On average, residents have three opportunities each week to participate in a GreenHouse-sponsored event. ![]() Residents are able to learn about the Madison community and its building projects, take part in cooking classes, canoe trips, and enjoy films and other travel opportunities. Events and programs linked to experiential learning, food and environmental justice take place multiple times each semester. This Explainer was adapted from “ Explained: Greenhouse Gases” by David Chandler, which originally appeared in MIT News.Being the hands-on environment that it is, GreenHouse has many student-led initiatives take place throughout the year. The ban was not because of climate change, but because CFCs were also destroying the Earth’s ozone layer. Luckily, CFCs were banned in 1987 under the international Montreal Protocol. There are many CFCs, but all have a huge warming effect: one, HFC-23, is counted as 12,690 CO 2 equivalents. By far the biggest way we add nitrous oxide to the atmosphere is by growing crops with nitrogen-based fertilizers.Ĭhlorofluorocarbons, or CFCs, were once used in refrigerators, air conditioners, and aerosols. It is best known as laughing gas, but that kind of commercial use makes up only a tiny part of our emissions. Nitrous oxide is a powerful greenhouse gas that lasts for over 100 years in the atmosphere. Instead, they come from livestock, changes in forests and wetlands, and leaks from gas wells and pipes. Methane is an especially hard greenhouse gas to measure, because most emissions don’t come from industrial plants. Methane reflects about 100 times as much heat as CO 2, but its lifetime in the atmosphere is much shorter: about 10 years. ![]() The number-two cause of climate change is methane, the main part of natural gas. So as the planet warms, we will tend to have more water in the atmosphere at a time-and that does heat the planet. But because water vapor quickly leaves the atmosphere as rain, we don’t have to worry about our “water emissions.” On the other hand, warmer air can hold more water vapor without causing a rainstorm. The most common greenhouse gas is actually water vapor, like in clouds. All of these sectors can make changes to emit less CO 2, but the same solutions won’t work for all of them.Ĭlick here to see data from the infographic above in a table. That includes burning fossil fuels for electricity and heat and to power our vehicles, but it also includes manufacturing concrete and steel, the refining process for raw oil and gas, fermentation (for instance, to make alcohol or pharmaceuticals), and the decay of plant matter (like after trees are cut down). This means that, even if we stop all new CO 2 emissions tomorrow, it will take many lifetimes before the warming effect of our past emissions fades away.įinally, many different industries rely on carbon-rich fuels or other processes that give off CO 2. The CO 2 we emit today will stay above us reflecting heat for hundreds of years. Second, it lasts a long time in the atmosphere. First, there is just so much of it: we now add over 35 billion tons of CO 2 to the atmosphere every year, mostly by burning carbon-rich fuel like coal and oil that had previously been trapped in the ground. There are three main reasons CO 2 is so central to the global warming happening today. ![]() The focus on “carbon”įor climate change, the most important greenhouse gas is carbon dioxide, which is why you hear so many references to “carbon” when people talk about climate change. This is the cause of human-made climate change: by adding greenhouse gases to the atmosphere, we are trapping more heat, and the entire planet gets warmer. But if the amount of greenhouse gases in the atmosphere changes, the strength of the greenhouse effect changes too. Without it, our planet would be too cold for life as we know it. The greenhouse effect is not a bad thing. ![]() This is called the “greenhouse effect,” in a comparison to the heat-trapping glass on a greenhouse. Greenhouse gases reflect infrared radiation, so some of the heat leaving the Earth bounces off the greenhouse gases in our atmosphere and comes back to the Earth’s surface. But when that same energy leaves the Earth, it does so as infrared radiation, which we experience as heat. When energy from the sun first reaches us, it does so mainly as light. The reason they warm the Earth has to do with the way energy enters and leaves our atmosphere. Greenhouse gases are gases-like carbon dioxide (CO 2), methane, and nitrous oxide-that keep the Earth warmer than it would be without them.
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