Is it Governments Job to Exaggerate Fears like so-called "Global Warming"?

The reason why the goverment does that is because they can't always predict exactly how these type of things turn out. Even with the best scientists in the world can only find patterns, correlations, and trend and decide what's most probable. Scientists can't predict the future exactly how it is. The government only doing that protect their citizens and they don't want to held accountable for threats they have neglected. It's better to overestimate a danger and have everyone safe then to underestimate a danger and have people hurt. So it's better for them to be safe then sorry.