The props beneath the global oil industry are slowly decaying. The big traded energy companies resemble the telecom giants of the late 1990s, heavily leveraged to a business model already threatened by fast-moving technology.Citigroup warns – or cheerfully acclaims, depending on your point of view – that world energy markets are entering a period of “extreme flux”, with oil caught in triple encirclement by cheap natural gas, much more efficient vehicles and breathtaking advances in solar power as scientists crack the secrets.The combined effect is to “bend” to the curve of global oil use over coming years, eroding the assumptions that have underpinned a threefold rise in Western oil industry debt to $600bn since 2005, much of it to hunt for crude in prohibitively expensive places. Costs rose 9pc in 2012 and 11pc last year, according to the US Energy Department.There may be little point battling icebergs to drill in the Arctic, or in trying to extract oil from the ultra-deepwater fields in the mid-Atlantic, beneath layers of salt, three kilometres into the Earth.The “oil intensity” of global GDP has already halved since 1980s. We are becoming more frugal. Gasoline demand in the OECD rich states has been sliding in absolute terms since 2007, punctuated by ups and downs, but dropping overall from 15.5m barrels a day b/d of crude to 14m b/d.