a lid on pots on your stove makes your food cook more efficiently?.
Not every action that you can take to cut back on your GHG emissions is manageable — not everyone can yet buy a hybrid or electric car or build a home that doesn’t rely on major power producers for energy. But, hopefully, we suggest some options in this book that fit your situation and can help you to make a difference.
Global warming affects everyone, and everyone can play an important role in stopping it. Balance the doom and gloom and — start thinking about the exciting opportunities you have to make a change.
Chapter 2
Looking Closely at Greenhouse Earth
IN THIS CHAPTER
What you’ve read or seen may make you think that the greenhouse effect and greenhouse gases (GHGs) are all bad. Actually, GHGs have long been the good guys.
Planet Earth is a tiny warm dot in vast frigid space. The atmosphere keeps the Earth warm because the atmospheric gases trap the heat of the sun, just as greenhouse glass does. Inside greenhouse Earth life is comfortable. Anywhere without a nice balance of GHGs, like say Venus (hot, hot, hot) or Mars (really cold), not so much.
When it comes to the survival of all living things on Earth including us humans, the home planet needs to be like the porridge in Goldilocks and the Three Bears: not too hot or too cold, but just right.
GHGs become a problem only when the atmosphere contains too much of them, which is happening today. Industries and farms, cities, and garbage dumps are pumping out an array of gases — carbon dioxide, methane, nitrous oxide, and a host of other substances. Humanity has knocked off kilter the life-preserving cycle that makes sure the Earth’s atmosphere has just enough carbon dioxide, the star GHG.
This chapter is the A-B-Cs of climate science. This is basic science, and it’s less complicated than you think! You know (from third grade) how plants use energy from the sun to soak up carbon dioxide and release oxygen. You probably remember the big word — photosynthesis. This chapter gives you the basics.
Examining Greenhouse Effect 101
If you want to understand the greenhouse effect, the best place to start is with the object that provided this analogy in the first place, the greenhouse. A greenhouse works by letting in sunlight, which plants and soil absorb, thus heating up the greenhouse. The panes of glass ensure that the warmer air doesn’t escape the greenhouse, or does so very slowly. If you’ve ever parked your car with the windows rolled up on a sunny day, you’ve experienced this effect. When you open your car door, you’re hit with a blast of hot air. The windows of your car have acted like the panes in a greenhouse, letting sunlight in, which heats the car, and then trapping that heat.
Certain gases in the atmosphere trap the sun’s heat in a similar way. These particular gases are called greenhouse gases because they cause this greenhouse effect. The Earth is bombarded by radiation from the sun. Some of this radiation can be seen (think visible light), and some of it can’t be (ultraviolet light, for example).
A portion of this radiation, about 30 percent on average, bounces off clouds, ice, snow, deserts, and other bright surfaces, which reflect the sun’s rays back into outer space. The other 70 percent is absorbed by land or water, which then heats up. And the Earth emits some of that heat — in the form of infrared radiation (electromagnetic waves most commonly known as heat). The unique qualities of the GHGs come into play: The GHGs absorb some of the escaping infrared radiation in the lower atmosphere, and re-radiate part of that back down. So, less of the radiation from the Earth’s surface gets to outer space than it would have without those gases, and that energy remains in the atmosphere and returns to the Earth’s surface — making both the atmosphere and Earth itself warmer than they would be otherwise.
To see the greenhouse effect in action, look at Figure 2-1.
© John Wiley & Sons, Inc.
FIGURE 2-1: The greenhouse effect in action.
If the planet had no atmosphere or GHGs, humanity would be left out in the cold. The Earth wouldn’t be able to keep any of the heat that it gets from sun. Thanks to GHGs, humanity is kept reasonably warm, enjoying an average temperature of 59 degrees Fahrenheit (15 degrees Celsius), some 62.6 to 64.4 degrees Fahrenheit (17 to 18 degrees Celsius) warmer than without GHGs.
Too much GHG turns the heat up beyond that to which societies and ecosystems have become adjusted. The atmosphere on the planet Venus is 96 percent carbon dioxide (the key GHG that we talk about in the following section). Because of Venus’s concentration of GHGs and its relatively close proximity to the sun, it’s extremely hot — surface temperatures of up to 500 degrees Celsius. Meanwhile, the atmosphere on Mars has 95 percent carbon dioxide, but it’s very thin, and the planet’s position is farther away from the sun than Earth, so it’s extremely cold — a chilly –80 degrees Fahrenheit (–60 degrees Celsius).
Focusing On Carbon Dioxide: Leader of the Pack
Earth’s atmosphere contains 24 different GHGs, but just one of them accounts for the overwhelming majority of the effect: carbon dioxide (or CO2, for short). This gas accounts for about 63 percent of the GHG warming effect in the long run. (In the short term, over the last 5 years, it has accounted for 91 percent. See Table 2-1 for more on the intensity of gases over time.) If you’re itching to know about the other 37 percent of greenhouse warming, check out the section “Checking
