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How do we know humans are causing climate change?
And what do we not know about climate change?
I had an opinion piece printed in the Albuquerque Journal this past Sunday called “Climate Change: NM Democrats were a disappointment in this year’s session.” It was a shorter version of this Complex Effects post from April where I point out some of the missed climate action opportunities from the last Legislative session in New Mexico. Despite plenty of great bills that would have decreased greenhouse gas emissions, and a majority control of the House, Senate, and executive, Democrats couldn’t pass a single bill that decreases greenhouse gas emissions.
Directly below my article on the Journal’s opinion page was another article titled, “Behind global warming is our old friend the sun.” I immediately knew the author didn’t know what they were talking about due to the usage of the term “global warming.” We don’t really use that term anymore because it’s not just warming that is happening - we’re experiencing harsher winters, hotter summers, and more extreme weather all around. Therefore, climate change is a more suitable term for what is happening to the earth.
The “opinion” piece goes on to talk about how all climate scientists work for the government, how they cherry-pick data, and any irregular heat we feel is just the sun doing its thing:
So, here is a little bit of the truth: the Sun has always [had] a major impact on our weather. It is called the solar cycle. Every twelve years or so the Sun, the major factor in creating our weather, not man, emits heavy radiation that literally causes the heating up of our oceans commonly referred to as the El Nino effect. This literally translates into a subtly warmer globe where we tend to have hotter summers and more hurricanes and tornadoes. Funny how the political scientists cherry-pick some of this higher temperature data to scare you into thinking that what is happening is man-made and if we do not do “something,” we will all perish.
Not only is this a very narrow understanding of how climate change works, but the author demonstrates their own ability to cherry-pick data. He completely avoided mentioning greenhouse gases, the albedo effect, or the fact that this past summer was the hottest in human history - not just the last 12 years. The article is a reminder that many people still do not understand the science behind climate change, and believe the legitimacy of climate change is somehow still up for debate.
Now, I don’t claim to be a climatologist, but I did take a few classes in college and know enough to explain the basic mechanics of climate change, how we know humans are behind it, and what we still do not know about the climate. In today’s post, I will explain all of this, and hopefully keep a few of you from falling into the same narrow mindset as the man I shared the Sunday Journal opinion page with.
What is climate change?
Climate change is a long-term process in which global temperatures and weather patterns change. There are a lot of things that affect global temperatures in the short and long term including but not limited to the angle of the sun, volcanic eruptions, the reflection of sea ice, and of course greenhouse gases, man-made or not.
My misguided friend from earlier was right in saying El Niño and La Niña are cyclical oceanic patterns that change the weather around the globe, but the 12-year cycle he refers to is a fairly short-term process. If you zoom out, you can see the 12-year sun cycle story is of little relevance when you look at the big picture. We are living in the warmest time in human history:
Just because the temperature on any given day may be cooler or warmer than the same date 12 years before, doesn’t mean anything. Climate change happens over long periods of time that are hard to recognize without zooming out.
As you can see in the graph above, the earth’s climate has warmed before. 13,000 years ago, for example, the earth was going through a long warming period after the last ice age due to increasing CO2 levels in the atmosphere. While the source of that increased CO2 is debated - we know that as CO2 increased in the atmosphere, the temperature rose. This is measured using ice bores from the Arctic that reflect the makeup of the atmosphere 13,000 years ago, which reveals CO2 levels, popular fauna of the time, and other telling signs of what the temperature and climate must have been like.
Today, CO2 is again changing our climate, but we know exactly where it’s coming from. We can measure the gases that come out of our vehicle’s tailpipes, manufacturing facilities, and within the atmosphere in general. Scientists, thanks to ice bores and regular measurements of our atmosphere, can paint a picture of the history of CO2 (and other greenhouse gases) pretty accurately.
The first scientist to notice CO2’s warming role in the atmosphere was a woman named Eunice Newton Foote in the year 1852. Using an air pump, two glass cylinders, and a few thermometers, Foote tested the impact of carbon dioxide against “common air.” She placed the glass cylinders in the sun and found that the cylinder with carbon dioxide trapped more heat and stayed hotter for longer.
The scientific discovery wasn’t celebrated until a male scientist “rediscovered” the phenomenon a while later. By the time we discovered and rediscovered CO2’s warming effects, the Industrial Revolution was already in full swing. Humans started burning unprecedented amounts of coal in order to power increasingly bigger machines, and few people, if any, understood the consequences of our blossoming manufacturing power.
We continue to build upon Foote’s discovery today and can describe how it works on a much larger scale. Greenhouse gases like CO2 warm the atmosphere through a fairly basic process that I’m sure everyone reading can grasp.
How do greenhouse gases warm the atmosphere?
First of all, greenhouse gases (GHGs) come in varying flavors. There’s methane, a very potent, but shorter-lasting, GHG that comes from many places (including cow farts). There’s also nitrous oxide and various synthetic chemicals that contribute to the changing climate, but the most common GHG, and therefore the one doing the most damage, is carbon dioxide (CO2).
When you drive a gas-powered car, fly a plane, make concrete, or produce energy using fossil fuels, carbon dioxide enters the atmosphere. Upon entering the atmosphere, it mixes in perfectly with the rest of the air and dilutes like Splenda in hot tea. It blends so well that if you measure CO2 levels in Hong Kong, Iceland, and Chile all at the same time, you will get the same reading across the board - making this an issue that knows no borders.
