Natural Factors Predict Imminent Global Cooling

A number of recent articles and scientific papers argue that the recent global warming of the last 20 years was not driven by higher concentrations of greenhouse gases as argued by the IPCC but by a number of natural cycles.

Global Cooling About to "Kick-in"? discusses these natural cycles (solar activity, Pacific Decadal Oscillation (PDO) and Arctic Oscillation (AO)/North Atlantic Oscillation (NAO)) in very readable non-scientific language and shows how they have all recently peaked so that global temperatures are now likely to fall as these factors trend downwards.

Solar Flare Intermittency and the Earth's Temperature Anomalies shows a strong correlation between the incidence of solar flares (sun spots) and global surface temperatures using historical data from 1856 to 2002 (full scientific paper in PDF format). Recently, the solar influence on climate has been controversial. On the one hand, it is known that during the Maunder minimum of sunspots around 1670, unusually low temperatures occurred in Europe (see graph for Central England), while on the other hand, satellite observations available since 1978 show that the Sun's total irradiance, though not being constant, changes by only by about 0.1 per cent during the course of the 11-year sunspot cycle. The latter discovery accounts for the IPCC view that "Natural factors have made small contributions to radiative forcing over the past century " (Climate Change 2001: The Scientific Basis). Clearly this IPCC view is wrong as the incidence of solar flares and global temperature anomalies have now been convincingly correlated.

New Little Ice Age Instead of Global Warming? shows that minima in the 80 to 90-year Gleissberg cycle of solar activity, coinciding with periods of cool climate on Earth, are consistently linked to an 83-year cycle in the change of the rotary force driving the sun's oscillatory motion about the centre of mass of the solar system. As the future course of this cycle and its amplitudes can be computed, it can be seen that the Gleissberg minimum around 2030 and another one around 2200 will be of the Maunder minimum type accompanied by severe cooling on Earth. This view is at complete variance with the IPCC predictions of global warming of up to 5.8 C during the next 100 years.

Over the years, there have been a number of articles that predict dramatic cooling around the North Atlantic basin even though the globe as a whole would warm because of a weakening of or a complete cessation of the Gulf Stream/North Atlantic Conveyor. These predictions would have far more serious consequences for Europe than the warming predictions of the IPCC:

So who should we believe? Recent measurements of global temperatures do indicate a cooling in 2003 relative to 2002, but 2002 was the second warmest year globally, a statistic both surface (since 1880) and satellite measurements of the temperature of the lower atmosphere (since 1979) agree on and global temperatures are still well above the long term averages:

Global surface temperature record anomaly from 1961-90 average from Climatic Research Unit:

Mean monthly temperature anomalies:
Jan-Apr 2002: +0.596 C                  Jan-Apr 2003: +0.433    C

Satellite measurements of temperature of the lower atmosphere - anomalies from 1979-98 average:
data here

Mean monthly anomalies:
Jan-June 2002: +0.267 C               Jan-June 2003: +0.171 C

However, satellite temperature data for June 2003 show temperature anomalies in the southern hemisphere below the 1979-1998 average

Global: -0.010 C    Northern Hemisphere: 0.167 C       Southern Hemisphere: -0.187 C

and this recent cooling trend is apparent in this graph of satellite measurements of temperature of the lower atmosphere .

Another approach is to assess whether or not the temperature rise in the first three years of the twenty-first century is consistent with the IPCC predictions which are rises of 1.4 to 5.8 C by 2100:

to achieve a rise of 1.4 C by 2100, global temperatures would have to rise by 0.014 C per year
to achieve a rise of 5.8 C by 2100, global temperatures would have to rise by 0.058 C per year

In 1999, the global surface temperature record had an anomaly of 0.340 C relative to the 1961-90 average while in 2002, it was 0.471 C, a rise of 0.131 C over three years or 0.044 C per year. Clearly the global surface temperature record for the first three years of the twenty first century shows a warming consistent with the upper range of IPCC predictions.

In conclusion, temperature data of recent years appear to support the anthropogenic global warming (AGW) predictions of the IPCC but Global Cooling About to "Kick-in"? offers persuasive arguments that this recent warming is the result of natural cycles. Trends in global temperature over the next few years are likely to determine whether the IPCC is right about greenhouse gases being the dominant climate factor dictating global temperatures or whether the AGW sceptics are right about natural factors being the cause of the recent global warming.