injections aerosols haute altitude refroidir pole terre

Researchers propose cooling columns by spraying chemicals on military aircraft

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The poles are warming much faster than the global average, resulting in unprecedented heat waves and accelerated melting of glaciers. Knowing how to slow global warming has become a demand for many researchers. Recently, some believe that the injection of aerosols (sulfur dioxide) to convert a portion of the solar energy, at very high altitudes, can be effective in cooling the poles. But such climate intervention comes with greatly increased costs and risks to global security.

A stratospheric aerosol injection is a potential climate intervention aimed at lowering Earth’s average surface temperatures by diverting a very small portion of incoming sunlight away from Earth. This injection is a controversial and untested climate intervention that can lead to undesirable effects, and is not offered as a substitute for emission reduction or adaptation.

However, injections of similar aerosols from large volcanic eruptions have long been known to significantly reduce surface temperatures, even at great distances from the source, as was the case after the eruption of Mount Pinatubo in 1991. There is also growing confidence in the dissemination of these Injections will be flight feasible and extraordinarily inexpensive, compared to others forward-looking measures To combat climate change or its effects.

However, there are practical limits to the height at which aerosols can be dispersed Atmosphere. Recently, a team of researchers led by Wake Smith of Yale University, evaluated the safety and cost-effectiveness of deploying to an altitude of 25 kilometers, which would be most effective, but also an altitude at which costs and risks increase. Their study was published in the journal Environmental Research Communications.

Conclusions after a series of large-scale studies

Indeed, following a 2018 study that outlined the techniques by which solar geoengineering could be performed, this new work directly answers a question posed by the National Academy of Sciences, Engineering, and Medicine in a landmark study in March 2021, which acknowledged the need for further research into the feasibility of aerosol deposition. Atmospheric altitude above 20 km. Indeed, previous studies indicated that propagating stratospheric aerosols at an altitude of 25 kilometers would be more efficient than 20 kilometers, prompting climate modelers to generally incorporate such large deployments into their studies.

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according to Article – Commodity Posted in Publishing IOPIn an appendix to this paper, lead author of the study Wick Smith says: There is a ceiling in the sky that conventional aircraft cannot operate above, and 25 km altitude is much higher than that limit. It should be noted that planes and warplanes regularly sail at an altitude of about 10 km, while 20 km is the range of spy planes and drones. It is easy to understand that hundreds of thousands of annual solar geoengineering deployment flights are planned at inaccessible altitudes. Even an elite spy plane has to overcome many obstacles.

According to the plan laid out in their work, the authors explained that a fleet of 125 military air carriers would release a cloud of microscopic particles from sulfur dioxide At an altitude of 13 km and at latitudes 60 degrees north and south – approximately between Anchorage and the southern tip of Patagonia. These aerosols will slowly drift towards the pole, shading the surface slightly below.

Concretely, particle injection (13 million tons required) will be carried out seasonally during the long days of local spring and early summer. The same fleet of aircraft can serve both hemispheres.

However, pre-existing military tankers such as the old KC-135 and A330 MMRT do not have sufficient payload at the required altitudes, while newly designed high-altitude tankers will prove to be more efficient. The study authors estimate that a fleet of about 125 such aircraft could carry enough payload to cool the polar regions by 2°C per year, bringing them close to average pre-industrial temperatures.

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Costs are estimated at $11 billion annually, less than a third of the cost of cooling the entire planet at the same volume of 2°C and a fraction of the cost to achieve net zero emissions.

Wake Smith warns that the plan will address an important symptom of climate change, but not the cause. mentioned in eulogy For 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 globally and shows that practical limits must be weighed against radiative efficiency in the design of solar geoengineering programmes. “.

Climate controversy

This plan was discussed among scholars. In fact, in an interview given to Sky Newsthe lead author felt that causing a real slowdown in melting ice And global warming, it would take about 175,000 high-altitude spy planes and drones flights each year.

However, these same jets release large amounts of carbon dioxide into the atmosphere, causing an explosion greenhouse gas effects At altitudes where their presence is more harmful to the climate. Wake Smith points out: There are widespread and reasonable concerns about deploying aerosols to cool the planet, but if the risk/benefit equation were to pay off anywhere, it would be at the poles. “.

However, cooling at the poles would only provide direct protection for a small part of the planet, although the middle latitudes would also see some drop in temperature.

Despite these objections, the authors argue that because less than 1% of the world’s population lives in the target spread areas, polar spread would pose a much lower immediate risk to the greater part of humanity than a global programme. In other words, global advantages outweigh local disadvantages. Wake Smith concludes: Any deliberate rotation of the global thermostat would be of common interest to all of humanity. “.

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Finally, the current study is only an initial step towards understanding the costs, benefits, and risks of conducting climate intervention at higher latitudes. This gives additional reason to believe that such tools could be useful in maintaining the cryosphere near the poles and in slowing sea level rise globally.

source : Environmental Research Communications

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