I believe Christie is correct that human activity does/can impact global climate change just by virtue of being part of the Eco system. However, if Christie meant to imply that human activity is in any way a major or even significant contributor/cause to the climate change he was really off base and not even in in the ball park. He needs to clarify his position on this with creditable references. He also should explain his acceptance of Muslim friendship.
Human activity can impact the local environment, but global climate change on Earth, Mars, Venus, and other planets is caused by the Sun. Mankind has zero measurable impact on global climate change.
Water vapor and clouds are the primary drivers of climate change, as driven by the Sun, whether it be cosmic rays or variations in solar radiation, or magnetic field changes, or distance from the Earth.