It seems that Wikipedia is of that opinion indeed. From: https://en.wikipedia.org/wiki/William_Happer:
In 2018, Happer, who is not a climate scientist and who rejects the scientific consensus on climate change, joined the National Security Council of the Trump Administration to counter evidence linking carbon dioxide emissions to global warming.
Happer disagrees with the scientific consensus on climate change, stating that "Some small fraction of the 1 °C warming during the past two centuries must have been due to increasing CO2, which is indeed a greenhouse gas", but argues that "most of the warming has probably been due to natural causes." Michael Oppenheimer said that Happer’s claims are "simply not true" and that the preponderance of evidence and majority of expert opinion points to a strong anthropogenic influence on rising global temperatures. Climate Science Watch published a point-by-point rebuttal to one of Happer’s articles. A petition that he coauthored to change the official position of the American Physical Society to a version that raised doubts about global warming was overwhelmingly rejected by the APS Council. Happer has no formal training as a climate scientist.
In May 2013, Happer and Harrison Schmitt published an op-ed in the Wall Street Journal, "In Defense of Carbon Dioxide," in which they termed elevated atmospheric CO2 "a boon to plant life." It was described by Ryan Chittum, a former Wall Street Journal reporter, in the Columbia Journalism Review as "shameful, even for the dismal standards" of the Wall Street Journal editorial page.
As to the article from "The best schools .org", it is disingenuous. Which brings us back to the discussion about "authoritative figures" started by Tom: Harper was chosen because he is perceived as an authoritative figure" by the public, because of is experience as a physicist, but his opinions on climate change make little scientific sense, as the article you cited illustrates. Chances are, however, that readers attach authority to the writer and forget to exercise their common sense when reading the article.
So you are saying that a reporter from the Wall Street Journal has more credibility than a world renowned scientist? Ryan Chittum is not a card carrying card member of the climate brigade either? Yet you reference his writing as if he were a scientific authoritative figure. Common sense should tell anyone that a warmer climate has more benefits than a colder climate especially at 200-ppm or 100-ppm C02. Would Michael Oppenheimer and Ryan Chittum have jobs if they did not tow the line with consensus and end up driving for Uber?