The wind energy production tax credit (PTC) expires at the stroke of midnight, Dec. 31, unless Congress votes to renew the tax break. A one-year extension would add an estimated $12.1 billion to deficit spending over 10 years. A six-year extension, advocated by the wind industry, could add $50 billion.

The fiscal cliff looms and the national debt already exceeds GDP, but if Congress cared more about the general interest of taxpayers than about the special interests of campaign contributors, the nation would not be sliding towards insolvency.

Whether Congress should renew the PTC or let it expire is the topic of this week’s National Journal Energy Experts Blog. Twenty wonks weigh in, including your humble servant. I heartily recommend the contributions by Sen. Lamar Alexander (R.-Tenn.), Craig Rucker, Phil Kerpin, Benjamin Zycher, Thomas Pyle, James Valvo, and David Banks.

My contribution addresses the environmental side of the debate, in particular the claim that recent extreme weather events demonstrate “just how badly our nation needs to take advantage of our vast wind energy potential,” as one contributor put it.

Below is a lightly edited version of my comment.

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Of all the lame arguments used to sell Americans on the proposition that wind power, an industry propped up by Soviet-style production quota in 29 states and numerous other policy privileges, deserves another renewal of the 20-year-old production tax credit (PTC), the lamest is the claim that the PTC helps protect us from extreme weather.

PTC advocates talk as if Hurricane Sandy and the Midwest drought were obvious consequences of anthropogenic global warming, and that subsidizing wind energy is a cost-effective way to mitigate climate change.

They are wrong on both counts.

Neither economic analyses nor meteorological investigations validate the asserted link between recent extreme weather events and global warming. When weather-related damages are adjusted (“normalized”) to account for changes in population, per capita income, and the consumer price index, there is no long-term trend such as might indicate an increase in the frequency or severity of extreme weather related to global climate change.

A 2012 study in the journal Climate Change  examined 370 years of tropical cyclone data from the Lesser Antilles, the eastern Caribbean island chain bisecting the main development region for landfalling U.S. hurricanes. The study found no long-term trend in either the power or frequency of tropical cyclones from 1638 to 2009. It did however find a 50- to 70-year wave pattern associated with the Atlantic Multidecadal Oscillation, a mode of natural climate variability.

A recent study in the Journal of Climate similarly found no long-term trend in the strength or frequency of landfalling hurricanes in the world’s five main hurricane basins. The data extend back to 1944 for the North Atlantic, to 1950 for the northeastern Pacific, and to 1970 for the western North Pacific, northern Indian Ocean, and Southern Hemisphere. Among other inconvenient findings: “The U.S. is currently in the midst of the longest streak ever recorded without an intense [category 3-5] hurricane landfall.”

Sandy was not even a category 1 hurricane by the time it made landfall. New York has been hit with more powerful storms at least as far back as the 17^th century. For example, the New England Hurricane of 1938 was a category 3 that killed 600 people. Carbon dioxide (CO2) concentrations in 1938 were about 310 parts per million (ppm), well below the level (350 ppm) advocated by NASA scientist James Hansen, activist Bill McKibben, and Al Gore as the upper limit consistent with climate stability.

What made Sandy so destructive was the hurricane’s merging with a winter frontal storm to produce what MIT climatologist Kerry Emanuel calls a “hybrid” storm. The usual suspects, of course, were quick to suggest that any such ‘freak of nature’ must be man-made. That is speculation, not science. In Emanuel’s words:  “We don’t have very good theoretical or modeling guidance on how hybrid storms might be expected to change with climate. So this is a fancy way of saying my profession doesn’t know how hybrid storms will respond to climate [change]. I feel strongly about that. I think that anyone who says we do know that is not giving you a straight answer. We don’t know.”

As for the Midwest drought, if it were a symptom of global climate change, then there should be a long-term positive trend in the Palmer Drought Severity Index (PDSI). Instead, as Cato Institute scholars Patrick Michaels and Chip Knappenberger point out, the PDSI from 1895 through 2011 is slightly negative, i.e., the trend is towards a somewhat wetter climate.

But here’s the kicker. Even if one assumes fossil fuel emissions revved up Sandy and the Midwest drought, extending the PTC for another year – or even another six, as advocated by the American Wind Energy Association – would provide no protection from climate-related risk.

Using IPCC climate sensitivity assumptions, Knappenberger calculates that even if the U.S. eliminated all CO2 emissions tomorrow, the impact on global temperatures would be a reduction ”of approximately 0.08°C by the year 2050 and 0.17°C by the year 2100 — amounts that are, for all intents and purposes, negligible.”

The U.S. will continue to emit billions of tons of CO2 annually for decades whether Congress extends the PTC or not. Hence even under IPCC climate sensitivity assumptions, the PTC is climatologically irrelevant and can provide no meaningful protection from extreme weather events.

Extending the PTC for one year could increase the national debt by $12.1 billion. A six-year extension could add more than $50 billion to the debt. As global warming policy, the PTC is all taxpayer pain for no climate gain.

With Senators Barbara Boxer (D-Calif.) and Frank Lautenberg (D-N.J.) citing Hurricane Sandy as a reason to have another go at climate legislation, to say nothing of the media spin depicting Sandy as punishment for our fuelish ways, it’s useful to look at some actual science.

In a study published in the journal Climatic Change, scientists Michael Chenoweth and Dmitry Divine analyze the history of tropical cyclone activity in the Lesser Antilles from 1638 to 2009. The Lesser Antilles are the string of islands lying along the eastern Caribbean Sea.

The Lesser Antilles intersect the “main development region” for Atlantic hurricane formation, making storm data there “our best source for historical variability of tropical cyclones in the tropical Atlantic in the past three centuries,” the researchers explain.

Using instrumental data on wind speeds going back to 1900 plus wind-force and wind-induced damage reports for earlier periods, Chenoweth and Divine estimate the Lesser Antilles Accumulated Cyclone Energy (LACE) for each year along the 61.5°W meridian from 18 to 25° N latitude.

Storms forming in this area include most that do or could make landfall in the U.S. In the researchers’ words: “About 60% of all tropical cyclones moving from waters off of Africa pass through 61.5°W south of 25.0°N, the remaining 40% either moving north of 25.0°N, dying out or re-curving to the east of 61.5°W.” Chenoweth and Divine note that LACE is “highly correlated” with Carribbean basin-wide Accumulated Cyclone Energy (ACE) since 1899.

So what did they find? In their words: “Our record of tropical cyclone activity reveals no trends in LACE in the best-sampled regions for the past 320 years. Likewise, even in the incompletely sampled region north of the Lesser Antilles there is no trend in either numbers or LACE.”

Chenoweth and Divine do find a “~50–70 year variability in ACE across the 18–25°N transect.” This wave-like pattern ”is possibly associated with the low-frequency variations in the Atlantic Multi-Decadal Oscillation (AMO), a mode of SST [sea surface temperature] variability that is global in extent but strongest in the Atlantic.” The scientists consider their data “sufficiently complete to be a reliable record back to 1785 and extends the evidence of this pattern further back in time.”

An obvious implication of the study, although not spelled out by the authors, is that natural variability dominates tropical storm activity in the Atlantic to the point that any global warming influence, if it exists, is still undetectable.

For a more detailed review of the study, visit the Center for the Study of Carbon Dioxide and Global Change. Also informative is World Climate Report’s review of Chenoweth and Divine’s 2008 study on tropical cyclones in the Lesser Antilles.