Andrew Rivken at the New York Times asks, is last year’s drop in U.S. CO2 emissions a blip or a trend?

According to the EIA report U.S. Carbon Dioxide Emissions in 2009: A Retrospective Review, U.S. energy-related carbon dioxide emissions fell by 7.0% last year. The downturn of the economy was responsible for only 2.4% of that reduction.

Population, per capita GDP, energy intensity of the economy, and carbon intensity of the energy supply all contribute to emissions. The only factor that increased in 2009 was population, by 0.9%. The remaining three factors – GDP, energy intensity, and carbon intensity – combined in roughly equal proportions to cause emissions to fall by 7.0%

The financial crisis hit the industrial sector of the economy the hardest, and energy usage by industry correspondingly fell the most – by 9.9%. Output from energy-intensive industries such as primary metals (-33.9%) and nonmetallic minerals (-17.4%) fell much faster than total industrial production, reflecting the fact that we’re outsourcing such production at the same time the service sector has been growing relative to the industrial sector of the U.S. economy. Also, carbon intensity fell due to fuel switching as the price of coal rose 6.8% from 2008 to 2009 while the comparable price of natural gas fell 48% on a per Btu basis.

But where CO₂ emissions occur doesn’t matter to the climate system. The fact that U.S. emissions (or those of other developed nations) are falling doesn’t matter much if those emissions are merely being “exported” elsewhere, primarily to China. And we’re exporting more than industrial production – we’re exporting energy and carbon intensity, as well. The result? China has now overtaken the U.S. to become the world’s biggest emitter of greenhouse gases – and shows no sign of easing off. Coal is the basis of the Chinese economy, fueling over 80% of electricity generation. China’s already-enormous coal consumption – now three times U.S. consumption – is still growing, for example at an astonishing rate 28.1% from first quarter 2009 to first quarter 2010.

Even if falling U.S. emissions are a trend and not just a recession-related blip, falling U.S. emissions mean nothing if global emissions continue to rise.

As Gail the Actuary points out at The Oil Drum, what can’t happen, won’t:

Combine unprecedented consumption levels with furious growth rates and you quickly arrive at absurdities and impossibilities. As in, it won’t happen. The wheels will fall off the wagon first.

Reducing emissions will require reducing the production of “stuff” – and not only in the U.S., but also around the world. Global economic shrinkage is the only way out of our climate predicament, and our current focus on economic growth will have to be replaced by concern with economic justice.

Limited supplies of fossil fuels mean that “economic growth” as we know it will come to an end, sooner or later, whether we like it or not. The question that remains to be answered is, before the wheels do come off, will we have already set the world on a path to unstoppable warming? Or will we accept the inevitable and act in time to save the ecosystem that sustains us?