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Greenhouse Gases are No Joke

While we question global warming, our atmosphere is changing

As the sun sets this week after 6:30, two bright lights emerge from the glare above the west horizon. The higher and brighter of the two is Venus, while neighboring Mercury shines just a few degrees below. The two planets appear closest together Saturday and Sunday evening when less than three degrees separate them.

Not only is Venus our nearest neighbor, it is also closest in size to Earth. While named after the Roman goddess of love, it is a hellish place, enshrouded in a dense, gaseous cocoon more than 60 miles deep.

Whether you accept global warming here on Earth, Venus offers a cautionary tale. In the infancy of the solar system, Venus and Earth coalesced from the same debris and the same gases leftover from the formation of the sun. But along the way, the two evolved quite differently.

Earth developed an atmosphere made up of 76 percent hydrogen and 21 percent oxygen with traces of carbon dioxide, helium and other gases. This mix allowed the sun’s rays to warm the planet while also providing the building blocks for water, which helped ensure that earth did not overheat.

However, Venus was not so lucky. Its atmosphere is primarily carbon dioxide with traces of sulfur. Only two percent of the sun’s rays reaches the surface as visible light, whereas all the heat penetrates the cloud cover and is then unable to escape, further raising the temperature. If water ever formed on the planet, it would have long ago evaporated in the 900-plus-degree temperatures — the hottest of all the planets. The only moisture on Venus rains down as concentrated sulfuric acid, disallowing any chance for life as we know it.

Global warming aside, we are changing the makeup of our atmosphere here on Earth as we burn ever-greater amounts of fossil fuels, the by-product of which is ... carbon dioxide.