Political Parties
I forsee two problems with this one:
a)Party loyalty, as mentioned above but perhaps more significantly, specifically because of the nature of our topic...
b)"mainstream" versus "protest/interest" party -the two main federal parties, liberal/conservative, have the most control at the national level -however, when we talk about "best equipped" it is probably the Green Party, as they specialize in/take part in/fund etc. environmental research and advocate policy based on this (a sort of bias, I guess?) -therefore, we can't really say "most effective"; the Green Party would be the most effective but they will not take power any time soon in Canada. The Conservatives are "most effective" in that they are the ones making up environmental policy, however are probably not saving/protecting/sustaining the environment as well as the Green Party would (or perhaps even the Liberals.)
Basically, the power of the party in the legislature i.e. whether they have a large legislative majority, or a minority (as is recently prevalent) to a large extent determines its "effectiveness". This would confuse the issue with environmental policy.
That said, if we could somehow overcome the obstacles, it's an interesting question...