Weather Eye with John Maunder

A graph of five global monthly temperatures January 1979 to June/July 2015 is shown below.

As the base period for the individual temperature estimates varies, they have all been normalised by comparing with the average value of the initial 120 months – or 10 years – from January 1979 to December 1988.

The heavy black line represents the simple running 37-month average of the average of all five temperature records.

The numbers shown in the lower right corner represent the temperature anomaly relative to the individual 1979-1988 averages.

It should be kept in mind that satellite and surface-based temperature estimates are derived from different types of measurements, and comparing them directly as done in the diagram above therefore may be somewhat problematical.

However, the different types of temperature estimates appear to agree quite well as to the overall temperature variations on a two-three year scale. Although, on a shorter time scale there are often considerable differences between the individual records.

All five global temperature estimates presently show a general overall stagnation, at least since 2002. As indicated on the chart, there has been no real increase in global air temperature since 1998, which was affected by the oceanographic El Nino event.

This stagnation doesn't exclude the possibility that global temperatures will begin to increase again later.

On the other hand, it also remains a possibility that Earth just now is passing a temperature peak, and global temperatures will begin to decrease during the coming years.

Time will show which of these two possibilities is correct.

One of the key global temperature graphs is monthly average surface air temperature – the thin line – since 1979 according to the Goddard Institute for Space Studies, at Columbia University, New York City, USA. The thick line is the simple running 37-month average. The graph is updated to July 2015.

The following link will take you directly to a monthly very comprehensive newsletter with global meteorological information updated to Jul 2015.

http://www.climate4you.com

The website referred to above is produced by Professor Ole Humlum, of the Institute of Geosciences, University of Oslo, Norway.

For further information on a wide range of weather and climate matters see: https://sites.google.com/site/theuncertaintybusinessclimate/