Here's everything we learned from an analysis of the colours on every metro map in the world

Pop quiz, hotshot. Where have you seen those colours before?


Too easy? Well try this on for size.


Oh, a wise guy eh? Well what about this?


Alright, alright, I’ll stop. As you obviously know, because that’s the kind of cool dude you are, those are the colour palettes used be three of the world’s most famous metro maps – the London Underground, Paris Metro and New York Subway respectively.

They come from the mildly mind-blowing Global Subway Spectrum, which catalogues the colours of every metro map in the world. It’s all the work of Chicago-based designer Nicholas Rougeux. Here’s his rather nifty explanation of his process.

Taken from Nicholas Rougeux's Global Subway Spectrum. Click to expand. 

The position of the dots on each colour wheel represents the exact shade. Blues are bottom left, greens bottom right, reds at the top; the further from the centre, the darker the shade.

Here’s the full selection from metro maps worldwide:


The version on Rougeux’s site is actually interactive, so if you hover over a colour, this happens:


There’s loads of other stuff you can do with this tool. You can see, for example, that Africa hardly a has any metros:

That’s just three systems, in fact. But Asia has loads:


So does Europe:


You can also view all the colours in this attractive waterfall arrangement:


Or in this interactive 3D graphic, which we frankly have no good way of reproducing on CityMetric, but which is nonetheless very, very cool:

This looks better when it moves, to be honest. 

Lining all the colours up in one place like this highlights the fact that certain colours are more popular. The metro maps of the world are festooned with reds, blues and greens; but there are slightly fewer yellows and purples, even fewer pinks, browns and oranges, and a bare handful of greys.

Least common of all seems to be black, which features in just two networks (London and Bilbao), so if you got annoyed with the Northern Line this morning, take some comfort in the fact that it is in some way special.

Rougeux’s work highlights another point, too. In all, the site categorises 162 different metro networks, and by default it arranges them by the number of colours they use. I counted them, because I do that sort of thing. Here’s the distribution:

Of the 162 networks on the site, only 12 of them uses 10 or more colours, and no network uses more than Seoul, with 15.

Partly this result from the fact that so many metro networks are pretty simple things: 134 of them – the vast majority – get away with five colours or less.

But there’s something else going on here, too. The New York Subway has at least 24 lines (more, if you count the expresses separately); yet it only uses 10 colours.

It does this, I suspect, because a map which uses 24 different colours would not be comprehensible at first glance. You’d need to look carefully to make sure that the blue line you were on, and the one you wanted to get to, were the same blue line.

In other words, thanks to the limitations of both cartography, and the human eye, there is a limit on the number of colours a metro map can use before it gets confusing.

We discuss this on the latest edition of our podcast, incidentally – so you should probably subscribe.

You can find the Global Subway Spectrum here.

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The IPPC report on the melting ice caps makes for terrifying reading

A Greeland iceberg, 2007. Image: Getty.

Earlier this year, the Intergovernmental Panel on Climate Change (IPCC) – the UN body responsible for communicating the science of climate breakdown – released its long-awaited Special Report on the Ocean and Cryosphere in a Changing Climate.

Based on almost 7,000 peer-reviewed research articles, the report is a cutting-edge crash course in how human-caused climate breakdown is changing our ice and oceans and what it means for humanity and the living planet. In a nutshell, the news isn’t good.

Cryosphere in decline

Most of us rarely come into contact with the cryosphere, but it is a critical part of our climate system. The term refers to the frozen parts of our planet – the great ice sheets of Greenland and Antarctica, the icebergs that break off and drift in the oceans, the glaciers on our high mountain ranges, our winter snow, the ice on lakes and the polar oceans, and the frozen ground in much of the Arctic landscape called permafrost.

The cryosphere is shrinking. Snow cover is reducing, glaciers and ice sheets are melting and permafrost is thawing. We’ve known this for most of my 25-year career, but the report highlights that melting is accelerating, with potentially disastrous consequences for humanity and marine and high mountain ecosystems.

