What is a Consensus?

Introduction

We are told that 97 to 98% of climate scientists agree that human activity is warming the planet. But then, you turn on the news and see a prominent politician say that statistic is based on "one discredited study." So, who is right? If the vast majority of experts agree, why does it feel like a 50/50 debate? Welcome to the podcast. I am Dr. Mac, and this is The Climate Translation.

What is a Consensus?

Before we talk about the numbers, we need to talk about the word itself: consensus. In science, a consensus is not just a group of people agreeing because they like each other. It is what happens when the vast majority of specialists in a field agree on a basic principle because the evidence has become so overwhelming that it is no longer worth arguing about. We live our lives by scientific consensus every day, often without realizing it. It is agreed that the Earth orbits the Sun. We accept that tadpoles grow into adult frogs. Almost all geologists agree that plate tectonics is a reality. And you would be hard-pressed to find a doctor who still thinks smoking is harmless.

Now, here is the catch: none of these examples, not even the Earth orbiting the Sun, have 100% agreement. You can always find an outlier. There is always someone who is willing to take a contrarian stance, sometimes for personal belief and sometimes for more complicated reasons. Humans are naturally skeptical, and in science, that is actually how progress works. We argue, we test, and we peer-review until a hypothesis survives enough interrogation to graduate into a theory. But when we reach a point where a vast majority of experts stop arguing about the basics, we call that a consensus. It is the point where the data has spoken loudly enough that we can move from asking "is this happening?" to "what do we do about it?"

This brings us to the clickbait soundbite that came out of Washington a few years back: the "One Study" claim. It is often reported that somewhere between 97 and 98% of climate scientists agree that humans are the main driver in the rapid climate shifts we are seeing on our planet. Yet, politicians continue to dispute this. One stated that the idea that there is a consensus is based on just "one discredited study," and that statement was covered in all the news outlets. As an educator, this is a "lightbulb moment" waiting to happen. If the consensus were a house of cards resting on a single academic paper, I would be skeptical, too. But the truth is, the house is built on a foundation of many major, independent studies.

The first major effort to measure this consensus did not look at scientists' opinions, but at their work. In 2004, a scientist named Naomi Oreskes (Oh-RES-kes) surveyed 928 scientific papers on "global climate change" and found that not a single paper rejected the consensus position that global warming is man-made. In 2009, a study by Doran and Zimmerman asked 3,146 Earth scientists a simple question: "Do you think human activity is a significant contributing factor in changing mean global temperatures?" While 82% of all Earth scientists said yes, the number jumped to 98% among actively publishing climatologists. In contrast, only 77% of non-climatologists who do not publish research agreed.

In 2013, Dr. John Cook and his colleagues at the University of Melbourne analyzed over 12,000 peer-reviewed abstracts and found that 97.1% of those taking a position agreed that humans are causing global warming. To be even more transparent, they asked 1,200 of the original authors to rate their own papers, and those scientists reported a 97.2% consensus. In 2021, in a massive study of 88,125 climate-related papers published since 2012, researchers found that the consensus now exceeds 99% in the peer-reviewed literature. Among the subset of confirmed climate experts with the highest level of expertise (20+ papers published), agreement reached a staggering 100%.

So, when you hear that there is "no consensus" or that it is all based on "one discredited study," remember that these numbers are not just a snapshot. They are the result of thousands of experts reviewing tens of thousands of papers over several decades. The "consensus gap" is not a lack of scientific agreement. It is a gap in how that agreement is communicated to the public.

The Celebrity Skeptic Trap

In my classes, I often tell my students that science is a team sport, but the media loves a solo superstar. And that is where the "Consensus Gap" gets dangerous. It is what happens when one of those outliers becomes the "celebrity" that everyone latches onto to justify their viewpoint.

I experienced this firsthand many years ago. I was working on a research grant to create a series of events at a major aquarium on the Gulf Coast. The goal was to have an open discussion with the public about the intersections of climate, weather, and human health. But before I took over the program, the guest scientist they brought in was just such a celebrity skeptic.

Now, the expert they tapped was a credentialed scientist. At the time, he was a professor and the state climatologist for one of the Gulf Coast states. But he was also a pioneer of what I call "Alternative Science." Back in 1989, he and his colleagues used satellite data to claim the Earth was not warming at all. Even though later reassessments by the Bush administration and other scientists found significant errors in his work, the damage was done. He had become a celebrity for the skeptical camp. He was the one they turned to when they wanted someone to back up their viewpoints.

Working with him was incredibly difficult. We disagreed on almost everything. While the vast majority of his scientific peers were looking at a mountain of evidence, he was teaching that human-induced climate change was essentially a hoax. And because he had the "Dr." in front of his name and a position at a university, he provided what political leaders call "scientific cover."

