Human-led climate impact rapidly cooling upper atmosphere even as lower atmosphere warms

Subject: Geography

Section: Physical geo

Context:

The Earth’s upper atmosphere, called stratosphere, has been dramatically cooling in response to human-induced climate change since 1986, according to a recent study. This is in complete contrast to the effects on the lowermost part of the atmosphere, the troposphere.

Details of the study:

Temperatures in the stratosphere were 12 to 15 times greater than what would have occurred naturally, without human influence.
The greenhouse gasses 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.
Natural variations include changes in solar activity, volcanic activities and climate patterns such as El Nino and La Nina.
Another study showed the summer mesosphere (extending 50 to 85 km above Earth’s surface, sitting above the stratosphere) over Earth’s poles is also cooling.
The air in the stratosphere and mesosphere is thin and carbon dioxide molecules are not in close proximity. So they do not transfer Earth’s heat.
Abundance of CO2 molecules in the lower atmosphere leads to trapping of heat.

Atmospheric layers:

Troposphere:

Extends from Earth’s surface to, on average, about 12 kilometers in height, with its height lower at Earth’s poles and higher at the equator.
Tasked with holding all the air that plants need for photosynthesis and animals need to breathe, and also contains about 99% of all water vapor and aerosols.
The temperature in the troposphere also decreases with height. The top of this layer is referred to as tropopause.
Most of Earth’s weather happens here, and almost all clouds that are generated by weather are found here.
Most aviation takes place here, including in the transition region between the troposphere and the stratosphere.

Stratosphere:

Located between approximately 12 and 50 kilometers above Earth’s surface, the stratosphere contains the ozone layer.
The temperature increases with height. Heat is produced in the process of the formation of Ozone, and this heat is responsible for temperature increase.
It is nearly cloud- and weather-free, but polar stratospheric clouds (occur mainly at high latitudes during the winter) are sometimes present in its lowest, coldest altitudes.

Mesosphere:

Located between about 50 and 80 kilometers above Earth’s surface, the mesosphere gets progressively colder with altitude.
The top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 °C (-120 °F).
Most meteors burn up in this atmospheric layer. Sounding rockets and rocket-powered aircraft can reach the mesosphere.
The transition boundary which separates the mesosphere from the stratosphere is called the stratopause.

Thermosphere:

It is located between about 80 and 700 kilometers above Earth’s surface, whose lowest part contains the ionosphere.
It can reach temperatures up to 2,000 °C (3,600 °F)
It is both cloud- and water-vapor-free.
The aurora borealis (Northern lights) and aurora australis (Southern lights) are sometimes seen here.
The International Space Station (ISS) orbits in the thermosphere.

Ionosphere:

It is not a distinct layer as the others mentioned above. Instead, the ionosphere overlaps the mesosphere, thermosphere, and exosphere.
It is an electrically conducting region capable of reflecting radio signals back to Earth.
The electrically charged atoms and molecules that are formed in this way are called ions, giving the ionosphere its name and endowing this region with some special properties.

Exosphere:

It is located between about 700 and 10,000 kilometers above Earth’s surface, the exosphere is the highest layer of Earth’s atmosphere and, at its top, merges with the solar wind.
Molecules found here are of extremely low density, so this layer doesn’t behave like a gas, and particles here escape into space.
The aurora borealis and aurora australis are sometimes seen in its lowest part.
Most Earth satellites orbit in this layer.