Aug 09 2019

Some Climate Change Cherry Picking

There is an industry of misinformation fueling climate change denial. It is often fairly sophisticated, and because it is dealing with a highly complex technical area, it’s easy to create an argument that sounds compelling. This results (as if often evidenced right here in the comments) in people who are confident that they are good skeptics and climate fearmongering is all nonsense. Of course they have to simultaneously believe in a rather absurd conspiracy theory regarding the scientific community, but they make that work somehow too.

Here are a couple of recent examples, both of which involve some subtle cherry picking. The first has to do with electric cars, which are frequently opposed by the denialists, in that they oppose subsidies to help bootstrap the market. This involves the “solution aversion” aspect of climate change denial – deniers are really motivated by the proposed solutions to climate change, which goes against either their politics or other interests. The claim that is often made is that producing electric cars has a higher carbon footprint than gasoline cars, and that if you are charging your car off the grid you are probably getting that electricity from fossil fuels. Therefore – electric cars are worse for the environment.

At the very least, I see climate change deniers delight in how stupid this makes the climate change believers appear.  This is a great example of cherry picking, because the two basic facts are correct but they are not the whole picture. Here, for example, is an article posted by Breitbart claiming that batteries are not green, concluding:

One of the authors, Mats-Ola Larsson at IVL, has made a calculation of how long you have to drive a petrol or diesel before it has released as much carbon dioxide as battery manufacturing has caused.

“The result was 2.7 years for a battery of the same size as the Nissan Leaf and 8.2 years for a battery of the Tesla-size.”

Truly the enduring mystery of why Tesla is now more highly valued than such non-Potemkin U.S. car manufacturers as Ford and General Motors grows more mysterious by the hour.

As I have pointed out before, you need to do an entire lifecycle analysis of any technology to see what the real impact is, on cost efficiency, energy efficiency, and carbon efficiency. Further, you have to carefully spell out the variables that affect any comparison. Here is a breakdown by Brian Dunning of how the Breitbart cherry picking occurred:

Here’s the only way that argument can be made to work. If you buy an electric car with the biggest battery that requires the most manufacturing resources, if you drive your electric car in the least efficient way, if you drive your electric car in the worst climatic conditions for battery life, if you charge it only with electricity generated entirely by oil or coal, if you do not properly recycle the battery at the end of its life, and if you choose for your comparison the biggest-battery electric car against the smallest, lightest, compact internal combustion car: only then will it be true that the lifespan of your electric car generates more greenhouse gases than an internal combu— Oh wait, no; crunching the numbers again, the answer is still no.

Of course it all depends on how long you drive the car. Even if we use the numbers provided by Breitbart, and say that the driving time before there is a carbon advantage to electric cars ranges from 2.7 years to 8.2 years, that is still a huge advantage. The average age of a car on the road right now is 11.8 years. The average life expectancy of a car, gasoline or electric, is about 8 years. However, for electric cars the life expectancy of the motor and body are longer, the main limitation is the battery. But if you replace the battery, the car itself can last for much longer. So at the very worst, even using the Breitbart numbers, perhaps you break even with an electric car vs a gasoline engine. But for the vast majority of electric cars, there will be a carbon advantage over a comparable gasoline engine.

And, this advantage will only increase over time. The greater the penetration of renewable energy the greater the advantage of electric cars. Further, gasoline engine technology is fairly mature. Meanwhile, we are still on the steep part of the curve when it comes to both electric vehicles and battery technology. Batteries are steadily improving, so even without any breakthroughs, every year the advantage is shifting more and more to electric vehicles.

Another article that engages in some very common denial cherry picking is by Accuweather founder and CEO Joel Myers. He is claiming that reports of a recent heat wave are overblown, and gives some statistics about the records for peak temperatures in various cities and states, and number of days of extreme temperatures.

This should always be a red flag for cherry picking when it comes to climate change – looking at anything other than average temperatures around the entire Earth over sufficiently long periods of time. This can cut both ways, of course, which is why we have to be careful when talking about any individual event or record. We always have to say, for example, that we cannot blame this one storm on climate change, but can look at the statistics about how likely such storms are.

Another example is that July was the hottest month on record ever for the planet. By itself, if this were the only piece of datum, you could not make much of it. But it is significant when put into the context of continuous forcing of average global temperatures upward over the last half century.

Myers, however, looks at record breaking temperatures and points out that:

New York City has not had a daily high temperature above 100 degrees since 2012, and it has had only five such days since 2002. However, in a previous 18-year span from 1984 through 2001, New York City had nine days at 100 degrees or higher. When the power went out in New York City earlier this month, the temperature didn’t even get to 100 degrees – it was 95, which is not extreme. For comparison, there were 12 days at 95 degrees or higher in 1999 alone.

The year 1999 immediately stuck out to me, because that was a particularly hot El Nino year. In fact, if you recall, climate change deniers used the 1999 peak as a way of denying that warming was happening at all, because it took until around 2015 for temperatures to clime above that peak. So if you start at that 1999 peak, you can claim that there has been no warming for the last 16 years, and they did. But that too was cherry picking. Now I don’t hear that argument much any more, since the four hottest years on record are the last four, and 2019 will certainly be in the hottest five years, and may turn out to be the hottest ever.

The bottom line is that Myers is simply relying on short term fluctuations to conceal the overall upward trend. But, he then commits another type of cherry picking:

Here is a fact rarely, if ever, mentioned: 26 of the 50 states set their all-time high temperature records during the 1930s that still stand (some have since been tied).

This time he is not cherry picking over time, but location. There was a warm period in the 1930’s – in the United States. World wide the 1930s were cooler than average. But if you look at record breaking temperatures in the US, there is a peak in the 1930s. Also, the deep south and parts of the mid west have not experienced that much warming, so those states will still have their records set in the 1930s. But the US represents only about 2% of the Earth’s surface area. Global warming is about average global temperatures, and does not mean that every place on Earth is experiencing warming (although eventually this will likely happen if trends continue).

Be on the look out for apparent cherry picking. If it seems like you are only getting a slice of the entire picture, you probably are.

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