What Is the Greenhouse Effect and How It Happens
It’s a great thing to live on planet Earth. While other planets in our solar system are either freezing cold or scorching hot, Earth has blessed us with relatively stable and mild temperatures. They are mostly due to the planet’s atmosphere, a thin layer of gases that protect it. But what is the greenhouse effect and why have we come to associate it with negative connotations?
More than 97 percent of climate scientists already agree that humans have left a very unfortunate footprint on Earth’s atmosphere. Over the past two centuries, we have changed it in dramatic ways, which has resulting in the so-called global warming. But in order to understand climate change, we must first become familiar with the greenhouse effect.
Energy Input and Output
Every day, the Earth goes through a delicate balancing act involving the radiation reaching the planet from space and the radiation reflected back into space. Enormous amounts of radiation constantly bombard the Earth and the sun is the primary source.
Solar radiation hits the Earth’s atmosphere in various forms, such as visible light, ultraviolet (UV), and infrared (IR). According to NASA, snow, clouds, ice, sand and any other large reflective surfaces instantly reflect back out to space around 30 percent of the radiation that reaches the atmosphere.
However, there is a remaining 70 percent of incoming solar radiation that the atmosphere, the land, and the oceans need to absorb. When they heat up, they release IR thermal radiation, which goes out back into the atmosphere and then into space. But what happens when the greenhouse effect comes into the mix?
What Is the Greenhouse Effect?
The transfer between the incoming and outgoing radiation that warms the Earth is often described by the term “greenhouse effect.” It refers to the fact that the planet’s energy exchange is in many ways similar to the way a greenhouse works.
Parts of our atmosphere serve as an insulating blanket that helps sustain life on Earth. Seeing that it’s just the right thickness, the atmosphere is able to trap sufficient solar energy to keep the Earth’s average surface temperature in a pleasant range.
The Martian or Venusian blanket are both unsuitable to support life. Our “blanket,” on the other hand, is a perfect collection of atmospheric gases called “greenhouse gases.” Unfortunately, it becomes a lot less than perfect when man-made actions interfere with the natural balance.
One of the most used definitions is that the greenhouse effect is the natural process which allows the Earth’s atmosphere to trap enough of the Sun’s energy to support life. While this natural phenomenon would not be damaging in itself, man-made activities have turned it into something harmful to the environment and our life on Earth.
Most scientists believe the effect is increased artificially by human activities, causing an artificial and toxic “blanket” in the atmosphere. These greenhouse gases include carbon dioxide and methane. Deforestation and fossil fuel burning contribute to CO2 concentrations, while rice paddies and landfills add more methane.
Evolution of the Term ‘Greenhouse Effect’
It was the early 1800s when atmospheric scientists first started using the term ‘greenhouse effect.’ However, back then, it merely described the naturally-occurring processes that trap useful gases in the atmosphere. The term was not linked to any negative connotations.
In the mid-1950s, there was a slight change in the way we use the term greenhouse effect. During this time, scientists started coupling it with increasing concern over climate change. In recent decades, the presence of an enhanced greenhouse effect in the news is almost always related to negative consequences.
Greenhouse Gases and Global Warming
As more carbon dioxide (CO2) and other greenhouse gases are released into the atmosphere, they form a suffocating blanket. In turn, the IR radiation cannot be released into space and our planet absorbs too much of it. The direct effect, called global warming, is the gradual heating of Earth’s atmosphere and surface.
According to EPA, these greenhouse gases are a mix of CO2, water vapor, methane, nitrous oxide (N2O) and small amounts of other gases. However, things changed since the early 1800s and the dawn of the Industrial Revolution. The burning of fossil fuels (such as coal, gasoline, and oil) has severely increased the abundance of greenhouse gases in the atmosphere, especially CO2.
„Deforestation is the second largest anthropogenic source of carbon dioxide to the atmosphere ranging between 6 percent and 17 percent,” according to EPA.
What Influences the Greenhouse Effect?
The most important factor in the atmospheric greenhouse effect is the type of surface first hit by sunlight. Various surfaces – ice caps, forests, deserts, grasslands, cities, ocean surfaces – radiate, absorb, and reflect radiation differently.
When sunlight falls on a white glacier, it is strongly reflected back into space. As a result, the surface and lower atmosphere experiences minimal heating. Meanwhile, sunlight falling on a dark city is strongly absorbed, highly contributing to the heating of the surface.
Cloud cover also has its effect in greenhouse warming. It reduces the amount of solar radiation reaching the Earth, while also reducing the amount of radiation energy emitted into space.
Can We Reverse the Greenhouse Effect?
The U.S. Global Change initiative estimates the temperature in the U.S. over the last 50 years has increased by 2 degrees. Precipitation has also increased by 5 percent. Not only that, but global warming puts coral reefs in danger as the ocean warms. Scientist fear they will not adapt quickly enough to the resulting climate change, resulting in more bleaching incidents and diseases.
Many scientists agree that the harm done to the Earth’s atmosphere is past the point of no return. From this point forward, we have three options:
- Do nothing and suffer through the consequences.
- Learn to adapt to the changing climate (such as reacting to rising sea level and related flooding).
- Or mitigate the impact of global warming (aggressive policies that reduce the amount of CO2 in the atmosphere).
The question, now that we know what is the greenhouse effect, is what will we do? The governments’ reactions over the next decade will probably influence our future in the longer term.