The number of countries in which greenhouse gases has peaked continues to rise, representing a "critical turning point" in the task of curbing climate change, according to a report by the World Resources Institute.

While offering a "silver lining", the rate of national peaking won't be fast enough to prevent emissions reaching a zenith before 2030, assuming countries implement their Paris climate pledges, the Washington D.C.-based think-tank said.

Any backsliding by China and the US, the two biggest emitters accounting for more than a third of the total, would also "significantly compromise" the peak projections, it said.

Most of the early peakers were former Eastern Bloc nations, whose heavy industry sectors hammered in the run-up to the 1991 collapse of the Soviet Union. Germany, France and the United Kingdom, though, had also seen their greenhouse gas pollution top out by that year.