A stunning new study in the Proceedings of the National Academy of Sciences (PNAS) finds that the growth rate of CO2 emissions has tripled in recent years:
CO2 emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1 percent/year for 1990-1999 to >3 percent/year for 2000-2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s.
That’s right. CO2 emissions are rising faster than in the most pessimistic U.N. scenario. So much for all those ostriches and global warming delayers who say that economic growth is the key to solving global warming or that the U.N. scenarios are too extreme.
The study finds that “global emissions growth since 2000 was driven by a cessation or reversal of earlier declining trends in the energy intensity of gross domestic product (energy/GDP) and the carbon intensity of energy (emissions/energy), coupled with continuing increases in population and per-capita GDP.” Sadly, “no region is decarbonizing its energy supply.” In short, coal remains king.
The study also makes an important point about equity in global climate negotiations:
Together, the developing and least-developed economies (forming 80 percent of the world’s population) accounted for 73 percent of global emissions growth in 2004 but only 41 percent of global emissions and only 23 percent of global cumulative emissions since the mid-18th century.
Cumulative emissions are what have driven the sharp rise in CO2 concentrations. So even as China is poised to become the world’s biggest emitter of carbon dioxide on annual basis, it will be many decades before the poorer countries surpass the richer countries’ total emissions since the dawn of the industrial age. That’s a key reason the rich countries agreed to go first in reducing emissions at Kyoto — that and the fact that the rich countries got rich by polluting and have an obligation to spend some of that money reducing pollution and helping poorer countries adopt cleaner technologies.
Finally, the study makes a point that has been a recurring theme of mine:
… the fraction of total anthropogenic [human-made] CO2 emissions remaining in the atmosphere … has increased slowly with time … implying a slight weakening of sinks relative to emissions.
The carbon sinks — the oceans, forests, soils, and tundra — are saturating, even as the carbon sources — the burning of fossil fuels plus deforestation — are growing.
Kudos to PNAS editors for making this an open access article.