Much is being said about climate change: is it real?  Are we causing it?  What can be done?  I have recently come across three fascinating discussions of how human-caused increases in atmospheric carbon dioxide may relate to various natural cycles, and how, too, it provides an amazing object lesson in the fine-tuning of the Earth and solar system.   Essential reading/listening.

How Ice Ages Happen: https://youtu.be/iA788usYNWA.

The Hiawatha Asteroid: https://www.reasons.org/explore/blogs/todays-new-reason-to-believe/read/todays-new-reason-to-believe/2018/12/17/did-a-giant-collider-help-give-us-extreme-climate-stability

Geologist Dan Britt, Orbits and Ice Ages: the History of Climate (2012): https://www.youtube.com/watch?v=Yze1YAz_LYM&feature=youtu.be