Currently, there are 412 parts per million (ppm) of CO2 in our atmosphere. During all of humanity's existence on this earth, levels have never reached that high. This is an issue that will not only effect the future of our planet, but it is effecting us right now.
To many people, these effects are difficult to see. They have occurred gradually over decades. But a quick google search of "global temperature" will show you a plethora of graphs from reputable sources that show that average temperature has been on an upward trend for the past 30 years.
Temperature isn't the only thing that changing climate effects. Warmer temperatures means more severe storms that occur more often. It means rising sea levels, which could displace coastal cities around the world. This is a big deal because the coastal economy of the US alone has a GDP of $7.9 trillion, and it is estimated that 40% of the world population lives on a coastline.
The fires that ravaged Australia from September of 2019 until January of 2020 were likely due to lowered rainfall and warmer temperatures (the claims that the wildfires were started by arsonists is wildly untrue). From those fires, many biologists believe that the Koala population has decreased enough in size that they will not be able to adequately rebound. Some have even said that their population has decreased by 80%. This is the realization of the prediction that anthropomorphic climate change (climate change caused by humans) could drive 1 million species to extinction.
Our situation is dire, and perhaps the most terrifying part is how difficult it is for us to realize that.
Earth and its History
Earth is a very old planet, and thus has a very large climate history. Much of this history is very difficult or impossible to read. But the amount that we can read tells a compelling story. Earth's climate goes through many cycles. There have been several Ice Ages where the earth is dominated by cold, and there have been several anti-Ice Ages, a sort of "heat age" where there is little to no ice present for a period of time. One of these "heat ages" was during the Cretaceous period. CO2 levels reached well over 1000 ppm. I've heard this as an argument that CO2 concentration is not a big deal. Since the dinosaurs were able to thrive during a period where the CO2 concentration was more than double what it is today, high CO2 levels can't be a detriment to life. This could be a fair argument, except life on earth today is vastly different than the life that was roaming earth during the Cretaceous period. During this period, temperatures were around 14° C above today's average temperature. That turns a comfortable 80° Fahrenheit day into a sweltering 105° one. Many of today's species, especially aquatic ones, would not be able to survive those harsh conditions.
Another one of these "heat ages" is called the Paleocene-Eocene Thermal Maximum (or PETM for short). This relatively short event happened in the wake of the mass-extinction of the dinosaurs while life was still trying to recover. Some fun features of this span of time were rain forests blanketing the poles and warm enough water that you could've comfortably done a triathlon in Antarctica (in fact that might have been preferable to doing one anywhere else). It is believed that this span of time fostered the evolution of mammals and primitive primates. This thermal maximum ended when large blooms of algae and sea plants sucked a large amount of carbon from the atmosphere, which significantly lessened the greenhouse effect and lowered the earth's temperature. These plants acted as a carbon sink, and essentially locked the carbon they took from the atmosphere inside of their cells. Eventually they died and sunk to the depths of the ocean. An ocean that we have since started to exploit for oil.
As you can see from these two examples, earth's climate is variable. It is likely that it will continue to change. But no change happens without consequence. While the PETM could have fostered the development of today's animals, it also likely caused the extinction of many others.
One thing differs between the situation we currently face and the PETM and Cretaceous period. That one thing is the cause of warming. While these examples are part of earth's natural cycle, a cycle that we can see repeating through time, what we are experiencing currently is not. The current rate that our CO2 levels are rising is a huge anomaly, and it is not difficult to realize that our consumption of carbon-based products (like oil) is to blame.
Here are some fantastic resources about the climate history of earth (#1, #2), a great video about the PETM, the summary of the Intergovernmental Panel on Climate Change's report to policy makers, and a post that I wrote last year about what you can do personally to lessen your impact on climate change.
As always, feel free to comment or ask questions. Thanks for reading.
"The climate crisis has already been solved. We already have the facts and solutions. All we have to do is wake up and change." -Greta Thunberg