I hope everyone had a great Victoria Day holiday weekend earlier this month; the “unofficial beginning of summer” as it is often called in Canada. Despite a temporary cool spell that has intruded as May draws to a close, I’m thinking maybe it’s time to retire the June solstice and replace it with Victoria Day, because the summer weather is increasingly beginning in May these days.
Since 2014, the meteorological summer, with daytime highs of 20 Celsius or higher most of the time, has started every year in the Chemainus Valley by early- or mid-May. This year, the warm weather arrived to stay on May 3, no less than seven weeks before the summer solstice. If evidence of global warming has been hard to find at other times of the year in these parts, it looks like earlier and longer summers are now becoming increasingly commonplace.
Long summers used to be quite uncommon here, but they started to become less rare after the end of the 20th Century. The third longest summer of the 21st Century in the Chemainus Valley was in 2003. The main period of warm weather ran from May 23 to October 2 of that year; a period of four months and nine days.
After that, it was six years before we had another summer that lasted over four months. The summer weather in 2009 ran from May 22 until September 26, a period of four months and four days, making that season the fourth longest summer of the 21st Century so far.
That was followed by a five-year wait before the arrival of our second longest summer on record. In 2014, the warm weather ran from May 12 to September 24, a period of four months and 12 days.
After that, it took only only two years to experience our longest summer of all. In 2016, the warm weather arrived at the very beginning of May, the earliest date ever recorded in the local valley area, and lasted until September 15. That was a record-breaking stretch of four months and 15 days, despite the fact the cooler post-summer weather intruded a few days before the fall equinox.
One puzzling thing about this apparent trend to earlier and longer summers is that it has been mirrored by a parallel but contradictory trend to earlier and longer winters as well. Ordinarily, with global warming, we should expect the summers to be longer, but the winters should be shorter.
The best explanation I can give for this contradiction is that global warming has been occurring mostly in the Arctic latitudes of the Northern Hemisphere and in regions that have a dry continental climate, while the Pacific Ocean has experienced cooling water temperatures at the mid-latitudes. The cooler-than-usual ocean temperatures have led to longer-than-usual winters on the West Coast. Conversely, the Pacific loosens its grip here during the summer so the influence of global warming can extend to Vancouver Island on a seasonal basis.
That said, our planet’s rising temperature trends continue to have only a weak influence on our local climate for now, so our summers are longer and drier than they used to be, but not really much warmer. The current long range outlook calls for late May and early June to see a temporary return to spring weather which should soon warm up again so that we’re teasing the early summer conditions as we get into the second week of June. So the normal steady increase we see in the mean temperature curve through May and June will likely be replaced with a short dip into cooler weather in early June, followed by a return to early summer that will have a flat temperature curve until July as we get into mid-summer weather with warmer mid-season levels.
This leaves us with one major question. How much longer can the Pacific Ocean continue to resist the effects of global warming? Although our summers are not getting much hotter for now, they are getting longer and drier as I’ve already noted. Even if it looks like this very big pond is buying us some time, it may be increasingly a short-term illusion.
The ocean may be delaying some of the more potentially catastrophic effects of climate change that are being predicted by most climate scientists if more action isn’t taken to counter the effects of escalating greenhouse gases in the atmosphere. However, that delay could break down at any time if rising global temperatures soon overpower and warm up the ocean’s cool waters. On that happy note, I wish you all a great summer!
(Chris Carss is a Chemainus resident and a longtime weather observer/recorder).