Carbon dioxide (CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. Although carbon dioxide mainly exists in its gaseous form, it also has a solid and a liquid form. It can only be solid when temperatures are below -78 degrees Celsius. Carbon dioxide is water-soluble only when pressure is maintained. CO2 is used by plants for photosynthesis. However, anthropogenic overproduction of CO2 increases the greenhouse effect, as carbon dioxide is the second most abundant greenhouse gas in the atmosphere after water vapor.

Every time you turn on a light, drive your car, or charge your cellphone, you are burning fossil fuels that release greenhouse gases (GHG) into the atmosphere. Your carbon footprint is the amount of GHG emissions you are personally responsible for emitting each year, and therefore, represents the impact you have on the environment. Although it is called a “carbon” footprint, it represents all greenhouse gases, from carbon dioxide (CO2) to methane. It is typically measured in units of carbon dioxide. It is useful for individuals, nations, and organizations to conceptualize their personal (or organizational) contribution to global warming.  There are many carbon footprint calculators that allow you to calculate your carbon footprint.

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas. It consists of one carbon atom covalently bonded to one oxygen atom. Carbon monoxide is produced from the partial combustion of carbon-containing compounds, notably in internal-combustion engines. Despite its serious toxicity, CO plays a highly useful role in modern technology, being a precursor to a myriad of products.

Being carbon neutral, or carbon neutrality, refers to the zero total carbon release brought about by balancing the amount of carbon released with the amount sequestered or offset. Being carbon neutral involves calculating total climate-damaging carbon emissions, reducing them where possible, and then balancing the remaining emissions by purchasing a carbon offset: paying to plant new trees or investing in green technologies (solar and wind power) or by buying carbon credits to remove them through carbon trading. There is ongoing debate as to the value of certain methods that aim to offset CO2 production.

Carbon offsetting means supporting the reduction of greenhouse gas emissions by the same amount that your daily activities add. In other words, you are neutralizing your impact by helping fund projects that prevent future greenhouse gases from entering the atmosphere. Carbon offsets are measured in metric tons of carbon-dioxide equivalent (CO2e). One carbon offset represents the reduction of one metric ton of carbon-dioxide, or its equivalent in other greenhouse gases. There are a number of projects that can offset carbon ranging from clean energy development to methane-capture facilities. There are two primary markets for carbon offsets. In the larger compliance market, companies, governments or other entities buy carbon offsets in order to comply with caps on the total amount of carbon dioxide they are allowed to emit. In the much smaller voluntary market, individuals, companies or governments purchase carbon offsets to mitigate their own greenhouse gas emissions from transportation, electricity use and other sources. Carbon markets have been imposed by laws such as the Kyoto Protocol.  However, the United States only has a voluntary market.

Carbon rationing is a means to control the total amount of greenhouse gases being produced. In a carbon rationing society, those producing more than their fair share of greenhouse gases can only do so by finding someone who is living within their fair share and has some ration to spare.

A carbon sink is a carbon dioxide reservoir that keeps increasing in size. Main natural sinks are the oceans' biological pump, as well as plants and other organisms that use photosynthesis to remove carbon from the atmosphere by incorporating it into their biomass to release oxygen into the atmosphere. The process by which carbon sinks remove CO2 from the atmosphere is known as carbon sequestration, and it tries to alleviate the accumulation of greenhouse gases.

A carbon tax is a tax on emissions of carbon dioxide and other greenhouse gases generated as byproducts during the combustion of fossil fuels. It is an example of pollution tax and helps reduce carbon emissions to efficient levels, which in turn slows down the process of climatic change. Boulder, Colorado passed the first carbon tax in the U.S. in 2006.

A product that is Certified AP (Approved Product) Non-Toxic has been "certified in a program of toxicological evaluation by a medical expert to contain no materials in sufficient quantities to be toxic or injurious to humans or cause acute or chronic health problems."

A certification awarded by Carbonfund.org, a non-profit that helps individuals, businesses, and organizations eliminate their climate impacts through the sale of carbon offsets. Carbon free certifies that the emissions required to obtain, transport, refine, manufacture and distribute a product has been offset.

See our definition of Energy-saving light bulbs.

Chlorofluorocarbons (CFCs) are a family of compounds containing chlorine, fluorine and carbon. They are generally non-reactive and have low flammability, low toxicity and low solubility in water. Major sources of CFCs are aerosol propellants, cleaning solvents, refrigerants, and plastic blowing agents. When CFCs are emitted into the atmosphere, they stay there for a long period of time and deplete the ozone layer. Spray consumer products advertise that they contain no CFC’s. However, CFC’s were banned in the 1980’s, so this claim is irrelevant.

Climate change is any long-term significant change in the average temperature, precipitation, and wind patterns that a given region experiences. It involves changes in the variability or average state of the atmosphere over time periods ranging from decades to millions of years. These changes can be caused by dynamic processes on Earth, external forces( including variations in sunlight intensity), and more recently by human activities. Climate change is important because it is an indicator to the impact humans are having on this planet.

Climate Counts is a collaborative effort to bring consumers and companies together in the fight against global climate change. It’s a nonprofit organization funded by Stonyfield Farm, Inc. and launched in collaboration with Clean Air-Cool Planet. Climate Counts Company Scorecard measures how serious companies are about stopping climate change. The higher the Climate Counts score (from 0-100), the greater the company's commitment to fighting global warming. Climate Counts’ scoring system determines whether a company has measured its climate "footprint,” reduced its impact on global warming, supported (or suggests intent to block) progressive climate legislation, and publicly disclosed its climate actions clearly and comprehensively.

Composting is a process in which solid organic materials are decomposed in the presence of oxygen through the action of bacteria and other microorganisms. This process is done by mixing together leaves, grass clippings, table scraps, and soil, and allowing the mixture to decompose into mulch, which is high in nutrients, and useful to fertilize gardens and flower beds.

The management of the human use of the biosphere so that it may yield the greatest sustainable benefit to present generation, while maintaining its potential to meet the needs and aspirations of future generations is termed conservation. It includes the preservation, maintenance, sustainable utilization, restoration, and enhancement of the environment.