The clean energy sector can be a capricious beast, all sunny investment one moment and dire outlook the next. There was a reminder for ministers from 23 economies – representing 90 per cent of global renewables and efficiency investment – at the Clean Energy Ministerial in London last week that the sector’s progress to date is still not sufficient to address the climate change challenge. The International Energy Agency warned that under current policies, carbon dioxide emissions will nearly double by 2050. “This would likely boost global temperatures by at least six degrees Celsius,” IEA deputy executive director Richard Jones told the conference, an eventuality that “would confront future generations with significant economic, environmental and energy security hardships”. The main outcome of the Ministerial was a raft of initiatives to ramp up energy efficiency, which the IEA said was lagging well behind the deployment of renewable power. Coincidentally, energy efficiency was the only sector in the WilderHill New Energy Global Innovation Index, or NEX, to rise last week, gaining 2.2 per cent. The NEX saw a moderate overall loss, retreating less than 1 per cent over the five days. There were some sunny investment announcements too. Cameron called for the North Sea to become the site of a “second industrial revolution” after announcing that more than 20 companies had signed up to a vision for it to become a hub for offshore wind and carbon capture and storage – provisionally dubbed Norstec after Europe’s Desertec solar initiative. The prospect of a North Sea supergrid took a further step forward as the grid operators of the UK and Denmark last week launched a feasibility study for a power interconnector.