Stopping Earth from heating up

The Earth is heating up to almost an unbearable degree giving rise to climatic problems bringing misery to human existence.
It was reported that Earth reached a bleak milestone in 2021 with concentration of carbon dioxide
(CO2) in the atmosphere hitting 150% of its value in preindustrial times. This state of affairs makes it incumbent on the world to decrease net emissions of carbon dioxide to zero by 2050. The problematic aspect, however, is that even if this target is achieved it would not completely stop temperature rise as reduction of CO2 takes time.
The portents are that the negative impacts of global warming will continue for decades.
The recent developments, however, points out that it might be possible to achieve a temporary reduction in global temperatures by tweaking the composition of Earth’s upper atmosphere in what is termed as Stratospheric Controlled Perturbation Experiment (SCoPEx) which aims to improve the fidelity of simulations (computer models) of solar geoengineering by providing modelers with experimental results vital to addressing specific science questions.
In this context it was stated that the ultimate source of Earth’s heat is the sun that drenches the daytime side of the planet in a constant flow of infrared radiation.

About 30% of this is reflected back into space by the atmosphere, while the rest warms the planet during the day and is radiated back into space at night. In the delicate balance that prevailed in preindustrial times, the incoming heat was exactly offset by the amount lost to space, ensuring average global temperatures remained constant.
The current problem is related to the fact that CO2 emissions have disrupted this balance by absorbing some of the heat that should be radiated back into space, trapping it inside the atmosphere. Volcanic eruptions, for instance, blast clouds of dust particles high up into the stratosphere, an upper layer of the atmosphere, forming a protective shield that prevents some of the sun’s heat from reaching Earth’s surface.
The SCoPEx technique wants to take a page from such eruptions by injecting particles into the upper atmosphere in order to lower temperatures.
The premise devised here is called stratospheric aerosol injection, or SAI promises to be simple and is explained through a high-flying aircraft or helium balloon would dispense batches of microscopic particles called aerosols into the stratosphere at altitudes of 12.4 miles or more — much higher than planes usually fly.
The aerosols would remain suspended in the air, too tiny to be visible as clouds from the ground but opaque enough to reflect a fraction of the sun’s energy back into space. In simulations, SAI appears to be a viable concept.
It was found that a fleet of high-flying aircraft could deposit sufficient aerosols to offset current levels of global warming but the aerosols would have to be replenished every few years and the method tackles only one of the symptoms of climate change rather than addressing its root cause, the greenhouse effect.
It is therefore pointed out that, at best, it is a stopgap measure, countering rising temperatures while countries simultaneously reduce carbon dioxide levels.
SAI, up to now, is theoretical, supplemented by a limited amount of data from volcanic eruptions. SCoPEx wants to make real-world measurements under carefully controlled conditions, allowing better calibration of the computer models.

Volcanoes mainly eject sulfur-based compounds but these compounds not only cool the atmosphere but also damage Earth’s protective ozone layer, which shields it from harmful UV radiation.
So the SCoPEx is focusing on a less harmful aerosol, calcium carbonate — chalk dust — which is hoped
will produce the desired cooling effect without harming the ozone layer.
The proposal is to deploy a large, uncrewed helium balloon that would be similar to a standard weather balloon except that it would be fitted with propellers to allow the team on the ground to maneuver it. On its first flight, which is tentatively planned for next year, the balloon would not release anything into the stratosphere. Instead, it would ascend to an altitude of 12.4 miles, where the team would test the maneuvering system and check that all the scientific instruments and communications function correctly.
If the test runs were to be successful, a second flight would perform a controlled release of 2.2 to 4.4 pounds of calcium carbonate at the same altitude. The balloon would be moving steadily in a straight line during the release,so the aerosol particles would form a narrow plume around 0.6 miles in length.
The balloon would then turn back through the plume, observing how the particles disperse over time and the extent to which they reflect sunlight. If the test proves successful then such release might involve injecting around 1.5 million tons into the stratosphere per year implying roughly a hundred aircraft would need to continuously fly payloads up to about 12 miles altitude.
Despite its brilliance SAI remains highly controversial as questions are asked that while sending green gases in the space created the climate crisis then how can pumping aerosols into it will make things better and moreover it might have unforeseen side effects.
There is the possibility that it could disrupt weather patterns, harm crops by reducing the amount of sunlight they receive, and — if sulfide aerosols are used — damage the ozone layer. Because of these concerns, the SCoPEx has put off helium balloon’s maiden voyage but it is considered advisable to go
ahead with the experiment than to do nothing at all.