As sunlight radiates into our atmosphere, it does so at a high frequency. CO2 isn’t so good at blocking high-frequency radiation, so it usually lets the sun’s heat in without an issue. From there, the sun’s heat connects with the earth and warms it up. To release this heat, the Earth also radiates energy, but in the form of low-frequency radiation. As the low-frequency radiation (heat) travels out toward space, CO2 gets in the way because it happens to be good at deflecting low-frequency radiation - trapping in the heat and driving climate change. Here’s a simplified illustration of that process:
You can think of it like a greenhouse - heat comes in and isn’t allowed to escape. This greenhouse gas effect is the major driving factor of climate change, and the reason we need to kick our fossil fuel habit ASAP.
Volcanic eruptions have the same effect on the atmosphere and can cause disruptions in global temperature, too:
The indisputable effect that CO2 and other GHGs have on the atmosphere is how we know humans are behind the huge temperature spike you see on the far right of the graph above. In fact, if you look at CO2 levels and global temperatures over 800,000 years, the correlation is very obvious:
While GHGs are the driving factor of climate change, the melting ice caps are of great concern as well.
The Albedo Effect
The Albedo effect is the positive feedback loop that occurs when warmer temperatures melt glaciers and snow on Earth, making the Earth less reflective, and in turn, soaking up more heat from the sun. The Earth then becomes warmer, melts more ice, becomes less reflective, and the feedback loop continues.
The longer this process unfolds, the faster it will unfold, and it’s already unfolding pretty quickly. Here’s an illustration of the estimated ice losses (and gains) from 1961 to 2016:
Glacier National Park, in Montana, had 150 sizable glaciers in 1850. Today, there are 26 glaciers large enough to be counted. You can’t blame that on 12-year sun cycles.
The rapid deforestation of places like the Amazon and Indonesia also have a role in changing the climate. In fact, forest loss is the cause of around 10% of the effects of climate change. Plants and wildlife serve as carbon sinks for the atmosphere, and when CO2 levels are high in the atmosphere, trees are more likely to grow due to the increased amount of “tree food” available to them. This means that left to its own devices, the Earth should be able to take all of this excess CO2 from the atmosphere and store it away in the form of trees, shrubs, and wildlife.
Unfortunately, agricultural, mining, and foresting practices around the world are keeping the forests from doing their thing. While some countries have experienced recent forest growth, it’s not making up for all of the deforestation happening in order to plant palm oil trees, alfalfa, and the like. According to the UN, “Over the decade since 2010, the net loss in forests globally was 4.7 million hectares per year.”
Here’s a map of the change in forest coverage that occurred by country in 2015:
One of the more common reasons for deforestation is to make room for palm oil trees - an ingredient found in 50% of the products in your local supermarket. Sometimes illegally, farmers will clear forested areas by digging ditches around the area they want cleared. The trenches allow the moisture in the land and vegetation to drain out, making it easier to burn. When the area goes up in flames, it releases more carbon into the atmosphere than the palm oil trees will ever be able to soak up.
This net loss of stored carbon is yet another example of how humans are causing the climate to change. Again, not really something you can blame on El Niño.
Humans are causing climate change. Period. The science is settled and has been for a while. What isn’t settled is how it will all play out if we don’t decarbonize.
What are the effects of climate change going to be long-term?
Generally speaking, the Earth is going to get warmer, ocean levels will rise, the mass extinction of animals will continue, fires will become more prevalent, hurricanes will get stronger and more frequent, and so on and so forth. You’ve probably heard about all of these effects or have even started to experience them, but how bad is it going to get? Nobody really knows yet.
Some models predict cataclysmic catastrophes, some predict that it won’t be that bad, and some even predict that climate change could trigger another ice age. Do you remember the movie ‘The Day After Tomorrow’? It’s a pretty ridiculous movie about an ice age that takes over the world in a matter of days due to the effects of global warming.
While the world will never freeze in a matter of days, the underlying science that they quote in the movie is based on an actual theory in climate science that goes something like this: Polar ice melts at a rapid rate and decreases the temperature of parts of the ocean. This causes currents in the ocean to reverse - bringing cold water to parts of the planet that aren’t used to it. Over time, this could cause temperatures to drop, ice would reform, the Earth would become more reflective, and it’s basically the Albedo effect but in reverse, and we’re plunged into another ice age.
Again, this is a pretty bizarre scenario that would play out over hundreds of years, but it’s technically possible. There are a lot of possible outcomes to climate change and none of them are that pleasant. Sure, some areas of the world may experience milder winters and longer growing seasons for crops, but overall, things will get worse - mostly for poorer countries. The fact that we don’t know exactly how bad it will get is not a reason to do nothing - it just means that we don’t know what we’re getting ourselves into. We should be scared to find out.
As the political fight around climate change rages on, climate skeptics will try to convince you of every conspiracy theory in the book, but remember that the science they are trying to muddy isn’t all that complicated. It really is as simple as I’ve spelled out in this post - air holds more heat if it has more CO2, white ice is more reflective than dark water, and humans put a LOT of CO2 into the atmosphere. 97% of all scientists around the world are not conspiring against you, they’re just doing their jobs.
If we are going to beat climate change, we will have to come to terms with what we do and do not know. We know that humans are causing climate change, but I’m okay with never knowing whose climate model predicted the end of the world the closest.
In Other News:
Advance Clean Cars 2 rulemaking process begins
The State of New Mexico is getting ready for a public hearing regarding the adoption of Advance Clean Cars 2 (ACC2) - a mandate that would increase the amount of electric vehicles, and decrease GHGs in New Mexico. The hearing will be Tuesday, September 19th from 4:30 to 6:30 pm MST. Opposition voices are expected to be great, so consider attending the event to voice your support, or submit your support virtually here.