In addition, there are tiny amounts of the unstable isotope carbon-14 (14C) on Earth.

Carbon-14 has a half-life of just under 6000 years and would have long ago vanished from Earth were it not for the unremitting cosmic ray impacts on nitrogen in the Earth's atmosphere, which forms more of the isotope.

Bacteria may be classified based on their shape: spherical (cocci), rod-like (bacilli), spiral (spirochetes), or comma-shaped (vibrios).

Other ways of classifying them are based on whether or not they are: gram positive or gram negative, aerobic or anaerobic, autotrophic or heterotrophic, etc.

including cholera, syphilis, anthrax, leprosy and bubonic plague) several other bacteria have been found beneficial. They’re also vital in recycling nutrients, such as the fixation of nitrogen from the atmosphere. In 1960, Libby was awarded the Nobel Prize in chemistry for carbon dating.Carbon has two stable, nonradioactive isotopes: carbon-12 (12C), and carbon-13 (13C).Germany is one of the biggest importers of gas, coal and oil worldwide, and has few domestic resources apart from lignite and renewables (but see later section). The preponderance of coal makes the country Europe’s biggest emitter of carbon dioxide.The 2016 increase in renewables generation was the smallest since 2009.