To maintain its temperature, the living Earth has both warming and cooling process. The greenhouse effect is one of the warming processes and it is essential for life on Earth. Otherwise, we’d all be frozen. Generally, when we think about the greenhouse effect, we tend to concentrate on the greenhouse gases in the atmosphere. These are a group of gases that let the incoming energy, sunlight, through, but then hold in some of that energy as it re-radiates away the Earth’s surface as heat. The greenhouse gases act as a complex insulation system. But just as a blanket doesn’t “warm” the bed (after all, the bed is cold when you get into it), the greenhouse gases don’t “warm” the Earth. The greenhouse gases hold in the heat coming off the Earth just as a blanket holds in the heat coming off your body. Shifting the focus to the source of the heat is a big eye-opener, because it is the heat that causes the problem.

It’s the heat coming off bare dry land and impervious surfaces that is driving the increase in the greenhouse effect, not the increase in one or more of the greenhouse gases, although they play their part. Over the course of centuries, humans have been destroying the forests, fields, and wetlands that once covered the Earth, and left behind bare land. A satellite view of the Earth shows this quite clearly. It’s estimated that 40% of the land that was once covered in green is now bare. Bare land re-radiates far more heat (infrared energy) than land that is covered in plants, especially forests. Our cities have become “heat islands.” We all know that bare land is hotter than land covered in vegetation: think of walking with bare feet in the summer on concrete, sand, or hard packed dirt; then think about walking on grass or on a forest trail. It is this heat, the heat you feel on your bare feet, that is driving the greenhouse warming we are experiencing.

Water vapor is by far the most abundant greenhouse gas, but that doesn’t diminish the importance of the other greenhouse gases, notably carbon dioxide, methane, nitrous oxide, and others. The greenhouse gases are not the same as each other, nor do they act in the same way. They have different absorbency spectra, different lifetimes, and so on. They work together, and it’s a fool’s errand to try and untangle the effects of one greenhouse gas from the collective.

Excerpted from “An Earthlings Guide to Planetary Health” (aka: The Regenerating Life Study Guide) coming to a website near you in early 2025. — Interested in an effective way to cool the planet?