Dirty habit: Our refining and use of oil is polluting enough, but liquid coal-based substitutes will spell even worse news, researchers say.

Credit: Walter Siegmund

SAN FRANCISCO: The demise of the world's oil supply could worsen future climate change, researchers have warned.

The fear is that upon our exhaustion of oil supplies, liquefied coal will take over as a primary source of fuel, accelerating the rise of global temperatures.

Dirty energy

"There's a focus on coal because it's the most abundant of the three fossil fuels by far... [But it's] also the dirtiest, in the sense that it releases the most greenhouse gas [per] unit of energy delivered," said Pushker Kharecha, a U.S. climate researcher with NASA's Goddard Institute for Space Studies in New York.

Kharecha presented the research findings at a recent meeting of the American Geophysical Union in San Francisco, California.

Replacing oil with coal-derived liquid fuels would increase average global warming by two degrees Celsius by the year 2042, three years sooner than currently expected, said climatologist Ken Caldeira, from the Carnegie Institute for Science in California, who also presented at the meeting.

Cut the coal

"Most future climate change will be a result of burning coal," he said. But replacing declining oil with wind, solar, or nuclear power could push the two-degree increase date back by 11 years, postponing the rise to 2056.

Given the exacerbated global warming effect of coal and coal-derivatives, Kharecha said, and in order to keep the end-of-century atmospheric concentration of carbon dioxide below 350 parts per million, "[all] coal emissions will need to be phased out proactively by 2030."

In the meantime, he said, "unconventional fossil fuels and coal-to-liquids must not be used as large-scale substitutes for oil and gas, unless all emissions are captured and stored."

A timely find

The findings are timely in the face of a predicted peak and subsequent fall-to-zero in oil production, which is sending scientists racing to find alternative fuel sources.

Peak oil could be reached as early as 2010 said Warren Wiscombe, chief scientist for the U.S. Department of Energy's Atmospheric Radiation Measurement Program in New York, who convened yesterday's research panel.

Indeed, the fact that oil prices skyrocketed earlier this year in response to small increases in demand is typical of a commodity at its peak of production, he said.

Responsible action on alternative fuels will need to be taken soon, he said: "We can't just wait for coal to run out."