Editing Nitrous oxide (section)

==Environmental impact==
Global accounting of {{chem|N|2|O}} sources and sinks over the decade ending 2016 indicates that about 40% of the average 17&nbsp;TgN/yr ([[Megatonne|teragram]]s, or million metric tons, of nitrogen per year) of emissions originated from human activity, and shows that emissions growth chiefly came from expanding [[agriculture]].<ref name="HTian" /><ref name=":0" />  

[[File:Major greenhouse gas trends.png|thumb|right|Trends in the atmospheric abundance of long-lived greenhouse gases]]

Nitrous oxide has significant [[global warming potential]] as a [[greenhouse gas]]. On a per-molecule basis, considered over a 100-year period, nitrous oxide has 265 times the atmospheric heat-trapping ability of [[carbon dioxide]] ({{chem|CO|2}}).<ref name="ar5" /> However, because of its low concentration (less than 1/1,000 of that of {{chem|C|O|2}}), its contribution to the [[greenhouse effect]] is less than one third that of carbon dioxide, and also less than  [[methane]].<ref name="clim">US Environmental Protection Agency, "[https://www.epa.gov/climate-indicators/climate-change-indicators-atmospheric-concentrations-greenhouse-gases Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases]" Web document, accessed on 2017-02-14</ref> On the other hand, since about 40% of the {{chem|N|2|O}} entering the atmosphere is the result of human activity,<ref name="denman" /> control of nitrous oxide is part of efforts to curb greenhouse gas emissions.<ref>{{cite web |url=http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg1/247.htm |title=4.1.1 Sources of Greenhouse Gases |work=IPCC TAR WG1 2001 |access-date=21 September 2012  |archive-url=https://web.archive.org/web/20121029023441/http://www.grida.no/publications/other/ipcc%5Ftar/?src=%2Fclimate%2Fipcc_tar%2Fwg1%2F247.htm |archive-date=29 October 2012 }}</ref>

Most human caused nitrous oxide released into the atmosphere is a [[Greenhouse gas emissions from agriculture|greenhouse gas emission from agriculture]], when farmers add nitrogen-based fertilizers onto the fields, and through the breakdown of animal manure.  Reduction of emissions can be a hot topic in the [[politics of climate change]].<ref>{{Cite web |last=Mundschenk |first=Susanne |title=The Netherlands is showing how not to tackle climate change {{!}} The Spectator |url=https://www.spectator.co.uk/article/the-netherlands-is-showing-how-not-to-tackle-climate-change |access-date=2022-08-28 |website=www.spectator.co.uk |date=3 August 2022 |language=en}}</ref>

Nitrous oxide is also released as a by-product of burning fossil fuel, though the amount released depends on which fuel was used. It is also emitted through the manufacture of [[nitric acid]], which is used in the synthesis of nitrogen fertilizers.  The production of adipic acid, a precursor to [[nylon]] and other synthetic clothing fibres, also releases nitrous oxide.<ref>{{cite web|title=Overview of Greenhouse Gases: Nitrous Oxide Emissions|url=https://19january2017snapshot.epa.gov/ghgemissions/overview-greenhouse-gases_.html|publisher=United States Environmental Protection Agency|date=October 6, 2016|access-date=July 14, 2019}}</ref>

A rise in atmospheric nitrous oxide concentrations has been implicated as a possible contributor to the extremely intense global warming during the [[Cenomanian-Turonian boundary event]].<ref>{{cite journal |last1=Naafs |first1=B. David A. |last2=Monteiro |first2=Fanny M. |last3=Pearson |first3=Ann |last4=Higgins |first4=Meytal B. |last5=Pancost |first5=Richard D. |last6=Ridgwell |first6=Andy |date=10 December 2019 |title=Fundamentally different global marine nitrogen cycling in response to severe ocean deoxygenation |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=116 |issue=50 |pages=24979–24984 |doi=10.1073/pnas.1905553116 |pmid=31767742 |pmc=6911173 |bibcode=2019PNAS..11624979N |doi-access=free }}</ref>

Nitrous oxide has also been implicated in [[ozone depletion|thinning the ozone layer]]. A 2009 study suggested that {{chem|N|2|O}} emission was the single most important ozone-depleting emission and it was expected to remain the largest throughout the 21st century.<ref name="sciozo">{{cite journal|doi=10.1126/science.1176985 |title=Nitrous Oxide (N{{ssub|2}}O): The Dominant Ozone-Depleting Substance Emitted in the 21st Century|year=2009|last1=Ravishankara|first1=A. R.|last2=Daniel|first2=J. S.|last3=Portmann|first3=R. W. |journal=Science |volume=326 |issue=5949 |pages=123–5|pmid=19713491 |bibcode = 2009Sci...326..123R |s2cid=2100618|doi-access=free}}</ref><ref>{{cite magazine|last=Grossman |first=Lisa |date=28 August 2009 |url=https://www.newscientist.com/article/dn17698-laughing-gas-is-biggest-threat-to-ozone-layer.html |title=Laughing gas is biggest threat to ozone layer |magazine=New Scientist}}</ref>