London can expect more extreme weather events over the next few years with the number of "uncomfortable" days of heatwave likely to double.The rise of intensely sunny days should prompt architects and planners to start including "cool culture" design features to make life more bearable for overheated residents and workers, say experts.
There is currently an average of 18 days a year of heatwave but there could be up to 51 days in the 2020s and most likely 33 days according to current predictions. The number of typically warm days would also increase in tandem with extreme events.
Dr Matt Huddleston, principal consultant on climate change at the Met Office, said: "London's temperatures are two degrees warmer than 30 or 40 years ago. On top of that we have an 'urban heat island' that's twice the level of 40 years ago."
London can be as much as 9C warmer than the neighbouring countryside.
Climate change expert Prof Martin Parry, of Imperial College London, said he had been pushing for adaptations to building regulations for more than 20 years.
He said: "We don't have a national set of building codes that have been updated for the observed warming climate. We've got building regulations that are based on data probably from '30s and '40s."
He suggested "a package of planning measures to make people feel more comfortable".
These could include: natural heat dissipation; designing for open spaces, greenery and shading; green roofs; and a cafe culture.
He told the London Assembly environment committee that uncontrolled air conditioning could add up to a third to the rising ambient temperature. The impact would be to pump more carbon into the atmosphere, adding to the global problem.
Intense rainfall, especially in the summer, was another worrying impact of climate change but he accepted planners couldn't endlessly adapt for every possible outcome.
"Where would one put one's money?" said Prof Parry. "I guess that it would be preparations for heatwaves given the role of heat islands and the debilitating effect of uncomfortable levels of heat in certain parts of London and on public transport."
