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Monique Keiran: Heat dome and atmospheric river aren't new terms, just new to us

By applying correct terminology now, meteorologists are helping to reframe the conversation around these events within the context of climate change
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An overpass crossing on the Trans-Canada ­Highway in Abbotsford last November, after a powerful ­atmospheric river dumped record rainfall across much of southern B.C. STEFAN LABBÉ, GLACIER MEDIA

A year ago, many of us heard the term “atmospheric river” for the first time.

In the days before last November’s deluge dumped record amounts of rain on the Pacific Northwest coast — 61.5 centimetres on Chilliwack, 54 cm on Abbotsford, 73 cm on Hope and 31.5 cm on Victoria — the news and weather media introduced us to the idea of rivers in the sky, long, narrow flows of moisture-laden air.

Unlike some other terms for the weather phenomenon, “atmospheric river” is sufficiently descriptive that ­anyone can figure out its general meaning without much of an explanation.

An atmospheric river isn’t a mere trickle or creek in the sky. And it’s not just any river — it’s not the Cowichan, the Campbell or the confused is-it-a-creek-or-is-it-a-river Colquitz — it’s a mighty river, like the Fraser in full freshet flood or the St. Lawrence or the Amazon. It’s a heap of rain heading for the coast.

Until last fall, we were more likely to call it a “pineapple express.”

Here, in this region, pineapple express, atmospheric river, tomato, tomahto — they’re the same thing. A pineapple express is an example of an atmospheric river. It carries rain northeastward to North America’s west coast from the tropical and sub-tropical Pacific Ocean. It’s a soggy aloha hailing from down Hawai’i-way. In fact, before the 1980s, pineapple expresses were called “Hawaiian storms.”

“Atmospheric river” is more general. These phenomena don’t just occur in the northeast Pacific, but the general processes and low-latitude ocean origins of the moisture are the same.

We were introduced to other technical weather terms last year, too. We learned that a heat dome is a high atmospheric pressure system that stalls and traps heat over an area, like a dome, for days or weeks, leading to heat waves. We also learned that a weather bomb or bomb cyclone is a rapidly intensifying storm.

They weren’t new terms. They were new-to-us terms. Meteorologists have been using them in their work for years.

And although last year’s events brought home to us their potential impacts on people, communities and ­surrounding environments, the ­phenomena aren’t new either.

In 1862, before Canada became Canada and British Columbia joined Canada, a 45-day series of pineapple-express-driven storms flooded California and Oregon with 2.5 metres of rain.

Keith Thor Carlson, in his book The Power of Place, the Problem of Time, quotes a 1936 account by Katzie First Nation Elder Peter Pierre of how his people experienced an atmospheric river that flooded the Lower Fraser Valley before Europeans arrived in the area. “It rained and rained without ceasing until the rivers overflowed their banks, the plains flooded and the people fled for shelter to the mountains where they anchored their canoes to the summits with long ropes of twisted cedar boughs.”

Likewise, heat domes have long ­histories, even though people usually called them heat waves. The Dust Bowl years of the 1930s were reportedly the result of a sequence of heat domes that stalled over the North American prairies for several years running.

The persistent high-pressure systems redirected any rainy weather systems coming in from the Pacific to the north or south around the affected vast region for months on end, which extended the drought and devastated thousands of families at a time when the economy was already bottoming out.

Earlier heat domes have been deadly, too. As many as 10,000 died across the U.S.’s southern plains in 1980, and almost 750 died over five days in Chicago in 1995 because of heat domes.

More than 600 people died because of the heat in B.C. last year.

The difference between how these events are referred to now compared to then is that meteorologists are now ­calling them by their scientific names even when talking to the public. ­Mainstream media have followed suit.

It could be in response to our changing climate. By applying correct terminology now, meteorologists are helping to reframe the conversation around these events within the context of climate change.

Climate scientists have determined that the extreme weather we’ve been experienced these past two years — the 2021 heat dome and resulting wildfires, last fall’s atmospheric river and resulting floods, and now this year’s drought — is all either the result of or significantly worsened by warming global temperatures. They’re local manifestations of a global climate trend.

For decades, these researchers have been warning that more extreme weather would happen more often.

Those ­predictions are now being ­realized.

And whatever we choose to call the rainstorms, the droughts and the heat, the impacts are undeniable and personal.

keiran_monique@rocketmail.com

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