Photo, “Earth Day,” by Catherine Lacey Dodd. Used under Creative Commons license. Original photo can be found at: https://www.flickr.com/photos/catherinelacey/8673252899/in/photolist-edqFV6-4H1dLj-bMZ9y2-J3szA-njGtj8-frEcu-4H1d8U-njqaQE-FAcWPV-4H1dx5-68Uhk9-Gvv6pa-Gvv5Xt-aW5KKT-4GW49x-Gvv66p-P3HPQ-4H6JHP-5ycG2L-Gvv6dP-HtZto-bQhr9D-bQhs2p-6hfxwR-bQhtji-bQhrgn-bBnP9w-bQhrTr-bBnNJw-bQhssZ-bBnN8b-bBnMoj-gGRtY-bBnNFs-9AFwVY-bQhsJX-bBnMu3-GfJ3WR-bBnNpq-bQhsa4-bBnNCh-bBnNfA-bBnN4y-bQhszR-bBnNQj-bB9Mzb-RmJU36-4H1dky-6hXoQy-Gvv5G8