Tyndall Data Set
Independent Variable / 0.5 / 1.0 / 1.5 / 2.0 / 2.5 / 3.0 / 3.5 / 5.0 / 10.0 / 15.0Dependent Variable / -5.0 / -7.5 / -10.5 / -14.0 / -17.8 / -21.8 / -24.5 / -25.0 / -36.0 / -42.5
Arrhenius Data Set
Independent Variable / 0.67 / 1.5 / 2 / 2.5 / 3Dependent Variable / -3.10 / 3.52 / 6.05 / 7.95 / 9.30
Keeling Data Set
3 / 4024 / 403
5 / 404
6 / 403
7 / 401
8 / 399
9 / 398
10 / 398
11 / 400
12 / 402
13 / 403
14 / 404
15 / 405
16 / 407
17 / 408
18 / 407
19 / 404
20 / 402
21 / 401
22 / 402
23 / 404
24 / 404
25 / 406
26 / 406
27 / 401
Tyndall Data Set (published 1861)
In the 1820’sJospehFourier worked out that the earth was much warmer than it should have been given the amount of radiation from the sun, and he hypothesized that gases in the atmosphere might be trapping or absorbing heat instead of letting it flow out into space.
In 1859John Tyndall built an apparatus that could measure if atmospheric gases could absorb heat as Fourier suggested.
The ratio spectrophotometer
Absorption was measured as the drop in temperature after heated air traveled through a tube filled with gas.
After showing that lab air could absorb heat, he tested each of the components of air separately. Only water vapor and carbon dioxide absorbed heat.
Then he measured the change in absorption as the amount of carbon dioxide in the tube was increased.
The increase in carbon dioxide was in inches of mercury as the CO2 tank was emptied.
CO2 Amount / 0.5” / 1.0” / 1.5” / 2.0” / 2.5” / 3.0” / 3.5” / 5.0” / 10.0” / 15.0”Heat Absorbed / -5.0° / -7.5° / -10.5° / -14.0° / -17.8° / -21.8° / -24.5° / -25.0° / -36.0° / -42.5°
Resources
John Tyndall (NASA Earth Observatory) -
Arrhenius Data Set (published 1896)
In the 1890’s, Svante Arrhenius decided to investigate whether a decrease in carbon dioxide in the atmosphere could be responsible for the ice ages.
Geologists had recently worked out that large sections of earth had been covered with massive glaciers several times in the past and nearly a dozen different hypotheses were proposed to account for it.
Arrhenius knew of the work of Tyndall and others and decided to test the idea that a change in carbon dioxide could cause a change in the earth’s temperature.
It was not possible to do direct measurements on the earth, so instead, he used work on the amount of heat transmitted from the moon as it passed through different amounts of earth’s atmosphere.
The moon, like earth, converts the light from the sun into heat and reradiates it into space. But the moon has no atmosphere, so no heat is trapped, and the amount of heat that should be reradiated can be calculated.
Accounting for the spread of the heat as it travels to earth, it is possible to estimate how much heat from the moon should reach earth.
By measuring this heat when the moon is at different angles in the sky , it is possible to measure how much of it is absorbed at each angle.
Because the angle is correlated with the amount of atmosphere the moon’s heat has to travel through, you can measure how much heat is absorbed by the atmosphere before it reaches earth’s surface.
From that, you can reverse calculate how much of the earth’s outgoing heat must be absorbed, or trapped by the atmosphere.
Arrhenius took this workand did just that.
Using the moon heat absorption data, temperature data from the 1885 Challenger Expedition and humidity records from 780 locations across the planet, he built a model that estimated the change in temperature that would occur with five different % changes in CO2 for 13 latitudes in four seasons and for the year (325 points).
% Change in CO2 / 0.67 / 1.5 / 2 / 2.5 / 3Mean Annual Change in Temperature at 40° N Latitude / -3.10 / 3.52 / 6.05 / 7.95 / 9.30
Resources
Svante Arrhenius (NASA Earth Observatory) -
Keeling Data Set (1958 to the present)
When Charles David Keeling was a graduate student at Caltech in the 1950’s he started a research project studying ari and water samples collected every few hours throughout the day and night at remote locations.
Using a gas manometer, he was able to reliably measure carbon dioxide concentrations to 0.1%.
One of the things he discovered is that CO2 increased at night and decreased during the day, with a nearly constant concentration of 310 ppm (parts per million) in the afternoon.
This was a much more regular result than any other researchers had been able to obtain.
Working with the Weather Bureau and the Scripps Institution of Oceanography (headed by Roger Revelle), Keeling set up a monitoring station at the Weather Bureau’s Mauna Loa Observatory in Hawaii, an ideal location for collecting air samples far from human influence.
He was using a new infrared gas analyzer to perform continuous measurements of CO2, but calibrated using his earlier manometric techniques to ensure that the data were of high quality.
Data collection began March 29, 1958, with CO2 at 313 ppm.
Within a year, the data showed seasonal oscillations in CO2 concentration with peaks in May and lows in November, due to the uptake of CO2 by plants in summer, and the release of CO2 from decaying vegetation in the winter.
Keeling also found that the average CO2 had gone up and that together with data from an Antarctic station, suggested that CO2 was increasing in the atmosphere.
The potential for the increase to signal a trend convinced the scientific community to continue the project as a long term study in order to see if the increase was correlated with fossil fuel use.
Year / Month / CO2 ppm2015 / March / 402
2015 / April / 403
2015 / May / 404
2015 / June / 403
2015 / July / 401
2015 / August / 399
2015 / September / 398
2015 / October / 398
2015 / November / 400
2015 / December / 402
2016 / January / 403
2016 / February / 404
2016 / March / 405
2016 / April / 407
2016 / May / 408
2016 / June / 407
2016 / July / 404
2016 / August / 402
2016 / September / 401
2016 / October / 402
2016 / November / 404
2016 / December / 404
2017 / January / 406
2017 / February / 406
2017 / March / 401
Resources
The Keeling Curve: Carbon Dioxide Measurements at Mauna Loa (American Chemical Society) -