Does the concentration of CO2 gas in the atmosphere cause warming of the earth's atmosphere? Or does it lead to less rainfall when it warms up? Or does the warming of the earth's atmosphere lead to an increase in rainfall on the earth's surface?

Equilibrium Climate Sensitivity (ECS) is the global mean change in surface temperature for a doubling of CO2 from the pre-industrial (PI) value. ECS is one of the key metrics used in assessing future global warming, and therefore plays a very important role in climate change related policy-making. One important question in this regard is how ECS changes in a warmer world. Several studies found that ECS increases at higher CO2 concentrations (e.g., Bloch-Johnson et al., 2021; Colman & McAvaney, 2009; Gregory et al., 2015; Meraner et al., 2013). And, more recently, Mitevski et al. (2021) found a non-linear and non-monotonic dependence of ECS on CO2 concentrations. In addition to the surface temperature response, the precipitation response is another critical aspect of climate change. To evaluate precipitation changes, the key metric used is Hydrological Sensitivity (HS). HS is defined as the difference in global mean precipitation per one degree of global mean temperature change from the PI control state. Previous studies have explored the response of the hydrological cycle to global warming by examining HS in terms of the global energy budget, and have described the mechanisms affecting it (e.g., Allen & Ingram, 2002; Held & Soden, 2006; Jeevanjee & Romps, 2018; O'Gorman et al., 2011). The fact that HS is energetically constrained means that the precipitation response can be separated into fast and slow components. The fast response depends only on the CO2 concentrations in the atmosphere, before the surface temperature has time to warm, and results in a decrease in precipitation. The slow response, in contrast, is associated with surface warming, and results in an increase in precipitation (Andrews et al., 2010).

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James Garry added a reply:

Mr Kashani,

You have written two rather facile queries, and part of a third.

"Or doe"

Abbas Kashani added a reply:

Does the concentration of CO2 gas in the atmosphere cause warming of the earth's atmosphere? Or does it lead to less rainfall when it warms up? Or does the warming of the earth's atmosphere lead to an increase in rainfall on the earth's surface?

James Garry added a reply:

Abbas,

1) Yes, the rising carbon dioxide content of the atmosphere does lead to an increase in the surface and globally-averaged air temperature.

2) As the partial pressure of water vapour is a strong function of temperature (and that vapour is also a 'greenhouse gas') we expect to see a rise in the global humidity - that in various locales should result in more rainfall.

Neither of these are contentious matters and are well-addressed in the literature.

1) https://journals.ametsoc.org/view/journals/atsc/47/4/1520-0469_1990_047_0475_ccatma_2_0_co_2.xml

2)

Article More rain, less soil: Long-term changes in rainfall intensit...

I recommend Google Scholar.

Very useful.

Mrutyunjay Padhiary added a reply:

Through the greenhouse effect, the amount of carbon dioxide (CO2) gas in the atmosphere is a significant contributor to global warming with many other greenhouse gases. Heat from the sun is trapped in the atmosphere when CO2 and other greenhouse gases build up, preventing it from escaping back into space. Global warming is the term for the total rise in temperature that results from this. Rainfall patterns can be impacted by Earth's atmosphere warming, while there is a complex relationship between CO2 concentrations and rainfall that varies based on local climate dynamics. Higher temperatures generally have the potential to alter the rates of evaporation and atmospheric circulation, which in turn can affect the patterns of precipitation. higher moisture can be held by warmer air, which could result in higher evaporation from lakes, oceans, and land surfaces. In certain areas, the increased moisture in the atmosphere may be a factor in the intensity of rainfall events. Higher temperatures, however, can also bring about modifications to weather patterns, including adjustments to air circulation and modifications to precipitation distribution. Also, variables including local geography, atmospheric stability, and variations in cloud cover can all have an impact on changes in rainfall patterns. While some places might have more rainfall than others, other regions might see less rainfall or changes in the frequency and severity of precipitation events. The ecosystems, agricultural practices, water supplies, and human societies may all be significantly impacted by these modifications in rainfall patterns. All things considered, even while the rise in CO2 concentrations in the atmosphere is the main cause of global warming, temperature variations that follow can have an impact on precipitation patterns, which can have complicated and varied impacts on the distribution and intensity of rainfall.

Michael Girimay Gebremedhine added a reply

Yes, the concentration of CO2 gas in the atmosphere does cause warming of the Earth's atmosphere. This is due to the greenhouse effect, where CO2 and other greenhouse gases trap heat from the sun, leading to an increase in the overall temperature of the Earth.

As for its effect on rainfall, the relationship between CO2 concentration and rainfall is complex and can vary depending on regional and global climate patterns. In general, however, a warmer atmosphere can lead to changes in precipitation patterns, including shifts in rainfall distribution and intensity. These changes can result in both increased and decreased rainfall in different regions.

Alexander Kolker added a reply

The statement such as "Increase in carbon dioxide gas in the air ... prevents the flow of long-wave radiations through the atmospheric layers thus retaining it. As a result, the atmosphere warms up leading to 'global warming'." can be found in 1000's of posts, blogs, papers, reports, etc, etc.

However, if one looks at simple physics and the energy balance in the atmosphere, it would become obvious that it is nonsense, of course setting aside the politics behind all global warming screams and alarmism.

Yes, it is well known that CO2 molecules have an absorption band of the infrared radiation (IR) around ~15 um that comes out of the Earth's surface, although the water vapor in the atmosphere is a much more potent IR absorber.

However, that absorbed energy cannot stay in the excited molecules for long and is radiated back in all directions. But even if we neglect all that radiation and look simply at the energy balance we can find that the excitation energy absorbed by CO2 must be transferred somewhere, i.e. to heat the entire atmosphere. A process of transferring the excitation energy (rotational, vibrational, and momentum) to the surroundings through molecular (mostly elastic) collisions is called thermalization. From the simple balance, we could see

Cp(co2)* M co2 *deltaTco2 = Cp air *Mair *deltaTair.

The ratio of the heat capacities of the CO2 and the air is about 0.89 in the temp range 300 - 350 K.

The content of CO2 in the air is about 420 ppm or ~0.05% weight, while the rest of air (N2, O2, Ar, and traces of other gases) is about 99.95% weight.

Hence, delta T air = 0.89 *0.05/99.95 * deltaT co2= 4.45 *10^-4 * deltaT co2 C.

If CO2 heats up due to infrared absorption by, say, deltaT co2 ~1 C, then the air (the entire atmosphere) will heat up to ~4.45.10^-4 C, that is an absolutely negligible amount.

In order to get the air (atmosphere) to increase the temperature to, say, 1.5 C, the amount of CO2 in the air must be about ~63% weight, i.e. the ratio CO2/air must be about 1.7 !!. In other words, the atmosphere must consist of about 2/3 of pure CO2. This takes place on Venera, or some other distant planets but will never happen on Earth in any scenario for 100000 years.

Of course, the above energy balance is oversimplified, and the physics of heating up or cooling down the atmosphere is much more complex and non-linear. However, the bottom line is that a minuscule amount of CO2 cannot result in global catastrophic warming. Assuming that human-produced CO2 is the only factor affecting the entire atmospheric temperature is a total nonsense and a typical alarmism which is fed by politics and financial interests.