Global Warming and Climate Change

by Dave Nichols

I want to use this time to bring our attention back to the subject of Climate change and how we, living in the industrial age, are making the planet hotter. We are making it hotter because we are putting more greenhouse gases in our atmosphere. The best known is carbon dioxide.

Prior to the mid-18th century, before the industrial age, there was some carbon dioxide in the atmosphere which contributed to warming. The average global temperature then was about 59F. A good deal of the warmth that allows life to exist is due to the presence of greenhouse gases. It has been known since the early 1800’s that, absent greenhouse gas, the global temperature would be slightly below zero Fahrenheit. The planet would be lifeless and frozen solid. A certain amount of greenhouse gas in the atmosphere is necessary to trap and then emit some of the planet’s heat loss back to the planet. At the beginning of the industrial age the concentration of carbon dioxide was just under 300 parts per million. Since then, it has been rising at an accelerated rate and is now about 420 parts per million. This increase has supercharged the warming effect. The last time it was this high was 3 million years ago, before humans, when the global temperature was 4.5-7.2 degrees higher than during the pre-industrial period. The sea level was at least 16 feet higher and possibly 82 feet higher at that time. Over the past 1/ 2 million years geologic data has shown that sea level change tracks closely with carbon dioxide concentration.

The current average temperature is about 2.5 degrees above the pre-industrial temperature. The 10 highest average global temperatures in the last 50 years have all occurred in the last decade.

Climate scientists generate theoretical models, and they look back at geologic data to make predictions about the impacts of climate change. Their predictions of rising sea level, extremes in heat, and the disruption of the biosphere present us with challenges that we must address. With advances in terrestrial and satellite sensors we can closely monitor the effects of climate change at a detailed level. Two good sources of information on this topic can be found on the nasa.gov website and a recent book by Lawrence Krauss, The Physics of Climate Change. My focus for future social action minutes will be to discuss not only the dangers of man- made global warming but also ways that it is being addressed and how we can help.