Wind farms and abuse of statistics: bird edition

When "wind farms are dangerous" really just means "there are a lot of birds".

When dealing with large numbers, it helps to have an idea of the expected order of magnitude. That way, you can know whether it is merely the number which is large, or the thing it's describing as well.

For instance, if I tell you of a country with 140,000 people in long-term unemployment, it's rather important for you to know if I'm talking about the US (population 280 million) or Luxembourg (population 525,000).

That's a test a Spectator article, Wind farms vs wildlife, failed quite badly this week.

The author, Clive Hambler, is a lecturer in biological and human sciences at Oxford university, and quotes a number of statistics to demonstrate how dangerous wind farms are to wildlife. For instance:

Every year in Spain alone — according to research by the conservation group SEO/Birdlife — between 6 and 18 million birds and bats are killed by wind farms. They kill roughly twice as many bats as birds. This breaks down as approximately 110–330 birds per turbine per year and 200–670 bats per year. And these figures may be conservative if you compare them to statistics published in December 2002 by the California Energy Commission: ‘In a summary of avian impacts at wind turbines by Benner et al (1993) bird deaths per turbine per year were as high as 309 in Germany and 895 in Sweden.’

Similar claims are made throughout. Apparently the annual death toll of bats in the US and Canada is "up to three million", "Norwegian wind farms kill over ten white-tailed eagles per year", and so on.

What is missing is any context through which we can examine these numbers. It might change our interpretation of the figures to know that:

Domestic and feral cats have also been considered a major source of anthropogenic-caused mortality with estimates near 100 million annual bird deaths [in the US].

Or that, on roads near wetlands in Canada:

223 birds were killed per mile per year.                                                                                            

Power lines in the US are estimated to kill:

…approximately 130 million birds per year.                                                                                                        

While we're banning things, we may want to keep an eye out for that scourge of the avian world, windows:

97.6 to 976 million bird deaths per year in the U.S. due to collisions with windows… based on an estimated 1 to 10 bird deaths per structure per year from a fatality study in New York.

All those figures come from a 2005 paper by the US Department of Agriculture.

In other words, even with the massive figures from Spain – figures which show deaths per turbine per year two orders of magnitude higher than equivalent figures cited in the above paper, which are based on an assumption that for every confirmed death, there's nineteen uncomfirmed, and which come from a set of guidelines which explicitly concludes wind farms are OK for birds if built correctly (pdf) –  wind farms kill fewer birds than cats, power lines, roads or windows. That comparison would have been rather useful to include in the original piece. With that in mind, the numbers in the piece become less a demonstration of the awesome mortality of wind farms, and more a confirmation that yes, there are a lot of birds in the world.

Update

It's been pointed out on Twitter that I'm not comparing like to like. Spain is smaller than the US, of course. Thankfully, the USDA also estimates the number of birds killed by wind farms in America: between 20,000 and 37,000 a year. I let you draw your own conclusions from the discrepancy.

Wind Turbines in Spain. Photograph: Wikimedia Commons

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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The deafening killer - why noise will be the next great pollution scandal

A growing body of evidence shows that noise can have serious health impacts too. 

Our cities are being poisoned by a toxin that surrounds us day and night. It eats away at our brains, hurts our hearts, clutches at our sleep, and gnaws at the quality of our daily lives.

Hardly a silent killer, it gets short shrift compared to the well-publicised terrors of air pollution and sugars food. It is the dull, thumping, stultifying drum-beat of perpetual noise.

The score that accompanies city life is brutal and constant. It disrupts the everyday: The coffee break ruined by the screech of a line of double decker buses braking at the lights. The lawyer’s conference call broken by drilling as she makes her way to the office. The writer’s struggle to find a quiet corner to pen his latest article.

For city-dwellers, it’s all-consuming and impossible to avoid. Construction, traffic, the whirring of machinery, the neighbour’s stereo. Even at home, the beeps and buzzes made by washing machines, fridges, and phones all serve to distract and unsettle.

But the never-ending noisiness of city life is far more than a problem of aesthetics. A growing body of evidence shows that noise can have serious health impacts too. Recent studies have linked noise pollution to hearing loss, sleep deprivation, hypertension, heart disease, brain development, and even increased risk of dementia.

One research team compared families living on different stories of the same building in Manhattan to isolate the impact of noise on health and education. They found children in lower, noisier floors were worse at reading than their higher-up peers, an effect that was most pronounced for children who had lived in the building for longest.

Those studies have been replicated for the impact of aircraft noise with similar results. Not only does noise cause higher blood pressure and worsens quality of sleep, it also stymies pupils trying to concentrate in class.

As with many forms of pollution, the poorest are typically the hardest hit. The worst-off in any city often live by busy roads in poorly-insulated houses or flats, cheek by jowl with packed-in neighbours.

The US Department of Transport recently mapped road and aircraft noise across the United States. Predictably, the loudest areas overlapped with some of the country’s most deprived. Those included the south side of Atlanta and the lowest-income areas of LA and Seattle.

Yet as noise pollution grows in line with road and air traffic and rising urban density, public policy has turned a blind eye.

Council noise response services, formally a 24-hour defence against neighbourly disputes, have fallen victim to local government cuts. Decisions on airport expansion and road development pay scant regard to their audible impact. Political platforms remain silent on the loudest poison.

This is odd at a time when we have never had more tools at our disposal to deal with the issue. Electric Vehicles are practically noise-less, yet noise rarely features in the arguments for their adoption. Just replacing today’s bus fleet would transform city centres; doing the same for taxis and trucks would amount to a revolution.

Vehicles are just the start. Millions were spent on a programme of “Warm Homes”; what about “Quiet Homes”? How did we value the noise impact in the decision to build a third runway at Heathrow, and how do we compensate people now that it’s going ahead?

Construction is a major driver of decibels. Should builders compensate “noise victims” for over-drilling? Or could regulation push equipment manufacturers to find new ways to dampen the sound of their kit?

Of course, none of this addresses the noise pollution we impose on ourselves. The bars and clubs we choose to visit or the music we stick in our ears. Whether pumping dance tracks in spin classes or indie rock in trendy coffee shops, people’s desire to compensate for bad noise out there by playing louder noise in here is hard to control for.

The Clean Air Act of 1956 heralded a new era of city life, one where smog and grime gave way to clear skies and clearer lungs. That fight still goes on today.

But some day, we will turn our attention to our clogged-up airwaves. The decibels will fall. #Twitter will give way to twitter. And every now and again, as we step from our homes into city life, we may just hear the sweetest sound of all. Silence.

Adam Swersky is a councillor in Harrow and is cabinet member for finance. He writes in a personal capacity.