We hear the word “unprecedented” a lot these days, whether it’s about heatwaves and heat domes in normally temperate parts of Europe, the huge fire outbreaks around the Mediterranean, or places which never had them before such as western France. We hear it about algal blooms, coral bleaching and fish kills, rapid glacier melting and more frequent and more severe storms. How do we prepare for conditions we’ve never or rarely encountered before?
Short of preventing the underlying heating, there are several things which governments and others are doing, beyond greening our cities, adding wetlands and water gardens, insisting on white roofs and so on, which we've discussed before. In this post I will mainly be talking about the impact on human health and some of the new mitigation measures being applied.
Extreme Heat
Many countries have been experiencing unusually high temperatures this month with even Nordic countries and the Arctic being subjected to “unprecedented” and prolonged heatwaves. Finland for example, had temperatures above 30oC for over three weeks. On the other side of the Atlantic, North America and Canada, not only sweltered but had one of their worst fire seasons. Temperature records were also broken in Japan, Korea and parts of China. In the Middle East, the Arab Emirates, Morocco and parts of Iran and Iraq had temperatures exceeding 50o C, affecting power and water supplies, education and labour.
Heatwaves, Temperature and Humidity
A heatwave refers to a prolonged period of abnormally hot weather, often lasting several days or more, and significantly warmer than the usual climate for a given location and time of year. In the UK that period must be at least 3 days. Australia, the EU, the USA and Africa use the Heat Wave Duration Index (HWDI) which stipulates that temperatures must exceed the normal daily maximum for at least five consecutive days by 5o C (9o F) based on a historical period such as 1961 – 1991.
Not all countries use the same measure for temperature. Japan, India and South Korea for example, use the WET BULB GLOBE TEMPERATURE (WBGT) as it is more indicative of heat stress in occupational or sports settings. Wet Bulb Thermometer readings give a combined reading for temperature and humidity.
The body’s primary mechanism for cooling itself is through sweating, but in hot and humid conditions with little airflow, this evaporative cooling mechanism cannot function when the air is already moisture laden and at 35o C (WBGT) it becomes lethal. For this reason WBGT is increasingly being used in climate risk assessments, workplace safety and urban planning to capture dangerous conditions which conventional readings may miss.
Heat Domes
Heat Domes are a relatively recent phenomenon. While they most likely existed in the past, the first time most of the public really heard about them was when Canada experienced a prolonged one in 2024. Although hot air normally rises, we are now seeing stagnant high-pressure systems trap hot air for days as temperatures rise, creating dangerous conditions where temperatures do not fall at night and just keep rising.
The reasons for this are complex but the short answer is, that as oceans warm -think melting glaciers and ice caps, as well as increasing CO2 and deforestation, the winds and powerful air currents we take for granted such as the Jet Stream, no longer behave as they used to and allow high pressure systems to build up. The air underneath then stays put and becomes hotter and hotter. This month (Aug 2025) Europe has had its own, creating a long - lasting heatwave and fuelling large wildfires.
Besides allowing temperatures to keep on rising, they increase evaporation and are linked to droughts and widespread damage to crops, trees and other organisms. They also contribute to the intensity and frequency of the wildfires we have been seeing, with those in Los Angeles, being a case in point. Note that these fires occurred in January, which is normally California's wet season.
Scientists warn that climate change is making these systems more likely and more severe, turning once-rare extremes into recurring threats.
Health Impacts
The World Health Organisation estimates that between 2000 and 2019 an estimated 489,000 people died from heat -related deaths each year and that in the 2022 European summer alone, there were 61,672 additional deaths attributed to heat stress.
High temperatures contribute indirectly to deaths from other conditions too, including heart disease, diabetes, high blood pressure and respiratory illnesses. People aged over 65 are 85% more vulnerable. People on low incomes who may not be able to afford air -conditioning or other cooling measures are also more vulnerable.
Just living in the city makes people a bit more vulnerable than country dwellers, because all that concrete and dark surfaces such as roads absorb heat, whereas trees and grass cool by releasing moisture into their surroundings. This makes cities at least 5% hotter than rural areas.
Diseases on the March
Many disease organisms such as salmonella also proliferate during hotter weather, and some diseases which were previously kept at bay by colder climates, are now moving polewards. In Australia they include diseases such as Dengue Fever, Ross River Fever and Japanese Encephalitis.
