One of the most compelling arguments in favor of building dense cities is environmental: cities use less energy per person than suburbs and emit less carbon per person. The reason is exactly the one you’d guess. People in big cities don’t own as many cars as suburbanites:

Ed Glaeser provides the nerd version of this in scatterplot form:

Glaeser’s chart is nearly unreadable, but all that matters is the red trendline: As cities get bigger, they consume less gasoline per person. Using buses or subways (or your feet) is far better for the environment than driving a car everywhere. It’s also cheaper to heat or air condition a single apartment building than it is to do the same for a thousand single-family houses. You can see this in the map below, where big cities are islands of green surrounded by sprawling suburbs in red:

However, there are a couple of things to watch out for. The first is industry: one reason that cities seem so green is because they’ve mostly zoned away dirty industries. However, just because steel mills and fracking operations are forced to operate elsewhere doesn’t mean cities aren’t benefiting from them. In fact, they benefit more than smaller places because big cities tend to be rich, which means they consume more than poorer or more rural areas. This chart outlines the size of consumption-based carbon emissions in big cities:

With the exception of a few big cities in Asia and Africa (light blue), carbon emissions due to consumption are higher than carbon emissions due to industry—in some cases, vastly higher. If you don’t count this, you’re underestimating how much carbon cities are really responsible for. The authors of this report estimate that urban carbon emissions are actually about 60 percent higher than normally estimated if you account for this.

Finally, here’s Ed Glaeser again, with a scatterplot showing the same thing. Cities with stringent land-use regulations basically outsource a lot of their carbon emissions, leading to lower per-capita carbon emissions in the cities themselves:

Even if you discount California, as Glaeser does, there’s a clear relationship: “Places with the least emissions tend also to regulate most heavily. This relationship is strongly statistically significant.”

What this goes to show is how complicated this whole issue is. Generally speaking, researchers agree nearly unanimously that big cities are environmentally friendly. The benefits from their lower number of cars combined with the economies of scale from packing lots of people into a single building are overwhelming. However, to get a true estimate of just how green cities really are, you also need to account for their consumption of goods and services that are produced in outlying areas thanks to land-use regulations.

And that’s tricky all by itself. Big cities tend to be pretty prosperous, which means their consumption of goods and services is high. But why? Do big cities tend to make people wealthier, which causes higher consumption? Or do richer people, who already have high consumption habits, tend to move to big cities? That’s hard to untangle. But to the extent that big cities support high incomes and therefore high consumption rates, they’re not quite as green as you might think.

I was at the market today and they had big sacks of M&Ms on sale. Two for seven bucks. Then I wandered to a different part of the store, and there were a whole bunch of crates full of half-price stuff—including the very same M&Ms I had seen in the candy aisle. But these were on sale for half off the regular price of $5.

So which was it? $3.50 or $2.50? The only way to find out was to buy one, so in the name of science that’s what I did. Here’s the answer:

They were on sale for $3.50, but everything in the crates was half off, so the final price was $1.75. Maybe I should buy more. M&Ms never go bad, do they?

To memorialize this great day, I also have an answer to one of the great philosophical questions of all time: Is it really turtles all the way down? As you can see, the answer is no. It’s just the one.

Say hello to Agadez:

Agadez is 4,000 miles from Aghanistan, where the Global War on Terrorism began. It’s 2,500 miles from Iraq, our next destination in the war. It’s 2,000 miles from Syria and 1,500 miles from Benghazi. This is where we’re building a $110 million drone base that will host nearly a thousand American troops, double the number of a few years ago. Here is Eric Schmitt:

Taken together, these parallel missions reflect a largely undeclared American military buildup outside the battlefields of Iraq and Afghanistan, often with murky authorities and little public attention, unfolding in remote places like Yemen, Somalia and, increasingly, West Africa.

In Niger alone, the Pentagon in the past few years has doubled the number of United States troops, to about 800 — not to conduct unilateral combat missions, but to battle an increasingly dangerous Al Qaeda, the Islamic State and even loosely associated extremist groups with proxy forces and drone strikes….Maj. Gen. J. Marcus Hicks, the head of American Special Operations forces in Africa, put it this way: “This is an insurance policy that’s very inexpensive, and I think we need to keep paying into it.”

….“Eliminating jihadi military leaders through drone operations could temporarily disorganize insurgent groups,” said Jean-Hervé Jezequel, deputy director of the International Crisis Group’s West Africa project in Dakar, Senegal. “But eventually the void could also lead to the rise of new and younger leaders who are likely to engage into more violent and spectacular operations to assert their leadership.”

The defeat of the Soviets in Afghanistan catalyzed the creation of al-Qaeda. The defeat of al-Qaeda catalyzed the growth of ISIS. The imminent defeat of ISIS appears to have already catalyzed the emergence of Hayat Tahrir al-Sham. Each group is smaller than its predecessor, but also more radical and more violent. It’s not clear if this represents progress or not.

