Prof Jones has looked at measures to mitigate the effects of heat in places such as Hong Kong, Singapore and Miami.
In Singapore, where temperatures in the city centre can be a 7C (45F) hotter than outside it, authorities are incorporating open spaces around buildings and lighter colours on walls and roofs, as well as increasing the amount of greenery in the city.
Nearly half of Singapore is now green space and more than 500,000 trees have been planted since 2020 – with a target of one million by 2030.
Varying building heights and even making the corners of buildings curved are all effective ways to reduce temperatures without the need for air conditioning.
But as trees are inexpensive and take time to reach full maturity, Prof Jones said UK cities should start planting as many as possible now.
The Welsh government said: “Trees on streets and in parks play a vital role in helping us adapt to the effects of a changing climate and in supporting wildlife in urban areas.
“Our Woodlands for Wales strategy, external explains how we want trees to be used more creatively in green infrastructure and around urban areas to provide people with better quality, easily accessible green space.”