The greenhouse effect acts like a warm blanket around Earth, comprised of gases like carbon dioxide, methane, and water vapor that trap heat.
This natural phenomenon keeps the planet at an optimal temperature for life. However, human activities such as burning fossil fuels have intensified this effect, increasing carbon dioxide levels and thus, global temperatures, disrupting Earth’s energy balance and amplifying warming.
Understanding the Greenhouse Effect
The greenhouse effect is the process through which heat is trapped near Earth’s surface by substances known as ‘greenhouse gases.’ Imagine these gases as a cozy blanket enveloping our planet, helping to maintain a warmer temperature than it would have otherwise.
Greenhouse gases consist of carbon dioxide, methane, ozone, nitrous oxide, chlorofluorocarbons, and water vapor. Water vapor, which reacts to temperature changes, is referred to as a ‘feedback’, because it amplifies the effect of forces that initially caused the warming.
A simplified animation of the greenhouse effect. Credit: NASA/JPL-Caltech
Carbon Dioxide’s Critical Role
Scientists have determined that carbon dioxide plays a crucial role in maintaining the stability of Earth’s atmosphere. If carbon dioxide were removed, the terrestrial greenhouse effect would collapse, and Earth’s surface temperature would drop significantly, by approximately 33°C (59°F).
The Goldilocks Planet
Greenhouse gases are part of Earth’s atmosphere. This is why Earth is often called the ‘Goldilocks’ planet – its conditions are just right, not too hot or too cold, allowing life to thrive. Part of what makes Earth so amenable is its natural greenhouse effect, which maintains an average temperature of 15 °C (59 °F) .
Human Impact and Climate Change
However, in the last century, human activities, primarily from burning fossil fuels that have led to the release of carbon dioxide and other greenhouse gases into the atmosphere, have disrupted Earth’s energy balance. This has led to an increase in carbon dioxide in the atmosphere and ocean. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps extra heat near Earth’s surface, causing temperatures to rise.
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2 Comments
“Water vapor, which reacts to temperature changes, is referred to as a ‘feedback’, because it amplifies the effect of forces that initially caused the warming.”
The above quote implies that water vapor is ONLY a positive feedback. As reality would have it, increased water vapor also results in increased cloudiness, which cools the surface through increased albedo. The effects of water vapor are often discounted by the rationalization that it is a ‘condensing gas.’ That means that it tends to precipitate out from the troposphere after a few days. However, the water vapor tends to remain relatively constant for the given seasons and climate zones in which the air masses reside. In doing so, the precipitation provides water for plants, which shade the ground, and sequester CO2 through photosynthesis. Additionally, evapotranspiration takes heat from the surface, transports it high in the air where it can radiate to space; when the cooled water falls back to Earth, it cools the surface. Thus, water acts as both a positive AND a negative feedback loop. The important question is, “What is the ratio of the heating-to-cooling effect in the feedback loop?” As is all too often the case, there are no numbers presented, except the presumed average temperature. Generally speaking, the temperature alone is less informative than the Heat Index, which also takes into account the relative humidity.
NASA’s explanation is NOT balanced as one would expect from an objective source. They should be embarrassed at presenting a grade school level explanation, sans measurements, that seems to imply the readers haven’t mastered even elementary arithmetic and have no acquaintance with such things as “margin of error,” routinely provided for political polls.
Personally, I tend to feel that someone is running a ‘shell game’ when they withhold facts, particularly numbers that might not support the qualitative claims.
“However, in the last century, human activities, primarily from burning fossil fuels that have led to the release of carbon dioxide and other greenhouse gases into the atmosphere, have disrupted Earth’s energy balance.”
It should be noted that the “other greenhouse gases” include water vapor. So-called fossil fuels are derived from carbohydrates, also known as hydrocarbons. When oil, gas, or coal is combusted, it not only releases CO2, it releases water. That is why on a cold day one sees ‘steam’ coming from the tail pipes of cars, particularly when they are idling or just warming up, because cool water droplets are visible, but water vapor isn’t. That is to say, combustion of fossil fuels is releasing water that has been sequestered as long as the CO2, and adding to the available water.
Once again, NASA is only telling part of the story. One can make any story sound reasonable if only some of the facts are used to support it. However, a critical reader should ask themselves why NASA isn’t presenting all the facts