Editor’s Note: Ban Ki-moon was the eighth secretary-general of the United Nations. Patrick Verkooijen is CEO of the Global Center on Adaptation, an international environmental organization that partners with the public and private sectors to tackle climate change. The views expressed in this commentary are their own. Read more opinion articles on CNN.

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Extreme heat is less spectacularly violent than an earthquake or hurricane, but from 2015 to 2019 it killed more people than any other weather hazard. Last month’s blistering heat waves in the US Pacific Northwest and Western Canada left hundreds of people dead, as these normally temperate regions grappled with record-breaking temperatures. With just over 100 days to go until the COP26 United Nations Climate Change Conference, these incidents are a tragic reminder that adapting to an increasingly hostile climate is as urgent as ever.

Ban Ki-moon

In British Columbia, for example, 719 deaths were reported in just one week, triple the typical number. The Canadian province had attributed only three heat-related deaths in the three to five years before the heat wave, according to the provincial chief coroner. And the intensity and frequency of these extreme heat events is only set to rise.

Relentless heat increases

Patrick Verkooijen

Heat waves generally are becoming more frequent and intense as greenhouse gases accumulate in the atmosphere. Almost every study of a significant heat wave since 2015 has concluded that climate change had some part to play.

The pattern is relentless. Every year, records are smashed in some part of the world, and last year tied with 2016 as the warmest year on record. Sweltering temperatures have become the norm in Jacobabad, a town of around 200,000 inhabitants in Pakistan’s Indus Valley that has become one of the hottest places on earth. Temperatures can top 126 degrees Fahrenheit and air conditioning is scarce, leaving the streets deserted and forcing farmers to till their fields at night.

The city, along with Ras Al Khaimah in the United Arab Emirates, has temporarily crossed the threshold beyond which the human body cannot sweat enough to cool itself down. A “wet bulb” temperature of 35 degrees Celsius (95 degrees Fahrenheit) – which factors both heat and relative humidity – can be fatal after a few hours, even assuming ideal conditions such as unlimited drinking water, inactivity or shade. In practice, the bar for this wet bulb temperature, which is measured by covering a thermometer with a wet cloth, is much lower – as shown by the deadly heat waves in Europe in 2003 that are estimated to have claimed 70,000 lives.

Exceptions becoming the norm

As the planet heats up, Jacobabad is unlikely to remain exceptional for long. The path to achieving net-zero carbon emissions by 2050 and limiting the global temperature rise to 1.5 degrees Celsius is extremely narrow and requires urgent action, according to a recent report by the International Energy Agency. Most countries have not reduced greenhouse gas emissions nearly enough to meet targets set in the December 2015 Paris Agreement. On current trends, researchers have warned that the probability of keeping global warming below 2 degrees Celsius is just 5%.

Mitigating climate change is essential and extremely urgent. But adapting to its ongoing effects is just as pressing. The threat to human lives is clear. So is the high economic and social cost. Extreme heat burdens emergency health services as well as energy, transportation and water resources. It puts workers in industries such as construction or agriculture at risk and leads to lower productivity, with potential annual wage losses reaching $170 billion in the United States alone by 2100.

Those living in dense urban areas, surrounded by heat-absorbing concrete and asphalt with little green space, are especially at risk. Extreme temperatures already affect more than 350 cities across the globe, and that number could reach 970 by 2050, affecting 1.6 billion people. As usual, it’s the most vulnerable segments of the population – the elderly and those on a low income – who suffer most.

Learning to live with extreme heat

The good news is that many cities are finding ways to learn to live with heat waves. One of the most successful has been Ahmedabad in India, which suffered a heat wave in 2010 that saw temperatures soar past 115 degrees Fahrenheit. It has since blazed a trail in India with South Asia’s first ever Heat Action Plan. This contains simple and effective strategies, including early-warning systems, training health care staff and painting roofs with white reflective paint to reduce heat absorption and lower temperatures inside, that have helped prevent more than 1,100 heat-related deaths.

Heat waves are predictable and a well-defined plan of action gives people time to act. Any city hoping to protect itself must first use temperature and health data to identify high-risk groups such as outdoor workers or elderly citizens. A heat wave response plan can include early-warning systems, cooling centers and strategies to communicate with citizens through phone calls, billboards and social media, as well as programs like New York’s Be a Buddy, in which New Yorkers reach out to at-risk neighbors during periods of extreme heat.

Successful plans also include longer-term urban planning, such as lighter color and water-retaining paving options for roads, which can sometimes reach summertime temperatures of 140 degrees Fahrenheit. Tokyo built 84 kilometers of cool pavements as part of roads construction and maintenance in priority areas, while in cities such as Barcelona, Spain; Medellín, Colombia; and Melbourne planting trees to provide cover has become integral to their plans. Paris, meanwhile, has deployed a combination of misting machines and cooling rooms, and fitted 35 fire hydrants with special misting/drinking devices.

Expanding action to the most vulnerable

Richer countries have the resources to implement these kinds of climate adaptation plans, but financing for adaptation in developing countries falls far short of what is needed. Many of these countries are on the front lines. Pakistan, for example, is low on the list of global polluters but is among countries more vulnerable to the effects of climate change. The human consequences are inexcusable: The World Bank estimates that climate change could push as many as 132 million people into extreme poverty by 2030.

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    Developed countries, therefore, must now deliver on their promise to jointly mobilize $100 billion in finance for mitigation and adaptation in developing countries – a promise which, though more than a decade old, has – shamefully – yet to be met.

    Beyond the moral obligation of developed countries to help the most vulnerable nations cope with extreme weather, what is at stake is not just the implementation of the Paris Agreement’s goals, but the ability of humanity to survive on our fast-warming planet.