Si, si, si lo que cuenta es lo que se mide, eso está claro.
(personalmente el tema del CO2 no es algo al que le vaya a dedicar mucho más tiempo, ya tengo una idea y es algo que para nada me parece preocupante, ... salvo el tinglao asociado y que poco tiene que ver )
Por si sirve, he revisado lo que miden las gráficas de referencia, como las de la NOAA (Mauna Loa o Barrow) y es esto:
fracción molar en aire seco,
...
What do we need to measure?
Most people assume that we measure the “concentration” of CO2 in air, and in communicating with the general public we frequently use that word because it is familiar. The quantity we actually determine is accurately described by the chemical term “mole fraction”, defined as the number of carbon dioxide molecules in a given number of molecules of air, after removal of water vapor. For example, 413 parts per million of CO2 (abbreviated as ppm) means that in every million molecules of (dry) air there are on average 413 CO2 molecules. The table below gives approximate values of gases in the atmosphere for 413 ppm of CO2 in dry air (this is roughly the average amount of CO2 in the atmosphere in the middle of the year 2020). All species have been expressed as ppm, turning 78.09% nitrogen into 780,900 ppm. The rightmost column shows the composition of the same air after enough water vapor has been added to make the mole fraction of water vapor in wet air 3%:
dry air 3% wet air
Nitrogen 780,900 757,473 ppm
Oxygen 209,360 203,079
Water vapor 0 30,000
Argon 9,300 9,021
Carbon Dioxide 413 400.6
Neon 18 17.5
Helium 5 4.9
Methane 2 2
Krypton 1 1
trace species (each less than 1) 1 1
Total 1,000,000 1,000,000 ppm
Why do we express the abundance of CO2 as a mole fraction in dry air?
The concentration of a gas is defined formally as the number of molecules per cubic meter. The goal of our measurements is to quantify how much CO2 has been added to, or removed from, the atmosphere. The concentration does not give us that information because it primarily depends on the pressure and temperature, and secondarily on how much the relative abundance of each gas has been diluted by water vapor, which is extremely variable. Only the dry mole fraction reflects the addition and removal of a gas species because its mole fraction in dry air does not change when the air expands upon heating or upon ascending to higher altitude where the pressure is lower. Nor does it change when water evaporates, or condenses into droplets. Why is this so important? Here is an example: The amount of CO2 is higher in the Northern than in the Southern Hemisphere as a result of the combustion of coal, oil, and natural gas. The measurement of this difference gives us crucial quantitative information about the emissions and removals of CO2. The concentration change produced by the addition of water vapor can be greater than the CO2 difference between the two hemispheres. In contrast, the difference in dry mole fraction does reflect the differences in emissions and removals between the hemispheres.
One often encounters in the literature the term “mixing ratio”. This is ambiguous. Does it apply to mass or to the numbers of molecules? In an attempt to clear that up one also often finds “mixing ratio by volume”, abbreviated as “ppmv” for CO2. However, that can still be ambiguous. Does it mean partial molar volume of CO2 relative to molar volume of whole air? That would only be correct if all the constituent gases of air behaved as ideal gases, which we know is not true. Furthermore, the calibration standards used for greenhouse gases in air are made as, and expressed as, mole fractions in (dry) air. All national metrology institutes, with NOAA/GML representing the WMO Global Atmosphere Watch community (see gml.noaa.gov/ccl/ ), participate in comparisons of reference gas standards that are called “Key Comparisons of Amount of Substance Ratios”. The unit of “amount of substance” is the mole.
...
https://gml.noaa.gov/ccgg/about/co2_measurements.html
Yo estoy un poco contigo y por eso decidí comprar el sensor y realizar las mediciones.
El enlace que has pasado podría explicar la diferencia de medidas entre las oficiales y estas y, lo más importante, deja claro que las condiciones de medida de la NOAA y sobre las que se basa toda la industria climática y miles de noticias al año, NO son condiciones reales de la atmósfera ya que se elimina el vapor de agua.
Parece entonces que la famosa gráfica ascendente de CO2 que está en todo Internet realmente no se corresponde con medidas reales de CO2 (al menos en superficie) y que su forma y oscilaciones anuales serían muy distintas si la medida se realizase a pelo.
Me parece grave que se use de manera oficial una gráfica de CO2 que casi nadie sabe interpretar y muy grave que toda la industria climática use como argumento esas 2PPM molares en aire seco de incremento al año cuando la realidad es que hay oscilaciones de 500PPM debido a causas naturales, al menos en superficie, como ya he dicho.
Muchas gracias por ese enlace, no lo había leído antes y me ha aclarado muchas cosas.
13 Respuestas
2653 Vistas