New York is experiencing a heat wave this week with the mercury indicating temperatures of 38C/100F and lethargy-inducing humidity. The power company ConEd has sent emails and alerts to customers advocating frugal use of air conditioning lest the infrastructure collapses - planetary considerations not being an American instinct. This morning the rooftops of New York hum with air conditioning units battling to win the struggle against the close humidity. Whilst the climate compares to London, there are at least 2-3 months guaranteed of searing heat. And equally, the winters are much harsher with far lower temperatures, often below zero for days at a time.