How much has the cost of housing gone up over the last few decades? There are several different ways of measuring this, but here are five:

• The CPI for shelter since 1990, deflated by the overall CPI. This measure accounts for both housing prices and rentals.
• The Case-Shiller index since 1990. This is a national index of home prices only, not apartment rentals.
• HUD’s affordability index for both homeownership and renting.
• The 10-City Case-Shiller index since 1990. This provides an idea of how much housing costs have gone up in our largest cities.
• An interpolated estimate from StreetEasy and Miller Samuel of average rents in Manhattan since 1992.

Note that I’ve removed the period from about 2000 through 2013 in some of the charts. There’s a lot of spikiness during that period thanks to the housing bubble, but in the end housing prices were only a little bit higher. Getting rid of this noise makes the long-term trends a little easier to see.

Donald Trump is unhappy with today’s New York Times piece about how he treats Michael Cohen “like garbage,” which might cause Cohen to flip:

The New York Times and a third rate reporter named Maggie Haberman, known as a Crooked H flunkie who I don’t speak to and have nothing to do with, are going out of their way to destroy Michael Cohen and his relationship with me in the hope that he will “flip.” They use….

— Donald J. Trump (@realDonaldTrump) April 21, 2018

Ha ha ha ha. Trump spoke with Haberman at least four times last year, on March 26, April 5, July 19, and November 1. Maybe more! How about it, Maggie? How many times have you spoken with Donald Trump since he began his campaign?

This is an artist's conception. It will be a very long time before California has anything more than that.California High-Speed Rail Authority

The LA Times reports today about a minor little cost overrun on the California bullet train. Over the course of five years, the cost of utility relocations along a short section of track near Fresno increased nearly 6x, from $69 million to $396 million:

The California High-Speed Rail Authority board on Friday took up the problem, hearing from its staff that the original estimate contained a number of miscalculations. The number of linear feet of utilities that have to be moved was underestimated, as was the cost per foot for the job, according to a staff memo. Then, there were utilities that nobody even knew were in the ground. The authority changed its mind about some of the work, as well, the report said.

….The history of the utility relocations suggests some turmoil in management decisions — which the rail authority staff said it would not repeat in the future….The staff said that “best management practices,” along with a new database, will enable it to better estimate costs in the future. “Additionally, the assumption that utilities will perform relocations will not be repeated,” the staff memo said.

No worries! This won’t be repeated in the future! I feel relieved.

The California bullet train is obviously one of my bugaboos, and I figure that all bloggers are entitled to one or two. But seriously, reading this stuff makes me wonder if anyone involved in this boondoggle has any experience whatsoever with large construction projects, let alone high-speed rail projects.

POSTSCRIPT: In fairness, I want to note that that this is not, strictly speaking, a new cost overrun. It’s all part of the “worst-case scenario” unveiled in January.

High-speed photos never get old, do they? Actually, yes they do, but I have an excuse for posting yet more of them. It rained a bit on Thursday, and later in the morning the sun was bright enough that I could crank the camera’s shutter speed all the way up to 1/32,000th of a second. Does that make a difference compared to 1/16,000th of a second? As near as I can tell, it doesn’t improve the hummingbird but it does improve the honeybee:

Since I’ve been shooting the night sky lately, I’ve also been experimenting with noise reduction. Here’s the problem: on a digital camera, if you keep the shutter open for an hour or two you’ll get lots of random dots caused by individual sensors firing for no good reason. So the camera has a noise-reduction feature that removes the dots. If you take, say, a one-hour exposure, it closes the shutter at the end of the shot and then keeps going for another hour. It’s basically taking a pure black photo during that time. It then compares the noise in the image to the noise from the black photo and removes the corresponding dots. Something like that, anyway. But it sure does work. Here’s a pair of two-hour exposures:

And finally, here are the moon and Venus last Tuesday, because why not?

Via Deutsche Bank, here are two interesting charts. The top one shows the average annual salary of residents in the world’s most expensive cities. The bottom one shows the average rent for a “mid-range” two-bedroom apartment as a percent of monthly salary.

Who’s photobombing whom? It all depends on your perspective, doesn’t it?

President Trump is desperate to help out coal miners, but the problem is that nobody wants coal these days. Old coal-fired generating plants are being shut down, and earlier this year the Federal Energy Regulatory Commission turned down a request to subsidize them. So now the Trumpies are looking further afield:

Under the approach, the administration would invoke sweeping authority in the 68-year-old Defense Production Act, which allows the president to effectively nationalize private industry to ensure the U.S. has resources that could be needed amid a war or after a disaster….The statute classifies energy as a “strategic and critical material” and gives the president wide latitude to protect providers, including by ordering businesses to accept contracts for materials and services. It was previously invoked in 2001 to keep natural gas flowing to California utilities to avoid electrical blackouts.

I can hardly wait for this. Maybe Trump will nationalize the country’s coal plants. Maybe he’ll nationalize the mines. Maybe he’ll force companies to buy electricity at inflated prices from coal-fired plants. Who knows? Maybe he’ll just order the federal government to buy lots of coal and then dump it in the ocean. It looks like exciting days are ahead for free-market capitalism.