In economic theory, an externality is a cost or benefit that spills beyond the transaction that creates it — onto bystanders who never signed up for the deal. Pollution is the textbook example: a factory’s smoke drifts over a nearby town, and the residents pay for it in health and clean-up costs that never show up on the factory’s balance sheet. For decades, the concept has been a cornerstone of environmental advocacy, a way to argue that markets have failed to price in the true damage they cause.
But according to a new opinion piece on American Thinker, environmentalists may have pushed that logic too far — and in doing so, have weakened their own case.
A useful idea, misapplied?
The piece, written by Bill Ponton and published September 7, 2026, concedes that externalities are real and that the concept makes sense in theory. It points to 19th-century England, where the popularization of the flush toilet brought unprecedented sanitation improvements but also sent raw sewage into rivers and lakes, imposing horrendous costs on people who lived downstream. Those external burdens helped galvanize the clean air and water acts of the 20th century, which forced municipalities to build wastewater treatment plants and shift responsibility to the polluters themselves.
That was externalities done right, the author argues. The problem is what happens when the tool is applied to problems where the remaining external costs have become marginal — and where the remedies may cost more than they save.
A changing landscape
Ponton argues that air and water quality in the United States have improved to the point where the residual external costs of pollution are now negligible. Further regulation, he writes, brings rapidly diminishing returns. Yet environmental groups continue to push for stricter controls, even in cases where the external benefits of their proposals may not justify the costs.
The clearest example, according to the piece, is the campaign to eliminate fossil fuel burning. The author claims that the external benefit to agriculture from higher atmospheric CO2 — measured in terms of increased crop yields — should outweigh the external cost of future shoreline remediation for sea level rise. By that logic, the net effect of fossil fuel emissions on society could actually be positive, when considering only the externalities.
Ponton suggests that the shrill tone environmentalists have adopted when discussing extreme weather is an attempt to inflate present-day external costs. Since costs closer to the present are discounted less in economic analysis, making climate impacts seem imminent and severe increases their perceived weight. But the author says that strategy has backfired.
An argument that cuts both ways
The piece stops short of denying climate change or rejecting the concept of externalities altogether. Instead, it warns that overstating the harms of fossil fuels — and understating their benefits — undermines the credibility of environmental advocacy. When the public sees the claims as exaggerated, the author suggests, they become less willing to accept even the reasonable regulatory measures that might be justified.
That is the core of the argument: that environmentalists have overplayed their hand, and in doing so, have weakened their own position.
It is a provocative claim, and one that runs against the scientific consensus on climate change. Most climate scientists and economists who study the issue conclude that the social cost of carbon — the total economic damage from each ton of CO2 emitted — is substantial and positive, far exceeding any agricultural benefit from fertilization. The Intergovernmental Panel on Climate Change and other major assessments have repeatedly found that the harms of warming, from extreme weather to sea level rise to ecosystem disruption, will outweigh the benefits on a global scale.
But Ponton’s piece is an opinion, not a scientific study, and it is framed as a commentary on the rhetorical and economic strategies of environmental advocacy rather than as a climate assessment. Its argument is that environmentalists have misapplied the concept of externalities by focusing on theoretical future costs while ignoring tangible present benefits.
A debate about framing
The debate over how to frame environmental policy is unlikely to be settled by a single op-ed. But the piece highlights a persistent tension within environmental advocacy: how to communicate urgency without being accused of exaggeration, and how to weigh deeply uncertain future risks against more certain present gains.
Environmentalists would likely respond that the stakes are too high to risk understatement — that the cost of acting too slowly on climate change far exceeds the cost of acting too aggressively. They might also note that agricultural benefits from CO2 are not the same as overall societal well-being, and that the damage from climate change will not be evenly distributed.
Ponton’s argument, by contrast, invites readers to consider whether the environmental movement has become its own worst enemy — by pushing so hard on externality arguments that it fails to account for diminishing returns and unintended consequences.
Whether or not one agrees with that assessment, the piece is a reminder that economic tools like externalities are not neutral. They can be wielded to justify regulation — or to argue against it. The question is who wields them, and how convincingly.
Source: www.americanthinker.com — https://www.americanthinker.com/blog/2026/09/how-environmentalists-have-overplayed-their-hand-in-arguing-economic-externalities/