With barely five months until make-or-break climate talks in Copenhagen, where the world will attempt to agree a new treaty on climate change, how significant are the G8 announcements?
Headline writers have drooled over the "historic" agreement to limit the global temperature rise to 2C, to cut world emissions 50% by 2050, and for the G8 to reduce its own pollution 80% by that date.
The numbers may sound reassuringly low, large and colossal, respectively, but there is significant political sleight of hand at play here. Does the 50% cut by 2050 sound familiar? The same countries agreed at the 2007 G8 summit to "seriously consider" such a target. By 2008, they had moved to "consider and adopt" it. Come 2009, well, we can consider it well and truly adopted.
Implicit in such a 50% reduction for the world, is a demand that developed countries cut their share by 80%. That is not ambition, that is mathematics. The baseline usually used is 1990, when the carbon pollution from rich countries dwarfed that from their poorer colleagues. To reach the average 50% decline, the bigger polluters need to make bigger cuts. Period. Announcing both as separate targets is like advertising a right sock free with every left sock bought.
Which brings us to the 2C ambition. Europe adopted such a target in 1996, so the UK, France, Germany and Italy are saying nothing new. Of the rest, Japan and Canada are hopelessly over their targets set under the Kyoto protocol, while the collapse of the Soviet Union means that Russia's emissions have dipped so low since 1990 that it can afford to increase them by a third between now and 2020 and still boast of a 10% cut overall.
For the US to agree to the 2C target looks a sizeable step when compared with the recent reign of George Bush, but not if you go back further to 1992, when the US joined other countries in signing the UN Framework Convention on Climate Change. The stated objective of the convention is to avoid "dangerous anthropogenic interference" with the climate. The EU and others put that dangerous threshold at 2C. Nearly two decades later, the US is merely starting to honour its promise.
The problem for the G8 is that the rich countries no longer have the lion's share of emissions, and that any action they take is pointless without the co-operation of developing nations such as China and India. Officials may have been briefing this week that the rich and poor world were poised to unite in a global pledge, but that is more spin.
The accompanying statement from President Obama's Major Economies Forum, which unlike the G8, does include China, India and other developing nations, talks only of "substantially reducing" emissions by 2050.
A commitment to cut emissions, by any amount and by any date, is the developing world's most valuable trump card, and not one that it will surrender for a handshake and a photo opportunity. In exchange it wants hard cash, and a better indication of what the US and others are willing to do by 2020, not by 2050. That will only come across the negotiating table in Copenhagen.