Where We Were, Where Are, and Where We Need to Be

Quantifying the global warming problem is as easy as understanding three numbers; 275, 388, and 350. 275 – During all of human history, up until about 200 years ago, our atmosphere contained 275 parts per million of carbon dioxide. Measuring in parts per million is a standard method of calculating the concentration of different gases in the atmosphere. This number provides the ratio of the number of carbon dioxide molecules to all of the other molecules in the atmosphere. The 275 parts per million that carbon dioxide historically represented in the atmosphere was a relatively constant number. Its presence is also a necessity because without some carbon dioxide and other gases, heat would not be trapped in our atmosphere and the planet would be too cold for humans, plants and animals to survive. 388 – As humans began to burn fossil fuels to power the Industrial Revolution, the level of carbon dioxide in the atmosphere began to rise slowly. Over the last 200 years, fossil fuels have become incorporated into many aspects of daily life including gasoline for cars, heating fuels, as a component of plastics, etc. The broad use of carbon dioxide emitting fossil fuels has now increased the level of carbon dioxide to 388 parts per million, a level scientists now agree is an unsafe level if we are interested in preserving our way of life. The rise in atmospheric carbon has resulted in the warming of the Earth with results that include massive melting of glaciers, the disappearance of Arctic Sea ice, droughts, and a variety of extreme weather. Sea levels are also rising and the disappearance of beaches is already occurring. Left unchecked, the rise in sea levels could be as much as several meters this century, which would be a disaster of epic proportions. 350 – This is the level of atmospheric carbon dioxide that represents stasis for the world’s environment as well as the safety level for maximum carbon dioxide in the atmosphere. Returning to this level will require that humans reduce their fossil fuel usage and replace it with renewable energy sources like solar and wind. Taking these actions as well as improving agricultural and forestry practices around the world could get carbon levels back to the 350 level by the middle of the century. The problem is, the longer we stay in the danger zone above 350 parts per million, the greater the risk for disastrous events. The time to start is now.