The area of this map coloured red has the same population as the area coloured blue

One of these things is, well, quite like the other, actually. Image: Ibisdigitalmedia.

Well, this is kind of crazy. Only 5 per cent of the world's population lives in the regions of this map shaded blue. Another 5 per cent lives in the area shaded red. Yoinks.

The image appeared on the MapPorn section of Reddit earlier this week, the only post made by an account called “IbisDigitalMedia”, and swiftly started racking up the up votes. It's not entirely clear who or what Ibis is – it might be a Dallas video production firm specialising in wedding videos, as unlikely as that seems – but since they’re clearly a corporate seeking viral marketing, we figured they wouldn't mind a reputable urbanism website reposting their map with a bit of commentary attached.

So, this is what we’re looking at here. The red area includes Bangladesh (pop: 156m), and the Indian states of Bihar (pop: 104m) and West Bengal (pop: 91m). It also includes two megacities: Kolkata in West Bengal (15m), and the Bangladeshi capital of Dhaka (13m).

In all, that’s a combined population of about 351m people in roughly 330,000 km2, giving a population density of 1062 people per km2. By way of comparison, the most densely populated country in Europe is the Netherlands. The density there is less than 500 people per km2.


The blue area includes – this list is not exhaustive, but still, take a deep breath before we get into it – Canada, Greenland, Iceland, Norway, Sweden, Finland, Estonia, Latvia, Lithuania, huge swathes of northern and Asian Russia, Mongolia, most of the Amazon basin, Patagonia, large swathes of Africa and the Arabic peninsula, the US states of New Mexico, Nevada, Utah, Kansas, Nebraska, Idaho, Wyoming, Montana, and both Dakotas, and pretty much the entire Australasian continent.

We haven’t done the maths on this – I mean, how? – but we’re taking it on trust that this is roughly 350m people, too. There are just over 7bn people in the world.

These less populated areas are largely, but not exclusively, the bits that aren’t all that fit for human habitation: deserts, steppes, tundra, rainforest. We're pretty sure it doesn't include a single megacity: the closest candidates appear to be Luanda, the capital of Angola (6.5m) and Toronto (6.0m).

The map is a bit of a cheat. We're assuming that whoever made the map calculated how many people 5 per cent of the global population is, and then started working their way down a list of big areas with low population density until they hit their magic number. It’s a slightly artificial way of doing things, and leads to odd things like the exclusion of the Nile valley and the thin sliver of South America on its populated Pacific Coast. 

It reminds us of this map, from another Redditor, valeriepieris, which is in its way more striking because it doesn't cherry pick what it shows in this way:

Anyway. The world’s population is really unevenly distributed, that’s the point here. It’s the old 53 per cent of the world’s population live on 3 per cent of its surface thing at work, once again.

One last thought. That red area is at enormous risk from sea level rises. If climate change has the effect that scientific consensus imagines it will, where are those 350m people going to go?

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Green roofs improve cities – so why don’t all buildings have them?

The green roof at the Kennedy Centre, Washington DC. Image: Getty.

Rooftops covered with grass, vegetable gardens and lush foliage are now a common sight in many cities around the world. More and more private companies and city authorities are investing in green roofs, drawn to their wide-ranging benefits which include savings on energy costs, mitigating the risk from floods, creating habitats for urban wildlife, tackling air pollution and urban heat and even producing food.

A recent report in the UK suggested that the green roof market there is expanding at a rate of 17 per cent each year. The world’s largest rooftop farm will open in Paris in 2020, superseding similar schemes in New York City and Chicago. Stuttgart, in Germany, is thought of as “the green roof capital of Europe”, while Singapore is even installing green roofs on buses.

These increasingly radical urban designs can help cities adapt to the monumental challenges they face, such as access to resources and a lack of green space due to development. But buy-in from city authorities, businesses and other institutions is crucial to ensuring their success – as is research investigating different options to suit the variety of rooftop spaces found in cities.

A growing trend

The UK is relatively new to developing green roofs, and governments and institutions are playing a major role in spreading the practice. London is home to much of the UK’s green roof market, mainly due to forward-thinking policies such as the 2008 London Plan, which paved the way to more than double the area of green roofs in the capital.

Although London has led the way, there are now “living labs” at the Universities of Sheffield and Salford which are helping to establish the precedent elsewhere. The IGNITION project – led by the Greater Manchester Combined Authority – involves the development of a living lab at the University of Salford, with the aim of uncovering ways to convince developers and investors to adopt green roofs.

Ongoing research is showcasing how green roofs can integrate with living walls and sustainable drainage systems on the ground, such as street trees, to better manage water and make the built environment more sustainable.

Research is also demonstrating the social value of green roofs. Doctors are increasingly prescribing time spent gardening outdoors for patients dealiong with anxiety and depression. And research has found that access to even the most basic green spaces can provide a better quality of life for dementia sufferers and help prevent obesity.

An edible roof at Fenway Park, stadium of the Boston Red Sox. Image: Michael Hardman/author provided.

In North America, green roofs have become mainstream, with a wide array of expansive, accessible and food-producing roofs installed in buildings. Again, city leaders and authorities have helped push the movement forward – only recently, San Francisco created a policy requiring new buildings to have green roofs. Toronto has policies dating from the 1990s, encouraging the development of urban farms on rooftops.

These countries also benefit from having newer buildings, which make it easier to install green roofs. Being able to store and distribute water right across the rooftop is crucial to maintaining the plants on any green roof – especially on “edible roofs” which farm fruit and vegetables. And it’s much easier to create this capacity in newer buildings, which can typically hold greater weight, than retro-fit old ones. Having a stronger roof also makes it easier to grow a greater variety of plants, since the soil can be deeper.


The new normal?

For green roofs to become the norm for new developments, there needs to be buy-in from public authorities and private actors. Those responsible for maintaining buildings may have to acquire new skills, such as landscaping, and in some cases volunteers may be needed to help out. Other considerations include installing drainage paths, meeting health and safety requirements and perhaps allowing access for the public, as well as planning restrictions and disruption from regular ativities in and around the buildings during installation.

To convince investors and developers that installing green roofs is worthwhile, economic arguments are still the most important. The term “natural capital” has been developed to explain the economic value of nature; for example, measuring the money saved by installing natural solutions to protect against flood damage, adapt to climate change or help people lead healthier and happier lives.

As the expertise about green roofs grows, official standards have been developed to ensure that they are designed, built and maintained properly, and function well. Improvements in the science and technology underpinning green roof development have also led to new variations on the concept.

For example, “blue roofs” increase the capacity of buildings to hold water over longer periods of time, rather than drain away quickly – crucial in times of heavier rainfall. There are also combinations of green roofs with solar panels, and “brown roofs” which are wilder in nature and maximise biodiversity.

If the trend continues, it could create new jobs and a more vibrant and sustainable local food economy – alongside many other benefits. There are still barriers to overcome, but the evidence so far indicates that green roofs have the potential to transform cities and help them function sustainably long into the future. The success stories need to be studied and replicated elsewhere, to make green, blue, brown and food-producing roofs the norm in cities around the world.

Michael Hardman, Senior Lecturer in Urban Geography, University of Salford and Nick Davies, Research Fellow, University of Salford.

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