May 29, 2007
Actual carbon emissions outpace scenarios
Carbon dioxide emissions from fossil-fuel burning and industrial processes accelerated sharply at the start of the millennium. According to a recent study, between 1990 and 1999 emissions rose by 1.1% a year, while from 2000 to 2004 they increased by more than 3% a year. The post-2000 growth rate exceeds the most fossil-fuel-dependent A1F1 emissions scenario developed by the Intergovernmental Panel on Climate Change (IPCC) in the late 1990s.
"The ultimate judge of our efforts to reduce carbon dioxide emissions is the global atmosphere, not any set of greenhouse accounts," Michael Raupach, co-chair of the Global Carbon Project at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) told environmentalresearchweb. "At present, CSIRO and other measurements show that atmospheric carbon dioxide concentrations are rising progressively faster each year – so the judgement of the atmosphere is that global efforts to reduce emissions have so far been spectacularly unsuccessful. The atmosphere is telling us that we need to do better."
The figures come from a study by researchers at Australia's Commonwealth Scientific and Industrial Research Organization; Oak Ridge National Laboratory, US; Climate and Environment Sciences Laboratory, France; University of East Anglia, UK; Kiel Institute for the World Economy, Germany; and Carnegie Institution of Washington, US.
According to Raupach, there are two separate causes for the acceleration. "The first is the 'exploding' economies of the developing world, led by China where emissions are growing at 11% per year," he said. "The second cause is in the developed economies, where there has been a slowdown in the rate of improvement of the carbon intensity of energy – the amount of fossil carbon burned per unit of energy generated – and the carbon intensity of the economy – the amount of fossil carbon burned per dollar of wealth created."
Until recently, better efficiencies in developed countries were causing the carbon intensity of both energy and the economy to decrease over time. But the improvements have stalled in many regions. "It is as if improvements to existing technologies are saturating or running down, and the next round of improvements needs new energy technologies – like renewables, clean coal – and ways of doing things, such as more determined energy-conservation measures," said Raupach.
All of the IPCC emission scenarios for the next century that were published in 2000 assume that the carbon intensity of energy and the energy intensity of gross domestic product (GDP) will decrease continuously. But without these decreases, emissions up to 2100 could be several times greater than the scenarios currently predict.
Raupach says that concern about emissions from the rapidly developing economies is warranted, and steps to reduce this emissions acceleration are desperately needed. "However, we equally desperately need to attend to the drivers of emissions in the developed economies, by vastly speeding up improvements (reductions) in the carbon intensity of energy and the carbon intensity of the economy," he said. "It's important to remember that the developed economies, with 20% of the global population, still emit nearly 60% of all the fossil-fuel carbon dioxide released each year."
The researchers looked at carbon dioxide emissions from seven sources: national combustion of solid, liquid and gaseous fuels; flaring of gas from wells and by industry; cement production; oxidation of nonfuel hydrocarbons; and fuel used for shipping and air transport (which is often not included in national figures as it comes from "international bunkers").
Now Raupach and colleagues plan to look at the relationship of emissions to the global carbon dioxide budget, and at continued increases in emissions as a source of Earth system vulnerability. The team will also look at future regional development trajectories, their emissions implications, and equity implications.
The researchers reported their work in PNAS.
About the author
Liz Kalaugher is editor of environmentalresearchweb.