With the evolution of cumulative effect studies over the last 30 years, for instance, there has been a difficulty for scientists to undertake these things, understandably, because of the repercussions of the conclusions from these studies, which would limit development. There is politics about cumulative effects. It comes into play in British Columbia, and it comes into play in the tar sands.
On February 3rd, 2011. See this statement in context.