Do greenhouse gases affect climate change and how does ozone layer depletion contribute to global warming?

Yes, greenhouse gases play a significant role in climate change, and the depletion of the ozone layer also contributes to global warming, albeit through somewhat distinct mechanisms.

Let's explore both aspects:

In summary, greenhouse gases are a primary driver of anthropogenic climate change, as they intensify the natural greenhouse effect and lead to global warming. Ozone layer depletion, while not a direct contributor to global warming in the same way, can have implications for the upper atmosphere and atmospheric circulation. Both issues are significant environmental concerns that require international cooperation and concerted efforts to mitigate their impacts.

Dr Gaurav H Tandon thank you for your contribution to the discussion

Although synthetic greenhouse gases do not damage the ozone layer, they have global warming potential meaning they contribute to climate change. The first synthetic greenhouse gases developed had a high global warming potential. As greenhouse gas emissions blanket the Earth, they trap the sun's heat. This leads to global warming and climate change. Five key greenhouse gases are carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, and water vapor. While the Sun has played a role in past climate changes, the evidence shows the current warming cannot be explained by the Sun.Since the Industrial Revolution, human activities have released large amounts of carbon dioxide and other greenhouse gases into the atmosphere, which has changed the earth's climate. Natural processes, such as changes in the sun's energy and volcanic eruptions, also affect the earth's climate. Carbon dioxide is responsible for 53% of the level of global warming. It is the result of processes such as fuel use, deforestation and production of cement and other materials. Global warming is the change in the climate of the earth causing it to heat up whereas the greenhouse effect is a naturally occurring phenomenon, constantly occurring due to the atmosphere and sunlight. Greenhouse gases absorb this infrared radiation and trap its heat in the atmosphere, creating a greenhouse effect that results in global warming and climate change. Many gases exhibit these greenhouse properties. Some gases occur naturally and are also produced by human activities. Greenhouse gases act similarly to the glass in a greenhouse: they absorb the sun's heat that radiates from the Earth's surface, trap it in the atmosphere and prevent it from escaping into space. The greenhouse effect keeps the Earth's temperature warmer than it would otherwise be, supporting life on Earth. Ozone layer depletion does not cause the greenhouse effect. It allows more ultraviolet energy to reach the Earth's surface, but it does not affect the absorption of heat inside the atmosphere. Expected cooling of the stratosphere caused by increases of greenhouse gases, most importantly CO2, essentially influences the ozone layer by two ways: through temperature dependencies of the gas phase reaction rates and through enhancement of polar ozone depletion via increased PSC formation. When the ozone hole forms each spring, total ozone concentrations in the lower stratosphere dip. The annual dip has caused a strong springtime cooling trend in the lower polar stratosphere over the past few decades. This springtime cooling amplifies the temperature contrast between the poles and the equator. Ozone depletion and climate change are linked in a number of ways, but ozone depletion is not a major cause of climate change. Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere. Chlorofluorocarbons or CFCs are the main cause of ozone layer depletion. These are released by solvents, spray aerosols, refrigerators, air-conditioners, etc. The molecules of chlorofluorocarbons in the stratosphere are broken down by ultraviolet radiations and release chlorine atoms.

Borrowing from EC web site: The main driver of climate change is the greenhouse effect. Some gases in the Earth's atmosphere act a bit like the glass in a greenhouse, trapping the sun's heat and stopping it from leaking back into space and causing global warming.

Next, Sunshine is the panacea to all diseases but without ultraviolet rays. Save the Ozone layer, save a life.

"Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth's surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability". Abstract of the well-cited paoer:

Barnes, P. W., Williamson, C. E., Lucas, R. M., Robinson, S. A., Madronich, S., Paul, N. D., ... & Zepp, R. G. (2019). Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future. Nature Sustainability, 2(7), 569-579.

Dr Anton Vrdoljak and Dr Jamel Chahed thank you for your contribution to the discussion

