Steve Shaw nails it. It is called the "Precautionary Principle".
It goes something like this: if there is a great risk, it is wise to not wait for the science to become 100% certain before acting to mitigate it. In fact, science by its very nature is never certain, so we use the precautionary principle all the time.
Let's say that there is a 1% chance that the children's tylenol you have been giving your kid is tainted. You would stop right?
Let's say there is a 0.5% chance that the inexpensive baby formula you have been using is tainted. You would spend extra for something else wouldn't you?
So why do so many people shut down this part of their brain when it comes to the risks to our kids associated with rapid anthropogenic climate change?
Right-wing blowhard brainwashing.