Query: The idea that the much smaller carbon dioxide cycle is now controlling the water cycle is not very likely.

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Scuba diving <=SEP=> Scuba diving is a mode of underwater diving in which the scuba diver uses a self-contained underwater breathing apparatus ( scuba ) which is completely independent of surface supply , to breathe underwater . Unlike other modes of diving , which rely either on breath-hold or on breathing supplied under pressure from the surface , scuba divers carry their own source of breathing gas , usually compressed air , allowing them greater freedom of movement than with an air line or diver 's umbilical and longer underwater endurance than breath-hold . Open circuit scuba systems discharge the breathing gas into the environment as it is exhaled , and consist of one or more diving cylinders containing breathing gas at high pressure which is supplied to the diver through a diving regulator . They may include additional cylinders for decompression gas or emergency breathing gas . Closed-circuit or semi-closed circuit rebreather scuba systems allow recycling of exhaled gases . The volume of gas used is reduced compared to that of open circuit ; therefore , a smaller cylinder or cylinders , may be used for an equivalent dive duration . Rebreathers extend the time spent underwater compared to open circuit for the same gas consumption , they produce fewer bubbles and less noise than scuba which makes them attractive to covert military divers to avoid detection , scientific divers to avoid disturbing marine animals , and media divers to avoid bubble interference .   Scuba diving may be done recreationally or professionally in a number of applications , including scientific , military and public safety roles , but most commercial diving uses surface-supplied diving equipment when this is practicable . Scuba divers engaged in armed forces covert operations may be referred to as frogmen , combat divers or attack swimmers .   A scuba diver primarily moves underwater by using fins attached to the feet , but external propulsion can be provided by a diver propulsion vehicle , or a sled pulled from the surface . Other equipment includes a dive mask to improve underwater vision , a protective diving suit , equipment to control buoyancy , and equipment related to the specific circumstances and purpose of the dive . Scuba divers are trained in the procedures and skills appropriate to their level of certification by instructors affiliated to the diver certification organisations which issue these certifications . These include standard operating procedures for using the equipment and dealing with the general hazards of the underwater environment , and emergency procedures for self-help and assistance of a similarly equipped diver experiencing problems . A minimum level of fitness and health is required by most training organisations , but a higher level of fitness may be appropriate for some applications .

Coal <=SEP=> Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams . The harder forms , such as anthracite coal , can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure . Coal is composed primarily of carbon , along with variable quantities of other elements , chiefly hydrogen , sulfur , oxygen , and nitrogen . A fossil fuel , coal forms when dead plant matter is converted into peat , which in turn is converted into lignite , then sub-bituminous coal , after that bituminous coal , and lastly anthracite . This involves biological and geological processes that take place over time .   Throughout human history , coal has been used as an energy resource , primarily burned for the production of electricity and heat , and is also used for industrial purposes , such as refining metals . Coal is the largest source of energy for the generation of electricity worldwide , as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases . The extraction of coal , its use in energy production and its byproducts are all associated with environmental and health effects including climate change .   Coal is extracted from the ground by coal mining . Since 1983 , the world 's top coal producer has been China . In 2015 China produced 3,747 million tonnes of coal -- 47.7 % of 7,861 million tonnes world coal production . In 2015 other large producers were United States ( 813 million tonnes ) , India ( 678 ) , European Union ( 539 ) and Australia ( 503 ) . In 2010 the largest exporters were Australia with 328 million tonnes ( 27.1 % of world coal export ) and Indonesia with 316 million tonnes ( 26.1 % ) , while the largest importers were Japan with 207 million tonnes ( 17.5 % of world coal import ) , China with 195 million tonnes ( 16.6 % ) and South Korea with 126 million tonnes ( 10.7 % ) .

