His fellow scientists call him a fraud, a charlatan and a showman, but Fred Singer calls himself "a realist."
Singer, an 84-year-old Princeton-trained physicist, is the grandfather of the global warming skeptics who dispute the established scientific consensus that global warming is real, that it is caused by the pollution humans are pumping into the atmosphere, and that it will be catastrophic if measures are not taken immediately.
"All bunk," Singer told ABC News in his characteristically blunt fashion. "I'm not really looking for popularity, you know."
Singer seems to enjoy being provocative.
"I hate to tell you this, but polar bears like to eat tiny little seal pups," he told a conference of global warming skeptics recently.
Singer does not deny the planet is warming, but says man is not the cause, and argues, against overwhelming scientific evidence, that a warmer planet will actually be beneficial for mankind and other species on the planet.
Polar bears, though, are not likely to benefit. They are starving because the Arctic ice cap is shrinking, which is cutting them off from seal populations, and some scientists have suggested they will be extinct in the wild before the end of this century if the warming trend is not reversed.
This is not the first time Singer has set himself against mainstream scientific opinion. He has also challenged the dangers of second-hand smoke, toxic waste and nuclear winter.
"He's kind of a career skeptic," said Kert Davies, a global warming specialist at Greenpeace. "He believes that environmental problems are all overblown and he's made a career on being that voice."
Davies says skeptics like Singer, many of them funded for years by the oil and coal industry, have been able to delay government action on global warming by a decade or more by convincing the public through a disinformation campaign that there was an ongoing debate among scientists about global warming.
"That's how people will remember Fred Singer, as someone who tried to slow down the reaction to global warming," Davies said. "And in the end that is going to cost lost lives, lost species and major economic damage around the world."
Singer responds by asking, "Suppose the other side is wrong.... They're forcing us to make tremendous economic sacrifices that will force people into poverty in the world, make life miserable for our children and grandchildren."
But scientists say there is no "other side." The debate about global warming is over, they say.
ABC News showed Singer's most recent report on global warming to climate scientists from NASA, from Stanford University and from Princeton. They dismissed it as "fabricated nonsense."
Singer insists he is not on the payroll of the energy industry, but admits he once accepted an unsolicited check from Exxon for $10,000.
Dan Harris, Felicia Biberica, Elizabeth Stuart and Nils Kongshaug contributed to this report.