Emissions of planet-warming carbon dioxide stayed level in 2015 at 36.3 billion tonnes (GtCO2) and were projected to rise "only slightly", by 0.2 per cent in 2016, according to the annual Global Carbon Budget report compiled by teams of scientists from around the world. "This third year of almost no growth in emissions is unprecedented at a time of strong economic growth," said research leader Corinne Le Quere of the University of East Anglia.

Driven largely by reduced coal use in China, this was a "clear and unprecedented break" with the preceding decade's fast emissions growth, at a rate of some 2.3 per cent per year from 2004 to 2013, before dipping to 0.7 per cent in 2014. "This is a great help for tackling climate change but it is not enough," said Le Quere.

For the world's nations to make true on the global pact to limit average global warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels, emissions must do more than level off, the study found. A decrease of 0.9 per cent per year was needed to 2030. The concentration of greenhouse gases in the atmosphere has continued to grow, the report warned, hitting a record level of 23 GtCO2 last year that looked set to reach 25 GtCO2

in 2016.

The analysis was published in the journal Earth System Science Data, to coincide with the UN climate conference in Morocco. Climate envoys are gathered in Marrakesh to put plans in place to execute the so-called Paris Agreement concluded in the French capital a year ago.

It envisions a dramatic reduction in greenhouse gas-producing coal, oil and gas use for energy. The new report said humanity has emitted 2,075 GtCO2

since 1870 -- adding 40 GtCO2 in 2016 alone. "We have already used more than two thirds of the emissions quota to keep climate change well below two

degrees," it warned. "The remaining quota would be used up in less than 30 years at the current emissions level."