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Climate Change Is Causing The Upper Atmosphere To Cool, And The Side Effects Are Terrifying
It turns out carbon emissions are far more damaging than we thought.
You might think that climate change is causing temperatures to rise. However, a recent study has shown this isn’t the case. You see, the increased levels of carbon dioxide generated by humanity's rampant use of fossil fuels, is causing the upper layers of our atmosphere to rapidly cool. This might sound like a good thing, but in actuality, it will cause some catastrophically adverse knock-on effects, from deadly extreme weather, to eroding the Earth’s life — protecting ozone layer and even potentially destroying satellites. But how is carbon dioxide cooling the upper atmosphere? How does a cooler upper atmosphere cause these destructive side effects? And is there anything we can do to stop this?
Climate scientists suspected for decades that the upper atmosphere would cool as carbon dioxide levels rose, and climate change started to bite, as their climate models suggested it would. However, only recently have scientists been able to take regular systemic measurements of the temperatures of the upper atmosphere. A recent study used detailed measurements from satellites to show that, indeed, the upper atmosphere is cooling. This is yet another bit of evidence that those climate models are accurate, which is worrying as they also predict massive amounts of climate change.
But how does carbon dioxide cool the upper atmosphere?
To understand this, you need to understand how the greenhouse effect, which makes carbon dioxide so problematic, works. Carbon dioxide is transparent to visible light, but it strongly absorbs infrared radiation, and when it does so, it heats up. Most of the light that reaches us from the sun is in the visible spectrum, allowing it to pass easily through the atmosphere. It is then absorbed by the Earth’s surface, heating it up. But when objects are heated up, they radiate this energy out through infrared radiation, and the hotter they are, the more infrared they give off. This is the light that thermal imaging cameras see. However, on a planetary scale, these properties combine to mean that visible light from the sun passes through the atmosphere, is absorbed by Earth’s surface, and radiated out as infrared light, which is absorbed by carbon dioxide in the atmosphere, which heats it up.
So, the more carbon dioxide there is in the atmosphere, the more solar radiation is trapped in the atmosphere, and the hotter the Earth gets (on average).
But this only works for the lower part of the atmosphere. You see, the upper and lower atmospheres have the same ratio of carbon dioxide in them, but the lower atmosphere is a lot denser than the upper atmosphere, meaning it can absorb more energy. This means that as the levels of carbon dioxide increase, less infrared radiation emitted by Earth’s surface makes it to the upper atmosphere. As such, the upper atmosphere cools. In fact, it cools more than the lower atmosphere heats up. At current rates of emissions, scientists believe upper atmosphere cooling could hit 13.5 °F (7.5C) during the century; meanwhile, the lower atmosphere is only set to heat up by 4.86 °F (2.7C).
As air cools, it contracts. So as the upper atmosphere cools, its depth shrinks, and by quite some margin. NASA data has shown that its depth has already reduced by 1,300 feet over the past 40 years, and the mesosphere, which sits above the upper atmosphere, shrank by 4,400 feet between 2002–2019. The increased temperature difference between the upper and lower atmosphere will also cause these two layers to mix far less than they used to.
This causes some astonishingly horrific knock-on effects, namely increased risk of space debris, ozone depletion and extreme weather.
Let’s start with the space debris, as that might seem like the most puzzling at first. It’s no secret that the space industry has a rubbish problem. Old and dysfunctional satellites and throw-away parts of rockets are left to drift in orbit. But orbital speeds are vast, and as they can’t be manoeuvred, this space trash can impact each other or active satellites at tens of thousands of miles an hour, obliterating them and creating hundreds more supersonic pieces of debris.
Normally, the thin wispy bits of the uppermost atmosphere interact with space debris, slowing them down and causing them to deorbit. But as the atmosphere cools and contracts, this orbital drag factor is reduced, meaning space debris stays in orbit longer and has the chance to destroy more multi-million dollar satellites.
But, that is the least of our worries, as the cooler upper atmosphere also eats away at the ozone layer. Ozone is a form of oxygen that can be found in high concentrations in the stratosphere around the entire world and acts as an atmospheric sunscreen, as it absorbs deadly UV light. UV is incredibly damaging to cells and DNA, and so some scientists think that the only reason complex life was able to develop on Earth was because an ozone layer protected it.
The problem is that ozone isn’t a stable molecule, and things easily break it down. This is why CFCs, which we used to use in aerosols and fridges, tore a hole in the ozone over the Arctic. Luckily, a treaty which banned CFCs has stopped the damage and helped the ozone layer heal itself. But a cooling upper atmosphere will also rip holes in the ozone. You see stratospheric clouds, which only form in cold conditions in the upper atmosphere, also destroy ozone. So as the temperature in the upper atmosphere drops, more of these clouds form (particularly in polar winters), and ozone is eaten away. This will cause elevated levels of cancer (in both humans and wildlife), wreak havoc on ecosystems, and greatly accelerate climate change.
The final brutal effect is more extreme weather. As I stated earlier, as the temperature difference between the upper and lower atmosphere gets larger, the two don’t mix. What’s more, carbon dioxide’s greenhouse effect is pumping more energy into the lower atmosphere. This means that the weather has more energy and less space to disperse that energy. This will cause dramatically more extreme weather that lasts far longer than anything we have seen before. Picture heat waves and droughts that last for weeks, sudden month-long snow storms or insane floods happening far more often than they do today. Conditions like this can cause massive amounts of damage to both ecosystems and humanity.
With all of this in mind, the fact that the upper atmosphere will cool by a massive 13.5 °F (7.5C) means that these knock-on effects won’t be insignificant. In a decade or so, there will be deadly and destructive storms and a new gaping hole in the ozone caused by a cooler upper atmosphere.
So, now we know that the upper atmosphere is cooling and the catastrophic effects it could have, what can we do about it? There is only one solution, cut carbon emissions dramatically. We have been dragging our heels on this for years, and we are getting to the eleventh hour. The question has to be asked, how much longer can we let this go on? And when will we take the drastic action needed to save the beautiful planet?
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