Researchers unearth 'new' extinction

A team of scientists has concluded that earth experienced a previously underestimated severe mass-extinction event, which occurred about 260 million years ago, raising the total of major mass extinctions in the geologic record ...

New insight into how much atmosphere Mars lost

A key tracer used to estimate how much atmosphere Mars lost can change depending on the time of day and the surface temperature on the Red Planet, according to new observations by NASA-funded scientists. Previous measurements ...

New route to carbon-neutral fuels from carbon dioxide discovered

If the idea of flying on battery-powered commercial jets makes you nervous, you can relax a little. Researchers have discovered a practical starting point for converting carbon dioxide into sustainable liquid fuels, including ...

Research sheds new light on Antarctic control of global climate

Scientists have made a new discovery that challenges previous understanding of the relationship between the polar Southern Ocean, next to Antarctica, and carbon dioxide levels in the atmosphere. Their findings show that, ...

Using lasers to study explosions

An explosion is a complex event involving quickly changing temperatures, pressures and chemical concentrations. In a paper in the Journal of Applied Physics a special type of infrared laser, known as a swept-wavelength external ...

Methane-producing microorganism makes a meal of iron

A new understanding of how an important methane-producing microorganism creates methane and carbon dioxide could eventually allow researchers to manipulate how much of these important greenhouse gases escape into the atmosphere. ...

Five climate change science misconceptions debunked

The science of climate change is more than 150 years old and it is probably the most tested area of modern science. However the energy industry, political lobbyists and others have spent the last 30 years sowing doubt about ...

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Carbon dioxide

Carbon dioxide (chemical formula: CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

As of March 2009[update], carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared.

Carbon dioxide has no liquid state at pressures below 5.1 atmospheres. At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below −78 °C and the solid sublimes directly to a gas above −78 °C. In its solid state, carbon dioxide is commonly called dry ice.

CO2 is an acidic oxide: an aqueous solution turns litmus from blue to pink. It is the anhydride of carbonic acid, an acid which is unstable and is known to exist only in aqueous solution.

CO2 is toxic in higher concentrations: 1% (10,000 ppm) will make some people feel drowsy. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.

This text uses material from Wikipedia, licensed under CC BY-SA