Debates on global climate change (GCC) have been heavily influenced by such factors as scientific evidence, media coverage, public concerns, partisan interest, and so forth. Focusing on the linkages among the congressional committees, hearings, and invited witnesses (and their sectors), this study investigates the relational conditions under which congressional committees have mobilized climate expertise to discuss climate change issues for the past decades in U.S. Congress. Our findings show that agenda setting and witness selection by the committees significantly differed across the party lines: more environmental scientists were invited to define GCC as a threat in Democratic Congresses, whereas industrial scientists, to search for solutions in Republican Congresses. Except for a few proactive committees, committee jurisdiction was limitedly exercised. Our findings presents strong evidence along which climate policy debates have been framed based on a biased input of climate expertise.