Cliff Asness, who runs AQR, one of the largest hedge fund firms in the world, e-mailed out a research paper on Tuesday to reporters and others making his arguments on climate change. The paper is labeled “very preliminary,” and Asness asked that it not be directly quoted.

The paper focuses on a chart of the Earth’s surface temperatures going back to 1880. Asness, who wrote the paper along with his co-worker Aaron Brown, does not deny that global temperatures are rising. But he says temperatures are rising at much slower rate than many suggest. What’s more, Asness and Brown say, based on the current pace of global warming, it will take another 500 years before the changes become a real problem.

Asness writes that he is not trying to deny the science of climate change, but that he is just looking at the data and what it says on its own. He offers other observations about climate change, including that the decline in Arctic sea ice or rising sea levels could just be the result of a mild increase in temperatures and not a sign that the world is about to get dramatically warmer.

Asness is bound to win some fans with his argument. Florida, for instance, reportedly banned workers in its Department of Environmental Protection from using the terms “climate change,” “global warming,” and “sustainability.”

But many scientists say there is little question that the Earth is warming and that it is a serious problem. “I’m not sure about the idea of beating people about the head and shoulders, but within less than a year, you will look like complete fools (if you buy this crap),” e-mailed Columbia University environmental science professor James Hansen, who took a look at the Asness and Brown paper at Fortune’s request.

Asness’ AQR manages about $122 billion. He regularly publishes research papers, but they tend to be about investing, not politics. But he has been an outspoken critic of President Obama in the past, and he is an active Republican donor. Then again, Asness’ views have not always followed GOP party lines. In 2011, Asness, along with other hedge fund managers, backed a push to legalize gay marriage. In early 2013, he wrote a piece for the conservative think-tank American Enterprise Institute criticizing his fellow Republicans for not taking up the issue of civil rights more forcefully.

This is not the first time Asness has waded into the global warming debate. Last year, he was criticized for an offhand remark he made about climate change in an article directed at economist Paul Krugman on the Fed and inflation. (A little more than four years ago, Asness and others predicted the Fed’s monetary stimulus would lead to inflation. It hasn’t.) In the piece, Asness wrote, “I’m amazed that a Paul Krugman can look at 15+ years of the earth not warming and feel his beliefs need no modification or explanation, but 4 years of the CPI not inflating is reason not simply to declare victory, but to decry those who disagree with him as ‘Knaves and Fools.'”

Krugman ally and UCLA economist Brad Delong wrote a blog post about Asness’ climate comments with the following headline: “Department of WTF!?”

In an e-mail response to Fortune, Asness declined to comment on why he decided to take on climate change again now. “In all honesty I’m just a curious guy and think this was an important point,” he wrote. Since publishing the paper, he said he’s been attacked mostly by people whose views are more conservative than his, mostly for agreeing that temperatures are warming, if ever so slightly, and that humans are responsible.

Asness declined to say if his beliefs on global warming have affected the way he invests. Some advocates have suggested that large funds should factor in the likely outcome of global warming when choosing their investments.

In the paper, Asness and Brown say that, at least so far, temperatures have risen much more slowly than scientists have predicted, and that we are still far away from the point at which rising temperatures would cause a problem. Asness admits that temperatures may rise more quickly in the future, but he argues that the data doesn’t show it. Asness asserts that if the next 135 years deliver similar temperature changes from what we saw in the past 135 years, we should be fine.

Gavin Schmidt, who is the director of the NASA Goddard Institute for Space Studies, says the paper that Asness and Brown put out is “not science, it’s just wishful thinking.” Schmidt says looking at temperatures in a vacuum, as Asness and Brown are doing, is misleading. Schmidt says that the predictions that temperatures will rise much faster in the future are based on measurements of the emissions of CO2 gases, which are known to heat the planet and are accelerating. He says that’s a much better method of predicting future temperatures, rather than just taking a chart of past temperatures and drawing a future trend line, as Asness and Brown have done.

“It’s not a happy thought, but this kind of folksey chartism is not going to cut it,” says Schmidt.

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