During his "My Take," Thursday, "Varney & Co." host Stuart Varney reacted to U.K. Prime Minister Rishi Sunak announcing a shift in Britain's climate agenda by delaying its ban on the sale of gas-powered cars. Varney argues a similar change is unlikely to take place in the U.S. because Democrats and "the Greens" won't let Biden reverse policy. STUART VARNEY: The alarm bells are ringing in "green circles" all over the world. Britain has reversed …