I, obviously, don't have a background in Climate Science, so I can't evaluate the hard data involved with Climate Change. However, I can evaluate how the supporters of Climate Change act and make their case, and evaluate their position based on their actions.
It is important to note, quickly, that there are several key elements to the Climate Change theory: 1) The climate is changing 2) primarily because of human activity, and 3) the change will cause Bad Things to happen. 1 is obviously true - the climate has been changing from Day 1.
First, the name keeps changing. In the Seventies and Eighties the name of the theory was Global Cooling. The exact same mechanics working in largely the same way that are today supposed to produce Global Warming instead would produce a Cooling. Except now these same mechanics are reduced to causing harm, now known as Climate Change (severe storms, tornadoes, droughts, etc).
The direction of worldwide temperature averages kept changing. In the Seventies and Eighties, the trend was to cooling, then in the late Nineties it shifted to warming. After the Global Warming movement took off, the warming trend came to a gradual halt over the last decade. The theory has had its top-line conclusions and its name changed, but none of the actual mechanics or data has been retracted or modified. The problem is simple; how can the outcome change without a change in the data or mechanics? But like a faith healer, the solution remains the same, even though the supposed problem keeps changing.
Second, proponents of the theory do not handle criticism or skepticism well. From public demands ranging from boycotts to imprisonment, the response from supporters of the theory does not reflect confidence in the theory. It appears to reflect a deep-seated fear that the data does not actually support the theory, and without the theory, the cause will fail. The approach that the supporters of the theory take is one of dogma, not of science.
There is a recent case of a climate researcher deciding to affiliate with an organization that is skeptical of the theory, and within one week, the researcher publicly rescinded his affiliation and apologized to the climate research community, explicitly on account of the harassment, vitriol and threats of boycotts he received immediately upon making the announcement. How can serious science be done, when even the potential of negative research is eliminated, and those responsible are forced to publicly renounce their heresy?
Third, the supporters act in a fundamentally dishonest way. Take the "97% of all research agrees" statistic. That number was reached by surveying all the articles in climate science, taking the research that explicitly rejected the theory (at least those that survived attempts to suppress it), and counting all the other research in climate science as accepting the theory. This includes articles that take no position, articles that assume it true for the sake of discussion, articles that mention the theory in passing, and articles that do not even mention the theory at all. That's an incredibly broad definition of the word "agree". By that definition, most everyone agrees with almost everything.
Fourth, there is a different set of rules for supporters of the theory than for their opponents. Opponents of the theory are dismissed for not having credentials in the field of climate science, but supporters of the theory can be leaders in the movement without needing even a basic college education. More importantly, if a critical researcher received a speaking from from a group that received a donation from an individual who holds some oil stock, that researcher is forever discredited as a tool of Big Oil. But a researcher who supports the theory can receive a direct grant from a government that embraces the theory, in order to build support for the theory, and this researcher is a serious and disinterested observer.
Finally, there is the primary issue that this movement and theory largely originated from the Environmentalist movement. The methods and solutions presented to fix the problem the theory presents are largely more-extreme measures of the environmental-cleanup that Environmentalists were preaching before the movement took off. Many of the Environmentalist activist groups have either fallen by the wayside or embraced the Climate movement. These activist groups even sell "credits" of carbon use, to be used to reduce the "official" carbon footprint of the purchaser.
There is only one other set of groups that rely on shifting conclusion, dogma, manipulated evaluations, purging heresy, different rules for themselves, and starting from their answer and seeking evidence. That group is religion. While not every religious person, faction or faith does all of these things, some do, and many do at least some of these. The Climate Change movement acts like a medieval religion in its promotion, defense and evaluation. It does not behave as if it is based on a scientific understanding of the facts, but as if it is a set of religious imperatives that will grant absolution.
And that's how you can tell it's a scam - the promoters aren't acting as if they believe it, they are acting as if they need you to believe it, as if they need to fool you just long enough to achieve their ends, like any false prophet, snake oil peddler or conspiracy seller.