Global warming is a phenomenon characterized by a slow warming of the surface temperature of the earth. The basic understanding is usually that the atmosphere immediately surrounding the planet is getting incrementally hotter each year, which in turn leads the surface of both land and sea to warm, as well. The term itself does not imply a cause or speak to a cause; rather, it is a statement of fact that most in the scientific community acknowledge as true and provable. What causes more disagreement is discussions of why the temperature seems to be rising, what potential negatives are likely to result, and what human communities can or should do to slow or reverse the trend. Most theories posit that human emissions of carbon dioxide (CO2) gas, whether through industrial processing or vehicle emissions, are chiefly to blame, while others suggest that the warming is simply part of the earth’s natural rhythm and will right itself with time. A lot of research around the world is devoted to the topic, and it’s often a hotly debated concept in political arenas and research institutes globally.
Basic Concept and Implied Meanings
In its most basic sense, global warming is exactly what it sounds like — the globe, meaning the earth, is getting warmer. According to most published research, the change has been extremely subtle; usually, the core temperature of the earth’s surface and the surrounding atmosphere has been measured to change just fractions of a degree each year. Year after year, however, this builds, with the result that the temperature today is significantly warmer than it was 100 or 200 years ago.
On its own the idea of a warmer planet isn’t overtly bad. Researchers who see the phenomenon as problematic usually focus their attention on the overall effects of the temperature shift, rather than on the shift itself. Warmer surfaces mean warmer oceans, for instance, which changes the biodiversity and habitats for numerous fish and sea life; warmer waters can also mean melting ice caps, which raise the level of the sea. Rising sea levels threaten coastal communities with floods and ground saturation, and might also impact larger weather patterns.
The Greenhouse Effect
One popular theory explaining the phenomenon relates to the "greenhouse effect." Gases that make up the atmosphere are analogous to a greenhouse in that they allow sunlight to pass through, then trap much of the heat from escaping. This naturally occurring phenomenon keeps Earth's surface warmer than it would be otherwise. Human produced compounds regularly released into the atmosphere in recent years have "thickened the greenhouse wall" beyond naturally occurring levels, however. When this happens, even less heat escapes, causing temperature to rise. This is called greenhouse warming.
While the scientific community generally accepts global warming as a proved concept, greenhouse warming is more controversial. It’s widely accepted that that human-produced compounds like carbon dioxide, methane, chlorofluorocarbons (CFCs), and others are being released into the atmosphere, yet some argue it's not clear how this factors into the changes in temperature.
Implications for Ozone
Another distinct issue commonly associated with both global and greenhouse warming is the ozone. Ozone is a naturally occurring gas in the lower atmosphere that helps trap heat. The burning of fossil fuels is believed to create even more ozone, and it is one component of smog. As ozone builds, so does trapped heat, which most scholars agree increases the greenhouse effect.
Additionally, ozone plays a role in the upper atmosphere where it shields the Earth from harmful ultraviolet (UV) radiation. According to most research, CFCs — the same human produced compounds that act like a greenhouse gas in the lower atmosphere — destroy ozone. This can result in holes in our upper ozone layer as seen over Antarctica where cold temperatures, atmospheric circulation, and other factors combine to "draw" these ozone holes.
Looking Towards the Future
What global warming means for the future, whether immediate or long-term, remains primarily unknown. Scholars can speculate and many of their models, based on past activity, are quite convincing; so are many of the changes the world today is seeing, including extreme weather patterns, coastal erosion, and melting ice caps. So much of the natural world is unpredictable, though, and it’s been very difficult to project what the future will hold beyond generalized and broad speculation.