Dengue which has reached epidemic proportions in Bangladesh, is expanding into Nepal. Lyme disease previously confined to the USA is being detected in Canada. Tick -borne diseases are also reaching Scandinavia while tropical diseases such as West Nile Fever and Dengue are increasingly appearing in Europe. Malaria – carrying mosquitoes have been found to be moving south at the rate 4 km per year.
How Countries, Cities and Communities are Responding to these new Challenges
Many cities are already incorporating cooling features such as wetlands, greener buildings, water features and shading into their urban design. See earlier posts on this here. We’ve also looked at how homes can be cooled with various architectural fixes such as breezeways, awnings, white roofs and simple measures such as closing curtains early in the day.
New elements include Advances in Forecasting, Urban Heat Mapping, creating Cool Corridors and using cooling materials, and establishing standards and guidelines for outdoor work and other activities. Of necessity I will leave the last two, plus advances in Fire Fighting for another post.
Advances in in Forecasting and Early Warning Systems
The World Meteorological Office reports that on average there has been one climate -related disaster every day for the past 50 years and the number of such disasters has increased 5 -fold since 1970. Early warning – within 24 hours of such an event, can reduce the damage by 30% and save 100,000s of lives. For those who think only in monetary terms, this would also mean saving around $US 3-16 billion a year. At present around a third of the world does not have an adequate warning system, although the WMO is working hard to remedy that.
The Copernicus ERA5 – Heat Data set provides hourly updates of UTCI around the world. UTCI stands for Universal Thermal Climate Index. This is a sophisticated measure which incorporates air temperature, humidity and wind speed as well as solar and thermal radiation. It provides not only a more precise guide to current conditions but when combined with climate models, allows for more accurate predictions to be made about the future.
Australia*
· In Australia this translates into daily weather forecasts from its Bureau of Meteorology which now include detailed information for each area, showing not only rainfall and temperature, but a ‘feels like’ measure which takes into account things like wind chill - an important factor which can lead to hypothermia in Tasmania and alpine regions, or in this case hyperthermia or heat exhaustion. It also has an Ultra Violet Radiation (UV component.
The latter is extremely important in a country like Australia with the world’s highest per capita skin cancer rates, in part due to its latitude, its lack of pollution (ironically) and its outdoorsy culture. A person may well feel cool under cloudy skies, in the mountains or by the beach, thanks to elevation and evaporative cooling, but UV exposure may still be very high. This applies to skiers too.
 |
| Part of our Weather App -scroll down and there's more |
The daily weather forecast also includes wind speeds and weather warnings for bushwalkers, roads, farmers, fishermen, boaties, plus local fire information. The Bureau of Meteorology’s Heatwave Service offers real-time alerts and severity maps across Australia.
* I'll be mentioning Australia a lot in this segment not just because I live there, but because it has long had a front row seat when it comes to extreme heat and other aspects of climate change.
 |
| The next screen shows the UV index - but there's no point showing it now because it's the middle of the night |
- Griffith
University’s ETHOS Project is a tech-based early warning system designed
for vulnerable populations, especially older adults.
- Improved forecasting also informs building regulations. For example, in Tasmania we must now take into account higher wind speeds when seeking planning approvals for new buildings and there are changes to regulations in many jurisdictions to ensure greater protection from fires.
Europe
- France’s Vigilance System now includes heatwave colour-coded alerts integrated with public health messaging and hydration campaigns.
- Spain and Italy are piloting urban heat vulnerability maps that combine satellite data with socioeconomic indicators to guide targeted interventions.
- The EU Copernicus Climate Service continues to refine UTCI-based forecasting, with real-time dashboards for cities like Paris, Rome, and Berlin.
Middle East & North Africa
- Saudi Arabia is investing in AI-driven heatwave prediction models to protect outdoor workers and pilgrims during Hajj.
United States
- The National Weather Service now uses a HeatRisk tool that blends temperature, humidity, and health vulnerability to issue tiered warnings.
- Cities like Phoenix and Los Angeles have launched Heat Officers and Resilience Hubs, integrating cooling centres* with early warning systems and community outreach.
Asia
- Japan broke national temperature records in August 2025 and responded with real-time heat alerts via mobile apps, especially targeting elderly populations.
