A red sky at night is the shepherd's proverbial delight. It was an Irishman, however, who first explained how the evening sky may sometimes be that colour, and that same Irishman was also the first to make a connection between changes in the carbon dioxide content of the atmosphere and the possibility of climate change.
John Tyndall was born in 1820 in Leighlinbridge in Co Carlow. Having commenced work as a surveyor for the Irish Ordnance Survey, he studied for some time in Germany, and in the early 1850s became a professor at London's Royal Institution. He went on to become perhaps the most eminent scientist of his generation, and made many important discoveries in chemistry, meteorology and physics.
One of Tyndall's many interests was the way in which radiant heat, or what we now call infrared radiation, is absorbed by gases like carbon dioxide and water vapour. In 1863 he published a paper about the possible effects of such atmospheric gases on the world's climate. He went on to strike a now familiar chord by suggesting that ice ages must occur during periods when the amount of carbon dioxide in the atmosphere is significantly reduced, and what we now call the "greenhouse effect" thereby considerably weakened. We now know that this is not a primary cause of ice ages, but research has shown that a diminished greenhouse effect has indeed had a hand in prolonging some of them.
At a popular level, Tyndall's fame lay in his skill at making difficult scientific concepts understandable and entertaining to the layman. He was acknowledged to be one of the foremost public speakers of his day, and had a talent for devising striking experimental demonstrations to illustrate his points; his sense of showmanship enthralled the genteel audiences that thronged to hear his Friday lectures at the institution.
One of his favourite demonstrations was to show that light passes invisibly through a clear liquid, but that the beam becomes visible when the liquid has tiny particles suspended in it, because then the light is scattered sideways. He inferred from this that dust suspended in the atmosphere must scatter the blue light from the setting sun, leaving only the red and orange light behind - and hence the reddish sunset.
Tyndall suffered from insomnia throughout his life. As the condition worsened in his later years, he took to drugs of various kinds, some of them potentially lethal, in attempts to alleviate his problem.
One of these was chloral, and 105 years ago today, on December 4th, 1893, John Tyndall died as a result of an inadvertently administered, but fatal, overdose.