I just can't agree that The Economist did anything "irresponsible" by publishing their article about a possible lower climate sensitivity in (leaked) draft reports of the IPCC 5AR.
The Economist's allegiance is to journalism and their readers, not to the IPCC. If indeed the IPCC is near concluding that equilibirum climate sensitivity -- or the transient climate response, the warming at the time of doubled atmospheric -- is lower than thought, as the recent paper by Otto et al suggested (for TCR, not ECS), that is indeed a huge deal, and no one can be blamed for reading every tea leaf they can find. The Economist gave plenty of appropriate caveats that put the information in the appropriate context.
It's a big deal because if the world has an extra 15 or 30 years to reach a given level of warming, then it has more time to develop/perfect alternative energy producing technologies -- and they are the real solution to the carbon problem, because CO2 emissions cannot be cut nearly enough without them.
Given the cost curve it's been on, large-scale solar energy could well be much cheaper then, cheaper even than fossil fuels. And it gives more time to buld up wind and nuclear, and maybe even see real advances in wave power or fusion.
The IPCC has made a fetish of secrecy, and I don't think it accomplishes much of anything. Sure, these documents are drafts and they may well change. But their final conclusions aren't holy writ, independent of how they got there. Given the publication of Otto et al and recent thinking like it, a final IPCC 5AR that had identical conclusions to the 4AR wouldn't be believable anyway. So what if the world knows the 5AR is leaning in a slightly different direction? I don't see that that information harms anyone, and it may well be useful for planning (to the extent anyone is planning, anyway).