A new report warns the past four years have been the hottest on record. Urban planning – including more urban greenery – could limit the impact of temperature rises on people’s health, if action is taken now.

Today’s World Meteorological Organization report on the state of the global climate in 2018 says this year is set to be the fourth hottest since records began. Cities – which will be home to 68% of the world’s people by 2050 – are particularly vulnerable to global warming.

Cities can trap heat and become ‘urban heat islands’, and the world’s warming urban areas will put billions of people in danger of heat-stress. Research shows clever city planning can play a crucial role in providing cooling solutions. For example by incorporating light-coloured surfaces, green roofs, as well as better building standards.

Often an overlooked solution, trees and vegetation also play a vital role in regulating temperature and in reducing dangerous heat stress for communities in cities. They provide shade, reflect heat, and help cool the air. Most green space initiatives are not being done explicitly for cooling reasons – they’re designed to mitigate climate change boost people’s wellbeing or tackle air pollution. But they will have an important cooling effect.

Many cities have recognised we’re heading towards a crisis point and are taking action. India declared the issue a national health priority after deadly heatwaves in 2010. Now, in cities like Ahmedabad, heat action plans are in place to provide an early-warning system for heat events as well as advice and support to help people cope with the effects. More support is needed to replicate these successful initiatives elsewhere.

We’ve examined trends in urban heat management as we prepare for the next round of Ashden awards, which celebrate radical innovation in sustainable energy. It is clear that cooling innovators needed more support and investment to develop their ideas.

The WMO report says this year temperature records were broken in cities including Helsinki, Lisbon, Riga and Seoul. Other major heat-related events included droughts in Australia and South America, fatal heatwaves in France and Japan and exceptionally high temperatures in many parts of the Middle East and North Africa.