panic and/or fear
Panic and fear are two very different things.
Fear is a normal human reaction to danger, real or perceived. Fear activates the fight or flight response that allows humans to act against danger. Without fear we wouldn't have evolved as we would have ignored threats and perish. Fear feels very uncomfortable to humans but when properly handled fear enhances our senses and wits and gives us an edge against adversity. If not properly managed, fear may become panic.
Panic is fear gone bad. When panic sets, mistakes are made on the fight or flight reaction, decreasing the chances of survival. Panic can manifest in different ways. In the case of climate change induced panic it can lead anywhere to severe depression to climate change denial. Fear without any hope of success may increase the chances of panic.
Historically fear is an excellent motivator. Dictators and unscrupulous leaders use fear of non existent threats because it works. Climate change is a real threat. Whoever doesn't fear it is because they don't understand it. Fear of climate change is the appropriate reaction to the understanding of climate change and the only thing that will motivate people into the appropriate action.
It is not immoral to scare people about real dangers. It is the natural order to tell people the truth even if it is scary, no, specially if it is scary. That is the only way people will jump into action. It is immoral to hide the dangers, because it blunts the reaction.
Leaders are believing the fallacy that as long as they know about climate change a solution will be found without "scaring" the people.
Guess what, most people can take it. Most people will react properly upon understanding the true scope of climate change. A few won't. That's a fact of life. But those who do react properly will do something. Some will do a lot, some a little, leaders emerge, work is accumulated and the stupid climate change problem is solved.
But since climate change is a problem for 2100, who cares.