- China’s Meteorological Administration is deploying machine learning models to forecast urban heat islands and guide infrastructure cooling retrofits.
These systems reflect a shift from reactive alerts to preventative measures.
Thermal Mapping
Creating Cooler Cities
Synthetic turf *and concrete reflect UV, increasing exposure. Natural shade from trees offers better protection, because trees not only produce shade but release moisture to the surrounding atmosphere, thereby also reducing heat.
* Especially avoid that fake grass. It's been found to be up to 80% hotter than real grass!
- Cumberland Council in NSW (Australia) stipulates that low density housing must not only have light-coloured roofs, but also walls and that paving should be permeable if possible. Hard surfaces must be shaded and incorporate trees and water sensitive design. Permeable surfaces include gravel, composite resin, porous bricks and clay, where traffic loads are light.
- In Parramatta, also in NSW all new residential developments must have reflective surfaces and a percentage of shading.
- An industrial development in Penrith (NSW) also requires the use of light-coloured roofs and paving, with a preference for the permeable kind. Carparks must use materials which reduce heat absorption and have trees to shade footpaths.
- The NSW Planning Department notes that solar panels can provide shade to roofs by redirecting a portion of the sun’s energy. There are also tips about using reflective paint on exterior walls, not exposing long thermally massive walls to the heat of the day and shading north facing walls (East/South in the Northern Hemisphere) with pergolas, shade sails or greenery to avoid the hot afternoon sun. Read more here.
- Australia’s
latest National Building Code (NCC 2025) includes provision for ventilation and
air circulation, though Germany, Sweden, New York- with some exceptions, and Japan go further, by
insisting on openable windows in
bedrooms and living areas to allow for cooling airflow.
Los Angeles is trialling reflective asphalt coatings on residential streets. These are showing surface temperature reductions of 10–15°F compared to untreated asphalt. It’s also integrated with shade structures, tree planting, and sensor-based monitoring.
The City of Phoenix is conducting pilot projects using heat resistant coatings on pavements. So far they have been shown to reduce temperatures by 2.4 o F at sunrise and a whopping 12o F at noon, although this had diminished somewhat when retested a year later.- Along with many greening initiatives the City of Adelaide (South Australia) is trialling road coatings to reduce urban heat effects as part of its plan to become one of the world’s first carbon neutral cities. So far the coatings have been shown to reduce surface temperatures by between 2.9o and 8.7o C. It is also trying out coatings for roofs and using light coloured paving.
[Can't wait for them to do the Adelaide to Darwin road. The last time we travelled this route, three of our tyres melted and this was only in early summer, not a heatwave].
Perhaps in future, consideration could be given to having some hydration stations and shaded areas along these long stretches, including those between Adelaide and Perth, along the West Coast of Western Australia and the more travelled routes in the interior where temperature above 50° C are not uncommon. We have now recognised the need for green corridors to enable animals to move from place to to place, but we have not yet done this much for humans.
Passive Cooling Corridors
- Instead
of isolated green zones, planners are designing connected cool corridors.
These are intended to channel cooler air into dense urban cores by aligning
with prevailing winds, using low rise buildings, permeable surfaces and water features. Penrith and
Parramatta are trialling this in Western Sydney.
- In Guangzhou’s Knowledge City in China, 29 km of shaded corridors are being constructed between
the subway station, shops, services and residential areas - small green or
shaded corridors as it were, to make walking between them more pleasant. China increasingly notes that perception matters as much or more than actual temperature with the addition of green spaces heightening the perception of coolness, irrespective of actual temperature changes.
- The World Bank Guidelines on Nature -Based Cooling offer 39 ways to cool
cities. Misting (page 46) may be an option for those countries which
cannot risk standing water features, which could attract disease – bearing
mosquitoes. It is also reputed to reduce temperatures by between 5 -15 o
C.
[Solar powered pumps may be necessary to keep waters moving and thus prevent mosquitoes from breeding, something I've had to consider with my own ponds]. - Another
suggestion for keeping cities cooler (p. 50) is to reduce the number of non - electric vehicles in an area, which, apart from adding to global warming through their emissions, also emit heat in the immediate area.
- In Tokyo,
planners are experimenting with wind tunnels to increase airflow in hot
areas.
