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Beautiful, isn't it? Scientists and nature-lovers, alike, have always known that we need to be good stewards of the environment. But, it wasn't until this image, called the Blue Marble, was taken on December 7, 1972, that people started to take notice. Here's an image of the North Pole from space from then. And, here it is today. The changes you see between these two photos are examples of climate change, due to global warming. The Earth is heating up, at what scientists believe to be an alarming rate. Since the beginning of the Industrial Revolution, air temperature at the Earth's surface has been heating up. The oceans are warming, too. And, the polar ice caps are melting. The result of increased greenhouse gases from pollution. Okay, fine. These greenhouse gases have only warmed the Earth by about 1.3 degrees Fahrenheit since 1906. Meteorologically speaking, it's a noticeable increase. More on that later. So, what exactly are greenhouse gases? In some ways, they're good. Without them, Earth's average temperature would be zero degrees Fahrenheit, which is pretty darn cold compared to the balmy 59-degree average we enjoy now. The greenhouse effect works like a blanket to keep the Earth's heat from escaping back out into space. The blanket is made of carbon dioxide -- CO2, necessary for plant growth, methane -- CH4, mostly from, well, [cow mooing], nitrous oxide -- N2O, and good old H2O, in the form of water vapor. So, when we destroy the rainforest, we increase the amount of CO2 in the atmosphere. When we have massive factory farms, we increase methane and nitrous oxide. And, more moisture in the atmosphere comes with increased humidity. All of which results in a thicker, warmer blanket. Now, remember how I said the Earth's temperature has risen, like, only one degree in almost 100 years? And, you're all probably like, whatever -- that's not that much. Well, let me break it down for you. Meteorological studies show that even the tiniest long-term change can have a major impact on our weather, triggering more severe storms, floods, increases in hurricane and tsunami activity, cyclones, tornadoes, and, yes, even more frequent -- snowpocalypses. All those melting glaciers mean that sea levels are rising. Low-lying cities, like Venice and New York City, are already under threat. Global warming could also be responsible for species' extinction. It would only take a 4-degree increase in the Earth's temperature to completely wipe out 15 to 37 percent of the Earth's plants and animals. Yeah. It's totally bananas. Now, you're not going to wake up tomorrow and find everything gone. That's not how it works. Which is also why it can be easy to ignore. Some people think we need to limit how much greenhouse gas we put in the air. But, regulations placed on industries, such as oil, manufacturing, and agriculture, to reduce pollution and greenhouse gas emissions are too costly. Others say, the bigger threat to our environment are emerging economies, such as China, where there are fewer regulations and rising energy needs. Others wonder if we're just too late. If whatever we do to control industry, encourage people to recycle or buy an electric car, is really going to make a difference in the long run. What do you think? What do you think we should do about global warming?