Accumulating consistent long-term temperature measurements at ground level is much more difficult than it might seem. Static ground based weather stations are very susceptible to changes in their local environment as land use changes around them and also to their being poorly maintained. Because of the Urban Heat Island Effect, caused by the local environment, a large city like London can be as much as 4-9°C warmer than its surrounding countryside. Many of the ground-based thermometers now in use were originally installed at airports, when they were only green fields, now they are massive developments. The chart above shows the longest, (1659 to date), unadjusted continuous temperature record from Central England. It has been extended further in to the past by the research efforts of Tony Brown of Climate reason. The record clearly implies that there has been some modest warming over the last centuries as the world has recovered from the Little Ice Age. In addition the older extension provided by Tony Brown is usefully beginning to show higher temperatures towards the end of the Medieval Warm Period.
By way of example of the official adjustments being made to the land based temperature record, consideration is given here to a single correctly sited and continuously well-maintained, rural US weather station is situated at Dale Enterprise West Virginia. Its records are instructive. The un-adulterated record even shows modest cooling of 0.29°C per century, if all other adjustments made by “climate scientists” are ignored.
However as is shown above the NASA GISS published “value added” temperatures for this same location. This shows a massive adjustment lowering of past temperatures before 1965 to give the impression of very substantial (+0.78ºC / century) warming at this station. Of particular interest is the apparent step wise adjustment of the homogenised data, which would seem to be truly spurious.
Cumulatively the result has been to emphasise warming from the US rural data sets by some 0.47ºC / century. These results are always a one-way street to emphasise the apparent amount of warming. The following table clearly shows the scale and impact of the overall adjustments in the USA. However this adjustment effect has not been confined to the USA. This type of manipulation of the data throughout all the rural data sets to show apparent warming seems to be an entirely common occurrence within the organisations that are the official guardians of the data.
Those National organisations should be above reproach in their scientific integrity.
In addition many rural and more northerly measuring stations were totally lost with the fall of the USSR. But since then many others still in operation have been deliberately ignored by the UK Meteorological Office, the Climatic Research Unit at East Anglia University and NASA GISS in producing their global data sets. Thus the number of stations being considered have been radically reduced, for example by omitting information from Russia particularly from more northerly and rural stations. The impact of the deliberate loss of these many mainly rural stations on measured temperatures can be seen below. The graph below shows the divergence between well-sited rural US weather stations and weather stations that are increasingly susceptible to the Urban Heat Island Effect (UHI). It should also be noted that Phil Jones at East Anglia CRU has also published papers explicitly discounting the Urban Heat Island effect.
In addition the adjustments made by these official promoters of the man-made global warming assertion has been progressive. This effect can be seen in the graphs of presentation of three different versions of global temperature produced by NASA GISS between 1980 and 2007. The promoters of this data set are now proclaiming that 2010 will be the warmest year on record. This is hardly surprising, if they have adjusted the past downwards and the present upwards. One can only conclude that if only well maintained and well sited rural stations were considered so as to avoid the Urban Heat Island Effect entirely and if the adjustments made by climate scientists devoted to the Man-Made Global Warming assertion were ignored that reports of the warming of the earth from ground based measurements would be much reduced.
But it is the protagonists of the Global Warming assertion who are also the official custodians of the data.
Global assessments of world surface temperature are made by combining temperature data from worldwide sources such as the adjusted one at Dale Enterprise Virginia. Sadly the un-auditable re-adjustment of temperature history by the official custodians of the data has become a phenomenon throughout the Western world. Recently it has become clear that many unwarranted adjustments always showing additional warming have been consistently made to the four main sources of accredited global temperature records. Some examples of such adjustments throughout the Western world include:
- USA: NASA GISS, (previously lead by the extreme Warmist advocate, James Hansen), have admitted errors and revised their data set downwards. It appears that in being determined to announce that 2010 is/was the warmest year ever, they have ignored available data stations in the Canadian and Siberian Arctic using only fabricated data, extrapolated from warmer measurement stations further south. They have also reduced the levels in their historic records for last century thus enhancing the appearance of Global warming. It is now slowly becoming clear that the satellite data provided by NOAA has also been comprehensively corrupted with over estimates and some quite ridiculous readings of temperature, (several hundred °F in the great lakes area), over a period of several years. This data has been distributed worldwide as the foundation of many climate models supporting the Man-made Global warming assertion. It may now be the subject of legal challenge.
- Russia: only 40% of the now limited available readings were used by the collators of temperature data always favouring warmer urban sites.
- Canada, many northern sites are now ignored in the collation of temperature data for the IPCC.
- UK: the evidence that both the UK Meteorological office and the East Anglia University Climatic Research Unit have made unwarranted upward adjustments to the data they publish to support the scientific case of the UN IPCC is clear from the release of data and e-mail correspondence in “Climategate”: eliminating data to “hide the decline”.
In a flagrant contradiction of normal scientific method University of East Anglia have admitted that they have destroyed the original records so their adjustment processes cannot be re-audited and reproduced in retrospect.
- Australia: another single example, one amongst many in Australia, from the data for Darwin in the Northern Territories makes the point about unwarranted adjustments made by NOAA/GHCN, the Global Historical Climate Network.
That shows how to turn records of -0.7°C cooling/century into 1.2°C warming/century with unexplained, and un-auditable adjustments.
It is certainly now clear that the Australian Government central research facility, the CSIRO, is wholly committed to the “Warmist” doctrine and supports it on behalf of their Federal Government.
- New Zealand: the following table shows the unexplained differences between recorded data and data published by the National Institute of Water & Atmospheric Research (NIWA) for several locations.
These results are now the subject of a challenge in the New Zealand High Court. As a result of the challenge the New Zealand government agency have now accepted that their records had been falsified deliberately as a result of the political pressure upon them. So there is a chance that in future other National records may also be subject to legal challenge. So it seems to have become common practice for national Meteorological Services worldwide to make these sorts of upward adjustments in the present and downward adjustments in the past, always with the intention of showing increased warming of their regions of the planet.
A suspicious mind one would consider that these sorts of adjustments were as a result of a coordinated international intergovernmental programme or at least well co-ordinated “groupthink”.
Having progressively adjusted upwards / “added value” to the basic ground based data sets, the final assessment of global temperature is then combined from this information and additional data is fabricated for the blank areas by interpolating intermediate temperatures over a grid for the huge territories where measuring stations do not exist. As a result it is hardly surprising that the published record used by the UN IPCC authorities shows significant worldwide warming.
Accordingly the quality of the record becomes questionable and entirely unverifiable in retrospect. Sceptics would certainly think that this was entirely intentional outcome. But it is on these bases that claims are made and officially published of the “warmest year ever” and the “warmest decade ever”.
On the other hand satellite measurements have taken a continuous whole worldview since 1979. They do not attempt to extrapolate temperatures to cover vast areas such as Russia, Northern Canada or to the poles from an increasingly limited and questionable set of ground based weather stations.
Current measurements, including the more recent and reliable satellite data, (ie since 1979), and weather balloon sources, certainly show some warming but no warming since the year 1999. Since about 1850, the end of the “little ice age”, there has certainly been some warming of the planet overall, perhaps as much as 0.5°C in the 90 years between 1850 and 1940. In the 70 years since 1940 the increase in temperature has been assessed at a maximum +0.3°C. Man-made CO2 in the atmosphere only became a possible concern after 1940 but the earlier rate of warming from 1850 to 1940 was about 30% faster than in the period 1975 -1995.