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A prominent meteorologist has refuted claims that Hurricane Lorenzo, which struck Ireland at the start of the month, was caused by rapid manmade warming of the Atlantic, as has been claimed in some media reports.

Professor Ray Bates, a former president of the Irish Meteorological Society, says that an analysis of ocean temperatures and tropical wind fields shows that the hurricane was predominantly due to natural variability.

“The isolated warm pool in the Atlantic that fuelled Lorenzo up to hurricane force was an anomaly. It was surrounded by seas whose temperatures were normal or below normal. Also, the warm pool was temporary. Areas in the hurricane’s path that were up to 1.5°C warmer than normal at the time of its passage had been up to 1.5°C cooler than normal three months earlier.”

Professor Bates’s analysis also shows that the wind field that steered Lorenzo in a west-north-westerly direction towards the warm pool, and contributed to its development through strong horizontal cyclonic shear, was unusual. By the time the hurricane had petered out, the winds in the area of its formation has returned to a normal pattern, which steers weather disturbances originating over Africa in the direction of the Caribbean. “The evidence clearly indicates that natural variability was the cause of Lorenzo”.

Professor Bates has set out his reasoning in a new paper published by the London-based Global Warming Policy Foundation. 

What Caused Hurricane Lorenzo? (pdf)

Professor Bates is available to discuss his findings.