Keeling

(By Pien Huang)

If the I8S route was mapped antipodally (on the direct opposite side of the world), we would have started south of France at the Bay of Biscayne, steamed for two weeks to the Northwest Territories, sampled parallel to the Hudson Bay, through the Great Lakes and down to Alabama, and out to Bermuda. As it is, we’ve seen nothing but ocean for the past three weeks.

There is less land in general in the southern hemisphere. This has to do with the way the continents drifted apart some 200 million years ago, and it is partly the reason that the Keeling plot looks the way it does. The original Keeling plot was published in 1961, based on measurements taken by Charles Keeling on Mauna Loa. It was the first time anyone had documented the rise of CO2 in the atmosphere, and its revolutionary nature is featured in Al Gore’s /An Inconvenient Truth/. The term “Keeling plot” has since become synonymous with any graph that shows the rise in carbon dioxide levels in the atmosphere over recent time. Beyond recording the rise in CO2 levels, this Keeling plot shows that CO2 fluctuates seasonally, and much more so in the northern hemisphere. This is because there is more land, and therefore more plants, in the northern hemisphere. Plants absorb CO2 to photosynthesize, and they release the CO2 when they die in the winter.

Climate change skeptics will try to use this fluctuation against you. They might argue that CO2 levels get higher and lower all the time, and they will point to the fact that we’ve had major ebbs and flows in the atmospheric CO2 content in the geological past (a really, really long time ago). What they won’t do is use exact numbers. You can refute them with the 180-240-370 rule, which they teach you in college: from ice core studies, scientists have determined that the levels of CO2 in the atmosphere have fluctuated between 180 and 240 ppmv (just a measurement label) as far back as we can tell. Our current levels exceed 370 ppmv.^1

It’s not entirely true for me to say we’ve seen nothing but ocean. We’ve seen plenty of birds, mainly albatross, petrels, and sometimes skuas. Tonight there was a squid alert from the winch operator (he sits in a tower outside controlling the wire during equipment launches), which took most of us from the control room out to portside. According to the sea veterans, squids are attracted to the flood lights which illuminate our night-time casts. We leaned overboard, squirting seawater from a hose (the same sea vets say the squids think it might be anchovies). Something white skippered across the waves. It might have been a small squid, but for the while after, every blob we saw disintegrated into seafoam.

Props to JJ Becker, and a shout-out to the school board of San Diego.

^1 Fischer, Gaston. Atmospheric lifetime of carbon dioxide. Population and Environment, 10:3, March 1989.