World Lightning: Thunderstorms and human population

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Time again to talk about the weather: Britain is suffering under heatwave conditions (also known as summer in other parts of the world), with the ongoing high temperatures and developing clouds going along with an increased humidity slowly increasing the risk for thunderstorms. Thunderstorms are not an uncommon phenomenon on the British Isles, but they are much less common and much less severe compared to other regions experiencing similar conditions much more frequently and more intensively. The Met Office explains that “Owing to the fact thunderstorms are created by intense heating of the earth’s surface, they are most common in areas of the globe where the weather is hot and humid. Land masses therefore experience more storms than the oceans and they are also more frequent in tropical areas than the higher latitudes. In the UK thunderstorms are most common over the East Midlands and the south-east.
As it happens to be, the part most prone to thunderstorms in Britain is also the most densely populated region. Comparing this to other parts of the world, it can be seen that some of the most risky regions are also some of the very densely populated places. In Europe, which is overall densely populated in many parts, the most affected areas are the people living in the Mediterranean countries, although the European population in general is amongst the least affected by thunderstorms when comparing this to areas such as the southern edge of the Himalayas in India – densely populated and experiencing very intensive thunderstorms. These details only emerge when changing the projection of data collected on lightning flashes from a conventional land area map (where this part of India for instance remains comparably small) to a gridded population cartogram. The following map shows the intensity of lightning flashes displayed as the number of flashes per square kilometre per year in each of the grid cells, while the distortion of the grid cells reflects the global population distribution, so that the most and least exposed populations are highlighted in this visualisation:

Equal population projection map of
(click for larger version)

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The Space of Climate Change

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Earth Day 2013In the face of unprecendented occurences of extreme weather, loss of species, and pollution, it is clear that climate change is affecting our planet. We cannot afford to wait any longer to act. This quote from the Earth Day 2013 website outlines the theme for this year’s Earth Day campaign which runs under the motto Climate change has many faces.
As the Earth Day campaign points out, the stories of the impact of climate change are extremely diverse: “A man in the Maldives worried about relocating his family as sea levels rise, a farmer in Kansas struggling to make ends meet as prolonged drought ravages the crops, a fisherman on the Niger River whose nets often come up empty, a child in New Jersey who lost her home to a super-storm, a woman in Bangladesh who can’t get fresh water due to more frequent flooding and cyclones.
All these tales have one thing in common: They are a story of our impact on planet Earth, but equally of the impact of a changing planet on human’s lives. Our species has become one that is not just living in the natural environment, but is one factor that changes the environment to a level that no other species did before. This is happening to an extent that geologists discuss whether this can be seen as a new geologic era. Nobel Prize laureate Paul Crutzen started promoting the idea of the so-called Anthropocene, a concept that has now left the scientific world and is increasingly entering the public debate regarding issues of global sustainability and humanity’s impact. Anthropocene.info is a project initiated by the International Geosphere-Biosphere Programme (IGBP) that aims to “to help visualize and better understand humanity’s geographic imprint in recent time.” Not only is it important to find better ways of understanding the complex interrelations of humans and their natural environment, to which visualisation can contribute, but also is it important to create a public understanding of issues relating to the challenges connected to global change.
Here is one example of a more challenging view existing knowledge that demonstrates how changing the view can make us rethink the way our natural environment is shaped. According to research by the US National Office of Oceanic and Atmospheric Research, “[t]he strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth’s climate is warmed by increasing levels of greenhouse gases in the atmosphere. Most hurricanes do not reach their maximum potential intensity before weakening over land or cooler ocean regions. However, those storms that do approach their upper-limit intensity are expected to be slightly stronger in the warmer climate due to the higher sea surface temperatures.”
This is relevant due to the impact of more frequent flooding and cyclones on humans mentioned earlier. So where are these spaces where this is relevant. We know from historic records where there are tropical storm tracks, and the emerging pattern on a normal world map may be familiar to some of us (see here). But what if we change the perspective and focus on the actual areas that have the highest density of tropical storm occurrences. Using the records from 1945 to 2008, this intensity can be turned into quantities which are suitable for visualisation using the gridded cartogram technique. The following map shows a gridded cartogram of tropical storm intensity visualised over land based on a 0.25 degree grid. The larger a grid cell, the more tropical storm activity has there been over the past >60 years, indicating where the most affected areas of tropical cyclones (with a sustained wind speed of ver 40 mp/h) has been and how the climate patterns shape the world in a highly relevant issue of the Anthropocene:

Gridded Cartogram / Map of Tropical Storm Intensity
(click for larger version)

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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?

Map Animation / Gridded Population Cartogram of Rainfall (Precipitation) patterns in relation to people

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:

Map / Gridded Population Cartogram of Solar Insolation in July 2011
(click for larger map)

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