Study strongly discredits AGW-Hurricane link

Reuters reports on a study that reaffirms an observation that was already well-known in the tropical meteorology community prior to the current AGW hysteria: while Atlantic surface temperatures are important, Atlantic hurricane formation and intensity are driven more by the Pacific's El Niño/Southern Oscillation (ENSO) phenomenon. Note in this article excerpt that its author still holds fast to the basic tenets of CoGW orthodoxy even while reporting on a study that discredits one of the many AGW alarmist talking points of recent years (especially post-Katrina).

Hurricanes over the past 5,000 years appear to have been controlled more by El Nino and an African monsoon than warm sea surface temperatures, such as those caused by global warming, researchers said Wednesday.

The study, published in the journal Nature, adds to the debate on whether seas warmed by greenhouse gas emissions lead to more hurricanes, such as those that bashed the Gulf of Mexico in 2005.

Some researchers say warmer seas appear to have contributed to more intense hurricanes, while others disagree. The U.N. International Panel on Climate Change said this year it was more likely than not that humans contribute to a trend of increasingly intense hurricanes.

Frequent strong hurricanes thrived in the Western Atlantic during times of weak El Ninos, or warming of surface waters of the Eastern Pacific Ocean, and strong West African monsoons even when local seas were cooler than now, the study said.

"Tropical sea surface temperatures as warm as at present are apparently not a requisite condition for increased intense hurricane activity," Jeffrey Donnelly, the lead author and researcher at the Woods Hole Oceanographic Institution, said in the study.

Intense hurricanes made landfall during the latter half of the Little Ice Age, a period of cooling that occurred approximately from the 14th to mid-19th centuries, he said.

Note the phrase "seas warmed by greenhouse gas emissions" in the second paragraph. Are Atlantic surface temperatures warmer than they were 50 years ago? 20 years ago? I actually don't know the answer to that question, and I welcome any information that you, dear reader, can provide.

If there has been warming, what is the source of the warming? Remember, the CoGW has conditioned us to assume AGW whenever some anomaly is observed in nature, but such an approach is scientifically lacking. Of course, this knee-jerk response also assumes that actual atmospheric warming has occurred, and to an extent that it would affect ocean surface temperatures. But has it? I will leave that discussion for another post.

Assuming that there has been ocean warming, could there be other causes? What about underwater volcanic activity? The Mid-Atlantic Ridge is extremely active volcanically -- can it be ruled out as a source of temperature changes?

Consider the ENSO phenomenon in the Pacific, which features the rapid cooling or warming of ocean temperatures, totally independent of the presence or absence of SUVs. Is there really nothing in the Atlantic that could possibly contribute to water temperature changes without our help?

But that's all beside the point. This study shows pretty clearly that ocean surface temperatures have little or no influence over the number or intensity of Atlantic hurricanes, regardless of the atmospheric temperatures over the ocean.

Why are we still talking about Katrina two years later? Is it the fact that it was a Category 5 hurricane? There have been other Category 5 hurricanes in the Gulf before Katrina -- such as Allen in 1980, which was much stronger at its peak than Katrina was.

No, the main fact that makes Katrina memorable is where it made landfall. Hurricane Allen came ashore at a more sparsely populated area of the Gulf coast (near Brownsville, Texas), and because the damage was relatively minor (compared with Katrina), most people don't remember it any more.

Katrina came ashore near a major city, and the strong side of the storm pummeled portions of Mississippi that had a lot of coastal development, so the visible destruction was much greater than that caused by Allen. Even so, Katrina would not have loomed so large in our memory if the retaining wall of one of New Orleans' canals had not collapsed.

So, before the 2007 hurricane season officially begins, we hear the voice of reason on what actually drives hurricane development. I think we can count on the pols and pundits to totally ignore this study when we get the first landfall this summer.