Something Strange Is Happening to the Ozone Layer North of Alaska — Scientists Are Watching

Ready? We are heading north across Alaska right now to show you something almost no one can see with their own eyes. Above these mountains, above the clouds, and far beyond the altitude where commercial aircraft fly, something strange can happen to the sky. There is no dark opening, no visible crack, no warning sound, but instruments carried by balloons and satellites have detected the ozone layer becoming dangerously thin across parts of the Arctic. And in the spring of 2020, the loss became so severe that scientists described it as an unprecedented Arctic ozone event. For weeks, a region of exceptionally low ozone formed north of Alaska, Canada, Greenland and Russia. It was not identical to the famous Antarctic ozone hole, but under the scientific threshold commonly used to map that hole, 220 Dobson units, an enormous area of Arctic atmosphere briefly qualified. Then, almost as suddenly as it appeared, the opening disappeared, not because the missing ozone instantly returned. The atmospheric structure holding the depleted air together broke apart, scattering it across the Northern Hemisphere. And that is why scientists are still watching the sky north of Alaska, because the chemicals that caused the original ozone crisis have not completely vanished. The Arctic atmosphere is changing, and when the right conditions align, the protective shield above North America can weaken with remarkable speed. So, let me show you what happened, why Alaska sits close to the edge of this atmospheric laboratory, and what could happen next. Because it turns out that one of the most important warning systems on Earth begins with a balloon rising into the darkness above the Arctic. Why are scientists watching north of Alaska? When most people hear the words ozone hole, they picture Antarctica. That makes sense. Every southern hemisphere spring, a large and persistent region of severe ozone depletion develops over the frozen continent. It has become one of the clearest symbols of human damage to the atmosphere. But the planet has two poles. the Arctic lies another enormous circulation system, the northern polar vortex. During winter, powerful winds can wrap around the pole and isolate a mass of extremely cold air in the stratosphere. Most years, this vortex is less stable than the one over Antarctica. Mountain ranges and large weather systems in the northern hemisphere send waves upward into the atmosphere. Those waves disturb the vortex, warm the stratosphere, and sometimes split the circulation apart. That instability normally protects the Arctic from developing a long-lasting Antarctic-style ozone hole, but not always. During certain winters, the vortex remains unusually strong. Temperatures inside it fall low enough for special clouds to form. Sunlight returns in late winter and activates chlorine chemistry. Ozone then begins disappearing. Alaska lies beneath the outer reaches of this shifting system. Depending on the position of the vortex, air with reduced ozone can move over the state or pass across neighboring Arctic regions. That does not mean Alaska permanently sits beneath a hole. It means the atmosphere above and north of Alaska is part of a rapidly moving polar system whose behavior can affect ultraviolet exposure across inhabited northern latitudes. And in 2020, that system did something extraordinary. What happened in the Arctic in 2020? The winter of 2019 to 2020 produced an exceptionally cold and persistent Arctic stratospheric vortex. Normally, atmospheric disturbances would weaken it. That winter, they did not. The vortex remained compact. Air inside it stayed isolated. Temperatures fell low enough for long enough to create extensive polar stratospheric clouds. By March, satellite instruments and weather balloon measurements were recording record-breaking ozone loss. At some altitudes, scientists found that roughly 90 percent of the ozone had been destroyed. Total ozone values over a broad Arctic region fell below 220 Dobson units, the value used to define the boundary of the Antarctic ozone hole. This depleted zone covered an area several times the size of Greenland at its peak. It was smaller and shorter-lived than a typical Antarctic ozone hole, but it was unlike anything previously measured in the Arctic record. The event was especially alarming because it occurred in the Northern Hemisphere. Unlike Antarctica, the Arctic is surrounded by heavily populated continents. A shift in the vortex can carry ozone-poor air toward Alaska, northern Canada, Scandinavia, Russia and, occasionally, farther south. By late April 2020, the vortex finally broke apart. Ozone-rich air mixed into the region, and