What is Global Warming?

Slightly embarrassed, a young reader asked “what is global warming?”. It is possible that while much of science has determined it to be a basic reality, there may be a transition towards no-longer explaining the reasoning behind it.

With that in mind, here is a breakdown of the basics of global warming and some of the science that informs said basics:

Firstly, what is global warming broadly?

Global warming broadly refers to how a planet (the Earth in our case) has a worldwide average temperature change. It can be thought of as if the entire planet increases or decreases (global cooling) in temperature.

This is not measured in one location. This temperature change is observed by checking temperatures across the entire planet at specific times of the year and comparing these temperatures with similar times in other years.

If on particular days of the year the majority of the planet is breaking temperature records from previous years, that is an indicator that the planet may be warming.

Often though, when global warming is talked about in conversation, it refers to ‘anthropogenic global warming’. This specifically means the increase in average temperature (global warming) due to human activity. The word ‘anthropogenic’ is left out, but is generally implied in context.

Global temperature change is one of the most complex systems humans attempt to measure.  There are many systems that interact with each other, some that are difficult and expensive to measure accurately. Some of the system that’s interact include but are not limited to:

Ocean currents, 

heat from the Earth’s core, 

solar radiation, 

the chemical composition of the atmosphere, 

and the reflectivity of the ground (snow reflects more energy via light than asphalt).

Even within the chemical composition of the atmosphere this can have subprocesses which include:

Cow farting, termite burping, automobile emissions, hairspray (beauty industry), mining, forest management, and a lot more.

Generally, though, when learning about global warming, especially anthropogenic, the first places to start are the greenhouse effect and the carbon cycle. For the sake of this piece, I will explain the greenhouse effect. The carbon cycle will likely require its own separate article.

For a bit of context: carbon dioxide (CO2) is frequently discussed, so much in fact, that ‘greenhouse gases’ are measured in CO2e (Carbon Dioxide Equivalent). CO2 is the baseline all other gases are measured against.

What is the greenhouse effect? It is an analogy that ‘greenhouse gases’ are trapping radiation from the sun on the planet turning the Earth into a ‘greenhouse’.

Here is a simplified breakdown on how science currently understands this process to work:

First, for context, radiation of energy creates heat. To massively simplify, energy is heat. (This is a massive oversimplification to the point of being slightly inaccurate but for people who know nothing about the greenhouse effect it may help to understand the concept).

1. The sun is really hot and radiates energy in all directions. Some of this is visible light, but to better understand this one could look into the electromagnetic spectrum and learn about radiation waves ‘above’ or ‘below’ visible light. Examples of these would be microwaves (like a kitchen microwave) and x-rays (like in a hospital).

2. These waves contact the Earth. 

Some are reflected by the Earth closer to space via layers like the magnetosphere.

Some are absorbed into the atmosphere by chemicals like Nitrogen, water vaper, carbon dioxide etc. 

Some make it to the ground and then are a combination of reflected, refracted, and absorbed.

3. The ground emits radiation waves. To better understand this an explanation of the electromagnetic spectrum and how it is even possible for humans to see, especially colour, provides a lot of context.

4. The radiation from the ground contact the Earth’s atmosphere. Some of these waves are reflected and go back to the ground, others make it through the atmosphere.

Due to how radiation of energy works this effectively means that a balance must be struck between the energy from the sun piercing the atmosphere and the energy from the surface piercing the atmosphere.

If more energy from the sun makes it to the surface than the surface is able to ‘dump’ into space, then the energy has a net increase, temperature rises.

The reverse is also true, if the ground ‘dumps’ more energy into space than reaches the surface from the sun, there would be a net decrease, temperature falls.

Energy from the Sun currently pierces the atmosphere at a high frequency Ultraviolet (UV) radiation. Much of the energy from the ground is emitted at a lower frequency Infrared radiation. CO2 and other ‘greenhouse gases’ allow UV to pierce them, but effectively send Infrared back to the ground.

The greenhouse gases in the atmosphere, the less of the Sun’s energy that can be ‘dumped’ into space after the ground effectively converts it into lower frequency radiation like infrared. This is the basic challenge of global warming.

Learn more and watch the full video here.

Vezina is the CEO of Prepared Canada Corp. and is the author of Continuity 101. He can be reached at info@prepared.ca.