The year 1998 is regarded as the earth’s warmest year based upon instrumental observations since 1860. The global surface temperature anomalies (compared to 1961-1990) for the nine years 1998 to 2006 have been as follows:

1998 0.52 °C,

1999 0.26 °C,

2000 0.24 °C,

2001 0.40 °C,

2002 0.45 °C,

2003 0.45 °C,

2004 0.43 °C,

2005 0.48 °C,

2006 0.42 °C

All these figures have an associated uncertainty of ± 0.1 °C which has not decreased in spite of the recent advances in the global atmospheric and oceanic observing systems. It has also remained random and there is no particular bias towards either the plus or minus side which could possibly be removed.

If the 2006 temperature anomaly of 0.42 °C, is compared with the 1998 temperature anomaly of 0.52 °C, the earth may be said to have cooled by 0.1 °C over the last nine years.

If the uncertainties of +0.1 °C or -0.1 °C are applied to both these values with the same sign, this conclusion will remain valid.

If the uncertainties of +0.1 °C or -0.1 °C are applied to the two years with different signs, the earth could be considered to have either cooled by 0.3 °C (0.52+0.1 – 0.42-0.1) over the last nine years, or the earth might have warmed by 0.1 °C (0.52-0.1 – 0.42+0.1) over the same period.

When scientists talk about small quantities and large uncertainties, we must exercise the freedom to form our own opinion. Since 1998, the earth could have been cooling or warming depending upon how we look at the figures.

Temperature anomaly data taken from World Meteorological Organization, World Climate News, June 2007, available online at http://www.wmo.ch/pages/publications/showcase/documents/WCN31_E.pdf

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