We were glad to see Oliver Wainwright draw attention to soaring heat in cities – a critical aspect of climate change (Metropolis meltdown: the urgent steps we need to take to cool our sweltering cities, 14 July). Indeed, the Intergovernmental Panel on Climate Change, to whose reports we have both contributed, says the amount of warming in urban areas can sometimes be twice that in surrounding areas because of the way cities are built.
It is heartening to read about some of the innovative ways being found to cool cities, from uncovering buried rivers to painting roofs white. But we noted that all the examples cited come from richer countries in the global north. Most city residents now live in the global south. For the most vulnerable people, who have done the least to cause climate change, adapting to greater heat in the cities where they live is an economic impossibility.
Justice demands that rich countries make a concerted effort to remedy this. Ahead of the next round of climate talks in Egypt, in November, they must commit to increasing climate finance for poorer countries to adapt to climate change. And cities of the global south, which currently receive a tiny proportion of global climate finance, need to be recognised as key theatres within which the battle against climate change will be fought and supported on their journey to becoming resilient.
Dr David Dodman
Dr Aditya V Bahadur
International Institute for Environment and Development
• Most air conditioning units are compression/refrigeration systems and, as Oliver Wainwright says, they are power-hungry and so make global warming worse. But there is an alternative: the evaporative system for cooling air.
The ancient Egyptians knew that wafting a current of air over soaked earthenware pots would lower the temperature of a room. This is how evaporative air conditioning works. We have experienced this system working brilliantly in an Australian heatwave of 40C. It is very simple: a fan blows a current of hot, dry air from outside a building through a box loaded with wood shavings or other material, kept soaked by dripping water. The water evaporates and lowers the temperature of the incoming air. The cooled air is then ducted through the building. Installation and running costs are about a tenth of those of compression systems. Another advantage is that you can leave your windows open.
Ann and Neil Holmes
Bromsgrove, Worcestershire
• With the UK sweltering in extreme heat, we are yet again faced with the reality that our buildings are ill-equipped for the high temperatures that are becoming the norm in summer.
The Climate Change Committee has consistently emphasised the need to address the risk of overheating, noting the serious policy void around retrofitting existing buildings to our future climate. A holistic strategy is urgently needed so that our buildings and their inhabitants can withstand extreme heat.
It is not just a matter of bolting air conditioners on to homes and offices. We need a clear, nationwide strategy that provides incentives and guidance for use of effective heat mitigation techniques in existing buildings and homes – shading, green facades, passive ventilation and use of light-coloured surfaces are just a few measures that can be used to help better equip us as our climate changes.
Sarah Winne
Managing consultant, Ramboll
• Have an opinion on anything you’ve read in the Guardian today? Please email us your letter and it will be considered for publication.
