Giving heat waves names and strength ratings, as for hurricanes, could drive home the spiking danger from a threat that kills more people in the US each year than storms and floods but rarely hits headlines, heat experts said on Tuesday.

People sit outside a cafe in London, Britain on Tuesday. Photo: Xinhua

"People do not understand this risk and we need to change that," said Kathy Baughman McLeod, director of the Washington-based Adrienne Arsht-Rockefeller Foundation Resilience Center, which works to cut climate change, migration and security risks.

With 2020 set to be one of the hottest years on record, in a long string of them, "extreme heat is or will be felt by everyone, everywhere, at some point. We have to build awareness to this invisible threat," she told an online event.

The push to name heat waves is backed by the Extreme Heat Resilience Alliance (EHRA), a new coalition of 30 big-city mayors and insurance officials, as well as health, climate change and policy experts from around the globe.

Unlike floods or storms, heat waves are largely an unseen risk, with many deaths occurring inside homes and losses apparent only when "excess deaths" above normal rates of mortality are examined, public health researchers say.

Heat deaths can occur from dehydration, heat stroke, kidney failure or as existing health problems are aggravated, the World Health Organization says.

Assigning heat waves names and risk ratings could help people better understand the scale of the threat as climate change brings more extreme heat, EHRA members said.

A report published on Monday by the US National Bureau of Economic Research found that by the end of the century, heat deaths globally could nearly equal those from all infectious diseases combined today, if the planet continues to warm at its present pace.

The research, done by the Climate Impact Lab and based on data from 40 countries, found the problem will be most severe in the already hot tropics, in countries from Bangladesh to Sudan, where people may struggle to afford adequate cooling.

Large parts of the world - from the Middle East to Siberia and Australia - have seen fast-worsening heat waves in recent years.

At Tuesday's event, Athens Mayor Kostas Bakoyannis said his city was one of those most at risk from extreme heat in Europe, and was likely to see the tourism it depends on slashed as summer heat waves grow. 

He described rising heat as "one of our city's greatest challenges."

Mayor Francis Suarez of Miami similarly said his city could see the number of 40 C days each year more than double to 100 by 2050, bringing stronger hurricanes from warmer seas and more mosquito-driven disease threats.

In cities like Chennai, soaring temperatures could undermine food and water security for the poor.
Newspaper headline: Hot weather poses deadly unseen danger