A millennium is a long time in meteorology. By and large, however, we of the second Christian millennium have chosen our epoch wisely, since for much of our planet's lifetime the spot occupied by what we now call Ireland was very different from the green and pleasant land we know today.
Eighteen thousand years ago, for example, Ireland was a barren waste, languishing under several hundred feet of ice. The only sounds to be heard were the whistling of the frozen wind and the rumblings of the deep crevasses as they opened and closed across the rough surface of that huge solid ocean.
This last ice age came to an end about 10,000 years ago, and the swift warming which followed carried our average temperature by 5000BC to about 20 C above its present value. This very warm spell, often referred to as the Postglacial Climatic Optimum, lasted from about 5000 to 3000BC.
There was a short, sharp shock around 1000BC. A change to much colder conditions took place over a relatively short period, and the drop in average temperature was accompanied by a general increase in storminess and rainfall. But the deterioration lasted a mere millennium; by the early centuries AD the climate had recovered, and was not significantly different from what it is now.
The trend for warmer weather continued through the Dark and Middle Ages. By the time of the Viking settlements, the average temperature over Ireland had increased to about 10C above present-day values; our ancestors and their uninvited guests enjoyed an unusually congenial climate, and across the channel the Normans, newly-arrived in the south of England, enjoyed wine from English vineyards.
During the next few centuries, however, it once again became cooler and often wetter. From about 1450 to 1850 there occurred what we call the Little Ice Age, during which the summers were short and the winters long and severe. Winter scenes depicted by contemporary artists contrast sharply with even the worst conditions familiar to us today.
But then came yet another change in thermal direction; from 1850 or thereabouts until the middle of the present century, the average temperature over Ireland gradually increased.
It then showed a small but persistent tendency to fall until the early 1970s, but in recent decades, as we know, each succeeding year has vied with its predecessor for the accolade of being the warmest year on record. Whether this tendency is to continue indefinitely, with all the global upheaval that the trend implies, we must wait to find out until the next millennium.