The ozone layer of the atmosphere was destroyed in the 20th century by aerosol sprays and chemicals in refrigerators, but it is now recovering and may even become completely obsolete in a few decades, according to a new scientific assessment. However, new technologies are emerging that can interfere with this global recovery process.

Ozone is a molecule made up of three oxygen atoms and dispersed in the lower part of the stratosphere (second lowest layer). earth atmosphere), blocks harmful ultraviolet radiation Suncan damage living tissue, cause cancer, and impair vision. Since the 1980s, when stratospheric ozone depletion and the vacuum in the ozone layer over Antarctica were first discovered, the world has come a long way in mitigating or healing this damage.

The Montreal Protocol, adopted in 1987, led to the global phasing out of chlorofluorocarbons, the most harmful ozone-depleting substances introduced in the 1950s as propellants in aerosol chemical sprays and as refrigerants in air conditioning systems, cars and refrigerators. .

In a report by the World Meteorological Organization Published on January 9 (WMO), it states that the ozone layer will fully recover within forty years. But he also cites four new technologies that could reverse the recovery process in the future. Here, the world’s leading experts express their views on the situation.

Satellite mega constellations

around the world now It orbits around 6,000 active satellites, more than at any time in human history. By 2030, that number could rise to a staggering 58,000. by the US Government Accountability Office (GAO).(opens in a new tab). Most of these satellites will belong to mega constellation operators like Starlink. from SpaceX, OneWeb or Kuiper by Amazon. Most of these satellites will be on low earth orbit, in space under 1,200 miles (2,000 kilometers) and will be regularly replaced by newer, more advanced models. This means that within a decade a large number of old, unused spacecraft will burn up in Earth’s atmosphere, because gravity drags old unwanted moons back to the planet.

These satellites are made of metals such as aluminum and titanium and contain other potentially toxic substances. Scientists worry that when these satellites burn, they may release harmful chemicals that can damage the regenerating ozone layer.

“Launching satellites from these large low-Earth orbiting constellations and vaporizing them during reentry is a very significant potential impact on both the climate and the ozone layer,” said Martin Ross, a researcher at the Aerospace Corporation in California, who studies the effects. . Space.com reported space systems in the stratosphere. “Currently, we know very little about what happens when these satellites evaporate and turn into particles and gases. We don’t know how active these particles and gases are, both chemically and radiatively. But we know that soon tons of this material will fall.”

Aluminum oxides, which can form during the combustion of aluminum-based spacecraft bodies in the past associated with the depletion of the ozone layer. Combustion of titanium can lead to the formation of titanium oxides, which Ross says can alter the optical properties of ambient air. There are other controversial elements found in satellite components – cobalt and lithium in batteries, traces of gold and lead – all elements not otherwise found in the upper atmosphere.

“There is the potential for a surprise in terms of chemical reaction with ozone,” Ross said. “This is something to understand. What kind of particles are these and what is their chemical reactivity?”

supersonic aviation

supersonic aircraft like the ConcordeAlready decommissioned, “flying at higher altitudes than conventional jet aircraft. Other supersonic aircraft, such as the Concordes, which fly 60,000 feet (18.3 kilometers) above the Earth’s surface, and those used by the military, spray pollutants into the lower stratosphere, where the protective ozone layer is present. According to the WMO report, If supersonic aviation becomes widespread, its emissions can “reduce up to 10% of the total ozone layer.”

“New supersonic and hypersonic aircraft are being developed that can launch water vapor and nitrogen oxides into the stratosphere,” Paul Newman, chief scientist in NASA’s Goddard Space Flight Center Earth Sciences Division, who worked on the WMO report, told Space.com. . “They’re not enough right now, but if you start flying thousands of these planes in the stratosphere in the future, that could have a significant impact.”

Airlines around the world are now looking forward to the next generation of supersonic aircraft, although the Concorde fleet, operated by British Airways and Air France, was withdrawn from service in 2003 following a sharp drop in passenger interest following a fatal accident in 2000. now being developed american company Boom Supersonic recently unveiled an innovative Symphony engine for its supersonic passenger jet called the Overture, which the company hopes can begin flight tests by the end of this decade. NASA also has a stake in the new supersonic aviation business with its experimental aircraft. X-59It aims to eliminate the intrusive noise traditionally associated with supersonic air travel.

Launching too many missiles

The WMO report also noted that while missile launches currently account for only about 0.1% of the ozone depletion detected, this number may increase in the future as the number of missile launches is expected to increase. New rocket engines are being developed using supposedly greener hydrogen and methane fuels, but scientists warn that not enough is known about the interaction of the exhaust gases from these rocket engines with the ozone-containing stratosphere, the upper layers of Earth’s atmosphere. layer and even higher mesosphere. Ross hopes the world’s space and atmospheric research agencies will soon launch high-altitude planes into the stratosphere to measure exactly what’s happening above Earth as fossil fuel-burning rockets and greener alternatives like hydrogen and methane pass.

“We want to do the same thing we did 25 years ago when solid rocket engines were seen as a threat to the ozone layer,” Ross said. “NASA, NOAA (US National Oceanic and Atmospheric Administration) and the US Air Force got together to measure real clouds in the stratosphere. And so we were able to see that solid-state rocket engines aren’t as bad as some models suggest.”

geoengineering

Experts also worry that geoengineering interventions are possible, attempts to slow it down climate change artificially, it can affect the ozone layer. There are no such plans yet, but scientists have been working for years on methods that could help reduce the amount of heat entering Earth’s atmosphere by increasing the albedo, or reflectivity, of the air around our planet. Such effects were observed after powerful volcanic eruptions that spewed large volumes of sulfur-rich ash into the stratosphere. It is known that after the eruption of Mount Pinatubo in the Philippines in 1991, the average global temperature dropped by about 1 degree Fahrenheit (0.6 degrees Celsius). The effect can be measured for at least 15 months.

Procedures that can simulate these processes in a calculated manner have already been outlined. But Newman cautions that the side effects of such interventions are not generally understood.

“People are starting to look at stratospheric aerosol injection (SAI) as a potential way to help us reach a future where we have fewer carbon dioxide emissions,” Newman said. “This is something we can think about in the case of catastrophic climate change – massive flooding, heatwaves that cause many deaths, crop destruction. The problem is that our models do a poor job of simulating the impact of SAI. We know this will change the stratosphere a lot, so There is concern that it could make the ozone hole over Antarctica even more severe.”

Despite this, the Montreal Protocol remains a huge success in terms of humanity’s ability to come together and prevent the causeless destruction of our environment. The ozone layer may not have completely disappeared, but scientists hope the lessons learned from efforts to protect it will shed light on our still unresolved fight against climate change. Source