Global carbon dioxide emissions from fossil fuels and industry have renewed their climb after a three-year pause, driven higher by quickening economic growth and the failure to find alternatives particularly to oil, international researchers say.
Carbon emissions will rise 2 per cent in 2017 to almost 37 billion tonnes as the world economy heads for 3.6 per cent annual growth. Total emissions, including from land clearing, push that tally to 41 billion tonnes.
A slightly faster pace of GDP expansion in 2018 will also send emissions from industry and fossil fuel combustion higher for at least another year, according to the 2017 Global Carbon Budget.
"This year's carbon budget news is a step back for humankind," said Amy Luers, executive director of Future Earth, a sponsor of the report.
China accounts for much of this year's forecast increase, with CO2 emissions in the world's biggest polluter on track to rise 3.5 per cent to 10.5 billion tonnes, after roughly flatlining in 2016. Contributing is a 6 per cent jump in coal-fired electricity generation in the first nine months of 2017 versus a year earlier.
While emissions from the US and the European Union - the next largest blocs - continue to decline, they are shrinking at a slower pace than the average for the past decade.
(See chart below of annual emissions as measured in giga or billion tonnes of CO2 per year.)
The updated emissions trajectory comes as delegates from almost 200 countries meet in the German city of Bonn to discuss progress on the Paris climate accord agreed two years earlier.
Pep Canadell, CSIRO researcher and one of the report's authors, said the results were "disappointing", with any uptick in emissions making it harder to reach the main Paris goal of keeping global warming to between 1.5 and 2 degrees above pre-industrial era levels.
"It's hard to comprehend how we're going to reach 2-3 per cent a year emissions reductions globally," Dr Canadell said. "For every year we're delaying these peak emissions, there's a penalty of a much higher emissions reduction level that's required."
He pointed to the steady rise of oil demand over the past three decades, providing fuel for transport but also a range of products from plastics and solvents.
Smoke spews from the sprawling complex that is a part of the Jiujiang steel and rolling mills in Qianan in northern China's Hebei province. Photo: AP
To keep promises the modest decline of global coal combustion in recent years would have to accelerate rapidly if replacements for other fossil fuels aren't found.
"Fundamentally, if we don't see clearer alternatives to replacing oil and gas in the next one or two decades, coal has to come down dramatically," Dr Canadell said.
While India offered a relatively positive change - annual emissions growth eased from 6 per cent on average over the past decade to 2 per cent in 2017 - the slowdown is expected to be temporary, the research by 76 scientists in 15 nations found.
The abrupt closure in March of Victoria's Hazelwood brown-coal-fired power station brought a 4 per cent cut of power-sector emissions in the months since, compared with a year ago, said Frank Jotzo, a professor at the Australian National University.
Lower emissions gas and black coal are filling most of the gap, although renewable energy is also helping.
Rising emissions from transport, industry and land clearing for agriculture will likely leave Australia's emissions close to previous years' totals.
India has been suffering severe pollution in parts of the north. Photo: AP
To meet the nation's Paris climate pledges, they need to fall about 1.5-1.7 per cent a year, or about 8-9 million tonnes of CO2, Professor Jotzo said.
Falling costs for solar and wind energy are helping to drive a surge in renewables. Worldwide growth has averaged 14.4 per cent annually over the past five years and more than half of new electricity generation capacity is clean energy.
In Australia however the Turnbull government's proposed National Energy Guarantee is intended to keep ageing coal-fired plants such as AGL's Liddell power station operating.
New renewable energy is not increasing fast enough to displace existing fossil fuel plants. Photo: Supplied
"The debate is very much around how [closure] could be avoided," Professor Jotzo said. "That quite directly contradicts the objective of reducing national emissions."
The research is published Monday in Nature Climate Change and Environment Research Letters.