In the U.K., Germany and France, leaders walk back as their plans’ exorbitant price tag becomes clear.

The biggest, most entertaining and also most telling climb-downs are happening in the U.K. Prime Minister Boris Johnson in October unveiled an ambitious policy program to get Britain to net-zero carbon-dioxide emissions by 2050. It was Mr. Johnson’s public-relations coup ahead of the COP26 global climate conference he hosted in Glasgow. It also was unusual in its honesty about what such environmental ambitions will cost individual households and businesses—a point politicians usually avoid for all the obvious reasons. Sure enough, the backtracks and U-turns began before that document was written. The most controversial component of Mr. Johnson’s net-zero boondoggle concerns an attempt to steer households away from the gas boilers on which 86% of them rely for hot water and central heating.

The net-zero gimmick will be with us for a long while yet, alas. The green true believers (or are they bitter clingers?) are busy devising rear-guard actions by which to insulate environmentalism from real-world political pressures, not least by enlisting gullible or cynical titans of finance to do via pension-fund investment allocations what can’t be done honestly via legislation. The political class remains rhetorically wedded to its earlier foolhardy promises, and the media is too enamored of reality-detached activists such as Ms. Thunberg. All the smarter then for politicians to resolve to discuss the matter as little as possible in the year ahead. As starving the atmosphere of carbon dioxide becomes a political liability, starving the issue of political oxygen will become the electoral tactic of choice.

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