The Intergovernmental Panel on Climate Change (IPCC) has just presented its summary report on how bad climate change is.
There’s one inconsistency in there which doesn’t undermine for me the key IPCC message — that climate change is a serious threat towards which mankind is hurtling.
But it has left me with a feeling that in one case at least figures have been selected to stress the threat.
The IPCC published on Saturday its handbook version of thousands of pages of climate change research.

On page 4 of this 23-page pocket guide it says that manmade greenhouse gas emissions rose 70% from 1970 to 2004.
But earlier this year, after an enquiry to the IPCC’s lead authors, I found that emissions of all greenhouse gases actually rose 49%. It’s a still a big increase, but not as big.
In its report published on Saturday the IPCC did mention in a footnote that the 70% figure only included greenhouse gases regulated by the Kyoto Protocol.
What it didn’t mention anywhere was that there’s a whole bunch of other greenhouse gases not included in the number, and whose emissions are rapidly falling.
These ozone-depleting gases (ODP gases) are very strong planet-warming gases, as measured in tonnes of carbon dioxide equivalent (CO2e).

Mankind emitted some 5.9 billion tonnes CO2e of such ODP gases into the atmosphere in 1970, but that fell to just 1.5 bln tonnes in 2004, after global efforts to stop a hole in the Earth’s ozone layer from getting any bigger.
So — total global greenhouse gas emissions including ODPs were 51.3 bln tonnes in 2004, up 48.6% on 1970 levels.
But excluding ODPs greenhouse gases increased by 74.0% to 49.8 bln tonnes — the IPCC’s headline number.
The IPCC summary is based on a more detailed report published earlier this year, which mentions that ODP gases have “declined significantly”, but only in passing. A 70% increase is the headline figure there, too.
Like I say, to me this doesn’t colour the IPCC message, but it does comes across as message management.