the dramatic low-ozone zone disappeared from satellite maps. But the event left scientists with a difficult question. Was this simply an extremely rare combination of natural weather conditions? Or could changes in the climate system make the coldest Arctic stratospheric winters more favorable for severe ozone loss? The answer is more complicated than it first appears. What is the ozone layer? High above Earth, mostly between about 15 and 35 kilometers, oxygen molecules are constantly being broken apart and rebuilt by sunlight. Some of that oxygen forms ozone, a molecule containing three oxygen atoms. Although ozone is dangerous when concentrated near the ground, stratospheric ozone is essential. It absorbs most of the sun's damaging ultraviolet B radiation before that energy reaches Earth's surface. Think of it as a thin, invisible sunscreen wrapped around the entire planet. Without it, more ultraviolet radiation would damage DNA. Rates of skin cancer and cataracts would rise. Crops and forests would be placed under additional stress. Microscopic organisms near the base of marine food webs could also be harmed. But the ozone layer is not a solid shell. It moves, thickens, and thins as winds transport air through the stratosphere. Scientists therefore measure it in Dobson units. A total column value near 300 Dobson units would form a layer only about 3 millimeters thick if all of that ozone were compressed to sea level pressure. That tiny amount of gas is one of the main reasons life can safely exist on land. In north of Alaska, scientists monitor it one balloon at a time. How do scientists measure something we cannot see? At Arctic monitoring sites, researchers release large balloons carrying compact instruments called ozone sondes. As a balloon climbs, the pressure drops and the balloon expands. The instrument measures ozone concentration, temperature, humidity, and altitude while transmitting data back to the ground. Eventually, high in the stratosphere, the balloon bursts. But by then, it has produced a vertical profile showing exactly where ozone is present and where it is missing. Satellites provide the larger picture. NASA, NOAA, European and other international instruments map ozone across the hemisphere. Ground-based spectrometers compare those observations from below. Aircraft and research campaigns add detailed measurements atmospheric chemistry. No single instrument tells the entire story. A satellite may reveal the size of a depleted region. A balloon can show that the destruction is concentrated at a certain altitude. Temperature observations reveal whether polar stratospheric clouds can form. Wind measurements show whether the vortex is keeping the air isolated. Together, these systems function like an atmospheric early warning network. And this is where DiscoverTube goes beyond the headline. For this investigation, we follow satellite observations, ozone sonde profiles, stratospheric temperature records, and peer-reviewed research from NASA, NOAA, the World Meteorological Organization, and international polar scientists. Researchers are not looking at a visible hole in the sky. They are reconstructing an invisible chemical event from measurements collected across thousands of kilometers. If you want more investigations into the forces changing America, from Alaska's atmosphere and melting permafrost to hidden faults, volcanoes, and extreme weather, subscribe to Discover 2. With more than 1,000 videos, there is always another discovery waiting beneath the surface or above the clouds. Now, to understand why the Arctic ozone layer can collapse, we need to enter one of the coldest places in Earth's atmosphere. What creates an Arctic ozone hole? The process begins with chemicals once used in refrigerators, air conditioners, insulating foams, spray cans, and industrial equipment. Chlorofluorocarbons, or CFCs, were stable near Earth's surface. That made them useful and dangerous. Because they did not break down easily in the lower atmosphere, they survived long enough to drift into the stratosphere. There, ultraviolet radiation split them apart and released chlorine. For much of the year, that chlorine can remain locked in relatively inactive compounds. But inside a cold polar vortex, the chemistry changes. When stratospheric temperatures fall below roughly minus 78 degrees Celsius, polar stratospheric clouds can form. These are not ordinary weather clouds. They develop far above the troposphere, in air that is normally too dry for clouds to exist. Reactions on the surfaces of their particles convert stored chlorine into forms that can rapidly attack ozone when sunlight returns. One chlorine atom can participate in a repeating reaction cycle, destroying many ozone molecules