Madam, - I refer to recent exchanges on your Letters Page on the topic of "Climate change and cheap flights".
On two occasions during the course of this debate, it has been claimed that average global temperatures have not risen over the last 10 years. This point is worthy of clarification.
Average global temperatures have risen over the last decade (1998 - 2007).
It is true that the rate at which temperatures increased has been slower than in the previous decade or two but they have, nonetheless, increased.
The year 1998 was, globally, the warmest year on record for over 150 years and has not since been surpassed.
However, the years since 2001 have been consistently warmer than the years 1999 and 2000, leading to a small rise in average temperatures over the decade.
I would refer the interested reader to the "WMO Statement on the Status of the Global Climate in 2007" (http://www.wmo.int/pages/prog/wcp/wcdmp/documents/WMO1031_EN_web.pdf), published by the World Meteorological Organisation which is the foremost authority on such matters.
Other authoritative sources on global climatological data include the UK Met Office Hadley Centre and the National Climatic Data Center of the National Oceanic and Atmospheric Administration (NOAA) in the United States.
The numbers and graphs are available on the websites of these organisations. - Yours, etc,
LIAM KEEGAN,
Head,
Climatology Observations Division,
Met Éireann,
Glasnevin Hill,
Dublin 9.