When it comes to how we know humans cause Earth's overheating, it's reasonable to ask questions. Skepticism can be healthy. It's what scientists and detectives are trained to use to eliminate false explanations and unsupported conclusions.
In this case, though, there's overwhelming compelling physical evidence — and we humans have our chemical fingerprints all over it.
What's the evidence that humans cause Earth's overheating?
A recently posted video from Instagrammer Simon Clark (@simonoxfphys) poses the question, "Are humans actually responsible for global warming?"
Clark — who identifies as a science communicator, video maker, podcast creator, and Ph.D. in theoretical atmospheric physics — began his answer by stating, "We know that the planet is warming, and we know that CO2 is responsible."
Here, Clark is referring to the gas with the most significant impact on trapping heat in the Earth's atmosphere.
As Clark said in the video caption, we know we are responsible for extra carbon because of "how the flavor mix of the atmosphere is changing." He explained that there are different isotopes or metaphorical "flavors" of carbon, and one in particular — carbon-14 — is the most interesting because it breaks down over time.
Essentially, Clark said that carbon-14 has decreased in recent decades as a fraction of the atmospheric "flavor mix," even as CO2 overall has increased. Further, an isotope associated with volcanoes — carbon-13 — has also been decreasing.
Clark summed up by saying the atmosphere's extra carbon can't be volcanic and must be very old. He concluded: "The only way to explain how the atmosphere's carbon isotope ratio is changing is extra carbon coming from fossilized organic matter — what we burn as fuel."
Or, as the National Oceanic and Atmospheric Administration put it, "Only fossil fuels meet all [the] criteria" for the carbon mix we've measured recently.
There is tons of other evidence that humans cause warming. For example, rises in average global temperature correspond extraordinarily closely with increases in heat-trapping gases from industrial activities.
Also, scientists have considered natural factors (such as changes in the sun's intensity) and found that these can't account for the Earth's warming.
According to a 2021 Cornell University analysis of over 88,000 studies, over 99.9% of peer-reviewed research agrees that humans are the primary cause.
Why is it important to know that humans cause Earth's overheating?
Understanding the cause of Earth's overheating allows us to address it more effectively.
With this, there is hope. According to projections, if humans seriously reduce carbon pollution by 2050, the global average temperature could be limited to a 2.7-degree Fahrenheit increase, avoiding the most severe impacts of an overheated planet.
"Knowing that human activities are the main driver of global warming … clearly defines the problem as one that is within our power to address," the Union of Concerned Scientists reported.
"With aggressive measures to reduce future emissions and adapt to those climate impacts we cannot avoid, we have a small window to avoid the worst climate change harms and build a better world."
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