At the moment, we’re on track to lose more than half of all the permafrost by the end of the century. Thousands of roads and buildings sit on this frozen soil – and their foundations are slowly transitioning to mud. Permafrost also stores almost twice the amount of carbon as is present in the atmosphere. While increased plant growth may be able to offset some of the release of carbon from newly thawed soils, much will be released to the atmosphere, significantly accelerating the pace of global heating.

Sea ice is declining rapidly, and an ice-free Arctic ocean will become a regular summer occurrence as things stand. Indigenous peoples who live in the Arctic are already having to change how they hunt and travel, and some coastal communities are already planning for relocation. Populations of seals, walruses, polar bears, whales and other mammals and sea birds who depend on the ice may crash if sea ice is regularly absent. And as water in its bright-white solid form is much more effective at reflecting heat from the sun, its rapid loss is also accelerating global heating.

Glaciers are also melting. If emissions continue on their current trajectory, smaller glaciers will shrink by more than 80 per cent by the end of the century. This retreat will place increasing strain on the hundreds of millions of people globally who rely on glaciers for water, agriculture, and power. Dangerous landslides, avalanches, rockfalls and floods will become increasingly normal in mountain areas.

Rising oceans, rising problems

All this melting ice means that sea levels are rising. While seas rose globally by around 15cm during the 20th century, they’re now rising more than twice as fast –- and this rate is accelerating.

Thanks to research from myself and others, we now better understand how Antarctica and Greenland’s ice sheets interact with the oceans. As a result, the latest report has upgraded its long-term estimates for how much sea level is expected to rise. Uncertainties still remain, but we’re headed for a rise of between 60 and 110cm by 2100.

Of course, sea level isn’t static. Intense rainfall and cyclones – themselves exacerbated by climate breakdown – can cause water to surge metres above the normal level. The IPCC’s report is very clear: these extreme storm surges we used to expect once per century will now be expected every year by mid-century. In addition to rapidly curbing emissions, we must invest millions to protect at-risk coastal and low-lying areas from flooding and loss of life.

Ocean ecosystems

Up to now, the ocean has taken up more than 90 per cent of the excess heat in the global climate system. Warming to date has already reduced the mixing between water layers and, as a consequence, has reduced the supply of oxygen and nutrients for marine life. By 2100 the ocean will take up five to seven times more heat than it has done in the past 50 years if we don’t change our emissions trajectory. Marine heatwaves are also projected to be more intense, last longer and occur 50 times more often. To top it off, the ocean is becoming more acidic as it continues to absorb a proportion of the carbon dioxide we emit.

Collectively, these pressures place marine life across the globe under unprecedented threat. Some species may move to new waters, but others less able to adapt will decline or even die out. This could cause major problems for communities that depend on local seafood. As it stands, coral reefs – beautiful ecosystems that support thousands of species – will be nearly totally wiped out by the end of the century.

Between the lines

While the document makes some striking statements, it is actually relatively conservative with its conclusions – perhaps because it had to be approved by the 195 nations that ratify the IPCC’s reports. Right now, I would expect that sea level rise and ice melt will occur faster than the report predicts. Ten years ago, I might have said the opposite. But the latest science is painting an increasingly grave picture for the future of our oceans and cryosphere – particularly if we carry on with “business as usual”.

The difference between 1.5°C and 2°C of heating is especially important for the icy poles, which warm much faster than the global average. At 1.5°C of warming, the probability of an ice-free September in the Arctic ocean is one in 100. But at 2°C, we’d expect to see this happening about one-third of the time. Rising sea levels, ocean warming and acidification, melting glaciers, and permafrost also will also happen faster – and with it, the risks to humanity and the living planet increase. It’s up to us and the leaders we choose to stem the rising tide of climate and ecological breakdown.

Mark Brandon, Professor of Polar Oceanography, The Open University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.