• Katie Gardner

Climate Change 101

Updated: Mar 9, 2021

Hey all!

In this post, I want to do a quick overview of climate change, a “101” if you will, to explain why I care so much about sustainability, as it is what motivated me to become more mindful of my effect on the environment. Even for those of us who spend all of our time working in cleantech or sustainability, it is motivating to re-read the science behind the phenomenon we are seeking to stop.

Now, sustainability isn’t only about preventing climate change (there are a ton of other issues out there, such as plastic waste and pollution from common chemicals), but it is a huge and urgent part of living a more sustainable life.

This post will do a quick recap of the basics, focusing on the effect of the 2018 IPCC report, and quickly touch climate contrarianism and how to talk to people who don’t believe in climate science. There will be extra sources at the end for those who are interested in doing additional reading. For those who follow me on Instagram, this is an expansion on a post from December 9, 2020.

Photo from Unsplash

The Basics

Over the past 50 years, the average global temperature has increased at the fastest rate in history. It will increase even faster if we as a species don’t reduce greenhouse gas emissions. Currently, the climate is 1℃ hotter than pre-industrial levels, and is predicted to rise to 1.5℃ by 2030 (Climate Health Connect).

When we talk about the Climate, we are not referring to the daily weather, which can vary greatly day to day. Rather, we are talking about the weather averages over a long period of time, such as 50 or more years. Climate Change describes the long-term changes over multiple decades. Modern statistical techniques can determine if weather extremes are due simply to natural variation or if they are a sign of a changing climate. Our weather changes are too large to be natural and are a sign of a changing climate (Health Connect).

Global Warming Mechanisms

The Earth is getting warmer due to air pollutants and greenhouse gases (GHGs) becoming trapped in the atmosphere. Greenhouse gases are the group of gases that absorb and emit energy, causing the aforementioned greenhouse effect. The most common are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. The latter four are the primary drivers of climate change, with carbon dioxide having the largest effect. The concentration of methane in the atmosphere is relatively low, but it has an 84x stronger radiative effect when compared to the more common carbon dioxide.

GHGs create a layer in the atmosphere, trapping sunlight, which otherwise would just reflect off the Earth’s surface. Less sunlight can escape than is received, raising the Earth’s temperature. This is known as the Greenhouse Effect. A certain amount of trapped heat is necessary for life to survive. However, over the past 70 years, the amount of heat trapped has dramatically risen, causing the Earth to warm unnaturally.

GHGs such as carbon dioxide have a long half-life, meaning these warming effects will be felt for potentially thousands of years. Our current level of warming was last experienced 3.5 million years ago, when the Earth was 2.3℃ warmer with sea levels anywhere from 33-65 ft higher.

GHG Emission Sources

Approximately 250 years ago, the Industrial Revolution began in Great Britain, quickly spreading across the globe. This period of time saw many technological advances, such as mechanizing agriculture and textile manufacturing, as well as transforming transportation with the introduction of steamships and railroads. Towards the end, the world was electrified with the invention of the lightbulb and the electric motor. The economic system also transitioned to capitalism. To power this revolution, we started to burn energy dense fossil fuels, such as oil and coal. Now, the majority of carbon dioxide emissions, the most common GHG (81.6% of all 2016 emissions), is emitted through burning the same fossil fuels that helped create the modern world.

Globally, fossil fuel carbon dioxide emissions are primarily due to energy production, though the manufacturing and construction industries and transportation sector each provide a large chunk of these emissions (2018 Numbers, International Energy Agency Report).

The more potent methane is primarily emitted through agriculture, such as livestock and rice cultivation, though the fossil-fuel industry comes in at a close second (from gas venting and fugitive emissions).

Global Warming Effects

A warming atmosphere leads to more extreme weather: longer/hotter heat waves, more intense droughts, more rain, and frequent, powerful hurricanes. We see these effects in SoCal with our heat waves and extreme droughts (for example, the 2015 California drought was the worst in 1,200 years). Glaciers will melt, snow will melt earlier, sea levels will rise, and pollution will worsen. Nature will suffer the most: insects and plants will lose their habits, affecting crop growth. Corals will go extinct. Furthermore, scientists are already surprised at the severity of effects at 1.0℃, so there are likely many effects that are not yet known.

The Contrarian View

I want to address a few contrarian views that are still floating around certain circles.

First: Yes, climate change is happening. Prominent voices also claim that the science is not settled: in reality, only a handful of scientists disagree (and many of those receive oil industry funding). In fact, 97% of climate scientists agree. Furthermore, scientists agree, with an overwhelming consensus, that climate change is driven by human activity, aka anthropomorphic effects (not just correlated to, or affected by… driven by).

