COLUMN: Global warming? Climate change? Or something else?

Columnist Greg Utzig on temperature trends across the world and in the Kootenays

This is the second in a series of columns addressing various issues surrounding Climate Disruption in the West Kootenay. Greg Utzig is a local conservation ecologist who has been working on climate change issues for two decades.

By Greg Utzig

The argument about whether the Earth is warming needs to end. The record is unequivocal. Since the late 1800s, the average annual surface temperature has risen more than one degree Celsius. Sixteen of the 17 warmest years in the last 136 years have occurred since 2000.

“Global warming” is a useful term for describing one aspect of the changes that occurred over the past century, mainly due to human emissions of greenhouse gases. But it doesn’t tell the whole story. Since other aspects of climate are also changing, the term “climate change” may be more useful.

As the temperature of the atmosphere increases, so does its capacity to hold water. The result is that precipitation is generally increasing in places and seasons that are normally wet, but also decreasing in seasons and locations that are drier.

In the West Kootenays, temperatures are projected to increase in all seasons. But precipitation is projected to decrease in the summer, and increase in the other seasons, particularly in the winter.

This may mean more snow at the higher elevations (good news for backcountry skiers). But the main result will be increased winter rains at mid and lower elevations due to higher winter temperatures.

These are general trends, and not every year will steadily represent them. Other cyclical patterns affect year-to-year variation in weather, such as El Niño. These cycles influence whether any given year is above or below the average long-term trend. But they do not negate the long-term trend.

As well, not all parts of the globe have warmed at the same rate. The Arctic Council (comprised of eight circumpolar countries including Canada) reported this year that the Arctic is warming at about twice the rate of North America (NA) as a whole.

This is important because temperature differences between the Arctic and the temperate regions drive the polar jet stream, the undulating high altitude winds that move weather systems west to east across NA. Historically the jet stream has been a wavy pattern that moves at a moderate pace across mid- and southern Canada and the northern U.S.

However, the jet stream has weakened as the difference between the Arctic and temperate zones has decreased. The flow of weather systems has become erratic, sometimes stalling for days, and the wave patterns have started to increase in amplitude, dipping further north and south.

When they dip further south, cold Arctic air moves south. The colder winters in Eastern Canada the past few years have coincided with the jet stream dipping far south into the northeastern US.

It also works the opposite way, with warmer air from the south moving further north. In the spring of 2013, that pattern allowed warm moist air from the Gulf of Mexico to reach Calgary. When the associated low pressure system stalled, intense precipitation continued for days and was one of the most costly ‘natural’ disasters in Canadian history resulted.

That series of storms eventually continued west resulting in severe flooding in the East and West Kootenays. Kaslo received more than 100 millimetres of precipitation in 48 hours, while Campbell, Schroeder, Fry and Hamill Creeks experienced severe flood damage.

In 2016 a slow-moving pattern in the jet stream facilitated the transfer of warm dry air from the U.S. all the way to Fort McMurray, resulting in extreme wildfire activity and another of Canada’s most costly ‘natural’ disasters.

This summer, when Arctic temperatures set new records, the jet stream was severely weakened. A large high pressure system stalled over B.C. and the Pacific northwest. This resulted in our hot dry summer and record-breaking fire season. That same high pressure system helped to hold Hurricane Harvey over Houston, resulting in record-breaking precipitation there. Fortunately, the jet stream is just now starting to increase in strength, finally breaking that pattern.

The increase in these ‘extreme events’ has caused many people to use the term ‘climate disruption.’ Global warming and climate change are reasonable expressions for gradual changes in average climatic conditions. But the changing averages aren’t most important. It’s the increase in frequency and/or magnitude of extreme weather events that generally has the greatest impacts, such as this summer’s drought and the current hurricanes.

The increase in extreme weather events is consistent with what climate models are projecting for the future. Economists, including the former Bank of Canada governor Mark Carney, are clear — there is an urgent need for government, business and investors to adjust to greenhouse gas emission reductions, or face the severe and costly consequences of ever-increasing climate disruption events.

We need to convince ourselves and our politicians that climate change is happening now, and that it’s wiser to move away from fossil fuels in the short term, not sometime in the future.

 

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