I... had not thought of the situation from that perspective.
On the one hand, I want to look at this and say 'conspiracy theory'... but on the other hand I could potentially see this being possible.
On the third hand, when in doubt, apply Hanlon's Razor: don't attribute to malice what can be adequately explained by stupidity.
To my knowledge, there had been an understanding that scientists were being fairly conservative with their statements of how bad things were going to get, and how fast it was going to happen.
I know of two primary drivers for this (which I am somewhat oversimplifying for brevity):
Scientists really didn't want to get it wrong by saying X will definitely happen by year Y, and then be wrong, thus giving ammunition to climate deniers and vested interests running counter-PR such as oil companies.
Scientists didn't want to paint a picture of unstoppable, inevitable doom that no person could possibly imagine a way for them to fix, or contribute to fixing, thus leading to the mindset of 'if there's no way to stop it why even try?'.