Question

What exactly are greenhouse gases, how do we get rid of them, and how else can we stop or reverse the global warming process?

Greenhouse gases (also sometimes called heat-trapping gases) are those that are transparent to visible light (like sunlight) but absorb thermal emission (infrared radiation) from the surface and impede its free flow to space. The name “greenhouse effect” comes from the way a glass greenhouse is heated by sunlight, with the glass acting to impede the outward flow of infrared energy. Most of us experience the greenhouse effect most strongly when we open a car parked in the sunlight with its windows closed. We all know how the inside quickly gets much warmer than the outside. In the Earth’s atmosphere, the primary greenhouse gases are carbon dioxide and (to a much lesser extent) methane. Water vapor also acts as a greenhouse gas, although its heating power depends on the presence of carbon dioxide to establish the basic thermal structure of the atmosphere. There are really only two ways to counter the warming process: (1) block some of the incoming sunlight (which happens naturally after a large volcanic eruption) or (2) reduce the amount of carbon dioxide and methane in the atmosphere. Long before we can think about getting rid of greenhouse gases, we need to dramatically slow their release from burning fossil hydrocarbons such as coal and oil. There are possibilities of removing carbon dioxide by planting many more trees and by liquefying the carbon dioxide from power plants and injecting it into underground reservoirs. But slowing the burning of fossil fuels, and stopping the destruction of our forests, are surely the logical first step. This means reducing our consumption of energy, much of which can be accomplished by rather simple conservation approaches, such as increasing the efficiency of autos and improving the thermal insulation of our homes.

David Morrison
NAI Senior Scientist
October 28, 2009