I will confess that my sleepy heart sang when I read the news that the National Trust would be introducing siestas for its staff. My people, I thought. A French friend of mine notes that Britain is one of the only countries where it is acceptable to withdraw socially for “a lie down” simply because you’re tired of company, but the working day, in its punishing Protestantism, is a different matter. Part of my dislike of offices, aside from them being the enemy of creativity for anyone who needs peace in which to work, is that there are never enough places to nap.

Naturally, I’ll be met with accusations of laziness for even saying this. We are in the middle of a tedious and strung-out debate about work and flexibility, and a disturbing number of people seem to have Stockholm syndrome. Only yesterday I read a piece in Fortune magazine entitled: “Want to work 9-to-5? Good luck building a career”. The concept of work/life balance has “become emblematic of a woke work environment – one that acknowledges that an employee base is composed of actual humans, often with spouses, children and outside interests”, said the writer. God forbid!

Of course, a switch to Mediterranean working hours actually extends the working day in one sense, with workers starting earlier and finishing later. Whether you consider this lazy or not is somewhat beside the point: the National Trust cites the fact that temperatures are becoming so extreme that working through the heat of the day is often too challenging. Some of its staff, particularly those working outdoors, are already starting earlier and taking a longer break to avoid the hottest parts of the afternoon. Could this be the future for all of us?

A 2019 study claimed that in 30 years’ time, London could have a climate similar to that of Barcelona. It isn’t just the increasingly intense heat that may make parts of the south inhospitable, it’s also extreme flooding of the sort we have already seen this summer. A study in 2020 estimated that within 50 years, a billion people will live in insufferable heat. We will probably see waves of migration – away from coastal regions and expanding deserts – on an unprecedented, global scale.

Setting aside the sheer horror of the crisis we face for just a moment, and assuming some semblance of a capitalist work system remains, I do find myself wondering what the implications of a warmer climate are for our day-to-day lives. A longer break in the middle of the day isn’t only used for sleeping; workers can return home, prepare food, spend more time with their families. People’s diets could improve – less heavy, more Mediterranean. The hastily grabbed supermarket sandwich consumed al desko – already ailing – may just die a death. It could be transformative for people’s sex lives, too. And their stress levels: anyone who has visited a hot country knows you have to adapt your pace of life. Everything becomes more leisurely, including even the speed at which you walk. Shops and businesses close at lunchtime, forcing you to relax.

Covid has already seen the UK and US become more alfresco societies, as ventilation became a criterion for socialising; a warmer climate would intensify the trend. In terms of urban planning, the way outdoor space is designed would need to change. We’d need more trees, more shaded spaces to keep people cool (the National Trust is already doing this). Architecture would hopefully adapt, too, with more of those hybrid indoor-outdoor spaces (courtyards, verandas, colonnades) that we are used to seeing in hotter countries. Homes will need to be adapted to try to combat the risk of overheating and related deaths.

Research shows that fewer than half of European cities have climate adaptation plans in place, and worldwide only 18% of cities with populations of more than 1 million do. There are exciting projects and policies happening, but more work needs to be done on how our lives and environments will need to change in the face of global heating.

Of course, none of it matters if we are all under water, in which case whether to siesta or not will be the least of our worries.

• Rhiannon Lucy Cosslett is a Guardian columnist and author