The vocabulary around environmental issues can, at times, be tricky to navigate, as in the case of global warming and the greenhouse effect. Whilst both phrases refer to a similar process of planetary warming, they’re both very different, and it’s important to understand those differences when looking at ways to address the challenge of climate change.
The greenhouse effect is, in fact, an important, natural and useful planetary process. In the case of the earth, the greenhouse effect refers to a situation where energy emitted by the sun enters the planet’s atmosphere, and is regulated by atmospheric gasses like carbon dioxide. These greenhouse gasses allow some energy to pass through, whilst also trapping energy within the earth’s atmosphere, retaining warmth for the planet.
A good way of explaining the significance of the greenhouse effect is by looking at the two nearest planets to the sun, Mercury and Venus. Although Mercury is the closest planet to the sun, it has no atmosphere, and thus no greenhouse effect. Venus, by comparison, has a thick atmosphere, and what scientists call a ‘runaway’ greenhouse effect. According to NASA, the average temperature on Venus is 880 degrees Fahrenheit, compared to 800 degrees Fahrenheit on Mercury. Despite being closer to the sun, Mercury’s lack of an atmosphere, and a greenhouse effect, means it’s cooler than Venus.
In terms of the earth, the greenhouse effect allows our planet to retain a stable, balanced temperature which provides the right conditions for life. Without any greenhouse effect, earth would lose much of its warmth to space, and colder temperatures could prohibit the development of life. What global warming refers to is when the process of the greenhouse effect becomes unbalanced, and warms the planet at increasing levels – leading to a similar scenario to Venus, a runaway greenhouse effect.
This unsettling of the greenhouse effect is caused by an increase in the greenhouse gasses. The burning of fossil fuels on earth has led to substantial increases in the amount of gasses like carbon dioxide emitted. As these gasses increase in the atmosphere, the greenhouse effect sees more energy from the sun trapped and less energy radiating out into space. Imagine the atmosphere like a blanket – the thicker the blanket, the more warmth is kept in. Adding carbon dioxide to the atmosphere is like thickening our atmospheric blanket, leading to rising temperatures, and global warming.
When scientists refer to reversing global warming, it’s important to highlight that they aren’t talking about reversing the greenhouse effect entirely. If the greenhouse effect ceases to operate, earth would eventually become a cold, lifeless planet. What needs to be reversed is global warming, that process of pumping more CO2 into the atmosphere.
Bill Nye, the American scientist and TV host nicknamed ‘The Science Guy’, explains that “It’s not that the world hasn’t had more carbon dioxide, it’s not that the world hasn’t been warmer. The problem is the speed at which things are changing.” Like a runaway train, a runaway greenhouse effect will be difficult to stop or reverse. So the best way of retaining a healthy, balanced greenhouse effect is to slow down global warming, and that’s the goal the world needs to aim for.