Washington (CNN) To the public, Washington Gov. Jay Inslee has written just one book, a 2007 policy piece about the future of green energy.

But to his family, the 2020 Democratic candidate and grandpa is much more prolific.

For the last 10 years, Inslee has written and illustrated one children's book a year for his three grandkids. A number of the books focus on nature, the climate and the effects the warming Earth has on the environment. They are a physical -- if not unique -- manifestation of the 2020 candidate's deep concern about climate change, the issue he has centered his campaign around -- and a way he can personally teach his three grandchildren about the impact humans can have on the world around them.

"These books are more for fun and being able to read to your grandkids. That is a treasure, that is priceless and that is why we wrote the books," Inslee told CNN on Tuesday.

The books were, until now, a private display of how intensely Inslee, who will appear in a CNN town hall Wednesday night, worries climate change. The candidate focuses on the issue at nearly every event he headlines and launched his campaign earlier this year because he believes he is "the only candidate who will make defeating climate change our nation's number one priority."

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