The first book starts with an asteriod strike on the moon that is much more severe than scientists anticipated. It follows the life of a young girl as she and her family cope with the resulting chaos.
These books would be a good way to reinforce what you've already told your own kids about the reasons that you are making changes in your own family's lifestyle. Reading this series would give youngsters a wider vision of the bald fact that life doesn't always just go on the same, day after day.
The books are available either in hard back or paper back. I would imagine they are also readily available on Kindle. Because they were written for young people there is nothing graphic or inappropriate in any book. That doesn't make the stories any less interesting but it does relieve parents of the necessity of reading them first. If you do pick one up, you may wind up reading the whole series anyway. I did.
The books are published by the childrens division of Harcourt. They are collectively called The Last Survivors Series.