Can global warming stop?

To prevent the worst effects of climate change, the world must lead to zero net emissions of carbon dioxide by 2050. But even if we could achieve that goal, it would not immediately stem the rise of the global temperature, as it would have to spend some time watching the effects of the CO2 reduction.

The negative effects of global warming will continue for decades. But is there anything else we can do to reduce global temperature? A group of researchers at Harvard University feel that it may be possible to reach a temporary decline in global temperatures by adjusting the composition of earth's upper atmosphere. Researchers hoped to test some of this technology and the sustainability of their theory since this summer, in what they call the Stratosphere Control Experiment ( SOPEX). Although the test has been suspended, the team still hopes the experiment will continue in a not too distant future.

The ultimate source of earth's heat is the sun, generating a steady flow of infrared radiation toward our planet. Some 30 percent reflect again in space from the atmosphere, while the rest warms the planet during the day and radiates back into space at night.

In the delicate balance that existed in pre-industrial times, the heat entering the Earth was compensated precisely by its lost amount in space, ensuring the constant position of the average global temperature.

Today the problem is that CO2 emissions spoil this balance by absorbing some of the heat that needs to be resurface in space by blocking it into the atmosphere. The more carbon dioxide in the atmosphere, the higher the planet's temperature rises.

In the long term, people have to reduce the amount of carbon dioxide in the atmosphere to prevent the worst effects of climate change. But other processes can produce short-term declines in global temperatures.

For example, volcanic eruptions scatter clouds of dust particles high in the stratosphere, an upper layer of the atmosphere, forming a protective shield that prevents some of the sun's heat from reaching the earth's surface.

For example, the eruption of Mount Pinatubo in the Philippines in 1991 caused the average temperature in the Northern Hemisphere to drop by about 0.5 degrees Celsius over the next 15 months. The SCOPEX team wants to follow the same example by injecting particles into the upper atmosphere in order to reduce global temperature.

The basic idea is called aerosolic stratspheric injection, or SAI is simple.

A high - altitude plane, or helium balloon, will distribute flocks of microscopic particles called aerosoles in the stratosphere at an altitude of 20 miles [20 km] or more - much higher than airplanes usually fly.

Aerosols will be suspended in the air. They are too small to be seen as clouds from the earth, but dark enough to reflect again in space some of the sun's energy back into space. In theoretical simulations, SAI seems to be a applicable concept.

The report by the Intergovernmental Panel for Climate Change (IPÇ) of 2018 found that a fleet of high altitude planes can deposit enough aerosole to offset current levels of global warming.

But aerosols must be fulfilled every few years, and this method addresses only one of the symptoms of climate change instead of addressing its root cause, greenhouse effect. At best, it is a temporary precautionary measure, which opposes rising temperatures, while countries drop their carbon dioxide emissions simultaneously.

So far, research on SAI has been theoretical, complete by a limited amount of data in the real world from volcanic eruptions. SCEPEX wants to measure in the real world under carefully controlled conditions, enabling a better calibration of computer models.

If we want to provide the decisionmakers with useful information that this scheme can work, we have to prove our models”- says project manager Frank Keute, from the Department of Chemical Chemistry and Biology at Harvard University.

Volcanoes mainly produce compounds based on sulfur. They not only cool the atmosphere but also damage the Earth's ozone protective layer, which protects us from harmful radiation from ultraviolet rays, UV.

So the SCOPEX team is focusing on a less harmful aerosol, calcium carbonate, or foam dust, which researchers hope will produce the desired effect of global cooling without damaging the ozone layer. / world.al