Western isles dating
the glaciers), and thermal expansion of the sea-water.]The Atlantic climatic era: the period 6200 BC – 3500 BC (approx.) is now regarded as a major ‘Climatic Optimum’.In the NW Europe / NE Atlantic region, pressure is thought to have been relatively higher, with the depression tracks much further north (and / or south .. highly blocked) & less intense than before or since.Prior to the age of scientific enquiry, the climatological data have been reconstructed using ‘proxy’ data, such as tree ring records (dendroclimatology), ice-core sampling, estate records, tales of war and the administration of great kings, monastic lists etc. Rapid warming in the period up to ~ 11500 BC, steadier warming thereafter: by 9000 BC, major ice sheets had been eroded significantly, though were still in evidence in the Highlands of modern-day northern Britain.As regards conditions over southern Britain, by ~11500 BC, it is estimated that mean winter-time temperatures were between 0 and 4deg C ( perhaps a little lower than today’s values) & high-summer values between 12 and 16deg C, again a little lower or similar to current figures.HEKLA (Iceland): COLDER/WETTER conditions for Europe (at least). [ Be wary over exact dating of such as volcanic eruptions in these ancient times; no-one was actually recording the event in a contemporary sense, so dating comes down to interpreting ice cores, ancient tree ring records etc., and a decade either way of error would be quite likely.]Periods of extended warmth (in a longer-term post Bronze Age cooling phase).Frequent dry, ‘blocked’ spells of anticyclonic weather – however this begs the question – were the winters often bitterly cold?
[However note that overall temperatures still ‘Major VOLCANIC eruption’.Inevitably, there is some element of subjectivity over what constitutes a ‘significant’ event.Also, the further back in time we go, the scrappier the information & the greater the probability of missing something.Much of the information contained in these records must of necessity be ‘tentative’ to say the least!Up to about 1000 years ago, we only have archaelogical evidence to reconstruct the record: some Roman chroniclers provide cursory evidence for the Romano-Celtic / British era, but it is not until roughly from AD 800 that documentary records make a major contribution – and of course, the era of instrumental record doesn’t really start until the 17th century, and even then, inconsistencies / errors in the instrumentation make the early record questionable.