That agreement stems from nearly 4,000 studies that suggest humans are culpable, compared to only about 80 that say we have nothing to do with the problem.
Those numbers should leave us pretty confident that humans are indeed fueling climate change. However, you could argue there's a (really) small chance those 2% of studies actually have it right.
So, a team of seven climate scientists and meteorologists decided to give climate contrarians the benefit of the doubt, picked half of their more popular studies, and tried to redo them. (The hallmark of a good scientific paper is that it's reproducible, meaning another scientist can do the same experiment and get the same or similar results.)
What happened? Beyond being unable to replicate most of the results, the team discovered major flaws in the papers. In fact, many papers left out essential data, and some even ignored basic physics.
Dana Nuccitelli, one of the scientists who helped analyze the climate denier papers for the journal Theoretical and Applied Climatology, summed up what his team found in a blog post for The Guardian.
Below are the three biggest, most common problems Nuccitelli and the team found with the small minority of studies that dispute human involvement in climate change.
Climate change deniers cherry-pick the data
Nuccitelli and his colleagues examined 38 widely referenced papers that dispute human involvement in climate change. The team learned that these papers often ignored critical background information or left out big sets of climate data.
In one example, the authors of a 2011 paper tried to show the lunar and solar cycle are responsible for climate change, but they ignored 6,000 years' worth of data that didn't jibe with their idea. Nuccitelli summed up the issues well in his post for The Guardian:
When we tried to reproduce their model of the lunar and solar influence on the climate, we found that the model only simulated their temperature data reasonably accurately for the 4,000-year period they considered. However, for the 6,000 years' worth of earlier data they threw out, their model couldn't reproduce the temperature changes. The authors argued that their model could be used to forecast future climate changes, but there's no reason to trust a model forecast if it can't accurately reproduce the past.
That 2011 study wasn't alone. Cherry-picking or downright manipulating data to get a desired result - no evidence of human-caused climate change - was the most common flaw among the climate denier papers examined by the team.
Climate change deniers ignore basic scientific facts
While most papers misconstrued or left out data, some simply ignored core scientific facts.
A handful of papers blamed climate change on the orbits of Jupiter and Saturn, but the researchers didn't offer any explanation for how that would be possible in the first place.
Other studies argued the greenhouse gases that fuel climate change, including carbon dioxide, don't drive global warming much beyond a particular saturation point - which would let humans off the hook for adding more and more to the atmosphere. However, that idea was disproved as far back as the early 1900s.
Climate change deniers can't agree on an alternative theory
While 97% of experts agree that humans are worsening climate change, the other 3% couldn't settle on an alternative explanation. Here's Nuccitelli again:
[T]he 2-3% of papers that reject that consensus are all over the map, even contradicting each other. The one thing they seem to have in common is methodological flaws like cherry picking, curve fitting, ignoring inconvenient data, and disregarding known physics.
The researchers say science is constantly evolving and changing, so no area of research is ever really "finished." However, science is based on evidence. Enough evidence leads to a theory, and a theory survives when it is tested over and over again and the evidence continues to support it. Then the scientific community comes to a consensus on that theory.
That's how 97% of experts came to agree on the theory that climate change is fueled by human activity, a conclusion that's been over a century in the making.
And right now there is no compelling evidence and no clear theory for an alternative to human-caused climate change, Nuccitelli concludes in his blog post.