Good news! Emissions of carbon dioxide, a key factor in global warming, are way down in one of the world's two biggest polluters, the United States.

Bad news? The 7.7% reduction since 2006 is in part because the US is burning less coal, and more shale gas – obtained by the controversial and highly-polluting hydraulic fracturing process.

If it's not one thing…

Actually, the really bad news is that global greenhouse gas emissions are growing so fast that within the next few years we may miss the chance to head off long-term, catastrophic climate change. The International Energy Agency's new report on 2011 greenhouse gas output shows the world's economies are increasingly unlikely to meet the target of limiting global temperature rise to 2 degrees centigrade – the threshold beyond which climate change will become unmanageable.

Americans can take some solace from the fact that the IEA report shows US output of CO2 dropped 1.7% last year. In fact, it has dropped a total of 7.7% since 2006. That's better than any other country or region.

...it's another

Some of that reduction comes from improved vehicle efficiency; some of it is a by-product of a slumping economy. But the IEA says another big factor was a massive shift from generating electricity by burning coal to using relatively clean-burning natural gas. And that's down to the explosive growth of hydraulic fracturing, or fracking, which opens up vast deposits of previously inaccessible gas.

Fracking is very popular with energy companies, which use it to extract cheap and abundant fossil fuel. But it's extremely unpopular with nearby residents, who occasionally find they can set fire to their tap water.

Double bind

As the rate of resource consumption continues to grow, thanks to a growing global population and rising standards of living in the developing world, this sort of environmental double bind is likely to become more common.

Finding a just and sustainable path forward is rarely simple or straightforward. Of course, in this case, a possible alternative would be meaningful investment in renewable energy sources – so that we wouldn't be forced to choose between polluted skies and poisonous water.

Take action: Pressure group petitions against fracking to back in the United States, and in the United Kingdom.