Legacy is a term we may hear and see in print from time to time.

According to www.thefreedictionary.com, it means "a gift by will," "something handed down or received from an ancestor or predecessor."

Our predecessors from the 1900s gave us such a legacy. Even as late as 2011, an "unprecedented" ozone hole developed in the Arctic, with continuing ozone holes forming over the Antarctic regions. This was not done on purpose. There was a lack of awareness and understanding about the impact of groups of chemicals, chlorofluorocarbons and hydrofluorocarbons had on the Earth's atmosphere.

These chemicals consist of volatile molecules and are used as refrigerants in our homes, cars and elsewhere in life. When released/leaked into the atmosphere, they rise into the stratosphere high above the Earth's surface, where they react with and destroy the ozone layer.

The chemistry is very complex, but it is clear that by reducing the ozone layer, increased amounts of high-energy solar UV radiation are able to reach the Earth's surface. This radiation is very harmful and can cause skin cancer and have other deleterious effects on life on Earth.

With some incomplete data but ongoing research, scientists sounded the alarm to policy makers, who rose to the challenge. In 1987, the Montreal Protocol was signed by President Ronald Reagan and Margaret Thatcher and came into force Jan. 1, 1989. Altogether, 196 countries have signed the Protocol to limit these and other similar chemicals, and to eventually stop their use. However, the legacy, the gift, stays with us and will for the next half century and more. Until the ozone hole closes, people from Scandinavia to Russia, Canada to Argentina will be at risk.

But what about carbon dioxide? Is there a legacy here as well? A gift from us to future generations?

The answer is yes. Let's take a look.

A train carrying black coal, a oil tanker carrying crude oil and a gas tanker carrying natural gas all have one thing in common: carbon, fossil carbon. All of these carbon forms (solid, liquid and gas) contain latent energy to help power our civilization. It is the combustion of this carbon, in the presence of oxygen, that produces carbon dioxide with the release of energy to power our cars, trucks, lights and coffee maker.

While all three sources of fossil carbon look very different, both physically and in transport, when combusted they all produce a gas that one cannot see, smell, taste or feel. These properties of carbon dioxide make it easy to ignore. The triatomic nature of this gas also provides it with another physical characteristic that we cannot sense without instruments: it absorbs infrared energy that would normally be emitted to space, i.e. the greenhouse effect.

The lifetime of carbon dioxide in the atmosphere is a continuing subject of study by many groups. The dynamics of the Earth's air, ocean and land and the partitioning of this gas between them is very complex. David Archer of the University of Chicago states, "A better shorthand for public discussion might be that CO2 sticks around for hundreds of years, plus 25 percent that sticks around forever."

As we continue to consume carbon in its various forms, we are indeed delivering a legacy to future generations. The correlation of carbon dioxide levels, from both ice cores and direct measurements, with increased temperature can be seen in the data provided by NOAA and a chart by Woods Hole Research Center, Mass.

On Nov. 9, 2011, the Energy Information Agency released a report (available on the Web) entitled, "World Energy Outlook." It goes on to state: "On planned policies, rising fossil fuel use will lead to irreversible and catastrophic climate change … We are on an even more dangerous track to an increase of 6 degrees Celsius (11 degrees Fahrenheit) … Delaying action is false economy."

In a final note, earlier in November 2011 the U.S. Department of Energy announced that the global output of carbon dioxide took the biggest jump ever in 2010 and that Chinese emissions now exceed the United States by 50 percent.

"And so it goes."

The scientific career of Raymond N. Johnson, Ph.D., spanned 30 years in research and development as an organic/analytical chemist; he is currently founder and director of the Institute of Climate Studies USA (www.ICSUSA.org). Climate Science is published the first Sunday of every month.