It’s an everyday metaphor to say that something “redraws the map,” but what happens when we mean that literally? Alternatively, when does reality change so much that we have to change our map to understand where we’re going to be living from now on?

The reality change that I have in mind is the soon to be ice-free Arctic. I don’t mean that there will be no ice at all: the term is used technically to mean less than a million square kilometers of ice, which may sound like a lot but is only one-sixth of the average summer minimum from 1981 to 2010. Waterways would be generally open; remaining ice would be mostly found along coastlines, just as pockets of snow remain year-round along high-altitude trails.

Increasingly open waterways were the trigger for this note, with reports this week that “the Chinese shipping company Sea Legend Line is poised to launch its container route along Russia’s Northern Sea Route, marking what is being billed as the first regular container service using the Arctic.” The incentives are substantial: “The voyage will cut the usual 40-day sailing time between between Ningbo on China’s east coast and Felixstowe in the UK by about half, depending on the conditions in the Arctic Circle,” noted the Financial Times.

The plausible consequences, though, are also substantial: “Heavy fuel oil used in shipping produces high levels of black carbon, a pollutant that accelerates Arctic ice melt by reducing snow and ice reflectivity,” notes the World Wildlife Fund. Further details from the Clean Arctic Alliance include,

Although shipping only contributes 2% of the black carbon in the Arctic, it has a much greater heating impact, as other sources of black carbon are higher in the atmosphere with less chance of falling on ice and snow. While most anthropogenic sources of black carbon pollution are being reduced in the Arctic, shipping emissions of black carbon have risen 8% globally in the past decade, and in the Arctic by 85% between 2015 and 2019 alone. With climate warming driving the ongoing loss of multi-season Arctic sea ice, the region is opening up to more shipping traffic; between 2013 and 2019 data published by the Arctic Council showed a 25% increase in shipping traffic and a 75% increase in the total distance sailed in the Arctic. We can expect that further increases in black carbon emissions from shipping will only further contribute to an already accelerating feedback loop.

Hence my opening notion that we are redrawing our maps – and I don’t just mean changing the names of countries from time to time, or even making cartographic adjustments to newly submerged coastlines as ocean levels rise. (Yes, that kind of redrawing of maps is already a literal thing: the NOAA notes that “In several low-lying coastal cities in the Southeast, the annual number of high-tide coastal flooding events has increased 500 to 1,000 percent since the 1960s. High-tide flooding is now accelerating at 75 percent of locations along the East and Gulf Coasts… Nationally, high-tide flooding is occurring twice as frequently now as 20 years ago.” Please pardon the digression.)

I’m talking here about a considerably bigger picture: our global understanding of what’s where, and of how we get from one place to another – because that’s also changing.

In many ways, a change of map is more than 400 years overdue. Admittedly, mapping the planet back then was not a straightforward task, without satellite photos to give us a clear view of how the continents are arranged. Even now, though, when people try to depict a (roughly) spherical planet on a two-dimensional surface, something’s going to be compromised. Possible priorities of different “projections” include keeping shapes the same, keeping relative areas the same, keeping relative distances from place to place the same, and keeping the layout of the land masses recognizable without regard to other attributes.

The map that’s probably most familiar from your childhood classroom wall is the Mercator, which is very likely the only one whose name you would even recognize – but which almost everyone knows is hugely wrong in relative areas of land masses near the poles of the planet. On this utterly familiar map, Greenland looks to be roughly the same size as Africa, when their actual area ratio is only about 1:14. So familiar, though, is the Mercator with all its distortions, that when someone is shown an alternative—for example, the area-preserving Gall-Peters projection—they may find it actually disorienting. On an episode of “The West Wing,” the dialog went “What the hell is that?” “It’s where you’ve been living this whole time. Should we continue?”

Apart from mere familiarity, the principle of Chesterton’s Fence suggests that we should know why the Mercator was ever used at all (let alone, apparently, preferred) before we decide it’s time for it to go. What was actually valuable about the Mercator projection, when it was invented in 1569? If you steer a constant compass heading, your course on a Mercator map is a straight line. Conversely, if one draws a straight line on such a map, a navigator need only keep the compass heading constant to follow that course. This is handy when the compass is the only tool at hand.

Where things go wrong, badly, is when one gets outside the equatorial regions – because as we near the poles, steering a constant magnetic heading sends us in a spiral. This “loxodromic” mode of navigation is only useful only for solving some variation of the familiar riddle, “If I go south 100 miles, east 100 miles, and north 100 miles, and I end up where I started, where was I?” The answer being, of course, “The north pole.” In days of old, though, we only needed to navigate in the mid-planet region where rhumb lines and shortest-distance, “great circle” routes are not hugely different. (In the special cases of sailing along the equator, or directly to the north or south, they are exactly the same.)

This has led me to observe on several occasions that the Mercator is the perfect tool for using primitive tools to travel in the places where we used to do valuable things – but that a world in which we have more accurate tools, and where people want to go to more different places, invites or even requires a different map. We may ask if an updated map should say, “but please don’t go here merely to save some time and money”; so we may need to implore, as an ice-free Arctic region becomes a reality.