Just over a decade ago, US Senator James Inhofe helped derail early bipartisan efforts to cap greenhouse gas emissions. His now-infamous 12,000-word, science-distorting speech concluded with a warning that international efforts to reign in climate-destabilizing emissions were not about saving the planet, or even humanity's place on it, but "handicapping the American economy".

"With all of the hysteria, all of the fear, all of the phony science, could it be that man-made global warming is the greatest hoax ever perpetrated on the American people? It sure sounds like it," the former chairman of the Senate committee on environment and public Works concluded.

While the "hoax" message helped sink 2003's Climate Stewardship Act, it has since fallen on hard times. The scientific understanding of human-induced climate change has tightened to a certainty on par with tobacco's link to cancer, and increasing numbers of Americans have begun to testify that they have personally been impacted by climate change and related extreme weather events.

On Tuesday, the US Global Change Research Program released a summation of climate impacts already being experienced across the US. The 800-page document, which White House adviser John Podesta called "actionable science", details the increasing incidence of extreme weather events, such as record-setting heatwaves, droughts and downpours, among the impacts already being experienced because of climate change.

The report's findings, and its projections of future events, make it harder for the forces rallied against collaborative international climate action to deny that climate change is occurring.



From denying to downplaying

Enter economist Richard Tol. In September, Tol, a professor at the University of Sussex, resigned his position with the Intergovernmental Panel on Climate Change team producing the working group's Summary for Policymakers in the most recent report on the environmental, economic and social vulnerabilities associated with climate change. He remains the coordinating lead author on the group's chapter about economics.

Claiming that the report's Summary for Policymakers was "alarmist" and didn't reflect the report as a whole, Tol, an advisor to the conservative British thinktank Global Warming Policy Foundation, and others have inspired a spate of stories suggesting an "upside" to the climate crisis.

Take this piece from Spectator columnist Matt Ridley: "We have a climate change consensus - and it's good news everyone". And from conservative think tank The Heartland Institute: "Benefits of Global Warming Greatly Exceed Costs, New Study Says".

"It is pretty damn obvious that there are positive impacts of climate change, even though we are not always allowed to talk about them," Tol told the Guardian.

Though his own research is being actively challenged as downplaying the economic costs climate change poses to the world, Tol's suggestion that a little warming may actually be good for us, as recently relayed by Bloomberg Businessweek, has since been picked up and amplified by numerous media outlets.

Drawing on Tol's past work, Ridley has argued that "climate change has done more good than harm so far," and will probably do so "for most of this century". And, on Fox News, conservative American columnist Cal Thomas quoted Tol, suggesting that "the idea that climate change poses an existential threat to humankind is laughable".

Dusting off an old argument

Has the denial camp has found its new meme? One that admits the warming is happening but insists – contrary to the overwhelming evidence – that it's beneficial?

Hardly, says Harvard University professor and science historian Naomi Oreskes, co-author of Merchants of Doubt. "One thing these folks have done for a long time is have a kind of repertoire of arguments, and, depending on circumstances, they trot out different ones," she said. "This is not new. This is recycled."

The "good news" of global warming has been promoted at least since 1992, the year President George W Bush attended the UN-sponsored Earth Summit in Brazil and committed the nation for the first time to voluntary greenhouse gas reductions. Already engaged in a public-relations war to dispel growing public concern about global warming, the coal industry lobby funded a 30-minute video promoting the purported benefits of carbon dioxide pollution.

In it, soil scientist Sherwood Idso stated that a doubling of carbon dioxide would produce a "tremendous greening of planet earth". An accompanying graphic showed a map of Africa transformed from brown to green. The message later found its way into Inhofe's 2003 speech when he claimed that agricultural productivity would be "30% higher in a CO2-enhanced world".

Industrially elevated atmospheric CO2 has since increased to about 400 parts per million, nearly90 ppm over 1950 levels. While this has resulted in some agricultural gains in recent decades, the overall impact of climate change on crop production has been negative thanks to rises in surface air temperatures, ground-level ozone and extreme weather, according to the most recent IPCC report.

Yet Idso, who has enjoyed support from fossil fuel industry and conservative thinktanks for years, persists. He makes virtually the same argument in Climate Change Reconsidered II: Biological Impacts, a collaborative report published last month for the libertarian Heartland Institute's Nongovernmental International Panel on Climate Change. Dismissing the potential of human industry to significantly affect the global climate, the report praises the "great greening of the earth" that has resulted from rising atmospheric CO2.

Zombie arguments

Environmental sociologist Riley E Dunlap calls such recycled contrarian messages "zombie arguments".

Based in Inhofe's backyard at Oklahoma State University, Dunlap is chair of the American Sociological Association's Task Force on Sociology and Global Climate Change. As part of his research, he tracks the various memes of climate change deniers in popular media and within the publications of think tanks like Heartland.

"While some contrarian scientists have changed their arguments over time so they are less out of step with the preponderance of scientific evidence, on skeptic blogs and among politicians one can constantly find these zombie arguments," Dunlap said.

A paper he co-authored in 2000 recorded 159 "counter-arguments" published by conservative US thinktanks between 1990 to 1997 challenging the dominant scientific evidence of warming. Likewise, he found 139 examples of arguments during the same period insisting that policy responses intended to slow or reverse global warming would "do more harm than good". He finally found 30 examples of the argument being made that global warming would be beneficial in some way.

A follow-up study in 2012 tracking similar arguments being made by conservative columnists replaced the beneficial language with the assertion that global warming is "not bad". It found all examples still being widely employed.

However, the so-called benefits honed in on by the business community seem to be more in line with the consensus science reflected in the IPCC reports. Raytheon, for example, is positioning itself to reap benefits from both a growing market for renewable energy and forecasting technology.

The defense contractor also anticipates that climate change will lead to a rising demand for weapon systems. A company report, Mother Jones reported, claimed that "climate change may cause humanitarian disasters, contribute to political violence and undermine weak governments".

The Pentagon's 2014 Quadrennial Defense Review echoes this conclusion, noting that climate change "will aggravate stressors abroad such as poverty, environmental degradation, political instability and social tensions – conditions that can enable terrorist activity and other forms of violence".

In other words, climate denial and threat minimization aside, when it comes to security, the Pentagon and its military contractors are planning for climate change. And their predictions of widespread, disruptive effects seem to be in close agreement with the IPCC's.

• This article was amended on 9 May 2014. An earlier version said Richard Tol resigned his position as a contributing lead author to the Intergovernmental Panel for Climate Change in March. In fact, Tol resigned his position with the team producing the working group's Summary for Policymakers in September 2013, but remains the coordinating lead author on the group's chapter about economics.

Greg Harman is an independent journalist based in San Antonio