The human, environmental and economic toll of extreme heat has played out across Europe, the US and China in 2022. New research says that ‘dangerous’ levels of heat are set to increase.
The scientific analysis warns of continuing increase in extreme heat.
Heat Index analysis shows 50-100% increase in dangerous heat exposure in the US.
Worst case scenarios project months of extreme heat – action must be taken.
The impacts of very high temperatures on public health and agricultural systems are significant and the impacts of climate change on heat waves are likely to present even more daunting challenges.
Extreme heat contributes to chronic illnesses and is associated with regular losses of outdoor labour time. And this is a global problem – it will play out in different ways around the world but preparations for its impacts need to be made.
Global temperature increases could see months of dangerous heat levels
According to a paper recently published in the Nature journal Communications Earth & Environment Probabilistic projections of increased heat stress driven by climate change: “Without emissions reductions more aggressive than those considered possible by our statistical projection, it is likely that by 2100, many people living in tropical regions will be exposed to dangerously high Heat Index values during most days of each typical year, and that the kinds of deadly heat waves that have been rarities in the midlatitudes will become annual occurrences.”
The research found that countries in the tropics and subtropics are likely to experience as many as 180 days of dangerous temperatures (a heat index above 39C on the National Weather Service scale) by 2050. By 2100, those regions would likely experience a heat index at that level for most of the year.
The analysis said that regions where the extremely dangerous Heat Index threshold is almost never exceeded today will experience between one and fifteen days when the extremely dangerous Heat Index threshold is exceeded each year.
The paper said: “We project that, by the end of the twenty-first century, these regions will include large portions of India and sub-Saharan Africa. According to the UN demographic projections for 2100, these regions are projected to include about 5.3 billion people by 2100, or about half the world’s population at that time.”
First Street Foundation adds heat to Risk Factors
The Nature analysis supports to support a recent warning from First Street Foundation, a New York-based non-profit climate risk research group, that a quarter of the US could see temperatures above 52C within three decades.
In the case of extreme heat, the First Street Foundation Extreme Heat Model found 50 counties, home to 8.1 million residents, that are expected to experience temperatures above 125°F in 2023, the highest level of the National Weather Services’ heat index. The analysis will be added to Risk Factor to allow people to see the risks facing their properties.
By 2053, 1,023 counties are expected to exceed this temperature, an area that is home to 107.6 million Americans and covers a quarter of the US land area. This emerging area, concentrated in a geographic region the Foundation calls the “Extreme Heat Belt,” stretches from the Northern Texas and Louisiana borders to Illinois, Indiana, and even into Wisconsin.
The report was based on its peer-reviewed extreme heat model along with the implications highlighted in The 6th National Risk Assessment: Hazardous Heat. The report identifies the impact of increasing temperatures at a property level, and how the frequency, duration, and intensity of extremely hot days will change over the next 30 years from a changing climate.
“Increasing temperatures are broadly discussed as averages, but the focus should be on the extension of the extreme tail events expected in a given year,” said Matthew Eby, founder and CEO of First Street Foundation. “We need to be prepared for the inevitable, that a quarter of the country will soon fall inside the Extreme Heat Belt with temperatures exceeding 125°F and the results will be dire.”