Context:
The Earth’s upper atmosphere, stratosphere, has been dramatically cooling in response to human-induced climate change since 1986, according to a recent study.
Structure of Atmosphere:
- Troposphere: Its average height is 13 km. Almost all the weather phenomena like rainfall, fog and hailstorm occur in this layer.
- Stratosphere: It extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying airplanes.
- It contains a layer of ozone gas.
- Mesosphere: It lies above the stratosphere. Meteorites burn up in this layer on entering from space.
- Thermosphere: In thermosphere temperature rises very rapidly with increasing height.
- Exosphere: The upper most layer of the atmosphere is known as the exosphere. This layer has very thin air. Light gases like helium and hydrogen float into space from here.
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Key Findings of Study:
- Unprecedented Stratospheric Temperature Increase: Temperatures in the stratosphere were 12 to 15 times greater than what would have occurred naturally, without human influence.
- Use of Satellite Data to understand Stratosphere: The team used data from satellites and computer models in their analysis and found the greenhouse gases released from human activities led to a mean cooling of about 1.8 to 2.2 degrees Celsius in the middle and upper stratosphere globally from 1986-2022.
- Impact of Human Activities vis-i-vis Natural Variations in Stratosphere: Without human activities, natural variations would have caused global-mean stratospheric temperature changes no larger than about 0.15 degrees Celsius over the same period.
- Natural variations include changes in solar activity, volcanic activities and climate patterns such as El Nino and La Nina.
- The opposite impacts of warming troposphere and cooling stratosphere across all latitudes are a unique fingerprint of greenhouse gases, the researchers explained.
News Source: Down To Earth
16 Sep 2023
