Was there such a thing as climate change before the recent period of global warming commenced around the 1980s? You may think this a strange question to pose – there was plenty for climate change specialists to examine and understand, looking both at modern instrumental observations of the weather and longer-term clues about weather and climate from evidence in the natural world, such as documentary evidence, analysis of pollen grains, ice cores and so on. The weather has always varied over all timescales – warm decades, cold months, stormy winters. Studying these variations helps us understand how the climate system works and benefits many sectors of the economy.

Why do I mention this today? Well, those who are sceptical about the importance and origins of global warming attach great significance to these past variations. Two examples from the UK media over the last week illustrate this rather starkly.

First, The Times of August 2nd included an interview with Michael O’Leary, Chief Executive of Ryanair in which he was quoted as saying ‘Climate change is not a big threat. If it is, why is the summer so crappy?’ He believes that ‘this global warming nonsense is no different to some of the more lunatic movements you’ve had throughout history. Now the nutbag ecologists say we’re boiling the planet to extinction’.  

The second example comes from several newspapers this week who misinterpreted research into ships’ logs, a valuable source of information on past weather. This research has identified a warm spell in the 1730s and stormy summers in the late 1600s (http://www.timesonline.co.uk/tol/news/environment/article4449527.ece).  

This helps to fill an important gap in our knowledge of past climates but the existence of a warm spell in the 1730s cannot be used to denigrate the importance of uniqueness of the current largely human-induced period of warming, an impression that will have been given to readers of The Sun (http://www.thesun.co.uk/sol/...) and the Daily Telegraph (http://www.telegraph.co.uk/ne...) On the contrary, it simply highlights what climate scientists of the past always known – that weather varies according to a variety of natural influences or drivers, many of these being regional not global. These effects will not be switched off by a new trend to warming – we just have to understand that climate change is multi-causal, a mixture of a global trend and several regional and global scale oscillations. Thus the unsettled summers of the last two years around the UK are mostly a reflection of the locations of high and low pressure centres rather than any termination of more widespread warming, an oscillation around a continuing trend to warming that has not ended. In a similar vein, the warmth of the 1730s was not the start of a trend. The weather was certainly not constant before global warming came along and there was much to keep climate specialists busy!

This entry was posted on 8.08.08 and is filed under . You can leave a response, or trackback from your own site.