Earlier this year the British Telegraph Newspaper published a story about the creation of a new megacity in the Chinese Pearl River delta region. “China is planning to create the world’s biggest mega city by merging nine cities to create a metropolis twice the size of Wales with a population of 42 million”, the opener of their story stated. The region mentioned here is an area covering the cities of Guangzhou, Shenzhen, Donggaun, Foshan, Huizhou, Zhaoqing, Jiangmen, Zhongshan and Zhuhai (as described in the China Urban Development Blog). The story was quickly picked up by many news sources back then, while Chinese officials were quick to deny the reports. Stories like this show, how urbanisation and megacities have become a buzz word, and are used especially in relation to the emerging economies in Asia in order to picture these – for western-centric eyes unbelievably – large and still growing populations in the most urbanised regions on the planet. A few thoughts on the relevance of megacities in their global context have been published on this website before (related to the map of the world’s megacities).
With special regard to the Telegraph story I have drawn another map showing the population distribution of China (based on 2010 Data from the Chinese Census and from estimates of SEDAC’s GPW database) and highlighted the Pearl River Delta region in this map. The equal-population map shows a gridded population cartogram in which every grid cell is resized according to the total number of people living there. This map makes the plans of a more integrated Pearl River Delta region more understandable, and perhaps slightly less exciting for those who interpreted the news as the creation of a new megacity, rather than the logical step in connecting an already populous region.
Tag Archives: gridded cartogram
In Focus: Global Population Shifts
According to recent estimates by the UN, the world’s population will reach 7 billion some time this year, and rise to over 10 billion by 2100. In an article for the “In Focus” section of Political Insight (September 2011, Volume 2, Issue 2) Danny Dorling and I show where the population is growing and where it is declining.
The map we created for this feature shows not only the growth and decline in relation to the global population distribution, but also highlights the places that are in growth an decline in two separate maps. This is a preview of the maps that we created for the article:
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When does it always rain on us?
Where rain (or more precisely: precipitation) is affecting most people, and where it falls mainly on uninhabited land has been part of the presentation that I gave at this year’s SoC meeting in Plymouth (where the delegates witnessed some of the rain from the maps shown below, but enjoyed a little bit of the late summer’s sunshine as well). An animation of these maps and the annual precipitation map have been published on this website last week (see here).
The following series of maps shows monthly precipitation patterns derived from monitored climate data of approximately 50 years (1950-2000, data obtained from http://worldclim.org/). The underlying popoulation grid is a gridded cartogram transformation of the global population distribution population data from SEDAC). As explained in more detail in the previous entry, this representation is a view of how the world’s population is directly exposed to the monthly precipitation patterns, shrinking all those unpopulated parts of the land surface while proportionally increasing the size of land according to the total number of people living there. The choropleth overlay visualises precipitation just as in a conventional map (also shown in the inset map. This shows, when it rains on humanity throughout the year – month by month: Continue reading
Where does it always rain on us?
Does it never rain in Southern California? And can we find the rain in Spain mainly in the plain? And what does that all mean for the people living in these places? Where does rain matter most for the population? In some places, it can be a much needed scarcity, elsewhere it appears in a much dreaded surplus. Wherever it is falling, rain matters a lot where people are. Partly, the global population distribution can be explained by climate patterns, with rain being a crucial factor for the agriculture in a region. In my presentation for the delegate’s session at this year’s 47th annual meeting of the British Society of Cartographers in Plymouth I took a closer look at the weather, or to be more precise, at climate patterns and their visualisation using gridded cartograms. Part of the presentation was an animation showing the global precipitation patterns projected on a gridded population cartogram. The following map shows the annual precipitation in relation to the global population distribution. The small map inset gives the conventional view of the same data, demonstrating how the perspective changes when seeing the same topic from two different views: Continue reading
A Solar World
British people are said to have an obsession for the weather. Therefore it is not surprising that weather stories have a common place in the media. A recent article in the Guardian’s Weatherwatch series (read more in Weatherwatch: Forget the Balearics – come to Bognor) was searching for the sunniest place in Britain. People living across the Channel may be quite surprised to hear that the concept of sunshine is known (or at least, does exist) in Britain, but it does. British holidaymakers may have actually been much better off staying on the island, rather than heading towards the European continent, as it turned out to be a quite wet summer 2011 there (but the records claim that it wasn’t much better on the British Isles either…).
Globally seen, and with a slightly more scientific twist, there is of course quite a lot sunshine in the northern hemisphere during the (northern) summer months. NASA Earth Obersavations regularly releases data of the solar insolation (the intensity of the sunlight that reaches the earth surface) on a monthly basis (see here for the data source and further details). The original NASA image (included in the below map as an inset) shows “where and how much sunlight fell on Earth’s surface during the time period indicated. Scientists call this measure solar insolation. Knowing how much of the Sun’s energy reaches the surface helps scientists understand weather and climate patterns as well as patterns of plant growth around our world. Solar insolation maps are also useful to engineers who design solar panels and batteries designed to convert energy from the Sun into electricity to power appliances in our homes and work places. […] The colors in these maps show how much sunlight (in Watts per square meter) fell on the Earth’s surface during the given time period” (quoted from NEO).
I used their data for a more experimental approach to visualise the most recent solar insolation (showing data for July 2011) using a gridded cartogram transformation. Instead of transforming people, the following cartogram resizes each grid cell according to the total energy of incoming sunlight reaching the land surface during the month July 2011. The cartogram shows the dominance of sunlight in the northern hemisphere during the northern summer season in the month just after the summer solstice. The seasonal variation of sunshine and the different distribution of sunlight between the northern and southern half of the planet become visible in their quantitative distribution. The northern landmasses are oddly bulging out of the map, while Antarctica disappears in the dark of the polar winter:
Maps for the 21st Century
499 years after Mercator’s birth we may feel that the age of discovery is long gone. We seem to have explored almost every patch of our planet, considerably supported by Mercator’s famous world map that allowed sailors for the first time to reliably navigate across the world’s oceans. His innovation was a significant contribution to the early days of globalisation. Globalisation has turned our planet into a human planet, where people have become a substantial component of the processes that influence our livelihoods – some go as far as calling this a new geological era, the anthropocene. But while we have maps and images of every spot of the earth, we do not fully understand the human environments and interrelations to the natural environment. Normal maps show where sheep and other lovely creatures of nature live but hide much of the so important populous spaces of humanity.
The maps that I created as part of my PhD research are based on a novel cartogram mapping technique, deploying Gastner/Newman’s diffusion-based cartogram algorithm in a new way. The maps give every person living on this planet the same amount of space, while reducing the least populated places to a minimum. The map projection is calculated from an equally distributed population grid so that, unlike in other cartograms, the transformed grid cells preserve an accurate geographical reference. This allows us to map a diverse range of geographical layers on top of the population projection. The new maps show the social and physical environment in relation to population and provide a fresh perspective on the complex geography of the 21st century world. The following animation shows a series of maps that demonstrate the visual capabilities of the technique (the video can be switched to HD resolution by clicking the 360p note in the bottom panel):
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