Global warming was something of a hot topic a few years back, no pun intended. Al gore set the movement squarely in the public eye with his film An Inconvenient Truth in 2006. The debate had already been fired up among political and scientific circles, but the film really helped bring the discussion to a broader audience.
The concept behind global warming differs significantly based on who you talk to, but there are a few basic principles both sides can agree on at this point. The first is that there are warming and cooling trends in the history of the world. The second is that we are in a significant warming trend. That is about as far as you can get in agreement, after that the two sides tend to start disagreeing with anything the other side says.
One side argues that global warming is being caused, or at the very least accelerated by human activity. Their thought process goes something like this: we dump billions of tons of carbon dioxide and other greenhouse gasses into the atmosphere each year. These clouds of gas thicken the greenhouse layer of the atmosphere, which functions exactly like the greenhouse glass does in an ordinary greenhouse. The layer traps heat inside the lower atmosphere. Without it, the sun's radiant energy would be mostly reflected back into space, and our planet would be unlivable.
So if the greenhouse layer of the atmosphere is so important, what's the problem? According to the conservationist side, the problem is that we're thickening it, making it better at trapping heat inside. As that happens, the temperature on earth goes up. This leads to an accentuation of other climate trends. Droughts become dryer, and last longer. Hurricanes, Typhoons, and monsoon rains all become stronger. Hot spells get hotter, cold spells get colder (which seems counterintuitive for a term like global warming, but it is true). On a more subtle, yet even more serious scale, the conservationists claim that the raising temperature is causing the ice caps to melt, raising the ocean levels around the world, and erasing coastal habitats for plants, animals, and humans alike.
The opposite side of the argument (we will call them skeptics here) say that there isn't enough proof that humans are meaningfully contributing to global warming. They argue that the earth has always undergone such warming and cooling cycles, and that we are overestimating our own contribution to the current cycle. The scientific community is less polarized than the political one on this issue, although even scientists will follow where the funding goes, which leads to some impressively biased research studies on both sides.
If the conservationists are right, we need to change our living habits, and change them now. The damage we've already caused will take lifetimes to undo, if indeed it can be undone at all. They urge legal restrictions and industry wide changes in things such as power generation, construction, and even farming. The skeptics argue that we don't have enough information to justify the kinds of sweeping reforms conservationists are after. We strongly encourage you to read what's been said on global warming and come to your own conclusion.