Each one of the four major greenhouse gases: H2O, CO2, CH4, and N2O does absorb the Sun radiation and thereby contributes in various degrees and ways to the global warming and to various environmental effects connected to it. H2O plays a special role. It has been heavily disputed among scientists since the middle of the 1800´s whether H2O or CO2 is playing the most important role for the global warming. It is essential to try and settle this and sort out who is playing the largest role – particularly in terms of ENERGY (heat, temperature) – to bring out the solution of the complex problem of global warming and climate change.
The increases and the latest reported concentrations of the four major greenhouse gases in the atmosphere since about the year 1980 when the global temperature started a mostly steadily increase are:
H2O: there is so far no reliable method presented for the measurements of its more precise average annual concentration and increase of its concentration in the atmosphere. That´s why the commonly used annual average value of 3% (equal to 30 000 ppm) for the year 1980 is used here. In order to find a reliable value of the increase during the time after 1980 measurements of the quantities of water in saturated air and clouds according to the following Figure 4 has been used to get probable and useful data. The Figure shows the amount of H2O as grams per cubic meter that saturated air and clouds are holding at various temperatures and at normal pressure.
It can be calculated from Figure 4 that the concentration of water vapor in the air increases by 7% per centigrade of temperature increase for the general average global temperature interval of around 15 degrees centigrade. For the period from 1980 and including 2016 the global temperature increase has been from 0.27 to 0.99 degrees centigrade above the reference level for 1980, or by 0.72 degrees centigrade. This corresponds to an increase of water vapor by 30000 x 7% x 0.72 = 1512 ppm. This value seems to be supported by the increase of the specific humidity of about 0.3 grams of water vapor per kilogram of air (= about average 3 %, although with some variations) over land and ocean during the period from 1980 and up to 2013 as reported by NOAA.
We have thus got for water vapor:
According to NASA/NOAA has been measured for CO2:
According to measurement by NASA/NOAA for CH4:
According to measurements reported by NASA/NOAA for N2O:
Water vapor has for a long time had a much higher concentration in the troposphere than the other three major greenhouse gases and much higher increase of the concentration in absolute numbers - but lower in relative extent.
Furthermore: The absorption of the light energy over its wave lengths/frequency spectrum is much higher for water vapor than for carbon dioxide as shown in the following Figure 5 published by Harvard edu.
Figure 5 by Harvard Education - Lecture 7 - Absorption/emission by atmospheric gases. Solar, IR and microwave spectra of main atmospheric gases .
The total energy absorption of water vapor is thus very much higher than for the other three major greenhouse gases which means that water vapor is the most important greenhouse gas. This is necessary information for the task before us: to find a workable solution for the global warming and climate change problem complex.
A study of the essential ENERGY properties of the four major greenhouse gases in the table in figure 6 below reveals how unique H2O is and how superior it is compared to the other three major greenhouse gases when it comes to the absorption and storing of large amounts of ENERGY.
|Gas||Melting temperature °Centigrade||Boiling temperature °Centigrade||Specific heat kJ/kilogram and degree (at 15° C)||Heat of vaporization kJ/kilogram (at 20° C)|
|CO2||-56 (at 5 atm)||-78.5 (sublimes)||0.832||147|
|CH4||-182.5||-161.5||2.210||510 (at -161.6 °C)|
H2O is the only one that exists in the three phases of: solid, liquid and gaseous at the existing temperatures in the seas, on the ground and in the troposphere. It is therefore the only one to absorb large amounts of ENERGY when melting and by vaporization. It transports enormous amounts of ENERGY around the globe.
Another factor that makes H2O unique in comparison to the other greenhouse gases is that it has (except for CH4) lower density. This makes H2O rising in the air more quickly after being emitted, mixing with other greenhouse gases – particularly with CO2 - forming clusters and complexes, and soon being cooled off and forming drops, clouds and then precipitates.
CO2 plays another important role in the “global warming drama” than being unnecessarily appointed to a kind of rival to H2O to the first and most important place when dealing with “the management of the ENERGY in the overall process”. Some of the CO2 emitted instead joins H2O in a rather loose “marriage” as carbonic acid and precipitates/goes back to the land areas and to waters, some of the CO2 emitted stays in the air and is dissolved in waters like the oceans and causes together with the carbonic acid an ongoing acidification of the oceanic waters which is harmful for some kinds of the organisms there, like e.g. the corals. A good part of the CO2 in the atmosphere is absorbed by the plants in the photosynthesis process.
H2O in liquid form on the ground, in wet material, in wetland areas and from the surfaces of open waters, lakes, seas and oceans all the time evaporates into the atmosphere in enormously large quantities and thus contributes with great amounts of water vapor “emitted” into the atmosphere and then makes shorter or longer journeys there before it precipitates. H2O is also a great ENERGY transporter around the globe in gaseous or liquid form by jet streams in the atmosphere and by the streams in the oceans.
The world population is growing presently by about 80 million people per year (abt. 1%) which means one billion people more on Earth after about every 13 years and so on… This means that we will get a demand for continuously increased consumption of energy and further higher increases also due to demands of higher and higher standards of living from less advanced groups of people. As a consequence we can expect a demand on increased global energy consumption.
Going back to Figure 3. we have there an overwhelming proof of the importance of the size and the growth of the world energy consumption from the fossil fuels in comparison to other sources in terms of the amounts and of the continuing increases by time (with the years 2008 – 2009 being exceptions) which have also been foreseen by the EIA (US Energy Information Administration) to continue at about the present rate for oil and natural gas (but no growth for coal) in their International Energy Outlook to 2040 published in 2017.
Another factor of importance is the general world economic activity which is determining the GDP (Gross Domestic Product) growth. A characteristic example of this is the data of annual growth changes presented by the World Bank for the years 1980 to 2016:
This is well in line with the clear downturn of the world fossil energy consumption for the years 2008 and 2009 for all: oil, coal and natural gas according to Figure 3. It is also visible in the global annual temperature curve according to Figure 1 with “Lowess Smoothing” and thereby adds to the evidence for the conclusion that the burning of the fossil fuels is an important cause of the global warming.
The high ability of water vapor to absorb sun radiation and its overwhelmingly high concentration in the atmosphere means that it is the superior carrier of ENERGY (heat) in the atmosphere around the globe among the greenhouse gases. To evaporate 1 kilogram of water at the temperature of 20 degrees centigrade requires about 2450 Joules and about 2250 Joules at 100 degrees centigrade which means that water vapor holds enormously large quantities of latent energy which are released at specific conditions to produce thunderstorms, heavy rainfalls, floods etc. Water vapor thus takes the most active part in various air movements like hurricanes, jet streams etc. with increasing devastating effects which cost the states and insurance companies increasingly large amounts of compensation for damages and failing production as the global warming increases.
Much misunderstanding about the greenhouse gases – particularly regarding H2O and CO2 when described in the mass media – often occur. One prime example is in connection with pictures of emissions from smoke-stacks (even from cooling towers at nuclear power plants!) where it says that it is CO2 that comes up and out therefrom when it really is condensing water vapor!(CO2 is an invisible gas at normal temperatures.)