Screenshot of a frame of a <a href="https://en.wikipedia.org/wiki/Climate_spiral" class="extiw" title="w:Climate spiral">Climate spiral</a> <a href="https://en.wikipedia.org/wiki/Data_visualization" class="extiw" title="w:Data visualization">Data visualization</a> of Earth's atmospheric CO2 (carbon dioxide) concentration beginning in 1958.
<ul><li>Independent variable is time:</li></ul><dl><dd><ul><li>Months are represented by angles about a center point</li>
<li>Years are represented by evolving colors as the years pass</li></ul></dd></dl><ul><li>Dependent variable is Earth's atmospheric CO2 concentration represented by distance from the center point, which expands smoothly due to generally smooth growth of CO2 concentration.</li></ul><ul><li>May 2017 publication date is estimated, based on content of graph and first Wayback Machine archive of 6 June 2017.</li></ul><ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20190819055209/http://www.climate-lab-book.ac.uk/spirals/">Footnote in source</a> states: "LICENSE Creative Commons License These blog pages &amp; images are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License."</li></ul>
Ed Hawkins, climate scientist at the <a href="https://en.wikipedia.org/wiki/University_of_Reading" class="extiw" title="w:University of Reading">University of Reading</a>
CC BY-SA 4.0
<p>Hawkins, Ed <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190819055209/http://www.climate-lab-book.ac.uk/spirals/">Climate spirals</a>. <i>Climate Lab Book</i> (May 2017). Archived from <a rel="nofollow" class="external text" href="http://www.climate-lab-book.ac.uk/spirals/">the original</a> on <span class="mw-formatted-date" title="2019-08-19">19 August 2019</span>. (<a rel="nofollow" class="external text" href="https://web.archive.org/web/20171119231432/http://www.climate-lab-book.ac.uk/files/2016/06/co2_2017.gif">Direct link to animated GIF</a>)
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<ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20190819055209/http://www.climate-lab-book.ac.uk/spirals/">Footnote in source</a> states: "LICENSE Creative Commons License These blog pages &amp; images are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License."</li></ul>