by Julia Rosen Friday, May 17, 2013
Back in January 2013, it became clear to Ralph Keeling, a scientist at the Scripps Institution of Oceanography who studies carbon dioxide, that sometime in the not-too-distant future, the concentration of this potent greenhouse gas in Earth’s atmosphere would creep above 400 parts per million (ppm) for the first time in human history.
It was also obvious to Robert Monroe, a communications officer at Scripps who covers the extensive climate research conducted at the institute, that this milestone represented a unique opportunity to raise awareness of climate change. While the exact number doesn’t mean anything specific for the climate system, Monroe says he recognized that its nice, round appeal had the ability to grab people’s attention. So, he did what anyone would do in 2013: He started tweeting.
For nearly half a century, Keeling’s father, Charles, and now Ralph, have continuously monitored carbon dioxide concentrations from the top of Mauna Loa in Hawaii, sniffing the clean, well-mixed air above the Pacific Ocean with gas chromatographs. These measurements, which together form the so-called Keeling Curve, helped establish the foundation of modern climate science. But most people have probably never seen what the data actually look like.
In terms of public awareness of carbon dioxide levels, Monroe says, many people “might tune into the carbon dioxide level in high school chemistry class, and then maybe tune back in if they watch ‘An Inconvenient Truth,’ and then go the rest of their lives with just a vague idea that there’s this number out there.” Monroe wanted to change that. “The idea was to make it more of a daily reality — a daily affirmation of where we’re at with climate.” Plus, he says with a chuckle, “it’s a way to build suspense.”
So every morning, Monroe gets the 24-hour readout from the Mauna Loa station from Keeling and his team and then tweets it into cyberspace as @Keeling_Curve. Though it sounds simple, this actually required the researchers to modify the way they analyze and output their data. The Mauna Loa team typically works in monthly averaged increments, but catching the first day above 400 required a finer comb. Keeling also stresses that these high-frequency measurements represent preliminary values.
When Monroe started tweeting on March 7, the daily average was a mere 398.57 ppm, but Keeling knew from historical patterns that it would continue to edge upward until peaking in May before it plunged down again as Northern Hemisphere plants grew their spring leaves and started sucking carbon dioxide from the atmosphere. And it seemed likely that this year, the peak would nudge us into a realm of carbon dioxide concentrations not seen for millions of years.
As it happened, they didn’t have to wait long into May. On May 9, they reported an average daily concentration of 400.08 ppm, while NOAA, which operates another instrument at the same site, reported 400.03 ppm. More days over 400 followed quickly. They measured 400.17 on May 13 and 400.27 on May 16.
“I think it really did hit people on the head,” says Monroe, who has monitored public reactions on his Twitter feed, and on the complementary website he and Keeling created that allows users to view the data and learn about the carbon cycle. “Judging from reader comments,” he says, “I don’t think people realized that we’ve never hit this level before in human history.”
Of course, he is quick to point out that humans have never lived with 380 ppm before, or 350, or even 300, the level of atmospheric carbon dioxide near the turn of the 19th century. The ice core record from Antarctica, which stretches back 800,000 years, shows that carbon dioxide concentrations did not exceed about 280 ppm at any point during that interval until the beginning of the industrial revolution.
But Monroe’s hunch was right; the number 400 feels like a milestone to thousands of Twitter users. Each day, Monroe’s announcement gets retweeted about 30 times, which, in the exponential universe of Twitter where each user has about 200 followers of their own, means that approximately 6,000 additional users will see it on top of the 4,000 people following the Keeling Curve directly. The Scripps campaign has also garnered enormous media attention, raising awareness beyond the realm of social media.
As of this week, the new Keeling Curve website had more than 100,000 views, up from what Monroe estimates as “maybe 20” before their effort caught on after Earth Day on April 22. On top of simply viewing the data, many of the visitors have delved into more scientific posts that explain what Earth looked like the last time carbon dioxide surpassed 400 ppm during the Pliocene and why concentrations vary more in the Northern Hemisphere than in the Southern. Monroe says he finds this engagement extremely rewarding, noting that “people are coming away with more knowledge about how the carbon cycle works, and that’s really nice to see.”
Monroe and Keeling plan to continue their campaign through the year, despite the impending decrease in carbon dioxide concentrations every summer. “I have a feeling there will be a core number of people who watch it and retweet it every day,” says Monroe, acknowledging that some of the momentum might fade now that we’ve broken 400 ppm. Although they are excited to continue the Twitter campaign into the future, in some ways, Monroe and Keeling may have already achieved their goal. Monroe says that part of the idea was to etch this event into our collective memory, the way we remember where we were when other life-changing events took place.
“[Keeling’s] hope was that people will say, ‘oh yeah, I remember back in 2013,’ or ‘I remember when concentrations used to be below 400.’ You know, ‘back when I was a kid…’ They will be telling this to their grandkids who will have grown up in a world with 450 or 500 ppm.”
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