Introduction
In 2009, the global average carbon dioxide (CO2) concentration in Earth’s atmosphere was about 0.0387% by volume, or 387 parts per million by volume (ppmv). Despite its relatively small overall atmospheric concentration, CO2 is an important component of Earth’s atmosphere because it absorbs and emits infrared radiation resulting in a phenomenon known as the Green House Effect. Cities are local hotspots for emissions resulting from human activities. Working together with the Pacific Science Center and Seattle’s Space Needle, NOAA’s Pacific Marine Environmental Laboratory has installed a carbon dioxide sensor on the top of the Space Needle to examine the variability in atmospheric CO2 over Seattle.
Daily Graph - This shows data collected every 5 minutes over the last 72 hours on the Space Needle. Variations in CO2 are related to human activities in and around the city (number of cars on the road, gas heating and cooking, etc.) as well as the local weather patterns (windy weather will blow locally produced CO2 away). |
Monthly Graph - This shows hourly averaged CO2 data collected on the Space Needle and from a buoy off the Washington coast (west of Aberdeen, WA) over the last 30 days. The CO2 values over Seattle are higher and much more variable because many of our daily activities such as cooking with gas or driving to work release CO2 into the atmosphere. |
Seasonal Graph - This shows daily averaged data collected on the Space Needle and from a buoy off the Washington coast (west of Aberdeen, WA) over the last few years. The Space Needle instrument was installed in February 2010 so the data record is still short, but the offshore buoy has been recording atmospheric CO2 since June of 2006. We measure the CO2 offshore because that usually gives us a good clean record of CO2 concentrations in the air entering the United States before local CO2 sources increase the CO2 levels. The seasonal CO2 cycle reflects natural variations in the growth of land plants in the Northern Hemisphere. In the spring and summer plants pull CO2 out of the atmosphere as they start to grow and put on leaves. This growth makes a noticeable drop in the northern hemisphere atmospheric CO2 concentrations. In the fall and winter when plants begin to die back and trees drop their leaves, the atmospheric CO2 increases. |
To learn more about how to read the plots or interpret what you are seeing, click on the links on the left hand side of the page.
Instrument developed by A. Jenkins, C. Cosca, S. Jones, and C. Sabine (NOAA/PMEL) with support from the Space Needle and Pacific Science Center. Figures provided by S. Jones (NOAA/PMEL). Text developed by C. Sabine and S. Jones (NOAA/PMEL).