You probably know that there are several such organizations and scientists, many associated with conservative groups, but by including "professional" and "relevant" your question is biased towards what you consider professional (probably everything that considers global warming 100% man-made).

As Richard Feynman said, science is the belief in the ignorance of experts. When there is a medially and politically forced consensus, it leads to "intellectual tyranny in the name of science".

One single scientist who disagrees with the notion that humans are primarily responsible for climate change would already show that there is no consensus, strictly speaking (Science is about questioning the majority belief). And there are hundreds of very reputable scientists who have disagreed with this over the years, and there is a lifely discussion around this, but those who control the political narratives make it appear there is none. Belief in the majority is not scientific, it's political.