Doctors say that over time the damage interferes with the natural exchange of oxygen and carbon dioxide in the lungs.

VOA: special.2010.06.23

Mister Schroeder says that carbon dioxide levels in the atmosphere are much higher now than they were in the past.

VOA: special.2010.01.26

They observed that for every molecule of carbon dioxide taken in by the plants, they lost forty-four percent less water.

VOA: special.2010.01.26

Plants naturally take in carbon dioxide they need for photosynthesis, the process of changing light energy to chemical energy.

VOA: special.2010.01.26

Their findings could help to engineer plants that grow better and more effectively in conditions with higher levels of carbon dioxide.

VOA: special.2010.01.26

A carbon footprint is the amount of carbon dioxide pollution that we produce as a result of our activities.

VOA: special.2011.04.05

Greenhouse gas emissions, such as carbon dioxide, are created in part by burning oil and coal for transportation and electricity.

VOA: special.2009.12.26

However,each time a plant takes in one molecule of carbon dioxide gas, it loses hundreds of water molecules.

VOA: special.2010.01.26

A new report says mangrove forests store more planet-warming carbon dioxide than almost any other ecosystem on Earth.

VOA: special.2011.05.10

The process releases some carbon dioxide, but Rajan Vempati says it would be reabsorbed into the soil naturally.

VOA: special.2009.12.01

Experts say some methods of tilling turning the soil to prepare for planting also release harmful carbon dioxide.

VOA: special.2010.01.05

The effort will help reduce carbon dioxide releases from the Empire State Building by more than one hundred thousand tons a year.

VOA: special.2009.05.22

The researchers added carbonic anhydrase genes to plants that do not react to higher levels of carbon dioxide.

VOA: special.2010.01.26

For example, the insects can smell carbon dioxide in the breath of a person or animal from as far away as sixty meters.

VOA: special.2009.05.26

For example,Mister Venter is working to design cells that can make it easier to capture carbon dioxide.

VOA: special.2010.07.20

But cement manufacturing produces around five percent of the carbon dioxide released by human activity worldwide.

VOA: special.2009.12.01

The carbon dioxide enters the plants through tiny holes or pores on the surface of leaves.

VOA: special.2010.01.26

They capture and store carbon dioxide, so experts say they can help fight climate change.

VOA: special.2010.04.20

Carbon dioxide is one of the gases that may affect the climate by trapping heat.

VOA: special.2009.12.01

The gas is mainly methane. It produces half the carbon dioxide of other fossil fuels.

VOA: special.2009.10.23

Carbon dioxide is released in cement manufacturing when fuel is burned and limestone is heated.

VOA: special.2009.12.01

But he is hard at work. He and his team currently are trying to make algae that can change carbon dioxide back into fossil fuel.

VOA: special.2010.07.20

Other threats include human pollution, acidification from carbon dioxide and rising temperatures in Earth's atmosphere.

VOA: special.2009.05.12

Rajan Vempati thinks rice hull ash could help the concrete industry produce less carbon dioxide.

VOA: special.2009.12.01

Some plants' pores can tighten to save water during conditions of high carbon dioxide.

VOA: special.2010.01.26