I'm personally of the opinion that we humans are in some ways contributing to climate change in this world, however, I still believe that mother nature is also just doing her thing for the most part.
My question though is if funding were available to put together a team to definitively say one way or the other exactly what effect "we" have on climate change, where would you put your money? You can only put your money in one place from the list of organizations included in the link and the organization would have five (5) years to produce their report. The problem I'd have is not knowing which, if any, of these organizations are bought and paid for by a particular political affiliation.
http://www.aag.org/cs/programs/interdisciplinary/climatechange/clearinghouse/organizations