A friend of mine recently said that intellectual honesty often requires imagining the worst. Of course, in the study of climate change and natural resources one needs only to read the analyses of scientists to imagine the worst.
Imagining the worst is not necessarily the same as believing the worst is inevitable or even likely. It can be merely a standard part of both scenario and emergency planning. Of course, imagining the worst can also be a double-edged sword with a sinister edge, sometimes eliciting Richard Hofstadter's paranoid style of politics.
When we imagine the worst concerning our political opponents or our enemies (sadly often placed into the same category), this is merely a reflex designed to justify our own hatreds and also a tool for broadly smearing those with whom we disagree. Clearly, this is not the same as seeking out solid evidence and using logic to construct a worst-case scenario.
In scenario planning the whole point is to consider seriously a range of possible outcomes and formulate plans for dealing with those outcomes. For example, the U.S. Energy Information Administration (EIA) reference case for world oil production (defined as crude oil and lease condensate) shows it rising from about 76 million barrels per day (mbpd) in 2012 to 99.5 mbpd in 2040. The low production case is 92 mbpd and the high production case is almost 103 mbpd.