I was wrong. Dead wrong.
Heading into this week’s conference on hurricanes and climate change I believed scientific thinking was moving toward embracing the belief that global warming had begun to induce hurricanes to grow slightly more intense than in the past, and possibly increase their numbers.
After all, the most visible research papers on the topic in the last 12 months, by Kerry Emanuel and Peter Webster, both purported to detect a modest trend toward higher intensity storms in recent years.
Both papers linked the evidence of more intense hurricanes to rising sea surface temperatures, and SSTs have risen slightly along with global temperatures in recent decades. The theory is simple: hurricanes need warm water to form, and warmer water generally allows them to grow very strong.
But a funny thing happened at the workshop today. A number of speakers gave talks, and most were dismissive of any upward trend in hurricane intensities and numbers during recent decades due to climate change. Among the facts I gleaned today:
• One researcher applied present greenhouse levels to models of storm activity between 1958 and 1970. Over most of the hurricane basins in the world, with artificially warmer seas than today, he actually found a reduction in activity. (The Atlantic basin increased a moderate 0.5 percent).
• Another researcher modeled the effects of a 5-degree Fahrenheit increase in SSTs on storm activity on the Atlantic basin. In comparison to the period 1961 to 1990, the modeled era of 2071 to 2100 produced a slightly decreased number of tropical storms and hurricanes.
• A third researcher presented a really nice dissection of Emanuel’s work and then reviewed the effect of rising SSTs on the Northwestern Pacific Ocean during recent decades. The conclusion? Changes in storm activity were not at all tied to global warming.
These aren’t global warming skeptics, folks. The people attending and presenting at this conference are among the “heads of state” in the field of climate and its effect on hurricanes.
The general consensus I have gleaned is that increasing SSTs will have some effect on hurricanes. But temperatures in the upper atmosphere are also likely to increase, so there may be no net increase in the “convective fuel” that hurricanes thrive upon. Wind shear may also increase as a result of global change, which also dampens their ability to form and remain organized.
It’s also important to note that no models are perfect, but they’re the best efforts to predict the future far into advance. Today they gave us some exhilarating results…