The Know Daily - Monday 8 June 2026

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A global “Sidewalk Joy” movement is turning ordinary streets into unexpected bursts of creativity, with more than 1,700 joyful spots now mapped around the world. Started by an American artist, the project encourages people to brighten their neighbourhoods with everything from miniature art museums and puzzle libraries to wishing trees and toy swaps. Honestly, it’s hard not to love the idea of a global map dedicated entirely to small pockets of happiness! 

🏙️ Urban heat islands

As summers get hotter, scientists and city planners are paying more attention to why cities often feel warmer than their surroundings – and what can be done to cool them down.

What is an urban heat island?
It’s when buildings, roads and pavements absorb heat from the sun during the day and slowly release it back into the air, particularly after sunset. Because cities tend to have less greenery and more heat-trapping surfaces (like glass, concrete and asphalt), they often stay significantly warmer for longer. The result is that cities effectively become "islands" of heat.

In the UK, city centres can remain 3-4°C warmer than surrounding rural areas overnight, with temperature differences occasionally reaching 8°C in larger cities like London. But studies by the European Commission's Joint Research Centre found some cities have surface temperatures as much as 10-15°C hotter during summer.

Why does it matter?
Urban heat islands aren't new, but they're becoming more noticeable as the climate warms. Heatwaves that might once have been uncomfortable can become more intense in cities because the built environment adds an extra layer of heat. Scientists expect the heat island effect to strengthen as cities continue to grow and become more densely populated.

That matters for people's health, particularly older adults, young children and those with existing health conditions. Hotter cities can also increase energy demand as more people turn on fans and air conditioning, leading to broader environmental impacts and stress on urban wildlife.

What’s being done about it?
One of the most popular solutions is planting more trees and vegetation to provide shade, reduce the amount of heat absorbed by surfaces and release moisture into the air. And it can be very effective – in Melbourne, street trees reduced the heat experienced by pedestrians by more than 18°C compared with open streets.

Other approaches include creating green roofs covered in plants, painting roofs with reflective coatings to reduce heat absorption, using lighter-coloured pavements that stay cooler in the sun, and redesigning neighbourhoods to allow more air to circulate.

What can you do in a hot city?
While urban planning is a long-term fix, there are a few things you can do to stay cooler during summer. If you're walking or commuting, stick to shaded routes where possible as parks and tree-lined streets can feel noticeably cooler than surrounding roads. At home or in the office, keep blinds closed during the hottest part of the day, stay hydrated and take advantage of cooler evening air by opening windows when temperatures drop. If you have outdoor space, adding plants can provide a small local cooling effect too. It won't solve the urban heat island problem on its own, but on a sweltering day, every degree counts.

💰 Money Monday: A proposed “Oyster card for the North” could save commuters up to £276 a year, according to new research.

• The bigger story: The idea is simple – one tap-in, tap-out system across northern transport networks, with fares automatically capped at the cheapest available rate. The proposal would link systems including Greater Manchester’s Bee Network and West Yorkshire’s planned Weaver Network, removing the need to navigate different tickets and fare structures when travelling between regions. Researchers estimate the scheme could generate up to £2.7bn for the economy over five years by making it easier for people to travel for work, training and leisure.

🗳️ Prime Minister Keir Starmer has assured supporters that he will stand in any Labour leadership contest that’s triggered.

👩‍⚕️ $215 million has been donated by Melinda French Gates to improve women’s reproductive and midlife health.

🛳️ Archaeologists are studying a shipwreck so well preserved it still contains stacks of pristine porcelain and luxury goods nearly 300 years later.

🧀 An ancient trick has been used by scientists to successfully turn food waste into edible cheese. 

🖼️ The world’s best cities for museums and galleries have been revealed… just in time for some cultural inspo ahead of summer holidays!

🔗 Last week’s most clicked: Vote for your fave wildlife to appear on new British banknotes, a new app to remember what our doctors tell us & a map of all the sleeper trains in Europe. 

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Trivia answer: B) They travelled more than 15,000 km across the Pacific  – one of the longest mammal migrations ever recorded.

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