THE GLOBE AND MAIL/ISTOCK
Mike Tipton is a professor of human and applied physiology at the University of Portsmouth’s Extreme Environments Laboratory.
All it takes is a quick look around our planet and you’ll see heat waves, droughts, hurricanes, cold snaps, fires and floods in greater numbers and of increasing intensity and duration. This is the result of a one-degree rise in the average global temperature above preindustrial times. In the next 50 years, as many as four billion people could be living in conditions deemed unsuitable for human life to flourish.
That these things are being predicted, or in some cases happening, is a matter of record, and it is a matter of strong scientific consensus that the planet is warming as a result of human activity. In the span of just 50 years, atmospheric carbon dioxide emissions have reached their highest concentrations in more than two million years. The trapping of solar radiation due to greenhouse gases has led to environmental energy gain at a rate that has doubled in the past 14 years.
Increased energy in the atmosphere results in higher temperatures and more extreme weather. We are living in the hottest period in 125,000 years, according to the UN’s Intergovernmental Panel on Climate Change (IPCC). Climate records are being broken around the globe; in the U.K., the Meteorological Office has reported that a severe heat wave is 30 times more likely to occur now than in 1750, and just a month ago, during a brutal one that stretched across Western Europe, 33 locations in Britain surpassed the country’s previous temperature record of 38.7 C, set in 2019. The record is now 40.3 C.
Definitions of heat waves vary between countries and regions. The World Meteorological Organization, for instance, defines a heat wave as five or more days during which the daily maximum temperature surpasses the average maximum temperature by five degrees or more. In Canada, however, a heat wave is defined as three consecutive days of temperatures of at least 32 C, but “heat warnings” are issued and vary by province. In Southern Ontario, such warnings are invoked 18 to 24 hours ahead of at least two days of maximum temperatures above 31 C and minimum temperatures above 21 C – or humidex values of 40 or higher. This recognizes the importance of high humidity levels in heat-related health problems and the link between high nighttime temperatures and the increased mortality seen during heat waves.
This increase in mortality is significant. The European heat wave of 2003 resulted in more than 30,000 deaths. On average, about 800 people die during a heat wave in the U.K., and heat waves caused an additional 2,000 deaths in 2020, according to the UK Health Security Agency. Many are people 65 and older, and the causes range from cardiovascular problems to hyperthermia and even drowning, as people seek relief in bodies of water.
In response to these deaths, The Physiological Society has joined the call for heat waves to be named, much as storms and hurricanes are. Doing so can bring focus and co-ordination while triggering responses to a more discrete and recognized threat.
Not everyone is in favour of such an approach. Some argue that such an initiative requires regional agreement on definitions and that naming a heat wave will not change people’s behaviour. But the evidence from the naming of storms and hurricanes does not support this position. In the U.K., storms – which now kill fewer people than heat waves – have been named as far back as the 1500s. By the early 1950s, U.S. meteorologists found that official, short and easily remembered storm names were a quick and effective way of gaining people’s attention and communicating the potential consequences of these events.
In June, the Spanish city of Seville became the world’s first to name and rank heat waves. There, heat waves initiate plans that include welfare checks for vulnerable communities, the opening of pools and air-conditioned shelters and preparing emergency services, schools, hospitals and transport systems. But the ways in which naming heat waves could help public-health announcements change the behaviour of individuals may be the most compelling argument in favour of such a system. After all, during the pandemic, the key life-saving advice boiled down to calls for behavioural change: wear a mask, stay apart and wash hands properly. With heat waves, physiologists similarly know a lot about how the body responds to heat, and we know that behaviour is the most powerful thermoregulatory response to heat stress. That’s why the advice during a heat wave includes rest, drink water and seek shade and a cool, ventilated area.
On a wider scale, one outcome of naming discrete heat waves should be to increase public awareness of the growing number of these events, which would help increase the demand to do something about them through smart buildings, urban design and action plans.
Hotter temperatures, and all that flows from them, will define our new normal going forward. While mitigation is critical, adaptation to what’s already here and set to get worse will be important, too. We must all learn to live with the threat posed by extreme environments, and knowing how to prepare for heat waves and modifying our behaviour during such events – as we do when a named storm comes around – should help.
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