<a href="//commons.wikimedia.org/w/index.php?title=Methane&amp;action=edit&amp;redlink=1" class="new" title="Methane (page does not exist)">Methane</a> concentrations
NOAA
<a rel="nofollow" class="external free" href="https://www.esrl.noaa.gov/gmd/dv/data/index.php?parameter_name=Methane&amp;frequency=Discrete&amp;site=MLO">https://www.esrl.noaa.gov/gmd/dv/data/index.php?parameter_name=Methane&amp;frequency=Discrete&amp;site=MLO</a> (<a href="https://en.wikipedia.org/wiki/Earth_System_Research_Laboratory" class="extiw" title="en:Earth System Research Laboratory">Earth System Research Laboratory</a>) Data is collected from Mauna Loa Observatory, 19.536 -155.576