Researchers suggest cooling the poles by spraying chemicals using military aircraft

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The poles are warming faster than the global average, prompting unprecedented heat waves and the rapid melting of glaciers. Knowing how to slow down global warming has become the desire of many researchers. Recently, some of them believe that the injection of aerosols (sulphur dioxide) to deflect part of the solar energy, at very high altitude, can be effective in cooling the poles. But such climate intervention would come with huge increases in costs and risks to global security.

Stratospheric aerosol injection is a prospective climate intervention that aims to reduce the global average surface temperature by deflecting a very small portion of incoming sunlight from Earth. This injection is a controversial and untested climate intervention that may lead to adverse effects, and is not offered as a substitute for emission reductions or adaptation.

However, injections of the same aerosols from large volcanic eruptions have long been known to significantly reduce surface temperatures, even at distances far from the source, as occurs after the eruption. of Mount Pinatubo in 1991. injections would be aeronautically feasible and extraordinarily cheap, relative to other forward-looking measures to address climate change or its effects.

However, there are practical limits to how high aerosols can be deployed in the atmosphere. Recently, a group of researchers led by Wake Smith of Yale University, assessed the safety and cost-effectiveness of deployment at an altitude of 25 km, which would be the most effective, but also the altitude where the costs and risks increase. Their study was published in the journal Environmental Research Communication.

Conclusions after a series of large studies

Indeed, following a 2018 study that explained the technologies by which solar geoengineering might be possible, this new work directly answers a question posed by the National Academy of Sciences, Engineering and Medicine in a landmark March 2021 study, which identified the need for more research on the viability of aerosol deposition above 20 km altitude. In fact, previous studies have noted that deposition of stratospheric aerosols at an altitude of 25 km can be more efficient than at 20 km, leading climate modelers to typically include such a high deposition. deploy their studies.

According to an article published in IOP Publishingappendix of this research, Wake Smith, the lead author of the study, says: There is a ceiling in the sky above which traditional aircraft cannot operate, and 25km is an altitude above that limit. “. It should be noted that airliners and military jets often fly at an altitude of about 10 km, while 20 km is the domain of spy planes and high-flying drones. It is easy to understand that the planning of hundreds of thousands that annual solar geoengineering deployment flights at altitudes inaccessible even to elite spy planes must overcome many obstacles.

Under the plan outlined in their work, the authors explained that a fleet of 125 military aerial tankers would release a cloud of microscopic sulfur dioxide particles at a height of 13 km and at latitudes which is 60 degrees north and south – roughly between Anchorage and the southern tip of Patagonia. These aerosols drift slowly up the pole, slightly shading the surface below.

Concretely, the injection of particles (13 million tons are needed) will be done during the long days of the local spring and early summer. The same fleet of jets can serve both hemispheres.

However, previous military tankers such as the older KC-135 and A330 MMRT do not have sufficient cargo at the required altitudes, while the newly designed high altitude tankers are more effective. The study’s authors estimate that a fleet of about 125 such aircraft could carry enough cargo to cool the poleward regions by 2°C annually, bringing them back close to their average pre- industrial temperature.

The costs are estimated at $11 billion per year, less than a third of the cost of cooling the entire planet by the same amount of 2°C and a fraction of the cost to achieve net zero emissions.

Wake Smith warned that the plan would address an important symptom of climate change, but not the cause. He says in an addendum to the original article: It’s aspirin, not penicillin. It is not a substitute for decarbonization […]. Our finding is expected to change the way climate intervention models are run around the world and show that practical limitations must be weighed against radiative efficiency in the design of solar geoengineering programs. “.

Climate controversy

This plan is debated by scientists. In fact, in an interview given to SkyNewsthe lead author estimates that to bring about a real slowdown in ice melting and global warming would require about 175,000 flights of high-flying spy planes and drones each year.

However, these jets themselves release large amounts of carbon dioxide into the atmosphere, bringing greenhouse gases to altitudes where their presence is most damaging to the climate. Wake Smith points out: There is widespread and justified concern about deploying aerosols to cool the planet, but if the risk/benefit equation is to be paid anywhere, it is at the poles. “.

However, the cooling of the poles will only provide direct protection to a small part of the planet, although the mid-latitudes will also experience some reduction in temperature.

Despite these objections, the authors argue that since less than 1% of the world’s human population lives in the targeted deployment areas, a polar deployment poses little direct risk to the majority. of humanity rather than a worldwide program. In other words, global advantages outweigh local disadvantages. Wake Smith concludes: Any deliberate turning of the global thermostat would be in the common interest of all humanity. “.

Finally, the current study is only a preliminary step towards understanding the costs, benefits and risks of undertaking climate intervention at high latitudes. This gives more reason to believe that such devices could prove useful in preserving the cryosphere near the poles and in the slow rise of global sea levels.

Source: Environmental Research Communications

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