We live at the bottom of an ocean of air. And this ocean is a protective layer surrounding the planet. It keeps us warm and provides us with the oxygen we need to breathe. It carries rain which, after a wet summer in Prince George, might not seem like such a good thing but it is essential for life and provides our drinking water. Our atmosphere is fairly unique in making Earth a blue-green planet.
Of course, living at the bottom of an ocean can also lead to turbulent times. The lower atmosphere is where devastating hurricanes and tornadoes reside. The monsoons of the tropics can pound vast regions into submission. Winter storms can freeze cities into submission. Summer heat waves can be just as deadly both directly through heat related deaths and in drying out the forests and scrub lands leaving them ready for fires.
It is the atmosphere which gives rise to the lightning strikes which start fires. The 560 forest fires burning through California arise from over 12,000 strikes in a 72 hour period. And without any rain, many of the fires will burn for a very long time before eventually being controlled.
Yes, we live blanketed in an atmosphere which envelopes us in safety and, at the same time, provides us with some of the more devastating catastrophes. But the lower atmosphere is just one of the envelopes we rely on for safety.
Extending between 15 and 30 kilometres above the Earth, in the heart of the stratosphere, is the ozone layer. It is a region of our atmosphere where molecular or diatomic oxygen mixes with triatomic ozone. The two molecules exist in a lopsided equilibrium (20.974% oxygen compared to 0.0015% ozone). It is the reactions which convert one into the other which absorb ultraviolet light. Indeed, the ozone layer only lets 1 in every 10 to the power of 30 photons of UV pass through. It is phenomenally efficient.
Even so, the rare photons of UV light which do make it through can cause severe damage. Skin cancers are linked to UV levels as are cataracts and macular degeneration. Sun burns and heat rashes arise from over-exposure. Other forms of life are also susceptible to UV radiation. Plants can bleach and leaves can curl. Bacteria die which might seem like a good thing except not all bacteria are bad. Many of our important ecosystem services rely on bacteria.
Fortunately, the ozone layer is naturally balanced and robust but add in anthropogenic chemicals and ozone depletion can occur. Chlorofluorocarbons were once common propellants for aerosol sprays and employed in refrigerators and air conditioning units. These compounds persist in the atmosphere wending their way to the ozone layer where a single CFC molecule wipes out 100,000 molecules of ozone and with them, our safety blanket.
In 1987, a landmark agreement to phase out ozone depleting substances called the “Montreal Protocol” was ratified by all member countries of the UN. The ozone layer – and the hole over the Antarctic – has been recovering slowly ever since. But it will be decades before it is fully recovered.
The atmosphere isn’t the only protection we have from the dangers of outer space. Earth’s magnetic field provides an additional safety coating. The magnetic flux from the Earth’s core sweep the solar wind around the planet preventing harmful sub-atomic particles from raining down on us. In combination with the atmosphere, the magnetosphere protects us from cosmic rays – interstellar radiation streaming from beyond the solar system.
Except the magnetosphere is undergoing changes which have left scientists puzzled. The North Magnetic Pole has picked up pace and is charging across the Arctic from Canada to Russia at 50 kilometres per year. And the South Atlantic Anomaly (SAA) appears to be splitting in two. Currently, this not having any visible impact on our daily lives but as the SAA expands westward, it is beginning to encompass South America. The anomaly lets in excessive amounts of cosmic radiation and this could potentially have a damaging impact for the people and the electrical systems of the continent.
In addition, due to a solar minimum, the magnetosphere of the Sun is allowing more cosmic rays to enter the Solar System, period. Measurements made by the students of Earth to Sky Calculus in California match those observed at the Sodankyla Geophysical Observatory and indicate a 20% increase in cosmic rays in the atmosphere over the past four years. A 20% increase may not seem a lot but for frequent fliers it can be equivalent to an extra chest X-ray or two per year. This is particularly troubling for pilots and air stewards as they are already classified as occupational radiation workers.
The good news? This solar minimum should soon pass. The bad news? We haven’t even talked about the Asteroids heading our way but the atmosphere should protect us.
