by Walter Starck (in Quadrant Online)
The average temperature for the Earth, or any region or even any specific place is very difficult to determine with any accuracy. At any given time surface air temperatures around the world range over about 100°C. Even in the same place they can vary by nearly that much seasonally and as much as 30°C or more in a day. Weather stations are relatively few and located very irregularly. Well maintained stations with good records going back a century or more can be counted on one’s fingers. Even then only maximum and minimum temperatures or ones at a few particular times of day are usually available. Maintenance, siting, and surrounding land use also all have influences on the temperatures recorded.
The purported 0.7°C of average global warming over the past century is highly uncertain. It is in fact less than the margin of error in our ability to determine the average temperature anywhere, much less globally. What portion of any such warming might be due to due to anthropogenic CO2 emissions is even less certain. There are, however, numerous phenomena which are affected by temperature and which can provide good evidence of relative warming or cooling and, in some cases, even actual temperatures.
These include growth rings in trees, corals and stalactites, borehole temperature profiles and the isotopic and biologic signatures in core samples from sediments or glaciers. In addition, historical accounts of crops grown, harvest times, freezes, sea ice, river levels, glacial advances or retreats and other such records provide clear indication of warming and cooling.
Recent Warming Nothing Unusual
The temperature record everywhere shows evidence of warming and cooling in accord with cycles on many different time scales from daily to annual, decadal, centennial, millennial and even longer. Many of these seem to correlate with various cycles of solar activity and the Earth’s own orbital mechanics. The temperature record is also marked by seemingly random events which appear to follow no discernable pattern.
Over the past 3000 years there is evidence from hundreds of independent proxy studies, as well as historical records, for a Minoan Warm period around 1000 BC, a Roman Warm Period about 2000 years ago, a Medieval Warm Period (WMP) about 1000 years ago and a Modern Warm Period now developing. In between were markedly colder periods in the Dark Ages and another between the 16th and 19th centuries which is now known as the Little Ice Age (LIA). The warmer periods were times of bountiful crops, increasing population and a general flourishing of human societies. The cold periods were times of droughts, famines, epidemics, wars and population declines. Clearly life has been much better in the times of warmer climate, and there is nothing to indicate that the apparent mild warming of the past century is anything other than a return of this millennial scale warming cycle.
Good News Unwelcome to Alarmists
This rather good news about a possibly warmer climate has not met with hopeful interest from those who purport to be so concerned about the possibly dangerous effects of anthropogenic global warming (AGW). On the contrary, their reaction has overwhelmingly been a strong rejection of any beneficial possibility. It is apparent that their deepest commitment is to the threat itself and not to any rational assessment of real world probabilities or the broader consequences of any of their proposed remedies.
Fabricating a Hockey Stick from Hot Air
This blanket rejection of any possibility other than the hypothetical threat of AGW has led to some strange behaviour for people who modestly proclaim themselves to be the world’s top climate scientists. Not only have they ignored and dismissed the hundreds of studies indicating the global existence of a Medieval Warm Period and the Little Ice Age, they have set out to fabricate an alternate reality in the form of a graph purporting to represent the global temperature for the past thousand years. It portrays a near straight line wiggling up and down only a fraction of a degree for centuries until it begins an exponential rise gradually starting at the beginning of the 20th century and then shooting steeply up in the latter part of that century. This hockey stick-shaped graph was then heavily promoted as the icon of AGW. It appeared on the cover of the third climate assessment report of the IPCC published in 2003 and was reproduced at various places in the report itself.
Among the emails between leading climate researchers released in the Climategate affair were a number which revealed a concerted effort to come up with some means to deny the existence of the MWP. The implement chosen to do this became known as the Hockey Stick Graph.
The methodology used to construct the graph involved the use of estimates of temperatures from a very small sample of tree growth rings from the Yamal Peninsula in far northern Siberia and ancient stunted pine trees from near the tree line in the High Sierras of California. This data was then subjected to a statistical treatment later shown by critics to produce a hockey stick form of graph even when random numbers were used as raw input data. To make matters even worse, the same tree ring data also indicated a significant decline in temperature for the 20th century, but this was hidden by burying it in a much larger number of data points from instrument measurements. The resulting study was published in the prestigious scientific journal, Nature in 1998. Remarkably, this very small, highly selected and deceptively manipulated graph was proclaimed to be an accurate representation of global temperatures and the extensive body of contrary evidence was simply ignored.