We know that global warming is upon us. The world has warmed by the best part of a degree in the last 150 years, and since 1976 the average global temperature has been increasing at a rate equivalent to nearly 2 per century, a rise unprecedented in the last 1,000 years.
We know that the warmest 10 years on record have all occurred since 1983, and that the warmest four of all occurred in the course of the 1990s.
But what about the situation here in Ireland? Has global warming reached our chilly shores, or is it still to come? Or as Auden nicely puts it:
When it comes, will it come without warning Just as I'm picking my nose? Will it knock on my door in the morning Or tread in the bus on my toes?
Met Eireann, as always, has the answers. The decade of the 1990s, as elsewhere, turned out in Ireland to be the warmest decade of the 20th century.
All weather-observing stations show a sharp rise in mean air temperature, and a closer look at the averages for a few key stations, where records are available for long periods, reveals a pattern over the years very similar to that observed worldwide.
Malin Head, for example, is a case in point. Records there go back 115 years to 1885. At that time, the average annual temperature there was about 0.2 of a degree below what we now take to be the norm, the 1961-90 average which is 9.39.
From 1885, the annual average fell slightly over the years until in 1915 it stood 0.5 below this "normal", then it rose steadily until about 1940.
After 1940, and for the next 40 years - although, as always, there were cold years and also very warms ones - no general trend was obvious.
In the late 1980s, however, the upward drift in the average annual temperature began and continues. If you take the period as a whole, from 1885 up to the present day at Malin Head, the long-term average works out as an increase in the average annual temperature of 0.7 or thereabouts.
So what does it all mean, and when will we begin to feel its impact? Or to quote Auden again:
Will it come like a change in the weather? Will its greeting be courteous or rough? Will it alter my life altogether?
But then, Auden knew nothing about climate change. He was on a different tack; his last line is:
O tell me the truth about love!