The earth’s atmosphere is a thin layering of gases – nitrogen, oxygen, carbon dioxide – that support many of life’s functions, including trapping enough of the earth’s circulating energy flows to warm the planet. While concentrations of these gases have varied over geological history, they have been relatively stable during the past several thousand years. During this time, moderate climate and temperatures have enabled human civilization to emerge and evolve. Global warmth distinguishes earth from cold, barren bodies such as the moon or Mars that lack our atmosphere and the life it supports.
During the Industrial Revolution in the early 19th century, we increasingly substituted energy from fossil fuels for labor from humans and domesticated animals. This created opportunities for the enlargement of human wealth, knowledge and technological gains that have greatly benefited civilization. It also began to alter the composition of atmospheric gas concentrations, a change that today threatens to erode that advantage. By trapping more of the sun’s energy, and releasing less of it back into space, we are disturbing the moderate climate conditions that support our civilization and economy.
Picture parking your car at a shopping mall on a hot summer day. Leave your windows half down, and when you get back from shopping the air inside the car is a little warmer than the air outside. Now roll the windows all the way up and leave the car again. When you come back you can feel the heat you’ve trapped inside with no way to escape.
That’s what we’re doing globally: rolling the windows up (increasing greenhouse gas concentrations) so more heat is trapped inside. Carbon dioxide, which is released when we burn fossil fuels like coal, oil or gas, is the principal greenhouse gas and the one that stays in the atmosphere the longest. Other greenhouse gases such as methane and nitrous oxide have more “trapping” effect. All contribute to global warming and can be controlled, but the world’s principal focus is on reducing carbon dioxide levels by finding substitutes for fossil fuel combustion or ways to contain emissions from their use. We sometimes use “carbon” or “carbon dioxide” as shorthand for “greenhouse gases.”
Below are links to several recent booklets and Web pages with clear explanations of climate basics. You can also read more about the local impacts of climate change on our Oregon's Climate page.