Hurricane forecaster William Gray said Friday that global ocean currents, not human-produced carbon dioxide, are responsible for global warming, and the Earth may begin to cool on its own in five to 10 years.

Gray, a Colorado State University researcher best known for his annual forecasts of hurricanes along the U.S. Atlantic coast, also said increasing levels of carbon dioxide won't produce more or stronger hurricanes.

He said that over the past 40 years the number of major hurricanes making landfall on the U.S. Atlantic coast has declined even though carbon dioxide levels have risen.

Gray, speaking to a group of Republican state lawmakers, had harsh words for researchers and politicians who say man-made greenhouse gases are responsible for global warming.

"They're blaming it all on humans, which is crazy," he said. "We're not the cause of it."

Many researchers believe warming is causing hurricanes to get stronger, while others aren't sure.

Gray complained that politics and research into global warming have created "almost an industry" that has unfairly frightened the public and overwhelmed dissenting voices.

He said research arguing that humans are causing global warming is "mush" based on unreliable computer models that cannot possibly take into account the hundreds of factors that influence the weather.

Gray said little-understood ocean currents are behind a decades-long warming cycle and disputed assertions that greenhouse gases could raise global temperatures as much as some scientists predict.

"There's no way that doubling CO2 is going to cause that amount of warming," he said.

Gray also said warming and cooling trends cannot go on indefinitely and believes temperatures are beginning to level out after a very warm year in 1998.

"We're going to begin to see some cooling," he said.