12 years is the time we have to reduce emissions enough to avoid temperature increases over 1.5 °C. You can read about more of the details in the Guardian e.g.
What is important to understand about CO₂ and climate is that there is great inertia in the system. Emissions today will continue to have impact for a long time to come. Just because we screw up the next 12 years does not mean we are doomed in a mere 12 years. It will take much longer for all the bad effects to play out. It is just at that point we have no way of stopping it from happening. We will just have to buckle up and ride out the storm.
Before getting too much into doomsday mood it is worth having some perspective. Humans are capable of making systems to survive in quite extreme conditions whether at deep seas or in outer space. Surely we are capable of making systems to deal with a few degrees higher temperature.
The question is not about mass extinction of humans but rather it is an economic question. A lot of humans are quite poor and will not have the financial means to protect themselves against the severe effects of climate change.
Millions of people could starve and die from sever drought and heat in poor parts of the world. But it is wrong to scare small children in rich developed countries into thinking that is the future that awaits them. For many of us that live far north in the rich west, the effects of climate change will be minimal. But that is no reason to be complacent.
We should care, because we should care about all of humanity, not at least because we in the west are the main culprits for this problem. Poor people will suffer the consequences despite having played only a minor role in this calamity.
Your daughter should care about climate change because she cares about the health of the planet and the well being of millions of other people, not because she is afraid of dying or having zero future.
If those of us who care about global warming keep peddling this exaggurated and bleak characterization of the next 12 years, then we will risk people not taking us serious anymore. If you want to win over people to the cause, you have to be truthful.