Atmosphere

 

Understanding Global Warming

Earth Atmosphere

Figure 1. Astronomy - Ch. 9.1: Earth's Atmosphere (29 of 61) by Michel van Biezen – Video No. 29.

Figure 2. Black body radiation curve for the Earth with absorptions bands for the various greenhouse gasses. The yellow colored area is not overlapped by water vapor absorption and represents the major contribution by carbon dioxide. Video No. 21.



Greenhouse gasses (GHG) are keeping us nice and warm with an average temperature of app. 15 oC. Without GHG the temperature on Earth would be 33 oC colder. The solar energy received at the upper atmosphere is 1361 W/m2 of which 48% reaches the surface of the Earth and then radiated back. However 5-6% of the incoming energy and reflected from the Earth is temporarily absorbed by GHG and thereby delaying the radiation back to space – the more delay the warmer it gets – Video No. 4.

Water vapor and CO2 are together responsible for 98-99% of the greenhouse effect, of which CO2 7½ % ~ 2½ oC. The Water the most because as a true dipole it has many absorptions modes covering a large part of the radiation spectrum. But there is a water vapor window where water vapor absorption is not completely overlapping the carbon dioxide absorption at 14-16 µm.

Figure 3. Astronomy - Ch. 9.1: Earth's Atmosphere (61 of 61) The Greenhouse Effect: What can we Conclude? By Michel van Biezen. Video No. 61.

Figure 4. Michel van Biezen  – Video No.: 56.

The effect of GHG depends also on the gas concentration. Half the effect of CO2 is achieved already at 20 ppm. Doubling the present level of 400 ppm will not raise the effect much. If, however, an even small effect of CO2 will raise the temperature this may cause more water to evaporate and cause a feedback mechanism thereby gearing the CO2 effect. Measurement of TPW (Total Precipitable Water) in the troposphere during satellite time does not confirm this is happening to any significant extent. Overestimation this feedback may be a major reason the climate models predict higher temperatures than actual being measured. Antero Ollila, Aalto University explain this in greater detail in “Challenging the Greenhouse Effect Specification and the Climate Sensitivity of the IPCC” – PCIJ 2019 and “Absorption in the Atmosphere” – video No. 5.

From IPCC AR5 we know that the atmosphere contains app 830 Gt carbon as carbon dioxide. IPCC also estimates the fossil carbon pool at 1.000-2.000 Gt carbon. Burning fossil fuels, half the carbon dioxide released will add to the atmospheric content and the other half is absorbed by the hydrosphere and the biosphere. This is contributing to the observed increase of carbon dioxide in the air. This extra carbon dioxide will not stay in the air forever but will eventually be absorbed by the oceans and plants. Pieter Tans has calculated how the atmospheric content of carbon dioxide will change if we burn 1.000 Gt and 1.500 Gt carbon respectively from the fossil pool – it is burning most of the known proved reserves. This will, however, never increase the concentration to more than at the most 600 ppm of carbon dioxide in the air – Carbon Pools.

So even burning all our known proven fossil reserves of carbon the atmosphere will peak at 600 ppm CO2 around year 2060 acc. to the assumptions made by Peter Tans. As explained by Michel van Biezen this will not contribute much to the temperature increase. That leaves us with the sun as the crucial climate driver.

CO2 emission and its distribution.

From Global Carbon Atlas[1] is downloaded annual emissions from gas, oil, coal, gas flaring and cement calculated as Gt C and from NOAA[2] CO2 at Mauna Loa as CO2 ppm and transformed to Gt C. The difference between emission and the part remaining in the air is absorbed by the ocean and land – the annual Flux is in Gt C.


Figure 5. The annual emissions calculated as GT C Carbon (blue) is subtracted the annual increase of carbon dioxide in the air calculated as GT C (maroon). The difference  in GT C must be absorbed in Land and Sea (gray). The emission is slowing down and so is the flux to Land & Sea, but the concentration of CO2  in the air is not - the concentration af CO2 in the air is climbing steadily. It seems that the air's content of CO2 is to a greater extent determined by an equilibrium between sea and air and less by the emissions and that equilibrium is shifting steadily due to an increasingly warmer ocean.



The rise in atmospheric CO2  fits with several things, burning of fossil fuels, time, heat, the world population, number of cars. Here is a correlation with rising sea temperature, where Henry's law gives a certain causal connection - but how big is the contribution from Henry's law? 
The sea temperature source:  Average Global Sea Surface Temperature, 1880-2015 - Link

Henry's law and its contribution to the increase in air CO2 is commented on at this Link.

In a closed system with carbon dioxide and water, it is easy to show that heat shifts the equilibrium towards more CO2 in head space and less in the water. On the other hand, it is not possible to show that the addition of CO2 increases the temperature regardless of the incidence of light - any kind of light.


When carbon dioxide CO2  is released into the atmosphere from the burning of fossil fuels, approximately 50% remains in the atmosphere, while 25% is absorbed by land plants and trees, and the other 25% is absorbed into the ocean. That is how it has been since measurements at Mauna Loa began. However, will this continue if the emission is reduced or will the flux air/sea&land follow the concentration and partial pressure of CO2  in the air? The latter is pictured below.


With increasing CO2 in the atmosphere, the uptake of CO2 in the sea and land increases, but at just over 380 ppm a certain saturation is detected. Sea and land appear to have a capacity of 5 GT C uptake per year

With increasing CO2 in the atmosphere, the uptake of CO2 in the sea and land increases, but at just over 380 ppm a certain saturation is detected. On land, the lack of other nutrients and water limits the plants' utilization of ever more CO2. In the oceans, surface water is saturated. Other circuits and simple mixing with deeper water cannot transfer CO2 to deeper water fast enough. This is hardly the full truth, because in recent years we have only added an extra 9 GT C to a total CO2 turnover which the IPCC estimates at approx. 200 GT C annually. An increase in turnover of "only" 5% should result in an annual increase in the atmosphere of 4 GT C would be surprising.

It only took a dozen years for radioactive CO2 created by atomic bomb tests to disappear - or rather to be replaced with CO2 from sea and land.

However, saturation of surface water and land is the only plausible explanation at the moment for the delay in CO2 uptake.


[1] Global Carbon Atlas. http://www.globalcarbonatlas.org/en/CO2-emissions

[2] NOAA. https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html


Understanding Global Warming, Oversigt - LINK






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