Via Hot Topic, a climate-change equivalent of those road-safety ads, highlighting the massive difference global emissions reduction policy will make. If we get a global agreement to reduce emissions, we're likely to limit the increase in average global temperature to 2.5 degrees. If we don't, the chances of that outcome become miniscule, and instead we're looking at around 5 degrees, with a ~25% chance of getting 6 degrees or more.
2.5 degrees is unpleasant but manageable; it means more droughts, water shortages, the spread of tropical diseases. I have trouble imagining what 5 degrees is like, but it will certainly mean major disruption to global food supplies and serious positive feedback. Since the models don't include positive feedback (as not enough is known about it), the "no policy" outcome is likely to be even worse.
So, which wheel would you rather spin?