The Montreal talks follow on from the Kyoto Protocol, which was signed in 1997 and called for 30% cuts by 2020.
Mr Meacher earlier told BBC Radio 4's Today programme further reductions in greenhouse gas emissions - widely thought to contribute to rising temperatures - are vital.
"We need now to aim for more. That is what climate change is telling us. We need to say minus 25% by 2025."
Does he mean minus 25% again, after the 30%? Or is there some reason that in this particular calculation, the numbers run the opposite direction of what I expect? Mr Meacher seems a capable enough man to know that 25 is less than 30, so I don't honestly think he's got it wrong - I just don't understand how that works.
Ye great numbers of environmental statisticians among my readership, what does this mean?