This is the heart of the problem. When you have one scientist who tells people what they want to hear, that they do not have to change their lifestyle or worry about the future, that one voice can muffle the 98% who are telling them the difficult truth. In the 90s and 2000s, this was not just a coincidence. There was a deliberate "battle plan" created by fossil fuel interests and free-market think tanks to recruit these "new faces" to add their voices to the debate. They knew that if they could manufacture a "celebrity skeptic," they could create the illusion that the science was still "up for debate." This allowed them to avoid costly changes to their business plans due to national and state laws and regulations.

He was charismatic, too. People bought into his message because he was articulate and likable. It did not matter that he was an outlier or that he had been caught manipulating data. As an educator, seeing that muddled message at the aquarium was heartbreaking. People were not leaving with a better understanding of their environment. They were leaving confused. And in the world of climate change, confusion is just as good as a "no" for those who want to prevent action.

So, how do we make sense of a world where 98% of experts are in agreement, but the outliers are the most vocal and charismatic speakers in the room? How do we cut through the noise when the person telling us "it is all fine" sounds so much more certain than the scientist talking about "ranges of probability"? We have to recognize that this is a classic "Consensus Gap." In science, a consensus is reached by people who have spent years learning how to work with complex data and identify what constitutes actual evidence. Public consensus, on the other hand, usually only happens when something is "blindingly obvious," like the existence of owls because we can see and hear them. Climate change is more complex, and that complexity makes it a target for misinformers. When a "celebrity skeptic" stands up with a credential and a smile, they are often providing what people are looking for: a reason to ignore the problem. It is a powerful psychological shield, but it is one that has been carefully manufactured by interest groups to delay action.

Closing the Gap

So, given this, how do you take this information and use it to have a real conversation with a friend, family member, or colleague who has latched onto one of those vocal outliers?

The first step is to acknowledge the trust factor. Do not start by attacking their intelligence. Start by acknowledging that we all defer to experts because none of us has the time to learn everything. Say, "I understand why you would listen to that scientist. They sound very convincing, and it is natural to trust an expert."

Next, use the "Doctor Comparison." This is the most effective "translation" for the 98% consensus. Ask them: "If you were seriously ill and 98 doctors told you that you needed a specific surgery, but two told you that you were fine, would you bet your life on the two? Even if one of those two was a celebrity doctor featured on podcasts and television?"

Then, highlight the "Expertise Variable." Explain that the debate is not "scientists versus scientists." It is "experts versus non-experts." Imagine you notice a large crack in the foundation of your house. You are worried the whole building might be shifting, so you ask for advice. You ask ten of your neighbors who are all handy with tools. They have built decks and fixed sinks. Eight of them say, "Yeah, that looks like a structural problem," but two of them say, "Do not worry about it, houses just settle naturally." You are at an 80% consensus, but you are still confused because those two neighbors seem really confident.

Next, you call in ten licensed general contractors. These are people who build houses for a living. This time, nine of them tell you it is a serious foundation issue. Now you are at a 90% consensus, and the signal is getting clearer.

Finally, you bring in ten structural engineers who specialize only in soil science and foundation failure. They spend every single day studying exactly why dirt shifts under concrete. All ten of them look at the data and tell you the same thing: "Your foundation is failing because of human-driven changes to the drainage." That is 100% consensus. This is exactly what we see in climate science. If you ask "scientists" in general, you get a high number. But as the level of active research and specialization in climate science increases, so does the agreement that humans are the primary driver.

Finally, expose the "False Balance." Help them see that the media often creates an "unbalanced perception of reality" by giving 3% of skeptics 50% of the airtime. When we try to be "balanced," we actually end up being inaccurate. The goal is not to win an argument. It is to help your friend or family member realize that they might be looking at a very small slice of the pie and mistaking it for the whole meal. When we close the "Consensus Gap," we move one step closer to actually understanding, and maybe fixing, the world we live in.

Conclusion

Thank you for joining me for this episode of The Climate Translation. My hope is that the next time you hear someone say "there is no consensus," you do not feel overwhelmed. Instead, I hope you feel like you have a toolkit to help bridge that gap. If you found today's analogies helpful, I would love for you to share this episode with someone, maybe that one friend who is always sending you links to "alternative" science. Let us start building those bridges, one dinner table at a time.

I am Dr. Mac. If you have a question about the climate that you have been too afraid to ask, or if you have a differing opinion, I want to hear from you. I can use your viewpoints in a future episode. You can reach me at TheClimateTranslation@gmail.com.

I will see you next time.