Whitehouse, The Global Warming Policy Foundation, 15 October 2012

Does it matter that campaigners and the media are actively peddling disinformation? For the most part, probably not, as the public is by now used to such nonsense on just about every subject from unemployment figures to Barack Obama’s birth certificate. But there is one group that should be very concerned about the spreading of rampant misinformation: the scientific community. It is, of course, thrilling to appear in the media and get caught up in highly politicized debates. But leading scientists and scientific organizations that contribute to a campaign of misinformation — even in pursuit of a worthy goal like responding effectively to climate change — may find that the credibility of science itself is put at risk by supporting scientifically unsupportable claims in pursuit of a political agenda. –Roger Pielke Jr, Denver Post, 12 October 2012

1) Global Warming Stopped 16 Years Ago, Reveals Met Office Data Quietly Released – Mail on Sunday, 14 October 2012

2) David Rose: Flawed Science Costs Us Dearly – Mail on Sunday, 14 October 2012

3) David Whitehouse: The Mail On Sunday And The Met Office – The Global Warming Policy Foundation, 15 October 2012

4) GWPF Criticises Met Office Over Hushed Data Release – Daily Express, 15 October 2012

5) Roger Pielke Jr: Climate Spin Is Rampant – Denver Post, 12 October 2012

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