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Sulfur hexafluoride (SF₆) comes from producing magnesium, and many types of industry use it in insulating major electrical equipment.

      HOW GOOD INTENTIONS INCREASED NITROUS OXIDE EMISSIONS

      Fossil fuels (which we discuss in greater detail in Chapter 4) contain nitrogen. When cars burn gasoline, they give off the nitrogen-based chemicals nitrogen monoxide (NO) and nitrogen dioxide (NO₂) — together known as NO_x gases. These NO_x gases create acid rain and smog in cities.

      In response to these environmental problems, governments in North America forced car companies to put catalytic converters in all their cars. Catalytic converters convert smog-causing chemicals into other chemicals that aren’t as damaging to our lungs and don’t cause acid rain.

Unfortunately, these catalytic converters turn NO_x gases, which don’t have an effect on climate change, into nitrous oxide (N₂O), which does! (One more reason, if you need it, why everyone should drive less.)

      Other players on the GHG bench

      The two GHGs that we talk about in the following sections do play a role in climate change, but they aren’t on the United Nations list of 24 GHGs and get left aside in most discussions about the impact of GHGs on global warming — not for scientific reasons, but because of decisions made in international negotiations.

      Water vapor

      As we discuss in the section, “Focusing On Carbon Dioxide: Leader of the Pack,” earlier in this chapter, water vapor is a huge player in the greenhouse effect. As shocking as it may seem, good ol’ H₂O (two parts hydrogen, one part water) causes the majority — 60 percent — of the planet’s greenhouse effect. But the ramped-up threat of climate change isn’t tied to water vapor. Water vapor remains an essential reason the planet is warm enough to sustain current life forms.

Unlike the production of the other GHGs, humans don’t directly cause the increase of water vapor. But the other gases that are produced heat up the atmosphere. When plants, soil, and water warm up, more water evaporates from their surfaces and ends up in the atmosphere as water vapor. A warmer atmosphere can absorb more moisture. The atmosphere will continue to absorb more moisture while temperatures continue to rise. See Figure 2-6.

      © John Wiley & Sons, Inc.

      FIGURE 2-6: Water evaporates and lingers in the atmosphere.

Water vapor also differs greatly from other GHGs because the atmosphere can hold only so much of it. When you watch a weather forecast, you hear the term relative humidity, which refers to the amount of water vapor currently in the atmosphere compared to how much the atmosphere can hold. On a really hot and sticky day, the relative humidity may be 90 percent — the atmosphere has just about taken in all the water vapor it can. When the relative humidity reaches 100 percent, clouds form, and then precipitation falls, releasing the water from the air.

      Ozone depleters

Chlorofluorocarbons (CFCs) are also considered GHG, responsible for about 12 percent of the greenhouse effect the planet is experiencing today. You don’t find much of these CFC gases around anymore because the Montreal Protocol of 1989 required countries to discontinue their use. CFCs break down the ozone — the layer throughout the stratosphere that intercepts the sun’s most deadly rays. (Without the ozone layer, the sun’s ultraviolet rays would kill all living things.) CFCs were mostly used in aerosol spray cans and the cooling liquids in fridges and air conditioning. The Montreal Protocol was a fantastic success. The use of chemicals that destroy the ozone layer is illegal — globally. And now the ozone layer has started repairing itself! A side effect of banning ozone-eating chemicals is that a lot of them were also GHGs. So protecting the ozone layer also helped the climate!

      

Because CFCs are already regulated under the Montreal Protocol, they’re not regulated under climate agreements. The recent Kigali Amendment to the Montreal Protocol will remove a significant amount of GHG that are also ozone depleters (Read more about what gases are covered under the Kyoto Protocol in Chapter 11.)

      RUNNING UP EMISSIONS WITH YOUR SNEAKERS

      Some of the sources of these gases are really wild. Here’s one: Nike came out with the popular Nike Air shoe, a running shoe with a cool little air-filled bubble in the heel, in the late 1980s. That bubble was filled with — you guessed it — a GHG (Sulfur hexafluoride, to be exact)!

      The amount of GHG in those shoes all together added an equivalent of about 7 million metric tons of carbon dioxide — or the emissions from 1 million cars — into the air when they hit the garbage dump after being worn out. In the summer of 2006, after 14 years of research and pressure from environmental groups, Nike stopped using the GHG in shoes and replaced it with nitrogen. We’re glad that bubble burst.

      Unfortunately, getting sulfur hexafluoride out of Nike runners didn’t eliminate all sources. Sulfur hexafluoride levels in the atmosphere continue to rise due to its use in the electricity sector. Concentrations of sulfur hexafluoride have been creeping up by about 0.36 parts per trillion (ppt) per year. In 2021, it made up 10.66 ppt of our atmosphere.

Chapter 3

      Recognizing the Big Deal about Carbon

      IN THIS CHAPTER

      

Looking into what else contributes to climate change

      

Linking carbon dioxide to temperature trends

      

Understanding what happens when the temperature becomes too hot to handle

      

Limiting greenhouse gas emissions

      Elizabeth and Zöe Caron wrote Global Warming For Dummies in 2009. Back then, the consensus of the world’s scientists was that

       Climate change was caused by rising carbon and other greenhouse gases (GHGs) emitted to the atmosphere ss a result of human activity.

       Climate change could become irreversible and catastrophic if emissions kept increasing.

       The use of fossil fuels had to be reduced drastically.

      The solid worldwide scientific consensus has only been reinforced since then. And now the consensus isn’t just among scientists — it has become common understanding. Humans are having real-time experiences of floods, fires, droughts, heatwaves, and other disasters. The worst-case projections for the speed and magnitude have turned out to be not worse enough.

Still, even though the science is settled, scientists still say global warming is a theory. A scientific theory is based on a set of principles

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