Our planet is more than the things we can see and touch. It is also our atmosphere, our air. We are the only planet we know of with an atmosphere that supports life as we know it. It wasn’t always like this. Our early atmosphere was formed from volcanic gasses including water vapour, ammonia, methane, hydrogen sulphide and
ten to two hundred times as much carbon dioxide as in today’s atmosphere. Much of the carbon dioxide dissolved in the oceans. Eventually a simple form of bacteria developed that could live on energy from the sun and carbon dioxide in the water, producing oxygen as a waste product. A lot of this early oxygen was taken up by oxidation of minerals in the sediments and rocks. The ammonia was split into nitrogen and hydrogen by sunlight and that hydrogen combined with other elements or was lost to space as it was so light. The oxygen level eventually increased and ultraviolet light from the sun split the molecules to create the ozone UV shield enabling life in the air and not just under water. Our atmosphere at present is about 78% nitrogen, 21% oxygen and 1% other gases.
We enjoy a relationship where plants use carbon dioxide for energy and growth and give off oxygen, while we and most animals use oxygen for our energy and give off carbon dioxide. But things change. In times past such as the Carboniferous era that had huge forests producing the coal measures (about 300m years ago) the oxygen level was higher than today allowing foot long dragonflies. And today we are facing problems of climate change caused by an increase in the levels of carbon dioxide and methane. Never was the composition of our air so important.
When I was a kid
I didn’t think there was anything there
where air reigns,
just the space between shapes and lives.
I didn’t think space mattered.
I didn’t see that I wouldn’t see
anything at all
if not held by space,
there would be no square or round or prism,
no place for love to grow between,
no words or songs or might have been,
I didn’t know
that air was so full
when it looked so empty,
that it carried chemicals
for our breath, our plants, our fire,
that it held up planes and slowed down cars,
that it pushed without weighing
anything at all,
that it moved to give wind
and rippled to bring sound
to my ear.
I didn’t understand
that air invisibly enables