The atmosphere contains several layers. These layers are differentiated by the composition and temperatures of these layers. One such layer, the stratosphere, warms as height above the Earth’s surface increases. The stratosphere is a layer of the atmosphere that extends some 10 – 15 km above the Earth’s surface. How does it warm? The Earth is protected from harmful ultraviolet rays by a layer of ozone molecules that are located in a region of the atmosphere called the stratosphere. This absorption of UV light is what effectively warms this layer of the atmosphere.
The changes in climate due to changes in ozone start with atmospheric temperatures. As concentrations of ozone increase, the temperatures also must increase. This increase in temperature is because of ozone’s ability to retain heat by processes of absorption. As the sun produces large amounts of ultraviolet light, some of this light passes through the entire atmosphere while some of this ultraviolet light becomes absorbed. Another reason that the stratosphere warms is because this ozone also absorbs infrared radiation that is emitted from the troposphere (the layer below the stratosphere). As concentrations of ozone decrease, so do stratospheric temperatures. Recent studies have concluded that over the past several decades, the stratosphere has cooled nearly 1° to 6° C. Some believe that a link between lower stratospheric temperatures and rising greenhouse gases could exist. A possible positive feedback loop is concerning some scientists. This feedback loop suggests that, as more ozone is lost in the stratosphere, the colder the atmosphere would get due to the loss of ozone. The colder the atmosphere gets the more ozone depletion that will occur.
Ozone and climate interactions are also known at the surface of the Earth. Ozone forms through the interaction of sunlight and photochemistry or how sunlight interacts with certain chemicals. Generally two groups of compounds are known for ozone creation; nitrogen oxides and VOCs or volatile organic compounds. As temperatures increase, chemical processes and interactions tend to increase. As one can expect, because we tend to see an increase in global temperature trends, we can also expect to see more days when ozone would impact human activities. However, there is still some speculation, as some chemical reactions are not modified by warming temperatures. Some scientists also speculate that ozone pollution in the troposphere is caused by a higher probability that higher temperatures will lead to a greater demand for air conditioning. Since most of today’s electricity is generated through power plants, the greater emissions of would likely cause more ozone pollution.
The complex interactions between Earth’s Ozone layer and global warming are a growing concern and an active area of research. While the science has matured greatly over the last several decades, there are many questions that still lack answers, but rest assured there are a number of scientists that are making strides, and finding solutions to complex problems.
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© 2018 Meteorologist Allan Diegan