Saturday, June 20, 2015

Changing Atmosphere

Earth amassed its atmosphere from the gases of cooling rocks.
“The earth was initially very hot and without an atmosphere. In the course of time it cooled and acquired an atmosphere from the emission of gases from the rocks.”
Stephen Hawking, A Brief History of Time
Today life persists in a thin band of Earth's atmosphere called the troposphere which has a mean height of 11 miles (~ 17 km) in the middle latitudes straddling the equator.

Layers of the atmosphere
source: NASA

While it's stands to reason that the atmosphere would continue to change over time, in recent decades the rate of change in the composition and characteristics of the atmosphere has become cause for concern, particularly when compared to the adaptive capacity of living organisms.

A range of public figures from naturalist David Attenborough, to science educator Bill Nye and entrepreneur Elon Musk have expressed concern over the impact of human activity on the composition and characteristics of the atmosphere.

On human population growth and industrialization:
"I would be absolutely astounded if population growth and industrialization and all the stuff we are pumping into the atmosphere hadn't changed the climatic balance. Of course it has. There is no valid argument for denial."
David Attenborough
On burning carbon-based fuels creating gases that trap the sun's radiant energy:
"Burning carbon-based substances like oil, gas, and especially coal, produces billions of tons of extra carbon dioxide each year. Methane gas from cows and pigs and other animals on our large farms ends up in the atmosphere as well, trapping more of the sun's energy as heat."Bill Nye
On the rapidly accumulating carbon dioxide in the atmosphere:
"We're running the most dangerous experiment in history right now, which is to see how much carbon dioxide the atmosphere... can handle before there is an environmental catastrophe."Elon Musk

Earth's standard surface gravity of 9.8 m/s2 holds down the atmosphere, while atmospheric escape is the loss of atmospheric gases to outer space.
“The oldest, easiest to swallow idea was that the earth was man's personal property, a combination of garden, zoo, bank vault, and energy source, placed at our disposal to be consumed, ornamented, or pulled apart as we wished.”
Lewis Thomas, The Lives of a Cell: Notes of a Biology Watcher