Global warming, climate change, the greenhouse effect, greenhouse gases, CO2, methane, ozone… How does one make sense of it all?
Here is a quick cheat sheet:
This label is used to describe a steady trend that has been noted since the beginning of the Industrial Revolution. The "global mean temperature" of our planet (a compilation of a bunch of temperature measurement taken around the globe) has been creeping up. Though your home town or favorite vacation spot may be cooler, or hotter, from year to year, if the temperatures around the globe are averaged there is indeed a steady trend - things are heating up.
Although "global warming" and "climate change" are often used interchangeably, there is a good reason to make distinction between these two terms. One way to think about this distinction is as follow: the globe as a whole is warming (global warming); this is causing all kinds of weather anomalies (climate change). Though some places may be warming (especially our planet's poles) other places may be getting dryer, wetter, stormier or even colder. Why is global warming causing such diverse climate change? Because warming our climate has all kinds of consequences. Two examples: warmer oceans result in more violent storms. Altered temperatures might disrupt traditional atmospheric currents like the Gulf Stream that warms Northern Europe.
The Greenhouse Effect
Our atmosphere can be thought of as a soup of molecules. Most of us know of oxygen (sometimes given the chemical notation O2), but there are a slew of other gases floating around out there. Some of these gases are particularly adept at retaining and reflecting heat. Much as glass panes provide a greenhouse with a nice heat-cloak, green house gasses help keep our planet warmer. In general this is a really good thing. Without them our planet would be one chilly place. The worry is that we are starting to see too much of a good thing which is probably a really, really bad thing. To great a volume of greenhouse gases in the atmosphere equals a planet that is getting too hot.
Greenhouse gases are the gases that cause the greenhouse effect (for more on the greenhouse effect jump up a section). The primary gas scientists are thinking about when they discuss global warming over a cup of hot coffee is carbon-dioxide (one carbon atom linked to two oxygen atoms: CO2). It turns out this gas is really good at soaking up and reflecting heat back at us when it hangs out in the atmosphere. So the more of it there is the warmer things get. Methane is also a greenhouse gas. In fact, it is almost 60 time more powerful than CO2 in warming our planet. Luckily there is less of this heat-loving molecule in the atmosphere -- mostly because it breaks apart more quickly than CO2. Though both Methane and CO2 age, and eventually breakdown, after floating around in the atmosphere for some time, CO2 takes a long time to do this - ever CO2 molecule that hops into the sky now is a guest that might still be hanging around a century from now.
Why are there more of these greenhouse gases than there used to be? Because we release them when we produce electricity or run our trains, planes, ships and automobiles powered by fossil fuels. Coal and crude oil (the basis of gasoline and diesel) are our main fossil fuels. When burned we can transform these fuels into energy, unfortunately a byproduct is the release of carbon which happily combines with oxygen and creates CO2.
Ozone and Holes in the Ozone Layer
Ozone and the ozone layer actually get tossed into the global warming debate even though they technically are elements of a different way we have changed our environment. The ozone layer is a gas layer in our atmosphere composed of ozone (O3). This onionskin of atmosphere is essentially our earth's sunscreen. Ozone helps keep most of the cancer causing UV rays that might reach us from reaching us. For a long time we were inadvertently ripping a hole in our ozone layer by producing chemicals called (here comes a mouthful) chlorofluorocarbons (or CFCs). These were used for, among other things, cooling our refrigerators and making Styrofoam. Luckily we noticed the problem they were causing, acted swiftly and for the most part banned CFC production around the globe. Happily the hole in the ozone now seems on the mend. Our experience here could be viewed as a good lesson advocating swift, decisive action to deal with global warming.