In just about every case, there are several variables involved, with many mechanisms at work about whose nature there is often only limited understanding and information. Given that human factors such as economic self-interest, political power, lifestyle preferences, ideological loyalties and even egos are also at stake, it is no wonder that there is often fierce debate about the very existence of the problems identified below, let alone trends, causes, consequences and solutions. In some cases, opponents argue that the changes feared by environmentalists will be beneficial and that, if they turn out to be worse than expected, then corrective technologies will facilitate quick and less expensive remedial measures. Phrases like global warming also bring not unattractive connotations, particularly for audiences in colder countries. Many of the issues have gone through a boom-slump attention cycle, sometimes more than once.
Some issues are more newsworthy than others.
Similarly, the alleged mistreatment of individual farm animals seems to provoke more anger than the elimination of entire species. The mass media play a particular problematic role in these matters. For a start they tend to focus on discrete events, rather than underlying processes. The media not only build up issues in exaggerated ways but also, to get a second bite of 'the apple', knock them back down again, perhaps by spotlighting some dissenting voice, again out of all proportion to the merits of the case. Often it is not difficult to identify the vested interests and value orientations at stake.