Our atmosphere and climate have undergone drastic changes, both in the past and present, because of incremental changes caused by living things.

The first such change occurred 3 billion years ago, when our atmosphere was about 20 percent carbon dioxide and had essentially no free oxygen. The temperature of the earth was in the right range for life, but the sun was gradually burning hotter, threatening the continuation of life on earth (which at that time was only bacteria).

Fortunately, some of these bacteria developed the ability to use chlorophyll to capture energy from sunlight. These cyanobacteria flourished, emitting oxygen and gradually decreasing the carbon dioxide in our atmosphere.

Carbon dioxide traps heat from sunlight, and the gradual decrease in CO2 has kept our earth from getting too hot for life. When CO2 levels first plummeted, the earth experienced an extreme ice age (average temp of -58 degrees F) that lasted for millions of years, but eventually temperatures rose and somehow, life endured.

In 1930, mankind began another incremental change to the atmosphere, when we started using a new coolant for refrigeration (chlorofluorocarbons or CFCs). CFCs began to damage the ozone layer that protects us from deadly ultraviolet radiation from the sun. Luckily, we stopped using CFCs in time to prevent serious damage to land life, but it was a close call.

Now, it is mankind, not cyanobacteria, that is causing an incremental in carbon dioxide in our atmosphere (increasing it), and again we are seeing a change in our atmosphere’s temperature.

Restoring balance to our atmosphere and keeping climate change from becoming too extreme will require a greater effort than we have contemplated to date. It is within our grasp, however, and it is the gift that our children require of us.

Richard Thomas

Waterville

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