Historical perspective on a changing climate?

 A Report on the February meeting of Resolven History Society

 

On a cold evening in the church hall, some global warming would have come in very handy, in order to infuse some warmth in the diminutive audience. Mr Trefor Jones had chosen to speak on the history of a warming climate, a topic with which he was very familiar as a former teacher and A level examiner of geography.

 

He began by discussing how climate has always changed over both geological and historical time. He spoke of the main features which caused this change including, the earth’s orbit, plate tectonics, volcanoes, atmosphere, ocean currents and the regular pattern of many ice ages over the last two million years known as the Pleistocene epoch. We are now living in an interstadial being the  warm period of between 12-15,000 years between ice ages, which includes all historical time.

 

Mr Then went on to describe how scientists became aware of the changes by comparing the landscape of the present day with that of areas still in the lock of ice. Folk references such as “Cantre’r Gwaelod “, in Wales were evidence of change and the land and sea were not constant entities. The Scilly Isles were one island during the Roman occupation of Britain owing to the existence of roads beneath the sea, and “Doggerland” in the North Sea has evidence of settlement. Samul Pepys recorded the weather of the so called little ice age in his diary, with snow falling in June in the 1650s and paintings of ice fairs on the Thames in the 1750s.

 

The means by which changes were measured firstly by thermometers from around 1850, to proxy data sources such as tree rings, ice cores, coral isotopes gave us a record in order to plot the temperature. One of the luminaries was Professor H.H. Lamb, a statistician who developed the dry as dust subject of climate science, by which you looked back at what had actually happened. He founded the Hadley Centre at the University of East Anglia.

                                                         Weather not climate?

Mr Jones then turned his attention to the Greenhouse effect, which everyone has heard of, but few actually understand that it refers to a spectrum of solar radiation intercepted on irradiation by certain gases. Carbon dioxide in the most well-known though the audience was surprised that it only amounted to 424 parts per million of atmospheric gases of which most was natural.The Mauna Loa observatory had noticed that this was increasing markedly through natural and anthropogenic effects recently and had warmed the climate since 1850, though this daye also marked the end of the little ice age. The largest proportion by far of greenhouse gases was water vapour, amounting to around 91%, and reference was mad to the huge explosion In the south Pacific in 2022, when billions of tonnes of water vapour reached the atmosphere. This may in time be an explanation of the recent warm, but gloomy summers recently?

 

In conclusion, Mr Jones turned his attention to the future. He noted that much forecasting was now based on models which needed solid data. The IPCC reports so vaunted by the political establishment often pointed towards adaptation to changes as against trying to stop something, and returning to a “normal” which is very difficult to measure, in a chaotic system which is constantly in a state of flux.

 

Following a question session, Mr David Woosnam, thanked Mr Jones for a thought provoking tal