Tag Archives: data
Bodele Depression
As someone interested in geography (and pretty pictures), I used to be on a mailing list run by NASA which showcased the most stunning and intensely thought-provoking satellite images of natural phenomena. One of the images and accompanying stories that has stayed with me since I first saw it years ago was of a region in Chad called the Bodélé Depression.
Although visually striking, what really captivated me was the mechanism behind the combination of wind and earth that is this natural conveyor belt, located at the southern edge of the Sahara, at the lowest point in Chad in central Africa. To quote from Wikipedia:
“Dust storms from the Bodélé Depression occur on average about 100 days per year … [a]s the wind sweeps between the Tibesti and the Ennedi Mountains in Northern Chad, it is channeled across the depression. The dry bowl that forms the depression is marked by a series of ephemeral lakes, many of which were last filled during wetter periods of the Holocene. Diatoms from these fresh water lakes, once part of Mega-Lake Chad, now make up the surface of the depression and are the source material for the dust, which, carried across the Atlantic Ocean, is an important source of nutrient minerals for the Amazon rainforest.”
This last sentence is the frankly rather unbelievable key to the story, and deserves closer scrutiny. In work published in 2006 (and subsequent reports), it was shown that
“…about half of the annual dust supply to the Amazon basin is emitted from a single source: the Bodélé depression located northeast of Lake Chad, approximately 0.5% of the size of the Amazon or 0.2% of the Sahara. Placed in a narrow path between two mountain chains that direct and accelerate the surface winds over the depression, the Bodélé emits dust on 40% of the winter days, averaging more than 0.7 million tons of dust per day. … About 40 million tons of dust are transported annually from the Sahara to the Amazon basin. Saharan dust has been proposed to be the main mineral source that fertilizes the Amazon basin, generating a dependence of the health and productivity of the rain forest on dust supply from the Sahara.”
As an analogy for what a single person or small group of individuals can do in the new era of digital media, this natural phenomenon seems to me to be unsurpassed.
Big data (2)
In this Analysis podcast, several themes come up relating to media and big data, data, privacy, secrets, and who controls and distributes each of these (government, media, individuals).
The interesting comment is that in the 20th Century framework, ideas, philosophies, and causes were promoted by groups which nucleated around an idea (political parties, unions, etc.) and derived their main strength from “strength in numbers” and could thus influence policy or decision-making generally. Today, things appear to have become more granular: it is possible for an individual to make waves without the backing of a party, and ideology has thus reached a much higher level of granularity than before, highly dependent on the individual.
The government has reason to fear the individual, just as the individual has reason to fear the state.
Big data (1)
Bringing together several strands of thought (society, geography, technology, behaviour) the following BBC Radio 4 podcast on The Bottom Line provoked some thinking on how changes in monitoring and networking (in many different contexts, mainly digital) are affecting how we behave.
The most fascinating part, it would seem, is the effect on behaviour. This has an impact on both the individual and society: each individual modified their behaviour (slightly (due to monitoring of some vital sign, for example), and by changes in aggregate behaviour one can observe changes in societal behaviour and modes. There are counter-balancing trends as we yield to a networked digital world, with demarcations and fences, as well as benefits of large datasets.
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