UV radiation releases heat into the stratosphere when it reacts with ozone. With less ozone there is less heat released, amplifying the cooling in the lower stratosphere, and enhancing the formation of ozone-depleting polar stratospheric clouds, especially near the South Pole.In a direct reduction in phytoplankton production due to ozone depletion-related increases in UVB. UVB radiation has been found to cause damage to early developmental stages of fish, shrimp, crab, amphibians, and other marine animals. Ozone depletion, on the other hand, is a radiative forcing of the climate system. Two opposite effects exist: Reduced ozone causes the stratosphere to absorb less solar radiation, cooling it while warming the troposphere; as a result, the stratosphere emits less long-wave radiation downward, cooling the troposphere. Ozone (O3) forms a layer in the upper atmosphere. It is essential for the survival of life on this planet. It shields the surface of Earth from harmful ultra-violet radiation (UV) coming from the Sun as these radiations can cause skin cancer and cataract in humans. It also harms the crops. Ozone is a gas made of three atoms of oxygen. It is a hazardous gas that is prevalent high up in the atmosphere. Ozone is a vital gas for all sorts of ecosystems on earth as it protects the environment from the damaging effects of UV radiation causing skin cancer and cataract and impairs our immune system. Ozone layer prevents UV rays from the sun to penetrate down the earth. Due to ozone depletion, UV rays strikes the earth surface. This can lead to various environmental issues including global warming and also a number of health related issues for all living organisms. Ozone layer depletion does not cause the greenhouse effect. It allows more ultraviolet energy to reach the Earth's surface, but it does not affect the absorption of heat inside the atmosphere. As greenhouse gas emissions blanket the Earth, they trap the sun's heat. This leads to global warming and climate change. The world is now warming faster than at any point in recorded history. Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature.

On Climate Models: From General Circulation Models (GCMs) and Earth System Models (ESMs). General Circulation Models (GCMs)which are the core of weather forecasting Models appeared in the 1960s with the pioneer's work of Manabe (2021 Nobel Prize in Physics). A fundamental point is that is difficult to speak about GCMs and even less of Climate Models without a minimum review starting from Atmosphere Dynamics Models genesis in the 1960s to the actual Earth System Models (ESMs) that participated in the last "CMIP6". These represent the State-of-art of universal knowledge about Climate and its modeling. The results published in 2021 covers 80 ESMs from as many research teams throughout the world. Nowadays, Climate Science and Modelling have attained an international critic-mass never reached in any other domain.

ESMs include a number of components that try to describe the evolution of intercoupled phenomena that govern Climate Phenomena. To understand how this works, one has to know about the progress achieved and still-opened questions related to Climate Models. Mathematically the resolution of the dynamic and the transport equations of physical quantities on more or less important scales provide accurate predetermination in a relatively short time. This is what meteorologists do to deliver us every day their newsletter. This is what the same meteorologists are trying to do with scientists from all sides to build climate models in the long term, sure inaccurate today, exactly as was the 1960s weather model of Manabe, Nobel Prize in Physics 2021, the pioneer of general circulation modeling. The very first general circulation models were based on atmosphere-only physical models (Manabe et al., 1965, Nobel Prize in Physics, 2021), which were quickly improved to take into account the hydrologic cycle and its role in the general circulation of the atmosphere (Smagorinsky et al. 1965). From there, climate modeling has made considerable progress by gradually integrating the many positive or negative feedback processes that occur at different scales between the different components of the system: ocean circulation (Manabe and Bryan, 1969), land hydrological processes (Sellers et al., 1986), sea ice dynamics (Meehl and Washington, 1995), and aerosols (Takemura et al., 2000), biophysical and biogeochemical processes (Cox et al., 2000). Models with these latter components are often called Earth System Models (ESMs) and more recent such models include land and ocean carbon cycle, atmospheric chemistry, dynamic vegetation, and other biogeochemical cycles (Watanabe et al., 2011, Collins et al., 2011). It should be noted that as a whole and for the same reasons, the horns of ESMs, which are based on physical formulations similar to those employed in general circulation models applied in meteorology, have not evolved much, except for the increase in the resolution of the calculations made possible thanks to the increase in the computing capacity or their capacity to assimilate increasingly abundant and precise data; in particular global satellite data, which complements and connects measurements on the ground or at low altitude.

Manabe, S., Smagorinsky, J., & Strickler, R. F. (1965). Simulated climatology of a general circulation model with a hydrologic cycle. Monthly Weather Review, 93(12), 769-798.

Smagorinsky, S. Manabe, and J. L. Holloway, “Numericd Results From a Nine-Level General Circulation Model of the Atmosphere,” Monthly Weather Review, vol. 93, No. 12, Dec. 1965, pp. 727-768.

Manabe, S., & Bryan, K. (1969). Climate calculations with a combined ocean-atmosphere model. J. Atmos. Sci, 26(4), 786-789.

Sellers, P. J., Mintz, Y. C. S. Y., Sud, Y. E. A., & Dalcher, A. (1986). A simple biosphere model (SiB) for use within general circulation models. Journal of the atmospheric sciences, 43(6), 505-531.

Meehl, G. A., & Washington, W. M. (1995). Cloud albedo feedback and the super greenhouse effect in a global coupled GCM. Climate dynamics, 11(7), 399-411.

