In the U.S., about half of the pollutants11 that contribute to anthropogenic climate change are directly attributable either to the energy and electricity we use in our homes and workplaces or to vehicles on transportation networks. The U.S. isn’t an outlier—this pattern of energy usage and emissions is pretty typical of industrially developed

While infrastructural systems do involve social agreements around technologies, they share another important element. It’s not just that everyone does things the same way. It’s that there’s a reason to do things the same way, together.

In the familiar water cycle, it falls to the ground in the form of rain or snow, and may be used by humans for drinking or irrigation or industrial purposes, before eventually evaporating, condensing into clouds, and falling to the earth again. But not all the water we use is part of this system, at least not on human timescales. Researchers from

Without currents which transport warm water to higher latitudes, western Europe might become as cold as western Canada.

Every electrical circuit, whether visible from space or only under a microscope, is a network.

Most of the technological systems that we consider to be infrastructure are networks, connections between different places in the world. This is most obvious for transportation, ways to get from point A to point B: roads, rail networks, air travel, shipping, or transmodal combinations. Faucets and drains are points on our water and sewage systems

The water doesn’t just flow downhill: the California Aqueduct, for example, goes up and over the Tehachapi Mountains, thanks to the Edmonston pumping station. Fourteen six-story-high pumps can push two million gallons of water per minute up two thousand feet at the highest single-lift plant in the world, helping to make the California State Water

Once we think of technology in this way, as combined and recursively assembled out of existing technologies, we can see why we can usually tell if a given piece of technology is older or newer. Technological development has a direction, because complexity tends to increase, not decrease.

Steel and concrete—the basic building blocks of civil engineering3—are two of the biggest contributors to greenhouse gas emissions. In part that’s simply because they’re used in such huge quantities—annual global production is about two billion metric tons of steel and about fifteen billion cubic meters of concrete, or about five hundred pounds of