- Tel Aviv is installing light-coloured awnings with solar panels over public
squares so that they are cooler by day and can be lit up at night.
Creative Cooling Solutions
Some of these are still in pilot phases, others are edging toward commercial viability. Most are eminently suited to existing buildings and homes. All will help cool them, reduce energy bills and reduce emissions.
- Phase Change Materials (PCMs)
Embedded in wall panels or ceilings, Phase Change Materials absorb and release heat as they shift between solid and liquid states—flattening indoor temperature swings without active cooling.
- Thermochromic or Electrochromic GlazingThese "Smart Windows" change their tint in response to rises in temperature or light exposure, reducing solar gain. Some versions are manually switchable. Others respond automatically.
- New
Cool Roof Coatings have moved beyond simple white paint, though that is still an effective and affordable solution. Some coatings reflect infrared radiation
while remaining aesthetically neutral (e.g., slate grey or terracotta
tones), useful for heritage-sensitive buildings. NEOtech Coatings for
example, block 96.1 % of solar radiation. NEOtech is widely promoted in
Australian urban planning because of rising temperatures and to reduce
energy consumption.
In the USA acrylics, polymers and hybrid paints have been widely adopted in California, Texas, and other hot-climate cities due to building code incentives. These can reduce inside temperatures by between 6 and 10o C. For more on this plus five other ways to cool roofs including green roofs, click here. - Of course, any type of insulation - especially in roofs, will reduce heat gain and slow heat loss in winter.
· Radiative Cooling Surfaces emit heat directly into the atmosphere at night, providing nighttime cooling without energy input. This technology is still emerging, but has been pilot-tested in California, the UAE and Tokyo's Haneda Airport.
When Coldrays Radi -Cool radiative film was applied to one of Haneda Airports’s sky bridges, the roof surface temperature dropped by 45.5 o F and the interior ceiling temperature by 14.7o F. It has since been used successfully at other airports such as Singapore’s Changi, Hangzhou International Airport and other buildings including a granary, greatly reducing its energy consumption.
- Using smart ventilation systems that pull in cooler air after sunset. Some examples follow:
Uses electrically controlled windows to release accumulated heat and pull in cool night air.
Often paired with thermal core activation—pipes embedded in concrete slabs circulate water to regulate temperature.
Ideal for offices, schools, and public buildings with large glass facades. Read More ...
2. Shenyang, China – Night Cooling in Office BuildingsBuildings using automated window systems to ventilate from 9 PM to 7 AM, were able to reduce cooling loads by up to 62.8%.
Strategic airflow planning and thermal mass (e.g. concrete walls) help dissipate daytime heat.
Some buildings reported 40% energy savings annually. Read More...
3. EllisCo’s Night Purge Ventilation (New Zealand)Uses thermal buoyancy and wind-driven airflow to flush out warm, stale air.
Especially effective in industrial and educational buildings with exposed thermal mass.
Designed to work even in cold climates, below 0°C. Read More here.
·
Hybrid cooling systems
combine evaporative and mechanical methods to optimize energy use across
varying climate conditions, switching modes based on humidity and temperature
for maximum efficiency. The Condair hybrid system for example, modulates between dry air, evaporative, and mechanical cooling depending on
ambient conditions. The mechanical system takes over when the humidity gets too
high for the evaporative system to work efficiently.
- Bioadaptive shading
The Solar Gate Project borrows from nature with pine cone-inspired shading that opens and closes with humidity—no electricity required. A 4D-Printed Smart Shade like this has been installed on the livMatS Biomimetic Shell at the Institute of Computational Design and Construction in Freiburg.
· Algorithmic Temperature Control systems use machine learning, fuzzy logic, or predictive models to regulate indoor climate dynamically—responding to real-time data, occupant behaviour, and even weather forecasts. They excel in maintaining microclimates with minimal energy waste.
AI-Based Thermal Comfort Models go beyond temperature—they factor in humidity, air velocity, and even occupant preferences to optimise comfort. Thermal comfort is like that 'feels like' measure on the weather App. It isn't always about what the thermometer says. It can be very subjective.
- Tokyo is trialling
misting zones in public parks. These come on automatically when the temperature exceeds 27.5o C.
Tokyo is also encouraging early morning and after dark tourism as well as promoting nature and its green spaces as a way of cooling off.
