As summer heat waves intensify and advocates sound the alarm on the lack of protections for the most vulnerable populations, one extreme weather expert is calling for access to cooling to be treated as a human right.

Much of Ontario experienced a multi-day heat event this week, with the humidex reaching up to 40 C in some areas. The planet's average temperature hit new records in the last few days, rising to an unofficial high of 17.18 C on Tuesday and Wednesday, breaking Monday's short-lived record of 17.01 C, according to the University of Maine's Climate Reanalyzer.

Blair Feltmate, head of the Intact Centre on Climate Adaptation at the University of Waterloo, has sought to bring attention to the need for greater heat adaptation as Canada is set to experience higher daily temperatures and longer heat waves under climate change.

Feltmate's research projects that between 2050 and 2080, almost all major Canadian cities will see an increase in maximum daily temperature between 3 C and 5 C, and the number of summer days above 30 Cwill double, triple, or quadruple in some cases.

In Toronto, that looks like maximum daily temperatures increasing to around 38 C, and the number of days exceeding 30 C rising from 15 to 16 days per summer up to 60.

"We need to think of access to cooling as a fundamental human right because if we don't make that provision literally people are going to die, Canadians are going to die, not just in the hundreds but potentially into the thousands," said Feltmate. He pointed to extreme heat events that led to more than 600 deaths in B.C. in 2021 and more than 80 deaths in Quebec City in 2018.

"As hot as it is now, and [Wednesday] set a new global record for the planet in terms of overall temperature, things are going to get hotter going forward."

Feltmate said there are approximately 500,000 people in the Greater Toronto Area who live in apartment buildings that are at least 40 years old and eight storeys or higher. If a major heat wave happened to coincide with an extended electricity outage, residents of those buildings could be without air conditioning, fans, elevator access or even water flow.

"The results could be lethal," he said.

Avoiding those deadly situations requires immediate steps to reduce heat stress. Feltmate said that could look like backup electricity generation for a couple of days for all apartment buildings, or subsidies for small, portable air conditioners, similar to a new B.C. program offering such ACs to low-income households.

Awnings over windows, window glazing to limit direct sunlight, trees and vines planted in and around buildings to provide shade can all reduce the impact of heat on residential buildings, Feltmate said.

Improving insulation and airtightness can also cut heating and cooling costs, he said.

Municipalities should play a large part in improving cooling access, he said, in particular to mitigate the "heat-island effect," in which urban areas are significantly warmer than surrounding areas. Dark and tarred buildings, roads and other infrastructure absorb and retain more heat from the sun than natural landscapes, contributing to warming between 3 and 5 C.

The heat-island effect could be combated with white, "cool" roofs or more trees and vegetation, among other design considerations.

But these actions require a combined response from all levels of government, particularly on the federal level, Feltmate said, as cities and towns would be better equipped to make such changes if directed by Ottawa.

Last week, Canada released its new national climate adaptation strategy, which will tie future federal infrastructure transfers to the provinces to projects that incorporate adaptation efforts.

One of the targets is for 80 per cent of health regions to have a plan to protect people from extreme heat by 2026, something officials said could include making sure there are adequate cooling centres available during heat waves. Another is the elimination of all heat-related deaths by 2040.

Some municipalities are getting ahead of the curve. Hamilton is poised to become one of Canada's first municipalities to require landlords install air conditioning to ensure indoor temperatures don't exceed 26 C, after an "adequate temperature" bylaw was passed by council in May.

Changes can't come fast enough for people most vulnerable to extreme heat, such as those who live and work outside and are already bearing the brunt of climate change, advocates say.

Chris Ramsaroop, an organizer with advocacy group Justice for Migrant Workers, called on Ontario to enact immediate emergency measures to protect the province's farm workers from the heat, including sheltering and cooling periods, access to free water, shade requirements and shutting down farms in extreme crisis events.

He said many of those workers, who fear threat of deportation for speaking out, are facing hot working conditions in greenhouses and are experiencing headaches and near-fainting due to the heat, but have been expected to keep up the regular pace of work.

"It's imperative the province enact steps and measures to protect all workers who have to endure this heat," said Ramsaroop.

In a statement, provincial Labour Minister Monte McNaughton called Ontario's farm workers "heroes" who are protected by health and safety laws, "regardless of their passport.

"As we experience increasing heat waves and the hazards of forest fire smoke, and a changing nature of outdoor work, we will not hesitate to take further action to protect those who put food on the table for families across our province," he said. The Ministry of Labour added it conducts inspections to ensure employers are meeting health and safety standards and urged workers who feel unsafe to report their concerns.

In response to this week's heat alert, Toronto activated its Heat Relief Network, which includes cooling locations such as libraries, community centres, private malls and municipal pools.

However, community worker and longtime advocate for the homeless, Diana Chan McNally, said many of those spaces are inappropriate for people experiencing homelessness, who may be subjected to harassment.

"Having an unhoused adult, for example, cool off in a children's splash pad is obviously going to set off some alarm bells," she said, criticizing the city for not having dedicated emergency cooling centres as it did in the past.

The City of Toronto said it "recognizes the need for additional services to help meet the complex needs of those living outdoors during heat warnings but the city continues to face significant financial pressures."

Chan McNally said emergency weather will come in all seasons, so there needs to be a shift from thinking of seasonal spaces in the summer or winter to year-round, 24-7 dedicated emergency weather spaces.