There is no public policy debate in which the language has been manipulated more than in the case of global warming. In fact, the language has been changed to such an extent that the words being used, when viewed objectively, have little to do with either the science or the public policy concerns.

Three expressions are so ingrained in the conversation that even skeptics (mis)use them. These terms are part of a propaganda drive meant to confuse the public on both the science and policy of global warming. The three terms are climate change, carbon, and emissions.

First, the expression used to identify the problem has changed subtly from the accurate and specific “global warming” to the inaccurate and general “climate change.” From the perspective of the propagandists, this language change is the most important.

The question of whether or not the planet is warming is factual, based on temperature data. The answer may be yes or no. On the other hand, the climate never has been unchanging and never will be.

By conflating “global warming” and “climate change,” propagandists like President Obama can refer to people who point to data showing that global temperatures have stopped rising over the last 15 years as “flat earthers” and “climate change deniers.” Of course, such accusations would be true if the issue were indeed climate change. But it is not.

Since most people do not have much knowledge of science, the propagandists have started lying. In newspaper articles and reporting on global warming, commentators have substituted carbon, C, for carbon dioxide, CO2. In terms of emissions, the issue is the latter, not the former.

CO2 is the greenhouse gas accumulating in the atmosphere that presumably will warm the planet to intolerable levels. It is CO2 emissions that government policies are meant to reduce. But carbon dioxide is rarely mentioned. Instead, we hear of “carbon taxes,” “carbon emissions,” and “reducing our carbon footprint.”

There is a propaganda-driven reason for this. CO2 is an invisible, odorless gas that helps vegetation grow and supports life on Earth. CO2 is not scary. On the other hand, carbon suits the propagandists’ purposes much better.

Most people associate carbon with a black, sooty substance that is harmful to inhale and soils everything it touches. The negative image of carbon presents a much better target for the shyster ad man than does CO2.

To make the trilogy complete, the propagandists have changed the goal of policy from reducing temperatures to reducing emissions. There is a very good reason for this. Temperature reduction resulting from policies such as the Waxman-Markey cap-and-trade legislation, designed to reduce CO2 emissions by more than 80 percent, would be unnoticeable. Using the Intergovernmental Panel on Climate Change’s own data and methods, the Waxman-Markey plan would have reduced global temperatures relative to what otherwise would occur by 0.2 degrees over the next 100 years.

In other words, a policy that would reduce CO2 emissions to levels last seen in the late 19th century, when people rode horses and buggies and used kerosene to light their houses, would bring about no noticeable gain in temperature reduction. Once again, the shyster ad man can shift attention away from reducing temperatures, the actual purpose of the policy, and toward reducing “carbon emissions,” which can be measured in terms of thousands of tons.

Honest policy analysts should just say no to this propagandist assault on language. Whenever “climate change” is used instead of “global warming,” or “carbon” is used in place of “carbon dioxide,” the person using those terms should be called out and made to explain himself.

When someone claims that a particular policy will reduce emissions by a certain amount, we should refocus the discussion on temperatures: “Tell me how much temperatures will be reduced and over what period of time.”

Propagandists, ad men, and magicians always invoke the same technique to perpetrate their illusion — take the audience’s eye off the ball. We will defeat these illusionists if we keep the ball front and center and in plain sight.

Dr. Roy Cordato is vice president for research and resident scholar at the John Locke Foundation.