Speaker: Steve Hartman –Chemistry Professor (retired), Brock University – Probus North Member

Topic: Feedback Loops and Climate Change: The Long View

The Earth’s atmosphere was very different 4.6 billion years ago when the Earth formed, It had high levels of carbon dioxide and no oxygen. This continued for the first 1½ billion years, until primitive single-cell life evolved a new kind of photosynthesis that produced oxygen as a by-product. Oxygen is highly reactive, and this changed everything on Earth’s surface. Eventually there was enough oxygen in the atmosphere to allow oxygen-breathing organisms including dinosaurs and humans to evolve.

Life is fragile, For billions of years, Earth’s atmosphere has remained in the very narrow temperature range that makes life possible. We will discuss how this happened, and how human activities are upsetting the system and putting our survival at risk.