There’s a 99.9999% chance humans are causing climate change

Man-made climate change has officially reached the golden standard — there’s just no other reasonable explanation other than we are causing it.

Climate change deniers often like to spread uncertainties and misinformation, but the causes surrounding climate change have been well-known for a long time now.

“The narrative out there that scientists don’t know the cause of climate change is wrong,” study lead author Benjamin Santer, an atmospheric scientist at the Lawrence Livermore National Laboratory said in a statement. “We do.”

The general mechanism is quite simple: we burn fossil fuels, this process releases carbon dioxide (and other greenhouse gases into the atmosphere), which traps heat. There’s absolutely no doubt that the planet’s climate is getting hotter — decades’ worth of satellite and ground data clearly show it. There’s also overwhelming evidence that points to human activity as the main culprit. While there are natural factors which can cause an equal and even greater impact, human activity is essentially a smoking gun here: the evidence indicates that all the current global warming is caused by humans.

In this latest study, scientists carried out a statistical analysis of satellite climate data, identifying the anthropogenic fingerprint in climate change. The analysis showed that humans are causing climate change to a confidence level of 5 sigma, the so-called gold standard of statistics — which translates a 99.9999% certainty. In other words, there’s only a one-in-a-million chance that the pattern of atmospheric heating is not the result of human activity.

Science doesn’t really ever eliminate uncertainty — it just reduces it, and when the uncertainty reaches very low levels, then that’s essentially a scientific certainty.

This isn’t the first study to strongly conclude that humans are causing climate change, it’s just trying to turn things up a notch. In 2013, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) concluded that it is “extremely likely” (95% probability) that mankind is causing climate change. Separate studies have also come up with similar conclusions.

Whether it’s 95%, 99%, or 99.9999%, the realistic takeaway is that we just can’t afford to deny climate change. It’s no longer a matter of any scientific debate — the evidence is out on the table. It’s time to take serious action to limit this process and its effects. Whether or not we believe in it, climate change will affect each and every one of us.

While the general population is still more skeptical than scientists, people are also starting to get on board with the issue. A 2018 poll from the Yale Program on Climate Change Communication found that 62% of Americans say that “global warming is caused mostly by human activities” — up from 47% five years ago. It’s still a pretty thin majority for a scientific certainty.

“Humanity cannot afford to ignore such clear signals,” were the words with which the study concluded.

The study has been published in Nature.

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