You can't see it, smell it, taste it or touch it, but you darn sure can hear about it.

Carbon dioxide - the gas that makes your pop fizzy and keeps the office ficus alive - has been collecting in concentrated amounts in the headlines as much as it is in the atmosphere.

And it's getting a bad rap.

But the greenhouse gas most associated with global warming is instrumental in making life on this planet livable.

As its name suggests, and as you might recall from high school chemistry, carbon dioxide is made up of one atom of carbon and two of oxygen. The gas is essential for plants, which "breathe" it in and then exhale the oxygen. They keep the carbon to help them grow. When the plants die, some of the carbon goes back into the air and recombines with the oxygen to make CO2 again.

People recycle carbon dioxide, too. The gas exists in very small amounts in the air we breathe, but when we exhale we release 100 times more CO2 than we took in.

Left to its own devices, carbon dioxide occurs in small amounts in the Earth's atmosphere. If you picture CO2 molecules as humans, the volume of carbon dioxide in the air is equivalent to just one person in a crowd of 2,500 people. But the gas plays an important role in the greenhouse effect. It helps to keep some of the sun's warmth from bouncing off the planet and heading back into space. Without carbon dioxide and the other greenhouse gases, Earth would be inhospitable for plant and human life.

So, we can't live without it. But, as you may have heard from all those headlines, people are saying life might not be so great with too much of it, either.

Extra carbon dioxide in the atmosphere can help trap extra heat. A CO2 analyst for the U.S. Department of Energy reported that the parts per million of carbon dioxide in the atmosphere prior to the industrial revolution was around 280. By 1900, the number had risen to 300.

Now, according to the Carbon Dioxide Information Analysis Center, the concentration has risen to about 380 parts per million. How that increase affects the global temperature is unclear. Scientists for the United Nations' Intergovernmental Panel on Climate Change have said the average global temperature could rise 21/2 to 10 degrees by 2100. Other scientists claim those figures are alarmist and the connection between temperature and more CO2 in the atmosphere aren't so directly related.

What is more clear is that your government has taken an interest in the debate.

"The message we give out about carbon dioxide, greenhouse gases and the climate-change debate that's going on, is there's probably going to be some federal legislation on that," Dave Glatt, director of the state Health Department's environmental health section, said.

Already, the DOE has invested more than $80 million to study carbon capture in a region that includes North Dakota. The Environmental Protection Agency has issued guidelines for storage.

So think what you like about global warming, but know that no matter what your opinion, there could be change looming. Federal mandates on emissions can be costly, and those costs have a way of trickling down to consumers across the board - from the price of electricity to your fizzy fountain pop.

(Unless otherwise noted, the information on CO2 came from the Energy and Environmental Research Center at the University of North Dakota. Reach reporter Tony Spilde at 250-8260 or tony.spilde@bismarcktribune.com.)