What is global warming?

When I first came up with the idea to create this blog, my thoughts were organized around creating content for people who already knew what I knew: global warming is real, and its dramatic acceleration is because of all the things that humans use that produce carbon dioxide as a byproduct.

What I didn’t consider at the time was that there are a lot of people who believe that global warming is a “thing” because they’ve heard it mentioned enough times, but they don’t actually really know why it’s a thing or what it means for the planet.

With that in mind, I think it’s important to try to explain the underpinning knowledge used in much of this blog’s future posts. Hopefully, by the time you finish this series of posts, you’ll have at least a generally better idea of what climate change / global warming is, why it’s a problem, and how you can have a small, but valuable, part in helping to try to remedy it.

So, with that said, let’s get into it!


What is global warming?

Put simply, global warming refers to the rapidly increasing overall temperature of the earth.

Historically, it’s been completely and totally normal for the earth’s temperature to fluctuate: we’ve had ice ages and temperate ages (like the one we’ve been living in for the past several thousand years). According to the National Geographic,

The average global temperature [has] fluctuated on a cycle of hundreds of thousands of years as the Earth’s position relative to the sun has varied. As a result, ice ages have come and gone. […] Occasionally, other factors briefly influence global temperatures. Volcanic eruptions, for example, emit particles that temporarily cool the Earth’s surface. But these have no lasting effect beyond a few years. Other cycles, such as El Niño[*], also work on fairly short and predictable cycles.

Often when you hear people talk about how global warming isn’t real or isn’t a problem, you’ll hear them make an argument about how the earth’s temperature has always changed.In the above quote from National Geographic, the critical caveat is that the earth’s temperature has fluctuated on a cycle of hundreds of thousands of years. This means it took around 1,428 human lifetimes  at minimum between each major change in temperature.

Over the past 50 years, though, the average global temperature has increased at the fastest rate in recorded history.

If you look at the graphs (right on desktop, below on mobile), you’ll see the same thing: the earth is getting significantly warmer, and has been with an ever-increasing pace since the mid-1900s.

Furthermore, scientists and environmental experts from all over the world only see the trend accelerating: all but one of the eighteen warmest years on record have occurred since 2001.

This is completely inconsistent with how our earth has behaved for millions of years prior, which tells scientists and environmental experts that these temperature changes aren’t normal, and raises a pretty big red flag.


Temperature data from four international science institutions. All show rapid warming in the past few decades and that the last decade has been the warmest on record.



Let’s go back to the statistics about global temperature variance across millenia for a moment. Remember how National Geographic mentioned ice ages being a normal part of the earth’s temperature changes? As it turns out, the difference between the average global temperature during an ice age and not-an-ice-age is only around 5° Celsius (9° Fahrenheit).§ In fact, it only takes a global temperature change of about 1-2°C, or 1.8-3.6°F, to put the world through a “little” ice age. 

Again, keep in mind that those otherwise very small numbers correspond to changes that usually happen over hundreds of thousands of years).

If you look back to those graphs that chart global temperatures across the past century, though, you should be able to see that we’ve already hit a .8°C change over the past 50 years.

What’s more, according to the ongoing temperature analysis conducted by the scientists at NASA’s Goddard Institute for Space Studies (GISS), the average global temperature on Earth has increased by about 0.8° Celsius (1.4° Fahrenheit) since 1880, and two-thirds of that warming has occurred since 1975. Given those numbers, we’re looking at global temperature change a rate of roughly 0.15-0.20°C per decade, which is about as far a cry from the historical norm as you could imagine.


The difference between “climate change” and “global warming”

For the purposes of day-to-day conversation, global warming and climate change are the same thing. Both refer to the same phenomenon that involves the earth’s rising temperature, and neither of them are “wrong.” That said, it’s often the case that scientists are more likely to use the term “climate change” instead of “global warming,” since “climate change” allows for more nuances and includes the various consqequences of global warming, such as melting glaciers, heavier rainstorms, or more frequent drought.

it is causing a set of changes to the Earth’s climate, or long-term weather patterns, that varies from place to place. As the Earth spins each day, the new heat swirls with it, picking up moisture over the oceans, rising here, settling there. It’s changing the rhythms of climate that all living things have come to rely upon.

* Since I didn't know this until I started writing this post, I've included some detailed information about El Niño:

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle [which] describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific[.]

La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña.

— Source

 Assuming a short cycle of 100,000 years between climate changes and a 70-year human lifespan
 Sources: NRDCNASA
§ Source: National Geographic
 Source: Nasa Earth Observatory

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