Where it all begins

I have already mentioned a concept called the Greenhouse Effect a couple of times.  I think it is time to discuss exactly what this natural phenomenon is, as it is the very basic building block upon which we understand climate change.

First, let's investigate incoming solar radiation.  The earth receives radiated energy from the sun in many different wavelengths, including Ultra Violet, Visible, and Infrared.  More wavelengths are emitted by the sun, but Earth's atmosphere is most effective in filtering out much of this radiation.  This energy which does reach Earth's surface is very useful for life on Earth, plants absorb it to make sugars and grow.  We humans obviously appreciate the visible light and the infrared radiation for warmth.  The chart below demonstrates the amounts of various wavelengths of radiation received by Earth's surface, which are generally shorter wavelengths.

Source: Nature Publishing Group

Much of this radiation which is absorbed by the Earth is re-radiated back out by the Earth at longer wavelengths.  The Earth's atmosphere is very good at blocking harmful radiation from the Sun, but it also prevents some of this re-radiated energy from escaping back out into space.  This, generally, is a good thing, as it helps keep Earth's atmosphere and surface warmer and makes Earth a nice, habitable place to live.  This action of the atmosphere preventing Earth's short-wave radiation from going out into space and reflecting it back toward Earth's surface is called the Greenhouse Effect.  The name is in reference to how glass in a greenhouse lets radiation in from the sun and traps it inside.  The greenhouse then warms up and is able to maintain an nice warm temperature despite outside temperatures.  This concept is demonstrated in the picture below.

Source: EarthlyIssues.com

While the Greenhouse Effect makes Earth a habitable place for us, in recent history it has become what is now referred to as the Enhanced Greenhouse Effect and is having a negative impact on Earth's atmosphere and climate.  The part of the atmosphere which prevents some radiation from escaping to outer space is a layer of Greenhouse Gases, which are naturally occurring in the atmosphere in low levels.  A few of these important Greenhouse Gases are CO2 and Methane, and in the atmosphere they function to trap Earth's long-wave radiation, keeping the surface and atmosphere warm.  With the advent of the Industrial Revolution and the dramatic increase in large scale burning of fossil fuels, the amount of CO2 released into the atmosphere has been rapidly escalating.  This increased amount of CO2 has heightened the function of the Greenhouse Effect, creating the Enhanced Greenhouse Effect.  Effectively, it's like the natural Greenhouse Gases are a blanket, keeping Earth's surface and atmosphere warm, however with human activity increasing the amount of Greenhouse Gases in the atmosphere the blanket has grown ever thicker and is creating a warmer and warmer climate across the Earth.