Over the past few years, similar signs of colder than usual weather have been recorded all over the world, causing many people to question the still fashionable, but now long outdated, global warming alarmism. Yet individual weather events or spells, whether warmings or coolings, tell us nothing necessarily about true climate change. Nonetheless, by coincidence, growing recognition of a threat of climatic cooling is correct, because since the turn of the 21st century all real world, long-term climate indicators have turned downwards. Global atmospheric temperature reached a peak in 1998, has not warmed since 1995 and, has been cooling since 2002. Some people, still under the thrall of the Intergovernmental Panel of Climate Change’s disproved projections of warming, seem surprised by this cooling trend, even to the point of denying it. But why?
There are two fundamentally different ways in which computers can be used to project climate. The first is used by the modelling groups that provide climate projections to the IPCC. These groups deploy general circulation models, which use complex partial differential equations to describe the ocean-atmosphere climate system mathematically. When fed with appropriate initial data, these models can calculate possible future climate states. The models presume (wrongly) that we have a complete understanding of the climate system. GCMs are subject to the well-known computer phenomenon of GIGO, which translates as “garbage in, garbage out”.
Alternative computer projections of climate can be constructed using data on past climate change, by identifying mathematical (often rhythmic) patterns within them and projecting these patterns into the future. Such models are statistical and empirical, and make no presumptions about complete understanding; instead, they seek to recognise and project into the future the climate patterns that exist in real world data.
In 2001, Russian geologist Sergey Kotov used the mathematics of chaos to analyse the atmospheric temperature record of the past 4000 years from a Greenland ice core. Based on the pattern he recognised in the data, Kotov extrapolated cooling from 2000 to about 2030, followed by warming to the end of the century and 300 years of cooling thereafter.
In 2003, Russian scientists Klyashtorin and Lyubushin analysed the global surface thermometer temperature record from 1860 to 2000, and identified a recurring 60-year cycle. This probably relates to the Pacific Decadal Oscillation, which can be caricatured as a large scale El Nino/La Nina climatic oscillation. The late 20thcentury warming represents the most recent warm half-cycle of the PDO, and it projects forwards as cooling of one-tenth of a degree or more to 2030.
In 2004, US scientist Craig Loehle used simple periodic models to analyse climate records over the past 1000 years of sea-surface temperature from a Caribbean marine core and cave air temperature from a South African stalactite. Without using data for the 20th century, six of his seven models showed a warming trend similar to that in the instrumental record over the past 150 years; and projecting forward the best fit model foreshadows cooling of between 0.7 and 1 degree Celsius during the next 20-40 years. In 2007, the 60-year climate cycle was identified again, by Chinese scientists Lin Zhen-Shan and Sun Xian, who used a novel multi-variate analysis of the 1881-2002 temperature records for China. They showed that temperature variation in China leads parallel variation in global temperature by five-10 years, and has been falling since 2001. They conclude “we see clearly that global and northern hemisphere temperature will drop on century scale in the next 20 years”.
Most recently, Italian scientist Adriano Mazzarella demonstrated statistical links between solar magnetic activity, the length of the Earth day (LOD), and northern hemisphere wind and ocean temperature patterns. He too confirmed the existence of a 60-year climate cycle, and described various correlations (some negative). Based on these correlations, Mazzarella concludes that provided “the observed past correlation between LOD and sea-surface temperature continues in the future, the identified 60-year cycle provides a possible decline in sea-surface temperature starting from 2005, and the recent data seem to support such a result”.
Thus, using several fundamentally different mathematical techniques and many different data sets, seven scientists all forecast that climatic cooling will occur during the first decades of the 21st century. Temperature records confirm that cooling is under way, the length and intensity of which remains unknown.