global warming; A group of Harvard researchers have come up with a controversial way to reduce the Earth’s temperature and plan to test it soon.
The Earth saw a bad turning point in 2021: Carbon dioxide concentrations reached 150% in pre-industrial times, according to the British Meteorological Agency.
Can we prevent global warming
To prevent the worst effects of climate change, the world must reduce pure carbon dioxide emissions to zero by 2050. But even if we are on the way to achieving this goal, it will not stop the sudden rise in temperature; Because it takes time to observe the effect of carbon dioxide reduction on global temperature, the negative effects of global warming will continue for decades. But is there a way to lower the temperature faster?
A group of researchers at Harvard University think that it is possible to achieve a temporary reduction in the Earth’s temperature by manipulating the composition of the upper atmosphere. The researchers hoped to test part of this technology and the practicality of their theory in an experiment called controlled stratospheric turbulence (SCoPEx). Of course, their testing has been postponed; But they still hope to implement it in the near future.
The ultimate source of heat is the sun, which overwhelms the sun’s side of the earth with a steady stream of infrared radiation. About 30% of this radiation is reflected into space by the atmosphere; While the rest of it warms the earth during the day and returns to space at night.
In the delicate equilibrium that existed in the pre-industrial era, the incoming heat was offset by the amount of heat returning to space, thus keeping the earth’s temperature constant. The problem today is that carbon dioxide upsets this balance by trapping some of the heat that needs to be returned to space, keeping the heat in the atmosphere.
The more carbon dioxide there is in the atmosphere, the higher the temperature. Humans must reduce the amount of carbon dioxide in the atmosphere in the long run to avoid the adverse consequences of climate change. But there are other processes that can temporarily lower the earth’s temperature.
Volcanic eruptions, for example, produce dust clouds that enter the stratosphere (the upper layer of the atmosphere) and form a protective shield that prevents some of the sun’s heat from reaching the earth’s surface. The 1991 eruption of Mount Pinatubo in the Philippines caused average temperatures in the Northern Hemisphere to drop by more than half a degree Celsius over the next 15 months. The SCoPEx team wants to emulate this process by injecting particles into the upper atmosphere to lower the temperature.
The basic idea (called injecting an aerosol into the stratosphere, or SAI), is simple. A helium balloon disperses microscopic particles called aerosols at an altitude of 20 km (or more) above the ground, which is much higher than the altitude at which airplanes usually fly. Aerosols are suspended in space and are so tiny that they cannot be seen from the ground in the form of clouds, But they are opaque enough that they can return some of the sun’s energy to space.
In the simulations performed, the injection of an aerosol into the stratosphere seems to be a practical concept. According to a 2018 report by the IPCC, a fleet of high-altitude aircraft can launch enough aerosols to compensate for current levels of global warming; But aerosols need to be refreshed after a few years, and this method, instead of solving the main cause, the greenhouse effect, counteracts only one of the symptoms of climate change and, at best, is a temporary measure that counteracts the rise in temperature; therefore, at the same time, countries must reduce their carbon dioxide emissions.
So far, research on SAI has been theoretically accompanied by limited data on real-world volcanic eruptions. SCoPEx researchers want to make more accurate measurements under controlled conditions to bring computer models closer to reality.
Volcanoes emit mainly sulfur compounds; But in addition to cooling the atmosphere, these compounds damage the ozone layer, which protects us from harmful UV radiation; Therefore, the SCoPEx team uses a more harmless calcium carbonate aerosol that hopes to achieve the desired cooling effect without damaging the ozone layer.
Recommended experiment
Researchers want to use a large unmanned helium balloon that resembles a standard meteorological balloon, But it does have propellers that allow researchers to control it from the ground up. The scientists, with the help of the Swedish space company, planned to launch the balloon in an area in Sweden.
The balloon will not enter the stratosphere on its first flight, scheduled for next year, and will instead rise to an altitude of 20 km, where researchers will test its maneuvering system with all its scientific and communication tools. To work.
If the experiment is successful, one or two kilograms of calcium carbonate will be released at the same altitude on the second flight. When calcium carbonate is released, the balloon will move in a straight line; Aerosol particles form a narrow column about one kilometer long. The balloon will then return in the same direction, and the researchers will examine how the particles scatter over time and how well they reflect sunlight. “The current goal is not to change the climate or even see if we can reflect sunlight,” said David Keith, a Harvard professor of applied physics and a project scientist, in an interview with HowStuffWorks.
“The goal is to improve our models of how aerosols form in the stratosphere.” According to Keith, at least another decade of research is needed before aerosols can be released on a large scale. During this release, about 1.5 million tons of aerosols may enter the stratosphere per year, and this requires 100 aircraft to fly continuously to altitudes of up to 20 km.
Disagreement over stratospheric aerosol injection
Of course, injecting aerosols into the stratosphere is still highly controversial.
One concern is that humans have caused a climate crisis by pumping greenhouse gases into the atmosphere; So how can you be sure that pumping the aerosol into the air will improve the situation?
Computer modeling shows that SAI is not dangerous, But it is likely to have unforeseen side effects. One possibility is that it will disrupt climate patterns, reduce the amount of light reaching agricultural products, damage agricultural products, and damage the ozone layer if sulfide aerosols are used.
In fact, some scientists warn against following the SAI path. “It’s a really scary idea to really try to control the whole climate,” Douglas McMartin, a senior professor of mechanical and aerospace engineering at Cornell University and professor of mathematical science and computing at the California Institute of Technology, told Smithsonian Magazine.
In addition, the State Board for Climate Change, in a 2018 discussion on Solar Radiation Improvement (SRM), concluded that uncertainties in areas such as technology maturity, physical perception, potential impacts, and management challenges make SRM possible in the future. Do not exist nearby.
But Kate argues that the real risk is for some organizations to try to do this without data from real-time experiments. The second big problem is that governments and companies that are reluctant to reduce carbon dioxide emissions are taking advantage of the SAI idea and saying that there is no need to reduce carbon dioxide emissions anymore. This situation can override the potential benefits of SAI.
Even if the SCoPEx mission is successful and the SAI is fully implemented, it will not replace carbon dioxide emissions reduction, it is just a complementary method, according to Lizzie Burns, CEO of Harvard Solar Radiation Engineering.
This method is like housing. If you need surgery and are taking painkillers, it does not mean that you no longer need surgery
