For 2010, emissions are likely to resume their upward track, scaling a new peak, they warned on Sunday.
Annual emissions of carbon dioxide (CO2) from the burning of oil, gas and coal were 30.8 billion tonnes, a retreat of only 1.3 per cent in 2009 compared with 2008, a record year, they said in a letter to the journal Nature Geoscience.
The global decrease was less than half that had been expected, because emerging giant economies were unaffected by the downturn that hit many large industrialised nations.
In addition, they burned more coal, the biggest source of fossil-fuel carbon, while their economies struggled with a higher “carbon intensity”, a measure of fuel-efficiency.
Emissions of fossil-fuel gases in 2009 fell by 11.8 per cent in Japan, by 6.9 per cent in the United States, by 8.6 per cent in Britain, by seven per cent in Germany and by 8.4 per cent in Russia, the paper said.
In contrast, they rose by eight per cent in China, by 6.2 per cent in India and 1.4 per cent in South Korea.
As a result, China strengthened its unenvied position as the world’s No 1 emitter of fossil-fuel CO2, accounting for a whopping 24 per cent of the total.
The United States remained second, with 17 per cent.
Fossil fuels account for 88 per cent of all emissions from CO2, the principal “greenhouse gas” blamed for trapping the Sun’s rays and causing global warming, the driver of potentially catastrophic changes to Earth’s climate system.
Concentrations of CO2 in the atmosphere from all sources reached a record high of 387 parts per million (ppm), the study said.
“The 2009 drop in C02 emissions is less than half that anticipated a year ago,” said Pierre Friedlingstein, a professor at the University of Exeter in Britain, which led the study.
“This is because the drop in world gross domestic product was less than anticipated and the carbon intensity of world GDP, which is the amount of CO2 released per unit of GDP, improved by only 0.7 per cent in 2009 — well below its long-term average of 1.7 per cent.”
There was one spot of good news, though.
CO2 emissions from deforestation fell sharply, thanks to slowing forest loss in tropical countries and to a pickup in reforestation in Europe, temperate zones of Asia and North America.
In the 1990s, emissions from deforestation were more than 25 per cent of the global total. In 2009, though, they were only 12 per cent.
Despite this, the news for 2010 is likely to be grim.
CO2 from fossil fuels is likely to increase by more than three per cent if predictions of 4.8 per cent in world economic growth are right. This means the fall seen in 2009 will have been just a blip as carbon pollution resumes its fast upward track.
The report by the Global Carbon Project, linking leading climate scientists around the world, was published in the run-up to the November 29-December 10 UN climate talks in Cancun, Mexico.
The conference aims at breaking the deadlock on reducing greenhouse-gas emissions and channelling aid to poor, vulnerable countries after the near-fiasco at the world climate summit in Copenhagen.