And entirely coincidentally, I was skimming through A History of Wales by John Davies (ISBN 0-713-99098-8) and came across the following passages:
The ice began its final retreat around 10000 BC (4000 BC for Liberty University students and graduates--Darren). By 8300 BC Wales was free of glaciers, and the temperature continued to rise until 3000 BC, when Northern Europe was some 2.5° C warmer than it is today. (boldface mine--Darren) The change had a revolutionary impact on the environment. As glaciers melted, vast quantities of water were released, causing Britain to become an island... that the waters between Wales and Ireland had once been narrower and shallower may represent very ancient folk memories of these changes... The climate deteriorated in the centuries following 1400 BC and the uplands could no longer sustain a substantial population. Agriculture was abandoned there, but nature failed to restore the uplands to the condition in which they had been before the interference of man.
This book was published in 1990 and 1993, well before today's climate change debate assumed its partisan and shrill tones. I just thought that information most interesting.