Global warming in 500 words
The four-step greenhouse effect, old methods to be considered madness, and what greenhouse gases have to do with a sink drain.
“Hey, how does global warming actually work?”
I suddenly felt the same nervous energy I’d get before a dance performance. Here I was, a climate tech founder at Climate Week NYC, shoulder-to-shoulder with investors, and getting quizzed by my boyfriend on the premises of why we were all there. In my eyes, it was a perfect storm.
57% of US adults know and believe the short answer: Earth is getting hotter, and human activities are to blame. However, I’d posit that only another fraction of that fraction could clearly explain the details.
After writing this post, I’ve counted myself in. And you’re about to join this cool, new club too.
Global warming is the greenhouse effect on overdrive
For those lacking a green thumb, a greenhouse is essentially a glass tent used to cover outdoor gardens, keeping them warm in cold conditions [1]. Earth’s atmosphere is the “greenhouse:”
Sunlight heats the Earth’s surface. Specifically, sunlight’s infrared waves are absorbed by Earth’s surface as heat energy.
Earth’s surface slowly releases that heat into the atmosphere. This process, radiative cooling, happens mostly at night.
Some of that heat is absorbed by greenhouse gases (GHGs)—think carbon dioxide, methane, and nitrous oxide [2]. The rest escapes to space.
The absorbed heat warms the atmosphere and Earth. It’s re-emitted in all directions, including back to Earth.
The greenhouse effect is a beautiful thing. Without it, we’d be icicles on a frozen rock. But it’s now in overdrive. Just like a sink drain getting clogged over time, excess GHGs clog up the atmosphere, making it harder for heat to escape. That is global warming.
With progress comes learning
It’s true that natural forces can cause warming and cooling periods. However, this warming is definitively our own doing.
We started burning fossil fuels like coal, natural gas, and oil in the 1800s and have only picked up the pace since then. While that burning granted us modern wonders like combustion engine cars and electricity that flows as freely as water, it also released and continues to release unfathomable quantities of GHGs [3]. GHG emissions are everywhere; your toothpaste, sweater, and sidewalk concrete are just three surprising carbon-emitting culprits [4].
Since pre-industrial times, carbon dioxide alone has increased in concentration from 280 to 416 parts per million (ppm). Earth’s average temperature, in turn, has increased by 1.0-1.3 degrees Celsius.
We need change, lest we end up with the dinosaurs
1.3 degrees may not sound like a lot, but imagine a world in which there are crocodiles living above the Arctic Circle. This was the case in the age of dinosaurs—and back then, the delta was only 4 degrees [5]. In other words, we’re already over a quarter of the way to that beyond-tropical reality. The Paris Agreement, the UN’s 2015 treaty on climate change, actually sets the bar at just 1.5 degrees. Yes, that is alarmingly close.
Air conditioners won’t save us, as temperature change is just the tip of the iceberg. Climate change means new diseases, shifted crop seasons, and more costly “freak” tropical storms, heat waves, and droughts [6]. David Wallace-Wells, author of The Uninhabitable Earth, helpfully paints a portrait of life after climate change here. What I’m especially motivated by is the terrifying prospect of triggering “tipping points” that would irreversibly alter Earth’s systems and that lower-income countries are paying the price for higher-income countries’ emissions.
We can be optimistic. As the global temperature increase inches closer to 1.5 degrees, governments, businesses, non-profits, and individuals are hard at work to turn this ship around. You can help by embracing change [7]—starting with refreshing your understanding.
Endnotes
[1] You may have also had the pleasure of dining in one in NYC’s “outdoor dining” setups.
[2] What makes a greenhouse gas so great at absorbing heat? The answer: good vibrations. Recall that different types of energy, like visible (light) or infrared (heat), have different ranges of wavelengths. It turns out that GHG molecules have structures that allow them to vibrate in complex ways that enable absorption of specific wavelengths—namely, radiated heat.
This same principle prevents GHGs from absorbing sunlight on the way into the earth’s atmosphere. The sun’s infrared waves’ wavelengths are too short.
[3] 52 billion tons is the world’s annual emissions in carbon dioxide equivalents and a hard number to wrap your head around. Bill Gates, How to Avoid a Climate Disaster (2021).
[4] Your toothpaste casing and sweater fibers contain plastics. Extracting, transporting, and refining oils for those plastics is a GHG-intensive process. Clearing forestland for extraction also releases stored carbon dioxide. And even if your sweater is polyester-free, the conventional cotton fibers were grown with GHG-intensive fertilizers. Concrete is made from cement, which releases carbon dioxide when manufactured.
[5] Bill Gates, How to Avoid a Climate Disaster (2021).
[6] For perspective, Hurricane Ian, with a cost of $53-84B in insured losses, was the United States’ 15th billion-dollar disaster in 2022.
[7] Making a change does not mean pulling the plug on GHG-producing processes and thereby lower-income countries’ modernization. It is unfair to tell these countries, which are experiencing the worst effects of climate change, to stop their growth. Instead, higher-income countries (like the US) should lend them financial support and quickly create, deploy, and cheapen zero-emissions technologies.