The scientists base their predictions on computer models, and these models are subject to dispute. The scientific uncertainty and disagreement exacerbate the search for policy consensus in this and many other policy areas such as the feasibility of a space-based missile defense system. The more complex the issue and the weaker the consensus among scientists and other experts on causes and solutions, the more likely gridlock is to occur. When scientific consensus reigns, Congress and other policymaking bodies are likely to reach agreement on what to do.