'Oceans cause global warming'

2007-04-28 13:25

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

Gray, a Colorado State University researcher, also said increasing levels of carbon dioxide in the atmosphere would not produce more or stronger hurricanes.

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

Gray, speaking to a group of Republican state politicians, had harsh words for researchers and politicians who said man-made greenhouse gases were 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 are not sure.

Dissenting voices 'overwhelmed'

A study published last week suggested that warming might make it more difficult for hurricanes to form because it produced more vertical wind shear, which could weaken hurricanes.

But the researchers, Gabriel A Vecchi of the National Oceanic and Atmospheric Administration and Brian J Soden of the University of Miami, said it was unclear whether the dampening effects of wind shear would cancel out the boost that warmer water gave hurricanes.

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

He said research arguing that humans were causing global warming was "mush" based on unreliable computer models that could not possibly take into account the hundreds of factors that influenced the weather.

Gray said ocean circulation patterns were behind a decades-long warming cycle.

'Global warming is pervasive'

He has argued before that the strength of these patterns can affect how much cold water rises to the surface, which affects how warm or cold the atmosphere is.

He also 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.

Kevin Trenberth, head of climate analysis at the National Centre for Atmospheric Research, said natural changes in the environment could not account for the magnitude of global warming in the past four decades.

"Since about 1970, the global temperature change is outside of the range of natural variability," he said.

He challenged Gray's assertion that ocean currents had more effect on temperatures than carbon dioxide.

"Global warming is pervasive. It has an influence on ocean currents, it has an influence on hurricanes, it has an influence on rainfall."

Gray countered that warming and cooling trends could not go on indefinitely and that temperatures were beginning to level out.

- AP