Heat waves like the one smothering Hamilton expected to become more common, say experts

As Hamilton sweats through its third straight day under a heat warning, experts are sounding the alarm that the kind of sweltering temperatures currently blanketing the city are forecast to be even more common in the future.

The most-recent spell of scorching weather comes as the United Nations Intergovernmental Panel on Climate Change (IPCC) shared a report warning that without a significant reduction of greenhouse gas emissions, there will be grave consequences.

The effects of climate change are already leaving their mark across Canada, with more intense wildfires, drought and heat waves.

For northern North America, which covers most of Canada, the report found that "temperature increases are projected to be very large compared to the global average, particularly in the winter."

"The higher the temperature gets, the more frequent, and the more severe these heat waves will become and the more frequent and more severe the fire weather conditions will become," said Greg Flato, senior research scientist with Environment and Climate Change Canada and vice-chair of the IPCC group that authored the report.

Experts say that in cities like Hamilton the effects of increasing heat waves are exacerbated by tall, dense buildings that stop air circulation and trap heat.

The minimum temperature for Hamilton has risen and it's expected to keep going up in the future, according to Altaf Arain, director of the Centre for Climate Change at McMaster University.

Warm spells, also referred to as heat waves, are also expected to become more common, jumping from a few events annually to 10 or more in the decades to come, he told a webinar put on by Environment Hamilton in mid-July.

Hamilton, along with essentially all of southern Ontario, has been under an extended heat warning this week.

Daytime temperatures have hit the high twenties or low thirties, with the humidex making it feel like 40 C.

The trend may drag on into Friday, according to Environment Canada, which said humidex values will again head toward 40 before cooler, less-humid air arrives Friday night.

The weather authority is directing residents to drink plenty of water and limit outdoor activities for cooler parts of the day.

Locally, the city has opened its cooling centres and is asking people to keep an eye out for any heat-related illnesses, especially for those 65 and older, young children and residents with chronic medical conditions.