The Keeling Curve: Atmospheric CO2 at Mauna Loa Observatory, annual peak and trough by year 1960 to now Source Scripps Institute This is the fourth of a series of essays about American agriculture and climate change. The first three, in order of appearance are these: 1. what-is-a-carbon-footprint 2. comparing-carbon-footprints-of-world-and-american-agriculture 3. Fossil [...]