The most precious legacies we can pass on to future generations are good air, clean water and healthy vegetation. There are billions of people in developing countries who have limited amounts of water or whose water is contaminated by improper/no sanitation.

America’s greatest estuary, the Chesapeake Bay is no longer producing the amount of seafood that Maryland fisherfolk depend for their livelihoods (due to farm runoff). But you can argue that the quality of the air we breathe is more critical as all humans share the same air, with a global mixing time of six years.

So the air from the worst industrial polluters to the air from pristine mountain valleys is mixed thoroughly. High smokestacks merely spread industrial fumes over a larger area so the local folk living nearby won’t be subjected to high levels of emissions.

There are still problems in large Asian cities where big industries and cars are concentrated; there the emissions in the air are high (as Pittsburgh’s were in the first half of the 20th century).

Humans have had three significant impacts on the atmosphere. The first impact that was diagnosed and improved was acid rain.

As all coal has small amounts of sulfur, burning of coal creates sulfur dioxide. In internal combustion engines, the temperature gets hot enough to combine the nitrogen (makes up more than 75 percent of our air) and oxygen into oxides of nitrogen such as NO and NO2.

Both the sulfur dioxide and oxides of nitrogen can combine with the water vapor in the atmosphere to make sulfuric acid and nitric acid. In addition, falling rain can mix with small particulates in the air that contain sulfur and nitrogen to also produce these acids.

In some lakes there is sufficient limestone to neutralize the acid rain. But if enough acid rain falls, these buffering compounds may be used up and the lake will become overly acidic, killing the fish. A number of lakes in New York State have no fish.

In Germany, the famed Black Forests are suffering due to acid rain. This has caused Germany to heavily promote both solar panels and wind turbines as emission free electrical sources.

The U.S. government has forced many mid-west power plants to limit their sulfur emissions using flue gas scrubbers where the sulfur dioxide is combined chemically to form calcium sulfate, which is discarded as waste.

Where there is fluidized bed combustion at a power plant, limestone is mixed with crushed coal as it’s being burned to draw away the sulfur. Despite all these efforts, our mid-Atlantic state rainfall is still mildly acidic.

The second impact to our atmosphere is the thinning of the stratospheric ozone layer due to chlorofluorocarbons (CFC’s) used by refrigerators and air conditioners. The ozone thinning was first discovered in Antarctica where the ozone levels had dropped by 50 percent.

Ozone or Oxygen-3 stops most of the sun’s ultraviolet rays from reaching the Earth’s surface. Without the stratospheric ozone layer, life would have never developed on land, remaining in the ocean where the ocean waters block the ultraviolet rays.

CFC’s are non toxic but eventually migrate to the stratosphere where they are broken up by the sun’s ultraviolet light. The chlorine atoms act as catalysts for breaking up the ozone molecules. One chlorine atom can preside over the destruction of 100,000 ozone molecules! CFC production has ceased in most countries and substitutes are now used in our refrigerators and air conditioners (that break up quickly and don’t affect the ozone layer).

But it will take several human generations before the ozone layer builds back; in the meanwhile, there is a higher risk for skin cancer among fair skinned people (such as the author, who has his skin cancer treated by a fine local dermatologist).

The third human impact to our atmosphere is the increasing amount of atmospheric carbon dioxide, which absorbs heat waves from the Earth’s surface and re-emits them back to the ground, increasing the average surface temperature.

The current label for this situation is climate warming or climate change. Unlike the above two effects, this has become highly politicized with a well funded opposition, who ascribe the observed warming of the Earth’s surface to natural cycles and not human activity.

Every year human activity puts an additional 8 billion tons of carbon into the atmosphere (actually 29 billion tons of carbon dioxide). For each gallon of gas our vehicles, lawnmowers or lake boats consume, there is about 20 pounds of carbon dioxide injected into the air.

Records that go back hundreds of thousands of years show clearly that our atmospheric carbon dioxide concentration is at high levels. The main result so far is increased warming of the polar regions, causing glaciers to erode and polar ice to get thinner.

As ice melts, there is more absorption of the sun’s energy by Earth’s surface, further increasing the temperature. As ocean levels rise (due to melting of ice and thermal expansion of water), large coastal populations are endangered by storms and more violent weather systems.

Much could be done to reduce our carbon dioxide output (America leads the world with 20 tons/person/year), but some Americans maintain that they are entitled to drive as much as they can afford and use as much electrical energy (mostly by burning coal) as they desire. And to modify our landscape with wind turbines, some very vocal people regard this as an abomination!

If these doubters want to see wind or solar panels that make electricity, visit our WISE Hybrid energy system at Frostburg State University.

Bob Doyle invites readers comments or questions: (301) 687-7799 or rdoyle@frostburg.edu .