Essay About Tiny Globe And Solar Radiation

Energy, Technology and Climate: Running out of Gas
Essay title: Energy, Technology and Climate: Running out of Gas
Energy, Technology and Climate: Running Out of Gas
David Goodstein
Published in New Dimensions in Bioethics, Yale University Press
We are faced with a grave crisis that may change our way of life forever. We live in a
civilization that evolved on the promise of an endless supply of cheap oil. The era of
cheap oil will end, probably much sooner than most people realize. To put this looming
crisis in perspective, and to judge its significance, it helps to start from the beginning.
Here is how it all works.
Nuclear reactions inside the Sun heat its surface white hot. From that hot surface, energy
in the form of light, both visible and, to our eyes, invisible, radiates uniformly away in all
directions. Ninety million miles away, the tiny globe called Earth intercepts a minute
fraction of that solar radiation. About 30% of the radiation that falls on the Earth is
reflected directly back out into space. That’s what one sees in a picture of the Earth taken,
say, from the moon. The rest of the radiant energy is absorbed by the Earth.
A body such as the Earth that has radiant energy falling on it warms up or cools down
until it is sending energy away at the same rate it receives it. Only then is it in a kind of
equilibrium, neither warming nor cooling. In any given epoch, the Earth, like the Moon
or any other heavenly body is in steady state balance with the Sun, neither gaining nor
losing energy. That is the primary fact governing the temperature at the surface of our planet.
The rate at which the Earth radiates energy into space depends on its temperature.
Because it receives only a tiny fraction of the Sun’s energy, it radiates much less energy
than the Sun does. So, it can balance its energy books at a temperature much cooler than
the Sun. In fact it can radiate as much energy as it receives with an average surface
temperature of 0 degrees Fahrenheit. The Earth’s radiation is not visible to our eyes. It is
called infrared, or below red radiation because its color is beyond the red end of what we
are capable of seeing.
Fortunately for us, that’s not the whole story. If the average surface temperature of the
Earth were really 0 degrees F, we probably would not be here. The Earth has a gaseous
atmosphere. The atmosphere is largely transparent to the white-hot radiation from the
Sun. The nitrogen and oxygen that make up nearly all of the Earth’s atmosphere are
transparent as well to the infrared radiation from the Earth, but there are trace gases,
including water vapor, methane and carbon dioxide that absorb infrared radiation. Thus
the blanket of atmosphere traps about 88% of the heat the Earth is trying to radiate away.
The books remain balanced, with the atmosphere radiating back into space the same
amount of energy the Earth receives, but it also radiates energy back to the Earth’s
surface, warming it to a comfortable average temperature of 59 degrees F. That is what’s
known as the greenhouse effect.
There is a tiny but vital exception to the perfect energy balance of the Earth-Sun system.
Of the light that falls on the Earth, an almost imperceptible fraction gets used up
nourishing life. Through photosynthesis, plants make use of