Extreme heat: Why it’s a global health issue and what we can do about it

Around the world, temperature records are being upended, and large parts of Asia, Europe and North America have spent the past few weeks under excessive heat warnings. On Sunday, China recorded its highest ever temperature of more than 52 Celsius (126 Fahrenheit); the same day, California’s Death Valley saw temperatures hit 53.33 Celsius (128 Fahrenheit), edging closer to the hottest temperatures ever reliably recorded on Earth.

While natural weather and climate patterns play an important role in extreme heat events, climate change driven by human activity continues to make these events all the more common. The average global temperature has been rising since the beginning of the 20th century, predominantly due to the burning of fossil fuels like coal, oil and gas.

The health consequences of such extreme heat can be catastrophic. From May to September 2022, the heatwaves in Europe caused more than 60,000 heat-related deaths, recent research suggests. And in 2021, academics analysing data from 732 locations in 43 countries concluded that 37% of heat-related deaths between 1991 and 2018 could be attributed to climate change.

Extreme heat also increases the instances of events like wildfires, which are currently raging in the US and Europe, bringing with them dire health consequences, such as respiratory issues and higher rates of heart attacks and strokes. Around 70 million people in North America are currently under wildfire-related air quality alerts, with the most vulnerable told to avoid outdoor activities. For people who need frequent medical supervision, such as those with chronic conditions, staying at home often means putting off routine but important healthcare appointments, which can increase morbidity and mortality, as we saw during the pandemic.

Other negative health risks related to rising temperatures are less obvious, but potentially just as serious. For example, experts have predicted that just half a degree centigrade increase in temperature will mean an increase in mosquito numbers, through the expansion of suitable habitats and low over-wintering temperatures leading to the spread of vector borne diseases. According to a study from the London School of Hygiene and Tropical Medicine, if emissions keep rising at their current levels, the population at risk of dengue and malaria — two mosquito-borne diseases — might increase by up to 4.7 additional billion people.

And the health effects are far from just physical. In 2022, researchers analysing the medical records of millions of US citizens found that extreme heat events increased mental health emergencies. Over the decade-long period of study, emergency hospital visits for mental health issues rose on average 8% on the hottest days. “This study establishes at an unprecedented scale that days of extreme heat can also impact people’s mental health in a substantial way,” the study’s author told journalists.

So what can be done? That’s the question we’re trying to answer with the World Economic Forum’s Climate and Health Initiative, which is bringing together a variety of stakeholders and policy-makers who are working in this area. So far, we’ve learned a few things.

The first is that there are already some incredibly effective solutions that are helping tackle the immediate health threats related to extreme heat. For example, in some countries, local municipalities have lengthened their swimming pool opening hours or created “cooling spaces” to give people a chance to cool off. In the workplace, companies in sectors where staff are particularly vulnerable to heat, such as construction, have introduced measures such as modified hours to allow people to work during cooler periods of the day. By bringing together all the relevant stakeholders, we hope to create opportunities for showcasing more existing solutions that might easily be scaled elsewhere.

The second lesson is that some of the solutions might not come from obvious places. Take the example of mobile clinics, something widely used in countries across Africa to expand access to healthcare for people living in remote areas. A similar service in countries affected by heatwaves could ensure continuity of care for vulnerable populations who aren’t able to get out during extreme heat events. By bringing together a real variety of healthcare stakeholders, we can reveal opportunities that might otherwise have remained unexplored.

And the third lesson is that, while all these adaptive measures are essential, we must still work on mitigation. Too many of the solutions to extreme heat involve doing things that will ultimately make the problem worse. In places like India and Brazil, for example, demand for air conditioning units is exploding. But while this might alleviate the effects of extreme heat, it will exacerbate the underlying cause of soaring temperatures: climate change. Instead, we need to find solutions that will help us adapt to the new reality of more extreme heat events while also tackling the root cause by reducing emissions. In India, for example, more and more people are turning to solar-powered AC units and installing thermal insulation to keep their houses cooler in climate-friendly ways.

Extreme weather events are more frequent than ever before, and they’re here to stay. Each one of them has a human toll and must act as a warning that the time to act is now. Climate change is here. It is a public health emergency that is already impacting the health and well-being of people in every country and every continent.

That is why we have a responsibility to ensure our healthcare systems become more resilient, so we are prepared to deal with the effects of not just extreme heat, but with all climate-driven health consequences. Bringing together all public and private stakeholders who are already working to tackle both the short-term impact and the longer-term causes offers us the best chance of progress.