I enjoy reading the blog by Dr. Jeff Masters at Weather Underground. In a recent post, Bob Henson said that atmospheric CO2 had reached a new high value. His supportive evidence linked to the Keeling Curve data maintained at Mauna Loa in Hawaii by the Scripps Institution of Oceanography. Each day you visit the Keeling Curve page, the most recent CO2 value is posted above the charts.
The images in this gallery were each obtained by hovering my mouse pointer over the time spans below the chart. As you go through the gallery, notice the cyclical pattern evident in the 1 yr, 2 yr, and 1958-to-Now images. Also note the rapidly increasing trend toward higher CO2 levels in the 1700-to-Now image. The impact we humans have had on the levels through fossil fuel use during this era is quite apparent. The final image includes a huge span of time inclusive of several global warming and cooling episodes. None of those episodes had levels of CO2 near those of today.
Keeling Curve Gallery
Global Monitoring of Greenhouse Gases
I’ve also been exploring the Earth System Research Laboratory – Global Monitoring Division to see what the data shows about greenhouse gas measurements, specifically Carbon Dioxide (CO2). The Earth System page looks like this screen capture below. It is an interactive map of monitored sites with many ways of displaying the data. Click it to visit the actual map and page.
The default site is the Mauna Loa station in Hawaii which has maintained continuous CO2 measurements since 1958. Notice the drop down choices to the right of the map. If you follow the link of the map and click Carbon Cycle Gases, you get these following choices.
A click on Time Series will give you another set of options. For this post, I tried out the four Time Span options and plot types above to see what they yielded. What follows are some observations.
CO2 Shows Seasonal Variations
The Mauna Loa data from the middle of the Pacific Ocean for the recent 2 years shows this cyclical pattern. Global winds carry the gases of the atmosphere and mix them quite thoroughly by the time they reach Hawaii. During the May to September time span, vegetation is increasing in the northern hemisphere. Plants take in CO2 to produce energy and O2. The atmospheric levels of CO2 decrease. From October to April, much of the vegetation decreases or goes dormant causing the CO2 levels to rise. Each year the peak value of CO2 is higher than the previous year.
A Specific Iowa Example
Here is the seasonal variation curve for just over 4 yrs at a monitored site near me in east central Iowa. The air samples are from ground level. This site is in the middle of the agricultural heartland of the U.S. Notice how the plot drops sharply from April to July as the growing season occurs. It remains well below the grey line average due to photosynthesis until about October. During the winter months November to March, the CO2 levels are high. Vegetation is not using the CO2 in the atmosphere of the northern hemisphere.
The Effect of Altitude
Data from the same Iowa site includes samples of gases from many different altitudes. A date of January 14, 2015 is used to illustrate this effect. That date would mean CO2 is at a peak value of about 413. The left-most chart shows the CO2 levels are less with higher altitude. High speed upper air patterns effectively mix the atmospheric gases. The more concentrated levels are found near ground level close to the decaying vegetation and soils. The same effect is shown for Methane CH4 and Carbon Monoxide CO.
Northern and Southern Hemisphere CO2 Different
This 3-D chart needs some explanation in order to fully understand all it displays. The horizontal axis is time. It covers the span from 2000 to 2010. The vertical axis is CO2 levels measured at dates along the time axis. Notice the cyclical pattern year-to-year of increases followed by decreases. The data for the Iowa location is in red. Over time, the trend of the CO2 values is increasing from left to right as expected. Sites all over the world report this same increasing trend.
The third axis on the bottom of the chart is the global latitude north and south of sites monitored for this chart. Both hemispheres exhibit a cyclical pattern. The northern hemisphere CO2 levels are significantly larger due to the greater amount of vegetation.
There is one more subtle effect shown in this chart. The peaks and valleys of the southern hemisphere are offset 6 months from those of the northern hemisphere. It is hard to see without being able to rotate the chart.
North Polar vs South Polar CO2 Changes
Comparison of two far north and far south stations is interesting. The one farthest north is at Alert, Nunavut, Canada 82.5˚N. According to the chart above, this station should see a large cyclical pattern from season to season. Here is their most recent data showing about a 15 point amplitude. Orange data points have yet to be certified.
The one farthest south is at the South Pole Station. It shows a small variation from season to season of only a couple of points. Notice the offset of 6 months between the peaks and valleys of these two charts.
Most of us are aware of the trend toward rising CO2 levels. Fewer realize the wide extent of the data collected and the efforts to certify the validity of the data. I have found it very interesting how much information is available. Climate change is taking place. The data recordings are widespread and cover a wide range of time. I don’t understand how anyone who claims to have an open mind can claim it is not happening. If we have gone past the point of no return, we should still strive to develop ways to run our economies with less negative impact on the planet. It can be done.