Amid the furore over snack food and drinks advertising and the industry's alleged role in fuelling Britain's drink problem, this issue has come up on the blind side.
At first, it might be hard to see why it has the potential to do enormous damage to the business. After all, aren't the country's big corporations falling over themselves to trumpet their green credentials? And will they not be expecting their agencies to communicate this commitment?
So, with big business going green and agencies willing to follow, why was Lambert worried enough to warn the Advertising Association: "If you don't get your responses to the climate change challenge right, you may find the barricades will be down and the barbarians flooding over the walls."
Lambert's point - and it's a disturbing one - is that the climate change issue is creating a climate of confusion. And one in which advertising will again become a soft target.
Already the issue is throwing up all kinds of ethical dilemmas. Lambert cites the case of Africa, which must find new ways of trading with the developed world and whose agricultural products are one of its few areas of comparative advantage. Does it make sense to suggest consumers should not buy Kenyan runner beans to cut back on food miles?
Add to that the Government's ambitious (some say unrealistic) targets for reducing carbon emissions and it's easy to imagine circumstances under which politicians go for a quick fix and regulate the messages advertisers can give about the environmental impact of their products.
Now adland faces a challenge - create a voluntary set of guidelines that prevent consumers being left dazed and confused by a wealth of conflicting information.
As Lambert rightly says, failure to do so is likely to lead to regulation of the most restrictive kind.
Stress still permeates adland's top tiers
Tim Lindsay quits Publicis, Michael Wall bows out of Fallon, Steve Harrison resigns from Harrison Troughton Wunderman, Jon Claydon parts company with Claydon Heeley. And all in the same week a Nabs survey claims agency managers are staying in their jobs longer. Interestingly, three of the four say they intend to take a break. Could there be a more powerful reinforcement of the survey's conclusion that industry stress levels remain high?