Cooling Centres
Although I have previously mentioned cool rooms for those without air -conditioning and those who are out and about, these are now becoming more than just emergency shelters. They are turning into places of community connection which incorporate amenities such as libraries, cultural spaces and community kitchens. Some also come with misting fans, hydration stations, and mental health support.
London, Toronto and Paris have all established extensive networks of cooling centres -usually in public buildings, and accessible online via interactive maps.
The ones in Paris are somewhat different. Its 800 ‘cool air islands’ include many more green spaces such as parks, woods and even cemeteries, all with colour coded levels of ‘coolness.’ There are places with mist -sprays, water games and places to swim.
· During France's recent record-breaking heatwaves in 2025, some prefectures have allowed swimming in rivers and lakes even if quality left something to be desired. Now Berliners want to do the same.
· In the USA, Arizona is supporting a school-based network in neighbourhoods especially affected by extreme heat. These offer daytime respite and usually provide air -conditioning, water, seating and shade. (Copilot). This sounds like an excellent idea during summer breaks.
· Tokyo has ‘heat stroke prevention centres’ usually based in places such as community centres and libraries.
· In India the City of Ahmedabad is providing cooling centres in malls, public buildings and temples, but rather than using an online map, it uses text alerts, regular media channels and WhatsApp mobile messages. The primary aim is to provide shaded areas for outdoor workers, poor communities, and other vulnerable populations.
- Athens has a dedicated app to enable people to navigate a cool route to the city. It has also extended the hours of its cooling centres to 20.00 hours.
Cooling Hubs
Community Cooling Hubs (CCHs) are an innovative approach being demonstrated in rural Rwanda and Kenya and one which is especially suited to poorer communities which do not have access to air -conditioning and may not even have electricity.
They are a centralised cooling facility which not only provides relief from extreme heat, but also refrigeration for produce and domestic food supplies, vaccine storage and the like, as well as a cool location for educational and medical services. Furthermore, they can be built to be sustainable and at low environmental and financial cost. This may be an option for poor urban communities too.
Raising Public Awareness
· Australian NGO, “Sweltering Cities" regards heatwaves as our deadliest environmental disaster. Begun in 2020, in response to heatwave conditions, it advocates for shaded bus stops, heatwave safe homes for renters, cool plans for hot suburbs and more. It also has lots of tips on its pages about heatwave safety.
· The Australian Red Cross held its first ever Extreme Heat Awareness Day in conjunction with Sweltering Cities on February 5 this year with posters, quizzes, and preparedness tips.
- PrepareCenter led by the Red Cross Red Crescent Climate Centre held it's 4th Heat Action Day on June 2. This is an international campaign with toolkits and community events, workshops, and art contests held in over 300 locations worldwide.
- The World Health Organisation ‘s “Beat the Heat Initiative” – Is about educating yourself, workers and others about dealing with extreme heat.
Why we shouldn't rely on Air Conditioning
If you are thinking this is all too hard, why don’t we just turn up the air-conditioning, air -conditioning only adds to the overall problem – cooling inside, but more heat being funnelled outside, even more so if the power for them isn’t coming from renewables. Mass demand exceeding supply during a heatwave can also lead to widespread blackouts, even when solar energy is at its peak.
On two of the hottest days in early 2025, over 150,000 air conditioners in Queensland had to be remotely powered down to 50% capacity using a system called PeakSmart. This demand management tool was deployed to prevent grid collapse, as simultaneous cooling demand overwhelmed supply.
Next Up: 2b Heat - Protecting Outdoor Workers and Others in a Hotter Climate
2c Heat - Fighting Fires in the Pyrocene
Thanks to Microsoft Copilot for the illustration and all the links. I am well aware that I stand on the shoulders of giants -from those who have designed and trained the models, the programmers and systems designers and engineers who came before, as well all those people who have willingly or unwillingly contributed to the knowledge base and images upon which it relies. And let's not forget those who gave us the internet and the communications that make it possible, not to mention the people who assembled all those tiny parts before we got robots to do it. Thanks to you all too.
You can tell that the rest was done by a human. I'm still trying to fix those bullet points and can't get the margins to line up, but this enough for tonight and I didn't want you to have to wait any longer for this post.
Comments