before it is removed from the process. The result is a chemical chain reaction on a continental scale. Three ingredients therefore matter ozone depleting chemicals extreme cold and a stable vortex that prevents warmer ozone rich air from mixing in Antarctica receives that combination almost every year the Arctic usually does not that is what made 2020 so unusual for months the northern atmosphere behaved more like Antarctica than scientists were accustomed to seeing but before we continue, this is exactly why DiscoverTube exists. We investigate the hidden forces changing our planet using scientific studies, satellite measurements, and evidence from organizations such as NASA, NOAA, and the USGS. From unusual activity beneath America's volcanoes and collapsing coastlines, to extreme weather and invisible changes high above the atmosphere, we go beyond the headlines to explain what scientists are actually discovering. With over 1,000 videos and a community of over 231,000 subscribers, another mystery is always waiting to be explored. So, if you are fascinated by the hidden side of our world, subscribe to DiscoverTube and turn on notifications. Because the instruments above the Arctic did not merely detect that ozone was disappearing, they also revealed the extraordinary chemical chain reaction responsible. and it begins with substances released at Earth's surface decades ago. Is this the same as the Antarctic ozone hole? No, and this distinction matters. The Antarctic vortex forms over a continent surrounded by ocean. It is generally colder, larger, and more stable. Severe ozone destruction returns there with remarkable regularity during southern hemisphere spring. The Arctic contains an ocean surrounded by continents, mountain ranges, and powerful weather systems. Those features generate atmospheric waves that frequently disturb the vortex. Some winters produce a sudden stratospheric warming. Temperatures can rise dramatically within days. The winds can weaken or reverse, and the vortex may split into separate pieces. When that happens, the chemical conditions needed for severe ozone depletion collapse. This is why describing every Arctic low ozone event as a new ozone hole can be misleading. Scientists often prefer terms such as severe Arctic ozone depletion or an ozone mini-hole. Some mini-holes are caused mainly by atmospheric motion, which stretches and redistributes ozone without requiring enormous chemical destruction. The 2020 event, however, involved exceptional chemical loss inside the vortex. It was real. It was record-breaking. But it was temporary, dynamic, and different from the annual Antarctic phenomenon. Could it reach Alaska? The vortex does not stay perfectly centered over the geographic North Pole. It wobbles, stretches, and sometimes sends lobes of cold stratospheric air over northern continents. When ozone-depleted air moves away from the Central Arctic, regions beneath it can experience temporarily increased ultraviolet radiation. For Alaska, the effect depends on timing. During the darkest part of winter, the sun remains low or does not rise at all in the far north. Even if ozone is reduced, ultraviolet exposure at the surface remains limited. The concern grows in spring when sunlight returns while snow and ice still cover the landscape. Bright surfaces can reflect ultraviolet radiation, increasing exposure to eyes and skin. That does not mean residents should assume a dangerous event is occurring whenever the polar vortex appears in a weather report. Surface UV depends on ozone clouds sun angle elevation and reflection from snow. It means monitoring matters. Scientists need to know not only how much ozone has been destroyed but where that air will travel as the vortex weakens a depleted air mass can move across Alaska or Canada mix with surrounding air or remain mostly over the Central Arctic Ocean This is why a phenomenon centered north of Alaska is not necessarily isolated from the United States. Nothing in the atmosphere stays neatly above one location. Is climate change making it worse? Here is the paradox. Greenhouse gases warm the lower atmosphere, but they can cool parts of the stratosphere. Colder polar stratospheric conditions could, in theory, allow more polar stratospheric clouds to form and create more opportunities for chlorine-driven ozone destruction. A 2021 study in Nature Communications found that the conditions favoring very large seasonal Arctic ozone losses had increased during the coldest winters over the previous half century. Its model analysis suggested that severe loss could remain possible for decades, depending partly on future greenhouse gas emissions. But scientists continue to debate how strong that effect will be. Other model