Cooling of Stratosphere

September 16, 2023

GS Paper I Geography

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.

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.