It's a common perception that science and religion are mutually exclusive. But there are many scientists who would consider themselves to be spiritual people.

For Christians, doing something about climate change is about living out our faith - caring for those who need help, our neighbors here at home or on the other side of the world, and taking responsibility for this planet that God created and entrusted to us.

I think the biggest pushback comes from people who perceive me to be a threat. Having bloggers who are dedicated to making up false information about you, having anonymous people write nasty emails and letters, having organizations file legal requests for your work-related emails, and all the other things that happen can be very depressing and discouraging.

A person of faith who shares conservative values and who says very clearly that climate change is real - and here's why we have to care about it - I think that we "unicorns" do pose a threat to people who want to muddy the waters and keep others in the dark.

Our carbon emissions have to eventually go to zero. We have to. Otherwise we're never going to have a stable climate and that's what our goal is for human civilization to thrive, a stable climate. We don't want one that's hotter, we don't want one that's colder, we want one that's stable.

When I talk to my neighbor, or to someone at church who doesn't accept that the planet is changing, I know that they don't know any better. They've been told this information by somebody they trust and it's not their fault. They've just never heard otherwise.

The word "evangelist" means someone who spreads good news. Studying the impacts of climate change as I do, it's hard to come up with good news. In many ways I feel more like a Cassandra or a Jeremiah than a good-news evangelist.