Editing Keeling Curve (section)

==Mauna Loa measurements==
[[File:Mauna Loa Observatory from air.jpg|The Mauna Loa Observatory|thumb|400x400px|alt=]]In 1957–1958, the [[International Geophysical Year]], Keeling obtained funding from the [[Weather Bureau]] to install [[infrared gas analyzer]]s at remote locations, including the [[South Pole]] and on the volcano of [[Mauna Loa]] on [[Hawaii (island)|the island of Hawaii]]. [[Mauna Loa]] was chosen as a long-term monitoring site due to its remote location far from continents and its lack of vegetation. Keeling and his collaborators measured the incoming ocean breeze above the [[Inversion (meteorology)|thermal inversion layer]] to minimize local contamination from volcanic vents.<ref name=":2" /> The data was [[normalization (statistics)|normalized]] to remove any influence from local contamination. Due to funding cuts in the mid-1960s, [[Charles David Keeling|Keeling]] was forced to abandon continuous monitoring efforts at the South Pole, but he scraped together enough money to maintain operations at the [[Mauna Loa Observatory]], which have continued to the present day.<ref name="rewards">{{cite journal|last1=Keeling|first1=Charles D.|date=1998|title=Rewards and Penalties of Monitoring the Earth|journal=[[Annual Review of Energy and the Environment]]|volume=23|pages=25–82|doi=10.1146/annurev.energy.23.1.25|doi-access=free|citeseerx=10.1.1.173.2051}}</ref> {{external media | width = 210px | float = right | headerimage=  | video1 = Scripps Institution of Oceanography at UC San Diego, [https://www.youtube.com/watch?v=rEbE5fcnFVs The Keeling Curve Animation], Scripps Institution of Oceanography at UC San Diego | video2 = Ralph Keeling, [https://www.youtube.com/watch?v=6WFCoJgt71A "The (Ralph) Keeling Curve"], Scripps Institution of Oceanography at UC San Diego | video3 = John Barnes, [https://www.youtube.com/watch?v=3jOAlC2dVtA Mauna Loa Observatory I Exploratorium], [[Exploratorium]] | video4 = Charles David Keeling, [https://www.youtube.com/watch?v=K0Z7RRKzrdg "The Keeling Curve Turns 50"]|video5=Charles David Keeling, 2005 [https://www.youtube.com/watch?v=aH1837EUvTI "Tyler Prize Laureate Lecture"], Scripps Institution of Oceanography at UC San Diego}}

Keeling's ''[[Tellus A|Tellus]]'' article of 1960 presented the first monthly {{CO2}} records from [[Mauna Loa Observatory|Mauna Loa]] and Antarctica (1957 to 1960), finding a "distinct seasonal cycle...and possibly, a worldwide rise in {{CO2}} from year to year."<ref name=":0">{{Cite journal|last=Keeling|first=Charles D.|date=1960|title=The concentration and isotopic abundances of carbon dioxide in the atmosphere|url=http://scrippsco2.ucsd.edu/assets/publications/keeling_tellus_1960.pdf|journal=Tellus|volume=12|issue=2|pages=200–203|doi=10.3402/tellusa.v12i2.9366|bibcode=1960Tell...12..200K|doi-access=free}}</ref><ref name="rewards"/>{{rp|pages=41–42}} By the 1970s, it was well established that the increase of atmospheric carbon dioxide was ongoing and due to anthropogenic emissions.<ref>{{cite journal|year=1965|last1=Pales|first1=Jack C.|last2=Keeling|first2=Charles David|title=The Concentration of Atmospheric Carbon Dioxide in Hawaii|volume=70|issue=24|pages=6053–6076|doi=10.1029/JZ070i024p06053|journal=Journal of Geophysical Research|bibcode=1965JGR....70.6053P}}</ref><ref name=":3">{{Cite journal|last1=Keeling|first1=Charles D.|last2=Bacastow|first2=Robert B.|last3=Bainbridge|first3=Arnold E.|last4=Ekdahl Jr.|first4=Carl A.|last5=Guenther|first5=Peter R.|last6=Waterman|first6=Lee S.|last7=Chin|first7=John F. S.|date=1976|title=Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii|journal=Tellus|language=en|volume=28|issue=6|pages=538–551|doi=10.3402/tellusa.v28i6.11322|bibcode=1976Tell...28..538K|issn=0040-2826|doi-access=free}}</ref>

Carbon dioxide measurements at the [[Mauna Loa Observatory]] in [[Hawaii]] are made with a type of [[infrared spectroscopy|infrared spectrophotometer]], now known as a [[nondispersive infrared sensor]], that is calibrated using [[World Meteorological Organization]] standards.<ref>{{cite web|url=https://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.pdf|title=How we measure background CO<sub>2</sub> levels on Mauna Loa|last1=Tans|first1=Pieter|last2=Thoning|first2=Kirk|date=March 2018}}</ref> This type of instrument, originally called a [[capnograph]], was first invented by [[John Tyndall]] in 1864, and recorded by pen traces on a strip chart recorder.<ref>{{cite news| url=https://www.nytimes.com/interactive/2010/12/22/science/earth/20101222-carbon/index.html | work=[[The New York Times]] | title=Sampling the Air | date=December 22, 2010}}</ref> Currently, several laser-based sensors are being added to run concurrently with the infrared spectrophotometer at the [[Scripps Institution of Oceanography|Scripps Institute of Oceanography]], while [[NOAA]] measurements at [[Mauna Loa Observatory|Mauna Loa]] still use the [[nondispersive infrared sensor]].