Second: Critics of global warming point to a “pause” in temperature rise. This has been debunked by several recent studies (Studies).

Third: 1.5℃ doesn’t seem like much… is it really that big of a deal??? Yes, it is a huge deal. Even at 1℃, weather has become more extreme, with more intense hurricanes due to warmer waters. Going to 1.5℃ would throw delicate natural balances off, devastating ecosystems and melting Arctic ice at an increasing rate. Sea levels may rise by as much as 1 meter (~3.28’) by 2100, as well as increasing rare floods to become common occurrences (IPCC). 1 meter may not sound like a lot, but this is an average, and some locations will see even higher sea levels, which will cause mass migration (NRDC).

Fourth: Many contrarians say “well, even if we accept that the climate is changing, it always has changed, and this is no different.” This is incorrect. In the past, climate changed due to natural causes, primarily variations in the Earth’s orbit (NASA). Glaciers advanced, and retreated naturally. Temperatures rose, and fell within certain limits. However, in the past 70 years (since 1950), the Earth’s temperatures have risen at a rate never before seen. Furthermore, this is caused by humans, not natural variations such as volcanos (A Skeptic’s Guide to Climate Change).

Historical Carbon Dioxide Emissions, NASA

Other great resources on this topic include this article by Scientific American on these and other climate contrarian views, this article by a professor at Stanford, and the Yale Program on Climate Change Communications.

What was the 2018 IPCC Report that Everyone Talks About?

In October 2018, the UN Intergovernmental Panel on Climate Change (IPCC) released a report, in which the authors warned that there are only 12 years (now 10, until 2030) to keep global warming below the target of 1.5℃, above which the pressure to the Arctic would be extreme and entire species could be eradicated, such as coral could be completely eradicated. Urgent, though feasible and affordable, changes are required to reach these targets (IPCC Report).

Prior to this report, it was thought that holding global temperatures to less than 2℃ would prevent unmanageable effects, and that we had more time. However, revised studies revealed that this original estimate was flawed, as the effects at our current temperature were more severe than anticipated. As a result, the timeline to prevent unmanageable change accelerated. At this point, we only have ten years left to prevent catastrophic effects. The world will need to take action, to focus on reforestation, electrification, and carbon capture, and carbon pollution needs to be cut by 45%.

What Does This Mean for Each of Us?

Things will change dramatically over the next 100 years if we don’t change now, which is terrifying. Climate anxiety is real (Scientific American). However, we are not yet past the point of no return, if we act collectively to take the necessary steps. As stated by the IPCC, it is feasible and even affordable, but we don’t have a second to waste.

How am I personally dealing with this? I decided to dedicate my career towards it and started this blog in order to do further research. I am an extreme example, but we each can take steps to prevent catastrophe. Individual behavioral changes can help with slight reductions, as we can all take steps to reduce our carbon footprints and live more sustainable lives (Bill Gates and Rashida Jones on Climate Change). However, the most important thing any one individual can do is advocate: support climate friendly politicians and lobby for climate friendly practices. Together, we can (and must) make huge changes over the next ten years.

How Do I Talk to People Who Don’t Believe in Climate Change?

Finally, as it is the holiday season, it seems appropriate to discuss how to talk to those who don’t believe the settled science on climate change (or any other topic where there isn’t actually a debate). It has been shown that talking about climate science helps people accept it, which in turn increases discussions about the topic!

Several podcasts and organizations have guidelines for these types of discussions, so I am going to share the steps outlined on a podcast I heard recently (How to Save a Planet’s “Trying to Talk to Family about Climate Change? Here’s How”), taken from the New Conversation Initiative:

  • Step 1: Set realistic expectations! Opinions likely won’t be changed in one chat (it may take months or years) but it’s worth the effort.

  • Step 2: Find a buddy to help support you. This isn’t an easy talk, and you need support too!

  • Step 3: Find a quiet moment to talk, one on one, and allow them to opt out.

  • Step 4: Listen! Ask questions, and follow up. Let them be heard and get their feelings out.

  • Step 5: Acknowledge that you disagree, and let them know what you think. However, let them know you want to talk openly and understand the other.

  • Step 6: Bring personal stories in: explain why you care and how it made you feel. Allow the other person to do the same.

The aforementioned podcast site has other great resources. If you want to bring in help, check out republicEn, a place for conservatives who care about climate change and want to help spread the word that one can be conservative and believe in climate science.


This post was just a primer on Climate Change, so if you really want to dig down into the science, here are a few additional sources that I found very useful while writing this.

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