Carbon capture and storage <=SEP=> Carbon capture and storage ( CCS ) ( or carbon capture and sequestration ) is the process of capturing waste carbon dioxide from large point sources , such as fossil fuel power plants , transporting it to a storage site , and depositing it where it will not enter the atmosphere , normally an underground geological formation . The aim is to prevent the release of large quantities of into the atmosphere ( from fossil fuel use in power generation and other industries ) . It is a potential means of mitigating the contribution of fossil fuel emissions to global warming and ocean acidification . Although has been injected into geological formations for several decades for various purposes , including enhanced oil recovery , the long term storage of is a relatively new concept . The first commercial example was the Weyburn-Midale Carbon Dioxide Project in 2000 . Other examples include SaskPower 's Boundary Dam and Mississippi Power 's Kemper Project . ` CCS ' can also be used to describe the scrubbing of from ambient air as a climate engineering technique .   An integrated pilot-scale CCS power plant was to begin operating in September 2008 in the eastern German power plant Schwarze Pumpe run by utility Vattenfall , to test the technological feasibility and economic efficiency . CCS applied to a modern conventional power plant could reduce emissions to the atmosphere by approximately 80 -- 90 % compared to a plant without CCS . The IPCC estimates that the economic potential of CCS could be between 10 % and 55 % of the total carbon mitigation effort until year 2100 .   Carbon dioxide can be captured out of air or fossil fuel power plant flue gas using adsorption ( or carbon scrubbing ) , membrane gas separation , or adsorption technologies . Amines are the leading carbon scrubbing technology .  Capturing and compressing may increase the energy needs of a coal-fired CCS plant by 25 -- 40 % . These and other system costs are estimated to increase the cost per watt energy produced by 21 -- 91 % for fossil fuel power plants . Applying the technology to existing plants would be more expensive , especially if they are far from a sequestration site . A 2005 industry report suggests that with successful research , development and deployment ( RD&D ) , sequestered coal-based electricity generation in 2025 may cost less than unsequestered coal-based electricity generation today .   Storage of the is envisaged either in deep geological formations , or in the form of mineral carbonates . Deep ocean storage is not currently considered feasible due to the associated effect of ocean acidification . Geological formations are currently considered the most promising sequestration sites . The National Energy Technology Laboratory ( NETL ) reported that North America has enough storage capacity for more than 900 years worth of carbon dioxide at current production rates . A general problem is that long term predictions about submarine or underground storage security are very difficult and uncertain , and there is still the risk that might leak into the atmosphere .

Ice age <=SEP=> An ice age is a period of long-term reduction in the temperature of Earth 's surface and atmosphere , resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers . Within a long-term ice age , individual pulses of cold climate are termed `` glacial periods '' ( or alternatively `` glacials '' or `` glaciations '' or colloquially as `` ice age '' ) , and intermittent warm periods are called `` interglacials '' . In the terminology of glaciology , ice age implies the presence of extensive ice sheets in both northern and southern hemispheres . By this definition , we are in an interglacial period -- the Holocene -- of the ice age . The ice age began 2.6 million years ago at the start of the Pleistocene epoch , because the Greenland , Arctic , and Antarctic ice sheets still exist .

Radiocarbon dating <=SEP=> Radiocarbon dating ( also referred to as carbon dating or carbon-14 dating ) is a method for determining the age of an object containing organic material by using the properties of radiocarbon , a radioactive isotope of carbon .   The method was developed by Willard Libby in the late 1940s and soon became a standard tool for archaeologists . Libby received the Nobel Prize in Chemistry for his work in 1960 . The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen . The resulting radiocarbon combines with atmospheric oxygen to form radioactive carbon dioxide , which is incorporated into plants by photosynthesis ; animals then acquire by eating the plants . When the animal or plant dies , it stops exchanging carbon with its environment , and from that point onwards the amount of it contains begins to decrease as the undergoes radioactive decay . Measuring the amount of in a sample from a dead plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died . The older a sample is , the less there is to be detected , and because the half-life of ( the period of time after which half of a given sample will have decayed ) is about 5,730 years , the oldest dates that can be reliably measured by this process date to around 50,000 years ago , although special preparation methods occasionally permit accurate analysis of older samples .   The idea behind radiocarbon dating is straightforward , but years of work were required to develop the technique to the point where accurate dates could be obtained . Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years . The resulting data , in the form of a calibration curve , is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample 's calendar age . Other corrections must be made to account for the proportion of in different types of organisms ( fractionation ) , and the varying levels of throughout the biosphere ( reservoir effects ) . Additional complications come from the burning of fossil fuels such as coal and oil , and from the above-ground nuclear tests done in the 1950s and 1960s . Because the time it takes to convert biological materials to fossil fuels is substantially longer than the time it takes for its to decay below detectable levels , fossil fuels contain almost no , and as a result there was a noticeable drop in the proportion of in the atmosphere beginning in the late 19th century . Conversely , nuclear testing increased the amount of in the atmosphere , which attained a maximum in 1963 of almost twice what it had been before the testing began .   Measurement of radiocarbon was originally done by beta-counting devices , which counted the amount of beta radiation emitted by decaying atoms in a sample . More recently , accelerator mass spectrometry has become the method of choice ; it counts all the atoms in the sample and not just the few that happen to decay during the measurements ; it can therefore be used with much smaller samples ( as small as individual plant seeds ) , and gives results much more quickly . The development of radiocarbon dating has had a profound impact on archaeology . In addition to permitting more accurate dating within archaeological sites than previous methods , it allows comparison of dates of events across great distances . Histories of archaeology often refer to its impact as the `` radiocarbon revolution '' . Radiocarbon dating has allowed key transitions in prehistory to be dated , such as the end of the last ice age , and the beginning of the Neolithic and Bronze Age in different regions .