Modern renewables jointly accounted for less than 1 per cent. The past decade was the first in two centuries with increasing CO, emissions intensities, owing to a “coal revival”, in contrast with the rapid conversion to natural gas in the 1990s. In 2010, the global share of coal reached an estimated 29 per cent, which in relative terms was higher than, and in absolute terms about twice as large as, at the time of the first oil crisis, in 1973.