Editing Keeling Curve (section)

==Legacy==

===Global monitoring===
Due in part to the significance of Keeling's findings,<ref name="rewards" /> [[National Oceanic and Atmospheric Administration|NOAA]] began monitoring CO<sub>2</sub> levels worldwide in the 1970s.<ref>Keeling, Charles D. (1978). "The Influence of Mauna Loa Observatory on the Development of Atmospheric CO<sub>2</sub> Research". In ''Mauna Loa Observatory: A 20th Anniversary Report''. (National Oceanic and Atmospheric Administration Special Report, September 1978), edited by John Miller, pp. 36–54. Boulder, CO: [[NOAA]] Environmental Research Laboratories.</ref> Today, atmospheric CO<sub>2</sub> levels are monitored at about 100 sites around the globe through the Global Greenhouse Gas Reference Network.<ref>{{Cite web|url=https://www.esrl.noaa.gov/gmd/ccgg/|title=ESRL Global Monitoring Division - Global Greenhouse Gas Reference Network|last=NOAA, Earth System Laboratory|first=US Department of Commerce Research|website=www.esrl.noaa.gov|language=EN-US|access-date=2018-11-25}}</ref> Measurements at many other isolated sites have confirmed the long-term trend shown by the Keeling Curve,<ref>[https://scrippsco2.ucsd.edu/graphics_gallery/other_stations/global_stations_co2_concentration_trends.html Global Stations {{CO2}} Concentration Trends]. Scripps CO<sub>2</sub> Program.</ref> although no sites have as long a record as [[Mauna Loa Observatory|Mauna Loa]].<ref name="KeelingWhorfContinuous">{{cite web|url=http://cdiac.ornl.gov/trends/co2/sio-keel-flask/sio-keel-flaskmlo_c.html|title=Atmospheric CO<sub>2</sub> from Continuous Air Samples at Mauna Loa Observatory, Hawaii, U.S.A.|last1=Keeling|first1=Charles D.|last2=Whorf|first2=T. P.|date=2004|access-date=2007-10-17|archive-url=https://web.archive.org/web/20160303173428/http://cdiac.ornl.gov/trends/co2/sio-keel-flask/sio-keel-flaskmlo_c.html|archive-date=2016-03-03|url-status=dead}}</ref>

===Ralph Keeling===
Since [[Charles David Keeling]]'s death in 2005, responsibility and oversight of the project was transferred to Keeling's son, [[Ralph Keeling]]. On the fiftieth anniversary of the beginning of the project, the younger Keeling wrote an article in [[Science (journal)|Science magazine]] describing his father's life and work, along with how the project has grown and evolved over time.<ref>{{Cite journal|last=Keeling|first=Ralph F.|date=2008|title=Recording Earth's Vital Signs|journal=Science|language=en|volume=319|issue=5871|pages=1771–1772|doi=10.1126/science.1156761|issn=0036-8075|pmid=18369129|s2cid=206512305}}</ref> Along with more precise measurement materials and funds for the project of monitoring of the Earth's {{CO2}} levels, Keeling wrote about his pride for his father's work and how he has continued it in his memory.

===Recognition===
In 2015, the Keeling Curve was designated a [[National Historic Chemical Landmarks|National Historic Chemical Landmark]] by the [[American Chemical Society]].<ref>{{Cite web|url=https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/keeling-curve.html|title=Keeling Curve - American Chemical Society|website=American Chemical Society|language=en|access-date=2018-11-25}}</ref> Commemorative plaques were installed at [[Mauna Loa Observatory]] and at the [[Scripps Institution of Oceanography]] at the [[University of California, San Diego]].

===Passing 400 ppm in 2013===
On May 9, 2013, the daily mean concentration of {{CO2}} in the atmosphere measured at Mauna Loa surpassed 400 parts per million ([[Parts-per notation|ppm]]).<ref>{{Cite journal|last=Showstack|first=Randy|date=2013|title=Carbon dioxide tops 400 ppm at Mauna Loa, Hawaii|journal=Eos, Transactions American Geophysical Union|volume=94|issue=21|pages=192|doi=10.1002/2013eo210004|bibcode=2013EOSTr..94Q.192S|issn=0096-3941|doi-access=free}}</ref> Estimates of {{CO2}} during previous [[geologic era]]s suggest that {{CO2}} has not reached this level since the [[Pliocene climate|mid-Pliocene]], 2 to 4 million years ago.<ref name="Montaigne">{{cite web|url=http://e360.yale.edu/feature/keeling_curve_son_of_climate_science_pioneer_on_co2_milestone/2650/|title=Son of Climate Science Pioneer Ponders A Sobering Milestone|last1=Montaigne|first1=Fen|website=Yale Environment 360|publisher=Yale School of Forestry & Environmental Studies|access-date=14 May 2013|archive-url=https://web.archive.org/web/20130608174549/http://e360.yale.edu/feature/keeling_curve_son_of_climate_science_pioneer_on_co2_milestone/2650/|archive-date=8 June 2013|url-status=dead}}</ref> This level of carbon dioxide, causing [[climate change]], suggests a continued worsening in natural and ecological disasters, which increasingly threatens human and animal habitats on Earth, if greenhouse gas emissions are not significantly reduced.