Query: In reality, gas produced by fracking is worse for the climate than coal.

Relevant passages:
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 % ) .

Greenhouse gas <=SEP=> A greenhouse gas ( abbrev . GHG ) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range . This process is the fundamental cause of the greenhouse effect . The primary greenhouse gases in Earth 's atmosphere are water vapor , carbon dioxide , methane , nitrous oxide , and ozone . Without greenhouse gases , the average temperature of Earth 's surface would be about -18 ° C , rather than the present average of 15 ° C . In the Solar System , the atmospheres of Venus , Mars and Titan also contain gases that cause a greenhouse effect .   Human activities since the beginning of the Industrial Revolution ( taken as the year 1750 ) have produced a 40 % increase in the atmospheric concentration of carbon dioxide , from 280 ppm in 1750 to 406 ppm in early 2017 . This increase has occurred despite the uptake of a large portion of the emissions by various natural `` sinks '' involved in the carbon cycle . Anthropogenic carbon dioxide emissions ( i.e. , emissions produced by human activities ) come from combustion of fossil fuels , principally coal , oil , and natural gas , along with deforestation , soil erosion and animal agriculture .   It has been estimated that if greenhouse gas emissions continue at the present rate , Earth 's surface temperature could exceed historical values as early as 2047 , with potentially harmful effects on ecosystems , biodiversity and the livelihoods of people worldwide . Recent estimates suggest that on the current emissions trajectory the Earth could pass a threshold of 2 ° C global warming , which the United Nations ' IPCC designated as the upper limit to avoid `` dangerous '' global warming , by 2036 .

Natural gas <=SEP=> Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane , but commonly including varying amounts of other higher alkanes , and sometimes a small percentage of carbon dioxide , nitrogen , hydrogen sulfide , or helium . It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years . The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas .   Natural gas is a fossil fuel used as a source of energy for heating , cooking , and electricity generation . It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals . Fossil fuel based natural gas is a non-renewable resource .   Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates . Petroleum is another resource and fossil fuel found in close proximity to and with natural gas . Most natural gas was created over time by two mechanisms : biogenic and thermogenic . Biogenic gas is created by methanogenic organisms in marshes , bogs , landfills , and shallow sediments . Deeper in the earth , at greater temperature and pressure , thermogenic gas is created from buried organic material .   In petroleum production gas is often burnt as flare gas . The World Bank estimates that over 150 cubic kilometers of natural gas are flared or vented annually . Before natural gas can be used as a fuel , most , but not all , must be processed to remove impurities , including water , to meet the specifications of marketable natural gas . The by-products of this processing include : ethane , propane , butanes , pentanes , and higher molecular weight hydrocarbons , hydrogen sulfide ( which may be converted into pure sulfur ) , carbon dioxide , water vapor , and sometimes helium and nitrogen .   Natural gas is often informally referred to simply as `` gas '' , especially when compared to other energy sources such as oil or coal . However , it is not to be confused with gasoline , especially in North America , where the term gasoline is often shortened in colloquial usage to gas .   Natural gas was used by the Chinese in about 500 BCE ( possibly even 1000 BCE ) . They discovered a way to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to boil salt water to extract the salt , in the Ziliujing District of Sichuan . The world 's first industrial extraction of natural gas started at Fredonia , New York , United States in 1825 . By 2009 , 66 000 km ³ ( or 8 % ) had been used out of the total 850 000 km ³ of estimated remaining recoverable reserves of natural gas . Based on an estimated 2015 world consumption rate of about 3400 km ³ of gas per year , the total estimated remaining economically recoverable reserves of natural gas would last 250 years at current consumption rates . An annual increase in usage of 2 -- 3 % could result in currently recoverable reserves lasting significantly less , perhaps as few as 80 to 100 years .

Shale gas <=SEP=> Shale gas is natural gas that is found trapped within shale formations . Shale gas has become an increasingly important source of natural gas in the United States since the start of this century , and interest has spread to potential gas shales in the rest of the world . In 2000 shale gas provided only 1 % of U.S. natural gas production ; by 2010 it was over 20 % and the U.S. government 's Energy Information Administration predicts that by 2035 , 46 % of the United States ' natural gas supply will come from shale gas .   Some analysts expect that shale gas will greatly expand worldwide energy supply . China is estimated to have the world 's largest shale gas reserves .   The Obama administration believed that increased shale gas development would help reduce greenhouse gas emissions . In 2012 , US carbon dioxide emissions dropped to a 20-year low .   A 2013 review by the United Kingdom Department of Energy and Climate Change noted that most studies of the subject have estimated that life-cycle greenhouse gas ( GHG ) emissions from shale gas are similar to those of conventional natural gas , and are much less than those from coal , usually about half the greenhouse gas emissions of coal ; the noted exception was a 2011 study by Howarth and others of Cornell University , which concluded that shale GHG emissions were as high as those of coal . More recent studies have also concluded that life-cycle shale gas GHG emissions are much less than those of coal , among them , studies by Natural Resources Canada ( 2012 ) , and a consortium formed by the US National Renewable Energy Laboratory with a number of universities ( 2012 ) .   Some 2011 studies pointed to high rates of decline of some shale gas wells as an indication that shale gas production may ultimately be much lower than is currently projected . But shale-gas discoveries are also opening up substantial new resources of tight oil / `` shale oil '' .