Posted May 13th, 2016 at 11:57 am (UTC-4)
Multiple laboratories around the world work with NOAA to collect air samples. Above, Refael Klein collects an air sample for the Scripps Institute of Oceanography. (Photo by Daren Lukkari)
The Global Monitoring Division (GMD) specializes in making long-term, continuous measurements of trace gases in the atmosphere which affect the Earth’s climate. GMD operates six baseline observatories that stretch from the Arctic Circle to the South Pole. These facilities act as the backbone of our data collection efforts.
Many of the data sets from our baseline observatories date back decades. If you are a climate modeler interested in seeing what stratospheric ozone levels were like in the 1990s, or a congressman interested in seeing the effects of environmental legislation on the abundance of CFCs, we can supply you with a trove of data, by-the-minute or by-the-hour averages, in some instances. Our data collection is free and open to the public, both foreign and domestic, so if you have a hankering to see what aerosol abundances were like on the West Coast of the United States last year, check out our website.
One of our longest measurement series, and perhaps the best-known, is our carbon dioxide (CO2) data set. At the South Pole, we have been measuring CO2 levels for the better half of a century — more or less since Amundsen-Scott Station first opened in 1957.
The first carbon dioxide measurements made at the South Pole were taken using glass flasks, a physical air sample that was then sent back to laboratories in the United States for analysis. We still use the same method and, over the course of my year on the “ice”, I will take over 1,000 air samples for research facilities all over the world.
Though the flasks are a critical component of our data collection, we only fill them a few times a month; the rest of the time, we take continuous CO2 measurements using an instrument called a LICOR CO2 analyzer.
To understand how the LICOR works, it helps to have a basic understanding of how CO2 behaves in our atmosphere, particularly when it comes to trapping heat energy that radiates off the Earth.
CO2 is one of many compounds (including water vapor and methane) that is considered a greenhouse gas. When energy is emitted by the sun, (in the form of light, some visible some not), and strikes the Earth, some is reflected back into outer space, and some is absorbed by the planet. The total amount of energy that is absorbed keeps the planet warm and at a livable temperature, and is re-radiated upwards at various wavelengths. This isn’t just true for the planet, it’s true for anything that has any temperature: you, me, a brick wall, a cloud — they all give off energy, all the time. It’s how thermal-imaging goggles work and why a hot pizza left on a counter cools down, it gives off energy in the form of heat.
The heat energy that leaves Earth, leaves it in a spectrum of different wavelengths. As it turns out, the most common wavelengths of energy the Earth emits are those that are absorbed by CO2 and other greenhouse gases. When CO2 absorbs the energy bouncing off the planet, it heats up and re-radiates energy in all directions, including back towards the ground. In effect, CO2 acts like the panes of glass in a greenhouse, letting high energy sunlight pass through, to warm the plants and environment inside, and trapping the heat that tries to escape.
During the summer months, air samples are sent back to their corresponding research groups, and new, empty flasks arrive at ARO. Transit to and from Antarctica can be tough on the equipment and the occasional flask is cracked.
The LICOR CO2 analyzer takes advantage of CO2’s ability to absorb energy at specific wavelengths to measure its relative abundance in the atmosphere. Outside air, which contains CO2, is pumped into the instrument at a specific rate.
As the air sample moves through the instrument, a light that emits energy at a wavelength that CO2 absorbs, is shined on the sample. Based on the amount of light absorbed, we can calculate the amount of CO2 present.
As one would imagine, global CO2 levels have been increasing dramatically over the last century. CO2 is a product of combustion, meaning anytime you drive a car, burn coal, or cook over natural gas — activities that have increased dramatically since the industrial revolution — you’re adding greenhouse gasses to the atmosphere and, in turn, helping warm the planet. In fact, thanks to the ever-increasing anthropogenic production of greenhouse gasses, over the past 100 years, the Earth’s temperature has increased by about 1.2F (0.7C). That’s about 10 times faster than the warming that occurred after the last Ice Age.
I check the data the LICOR is producing every day, sometimes multiple times a day. The values we get have increased steadily since I first arrived at the South Pole in November, and currently sit just below 400 parts per million — meaning that for every 1 million air molecules, about 400 are CO2.
As the CO2 levels tick up, you can almost follow the trends in industry and popular culture. From the most remote place on the planet, I can watch oil prices fluctuate and see what cars are the most popular. From the South Pole, I can observe 7 billion people in motion, turning on lights, watching TV, and cracking open a beer.
I can watch the climate change, 1-part-per-million CO2 at a time.
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