![Long View Item 041](https://calendar.calacademy.org/sites/default/files/styles/manual_crop_standard_960x540/public/assets/images/blog_longview_item041.gif?itok=tsuHiju1&c=113ebd5fa633313ed81494c3fefcb27c)
Antarctic Item 041 is a 2.5-inch discarded rivet that I found at McMurdo Station. Although it lacks the bend of my previously posted wire pieces, I'll make the case that this too resembles a line graph — specifically the Keeling Curve, which is more of a steep, steady incline than a curve. The Keeling Curve is a graph that plots the ongoing change in concentration of carbon dioxide in Earth's atmosphere. Recorded from atop Hawaii’s Mauna Loa since 1958, it is the longest-running such measurement in the world. The Keeling Curve shows that atmospheric carbon dioxide levels are increasing, and doing so at a faster rate each year. In May 2013, CO2 concentrations in the global atmosphere surpassed 400 parts per million (ppm) for the first time in human history.