When it comes to eating and breathing, plants are a lot like people. We are constantly soaking up nutrients from the land, water, and air to sustain ourselves. Photosynthesis, the process by which plants  produce their food, requires sunlight, water, and carbon dioxide. That’s right — the gas associated with global warming and often mislabeled as a “pollutant” is to plants what oxygen is to humans. (And plants are pretty necessary to sustaining human life!)

Modest increases in the the amount of CO₂ in the atmosphere stimulates plant growth and has long been known to increase crop yields. Recent studies indicate that CO₂ has played significant role in the greening of the globe, especially in warm, arid environments, over the past few decades.

These beneficial effects of CO₂ are routinely ignored in the policy discussions regarding climate change. Climate activists often use a metric called the “social cost of carbon” to justify taxing or regulating fossil fuels, which provide about 80% of our energy. And most of the models that attempt to quantify the social cost of carbon (SCC) — the presumed future cost of our current CO₂ emissions — fail to factor in higher crop productivity.

That’s why a new study that does account for global greening finds the social cost of carbon might be negative — meaning carbon dioxide emissions could actually benefit society.

The problem with assigning a social cost to our current CO₂ emissions is the vast uncertainty in future global CO₂ emissions, in the effects of CO₂ on the future climate, and in the economic and human impacts of climate change. The EPA tries to address this problem by running a wide range of scenarios, applying probabilities to them, and averaging the results.

The headline-grabbing studies on social cost of carbon are entirely a result of the input parameters the modelers choose to use. It’s not difficult to produce any SCC value you want by simply changing the variables. Most of the forecasted damages from CO₂ emissions in the SCC models come from the most extreme cases. However, using more realistic upper limits reflective of the more likely mild and manageable changes in our climate renders such dramatic warming, and the associated extreme damages, virtually impossible.

If the warming caused by CO₂ remains mild, as is most likely, the benefits of increased atmospheric CO₂ — higher crop yields, more vegetation, fewer deaths from cold weather — could easily outweigh any downsides.

All in all, social cost of carbon is about assumptions, not evidence.

Despite all of these uncertainties, the EPA under the Obama administration planted its flag on an average SCC of $42 per ton for 2020 U.S. emissions to justify numerous regulations, costing taxpayers many billions of dollars. The Trump administration has modified federal SCC calculations to include only potential damage within the U.S., rather than around the world, thereby reducing the average to $7 per ton for 2020 emissions.

The current EPA should correct the underlying flaws of the models it uses or at least make the public and policymakers more aware of the uncertainties surrounding the actual effects of CO2. However, while these flaws can be debated endlessly, the fundamental problem with the entire SCC enterprise is that there is no widespread discussion of the social benefits of the activities that create our CO₂ emissions.

Carbon-emitting fuels provide nearly 80 percent of our energy in the U.S. The social cost of eliminating that energy is easy to calculate: unreliable, unaffordable energy; declining healthcare and quality of life; lost jobs and higher poverty; dependence on hostile and unstable nations for oil.

Ultimately, the cost of CO₂ is likely very small — much smaller than the cost of attempting to eliminate CO₂ emissions, which would have little effect on global temperatures anyway. Political carbon pricing schemes will simply impose a cost on Americans that a vast majority have said, by their energy choices and by consistent nationwide polling, that they do not want to pay.

The social cost of carbon, once a purely academic exercise, has been turned into a political weapon to justify any desired regulation. Given this state of affairs, the Trump administration should dispense with the social cost of carbon in its regulatory processes and send it back to the academic realm where it belongs. Our economic freedom and prosperity will be better off for it.