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.

Numerous politicians, pundits, and activists, and even some scientists blame fossil-fuel emissions for the death and devastation wrought by Hurricane Sandy. Such allegations are ideological, not scientific.

As noted previously on this blog, when hurricane 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 hurricane frequency or power related to global climate change.

Moreover, 370 years of tropical cyclone data from the Lesser Antilles (the eastern Caribbean island chain that bisects the main development region for landfalling U.S. hurricanes) show no long-term trend in either power or frequency but a 50- to 70-year wave pattern associated with the Atlantic Multidecadal Oscillation, a mode of natural climate variability. 

A new study by Jessica Weinkle (University of Colorado), Ryan Maue (Naval Research Laboratory), and Roger Pielke, Jr. (University of Colorado) dumps more cold water on claims that global warming significantly (detectably) influences hurricane behavior.

The researchers examined data on the number and power of hurricanes making landfall in the five main hurricane basins: North Atlantic, northeastern Pacific, western North Pacific, northern Indian Ocean, and Southern Hemisphere. The data extend back to 1944 for the North Atlantic, to 1950 for the northeastern Pacific, and to 1970 for the other basins. The data for all basins is current through 2010.

Here’s what Weinkle, Maue, and Pielke, Jr. found:  

We have identified considerable interannual variability in the frequency of global hurricane landfalls; but within the resolution of the available data, our evidence does not support the presence of significant long-period global or individual basin linear trends for minor, major, or total hurricanes within the period(s) covered by the available quality data. Therefore, our long-period analysis does not support claims that increasing TC [tropical cyclone] landfall frequency or landfall intensity has contributed to concomitantly increasing economic losses.

Figure explanation: Red bars indicate the number of major (category 3-5) hurricanes, blue bars indicate the number of minor (category 1-2) hurricanes.

Pielke Jr.’s blog provides an update for North Atlantic hurricanes through November 2012. Extending the study period to include Hurricane Sandy (which, incidentally, was downgraded to a tropical storm by the time it made landfall) doth not a long-term trend make!

Pielke, Jr. points out some interesting details from the updated study, such as:

• 1971 had the most global landfalls with 30, far exceeding the second place, 25 in 1996.
• 2011 tied for second place for the fewest global landfalls with 10 (and 3 were intense, tying 1973, 1981 and 2002). 
• The US is currently in the midst of the longest streak ever recorded without an intense hurricane landfall. 
• There have been frequent four-year periods with more than 25 landfalling major hurricanes, or more than a 100% increase of what has been observed over the past 4 years. 

Pielke, Jr. concludes: “Anyone who’d like to argue that the world is experiencing a ‘new normal’ with respect to tropical cyclones is simply mistaken.”

But, someone might say, 1970 roughly marks the advent of the “anthropocene,” the era in which fossil-fuel emissions start to mess up the climate; earlier eras had calmer weather. The Weinkle et al. study also contradicts that hypothesis. Pielke Jr. writes: 

There is even evidence in our paper (see our Figure 2) that the period before 1970 saw more intense hurricane landfalls than the period since. Older data from the North Atlantic and Western North Pacific (which together represents 64% of all global intense landfalling hurricanes 1970-2010 and 69% of all hurricanes) indicates that landfalling intense hurricanes in these two basins occurred at a 40% higher rate from 1950-1969 than 1970-2010. There were 9 intense landfalls in 1964 and 1965 in just these two basins, which equals the global record for all basins post-1970.