Recent Summers (2003-2007) in NI: A Reply to Peter Henderson

[acbrixton]

aldergove.docaldergrovetext.docPH recently complained that NI summers had recently been ‘poor’ and that with GW he expected better summers and specifically summers with maxima exceeding 90f…

1. What do we mean by a ‘good summer’?

2. The dangers of reliance upon memory alone;

3. The implications of AGW for regional seasonal weather patterns.

1. In NI it is customary to define summer as including May (it is often the driest/sunniest month although never the warmest) which I have included in the table attached. There are, I suppose, three main factors in judging summer weather in NI: temperature, sunshine and rainfall (I exclude Relative Humidity as it is rarely an issue in NI and in any event I have no data). However simply giving data for mean rainfall, sunshine and temperature whilst useful for a meteorologist is less so for the layman: in summer average maxima are more useful than the mean, so too would be a measure of dull/sunless days and the number of dry days.

It is worth pointing out too that in a maritime climate only rarely can an entire 3 month season exhibit uniform characteristics, still less a 4 month season. Thus it becomes difficult save in all but the most exceptional seasons to accurately sum up an entire season as ‘good’.

Finally in my experience (I am ¾ NI, boarded in NI for over 2 years and have many relatives in NI) unrealistic whining about summer is one of the things that unite all NI residents: more so even than in England there is an unrealistic expectation of weeks of unbroken warm sunshine and blue skies.

2. Individual recollections of individual months’ weather (let alone entire seasons) are notoriously unreliable unless backed up by data or diaries.

4. Attempts to predict regional/seasonal climatic changes from AGW are tentative and uncertain. Not all regions/seasons will warm at the same rate (some may even cool). More difficult still are attempts to predict rainfall/cloud cover patterns. Finally no AGW proponent argues that AGW entails an unbroken linear year on year warming. The expectation that NI’s equable damp and cloudy climate can suddenly be transformed into an approximation of southern France is nonsensical. The highest recorded temperature in NI is 30.8°C at Knockarevan (near Belleek, Co. Fermanagh) on 30 June 1976, and at Shaw's Bridge, Belfast (Co. Antrim) on 12 July 1983. I would be surprised if those records are not exceeded in the next 5-10 years if current trends continue although 90f (32.3c) may take longer.

See the 2 attachments for details...

regards

ACB