Dear editor,

As W.H. Welsh writes in his letter (The Earth鈥檚 climate is in a constant state of flux, Feb. 21 letter), the earth has seen many warmer and cooler periods throughout its long history. Some have been severe, some mild. In fact, since the end of the last ice age about 10,000 years ago, variations in global temperatures have been relatively minor. The remarkably stable climate over these 100 centuries has allowed human population to grow and civilization to flourish.

What the earth is now experiencing isn鈥檛 a minor fluctuation such as the Roman warm period or the 鈥淟ittle Ice Age鈥� circa 1700. In the chilliest February here in memory, it may be difficult to appreciate that the last five years on earth have been the five hottest since modern record-keeping began 150 years ago, and the last 20 years likely the hottest for over 100,000 years as recorded in Greenland鈥檚 ice cores. The rapid up-tick seen since 1980 seems unprecedented 鈥� far from a normal variation. Yes, on any graph, no matter the timeline, it鈥檚 shaped much like a hockey stick.

The cause is the increasing quantities of greenhouse gases present in the atmosphere. Human activities since the beginning of the Industrial Revolution have produced a 40 per cent increase in the atmospheric concentration of carbon dioxide (CO2), from 280 ppm in 1750 to 316 ppm in 1958 and to a monthly average of 411 ppm in 2018. NASA tells us that not since the Pliocene Epoch, three million years ago, have CO2 levels been this high. Because of the Pliocene鈥檚 extended high temperatures, sea levels were 25 metres higher than today.

If Welsh is seriously concerned about our economic well-being, he will have to consider the worldwide costs of more frequent extreme weather events, the damage to agriculture and fishing and forests, and the high price of retreat from our populated coasts due to rising seas. I thought it odd that he sees the call for quick action as attacks on 鈥渨estern civilization鈥�, which he names as Europe, North America, Australia, and New Zealand 鈥� those countries with privileged, predominantly 鈥榳hite鈥� populations. On the contrary, climate affects the entire world and Canada has done much less than many countries to address the emissions crisis.

We are in an unparalleled global emergency, already well underway and accelerating. This is no time for whistling in the dark, despite strong temptations to wish that it will just go away, or that we could simply continue doing 鈥渂usiness as usual.鈥�

Tom Pater

Courtenay