research, published in 2023, concluded that Arctic Spring ozone minima should generally become weaker over coming decades as ozone-depleting substances decline. That work did not project a notable long-term worsening of Arctic minimum ozone. These findings are not necessarily as contradictory as they sound. The atmosphere is responding to two forces at once. First, chlorine and bromine left by old human-made chemicals are slowly decreasing because of the Montreal Protocol. Second, greenhouse gases are changing atmospheric temperatures and circulation. The long-term ozone trend is toward recovery, but individual Arctic winters may still produce surprising extremes when weather creates a cold, isolated vortex. Scientists are watching because recovery does not happen smoothly. A healing ozone layer can still experience a severe seasonal event. Did the Montreal Protocol solve the problem? It changed the future. In 1987, countries agreed to the Montreal Protocol, beginning a global phase-out of the chemicals destroying stratospheric ozone. Every United Nations member state eventually ratified it. Without that agreement, chlorine levels would have continued rising. Ozone destruction would have spread far beyond Antarctica, exposing much of the planet to far more ultraviolet radiation. Instead, concentrations of major controlled ozone-depleting substances are declining. The 2022 scientific assessment, supported by the United Nations, projected that, if current policies remain in place, ozone should return to approximately 1980 levels around 2040 for most of the world, around 2045 in the Arctic, and around 2066 over Antarctica. That is one of the greatest environmental successes in modern history. But it is not finished. Many ozone-depleting compounds survive in the atmosphere for decades. Old cooling equipment and insulating foam still contain chemical banks that can leak if they are not safely recovered. Unexpected emissions must be detected. Replacement gases must be managed because some do not destroy ozone but strongly warm the climate. And the atmosphere itself can still produce extreme conditions. The 2020 Arctic event did not prove that the Montreal Protocol failed. It proved why the agreement, and the monitoring network built around it, must continue. What are scientists watching next? Every Arctic winter begins another experiment. Scientists watch the strength of the polar vortex. They measure temperatures at different altitudes. They track the formation of polar stratospheric clouds. They compare chlorine chemistry with ozone profiles. And when the sun returns, they look for the signature of rapid destruction. The most important clues may appear weeks before the public ever hears about an ozone event. A vortex that stays strong into March. An unusually large region below the cloud-forming temperature threshold. Balloon profiles showing ozone disappearing within a narrow layer of the stratosphere. Satellite maps revealing a low ozone region rotating above the Arctic Ocean. Then comes the final question. Will the vortex break apart? Or will it survive long enough to deepen the loss? That uncertainty is what makes the region north of Alaska so important. It sits near the boundary between a protected Arctic atmosphere and an air mass capable of carrying ozone depletion toward populated land. what happens next? The strangest part of this story is that it contains both a warning and proof that global action works. Human activity damaged the ozone layer. Scientists detected it. Nations responded. The chemicals responsible are declining, and the protective layer is slowly recovering. But recovering does not mean invulnerable. The record Arctic loss of 2020 showed that cold atmospheric weather can temporarily overpower the gradual healing trend. It showed that the northern vortex can create Antarctic-like chemistry when the conditions align. And it showed why measurements from remote places, from Arctic balloon stations to satellites orbiting hundreds of kilometers above Earth, still matter. There is no permanent hole sitting above Alaska tonight. There is something more complex. An invisible shield in recovery. A polar atmosphere capable of sudden extremes and a scientific network waiting for the next unusual signal. The sky looks unchanged from the ground, but far above the ice, chemistry, temperature and wind are deciding how much solar radiation reaches the surface. And scientists are watching every layer. If you want to see more investigations based on real measurements, satellite data and peer reviewed research, subscribe to DiscoverTube, because some of the most important changes on Earth are happening in places we cannot see, and the next discovery may already be forming above us.