Takemura, T., Okamoto, H., Maruyama, Y., Numaguti, A., Higurashi, A., & Nakajima, T. (2000). Global three‐dimensional simulation of aerosol optical thickness distribution of various origins. Journal of Geophysical Research: Atmospheres, 105(D14), 17853-17873.

Cox, P. M., Betts, R. A., Jones, C. D., Spall, S. A., & Totterdell, I. J. (2000). Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature, 408(6809), 184-187.

Watanabe, S., Hajima, T., Sudo, K., Nagashima, T., Takemura, T., Okajima, H., ... & Kawamiya, M. (2011). MIROC-ESM 2010: Model description and basic results of CMIP5-20c3m experiments. Geoscientific Model Development, 4(4), 845-872.

Collins, W. J., Bellouin, N., Doutriaux-Boucher, M., Gedney, N., Halloran, P., Hinton, T., ... & Woodward, S. (2011). Development and evaluation of an Earth-System model–HadGEM2. Geoscientific Model Development, 4(4), 1051-1075.

Besbes, M., & Chahed, J. (2023). Predictability of water resources with global climate models. Case of Northern Tunisia. Comptes Rendus. Géoscience, 355(S1), 1-22. Available on:

Dr Jamel Chahed thank you for your contribution to the discussion

Ozone depletion and climate change are linked in a number of ways, but ozone depletion is not a major cause of climate change. Although synthetic greenhouse gases do not damage the ozone layer, they have global warming potential meaning they contribute to climate change. The first synthetic greenhouse gases developed had a high global warming potential. UV radiation releases heat into the stratosphere when it reacts with ozone. With less ozone there is less heat released, amplifying the cooling in the lower stratosphere, and enhancing the formation of ozone-depleting polar stratospheric clouds, especially near the South Pole. Ozone layer depletion does not cause the greenhouse effect. It allows more ultraviolet energy to reach the Earth's surface, but it does not affect the absorption of heat inside the atmosphere.Ozone (O3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it. Greenhouse gases act similarly to the glass in a greenhouse: they absorb the sun's heat that radiates from the Earth's surface, trap it in the atmosphere and prevent it from escaping into space. The greenhouse effect keeps the Earth's temperature warmer than it would otherwise be, supporting life on Earth. Ozone depletion and climate change are linked in a number of ways, but ozone depletion is not a major cause of climate change. Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere. When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created. Ultraviolet radiation not only affects humans, but wildlife as well. Excessive UV -B inhibits the growth processes of almost all green plants. There is concern that ozone depletion may lead to a loss of plant species and reduce global food supply. Once the ozone layer is depleted, ultraviolet rays will pass through the troposphere and eventually to earth. These rays cause ageing of the skin, skin cancer, cataract and sunburn to humans as well as animals.

The famous article [1] by Solanki et al. 2004, on the Unusual activity of the Sun during recent decades (1132 citations), reported that the Sun was responsible for all the global warming prior to 1970, at the most 30% of the strong warming since then can be of solar origin". This means that less than a third of global warming can be attributed to the Sun activity. What about the two remaining thirds?

To understand the question let's consider that the climatic parameter T (temperature), depends on Sun Activity (SA), GHG (so on Partial Pressures of all gases that compose the atmosphere, say for simplification x) and on a set of other climate parameters T(x,y, z...), (y, z...) being, for example, seismic activity, photosynthesis (all elements of carbon Nitrogen, phosphorus Cycles ..), etc. What is accessible to measurement is the total differential DT, which is written as a function of the partial differentials (dT) in the form:

DT=(dT/d(SA))D(SA)+(dT/dx)Dx+(dT/dy)Dy+(dT/dz)Dz+.....

The authors of the paper have achieved reconstructions of solar total and spectral irradiance as well as of cosmic ray fluxes. Let's consider that the parameter (SA) evolves and the calculation of its effect on (T) is DTSA we have thus:

DTSA=(dT/d(SA))D(SA)

By comparing with surface temperature records DT, the authors found that DTSA is at the most 30% of DT. So the 70% of DT which corresponds to DT-DTSA is given by:

DT-DTSA=(dT/dx)Dx+(dT/dy)Dy+(dT/dz)Dz+.....

Further research is needed in order to determine as much as possible the remaining partial derivatives. At the state of our knowledge, it is almost impossible to close the equation because some of the partial derivatives are not even understood.

[1] Solanki, S., Usoskin, I., Kromer, B. et al. Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature 431, 1084–1087 (2004).

Dr Jamel Chahed thank you for your contribution to the discussion