Passage
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1. Back in 1962, when John Glenn orbited the Earth, he demonstrated that lights at night made it possible for human activity to be traced from space. Since then, satellite imagery of night-time lights has been used with some success to measure developments on our planet. All such observations to date have been quite crude, since most of the data comes from one ageing network of satellites which can only produce low resolution snapshots.
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2. Their research shows a link between changes in a country's Gross Domestic Product (GDP) and the intensity of its electric lighting, both domestic and commercial: on average, as a country's GDP increases, its night-time light emission becomes more intense. The work is particularly promising for measuring growth in the developing world, where reliable statistics are hard to get.
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3. Henderson and his colleagues also used the DMSP data to examine economic activity on sub-national scales, investigating the relationship of African cities to nearby agricultural regions.
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4. Chris Elvidge leads a team that removes contaminating natural phenomena like moonlight, lightning, and forest fires from the images, but he says that human choices of how buildings and streets are lit, and even which variety of light bulbs are used, all alter the patterns and intensity of light, adding uncertainty to any conclusions.
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5. They have used night-time DMSP data to detect gas flares, the deliberate burning of excess natural gas left over from petroleum production, which may account for as much as 2% of all the carbon released into the atmosphere each year by human activity.
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6. Sutton is suggesting to NASA that it should develop and launch a Nightsat, a state-of-the-art satellite devoted solely to gathering high resolution, full-colour data on nocturnal lights across the globe.
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7. Humans are in a unique position, because Earth's carrying capacity for us depends on how we choose to live and to use technology. But our influence on Earth's carrying capacity is often unpredictable and difficult to discern. Sometimes our choices will increase the impact we have on the environments we live in; sometimes they will decrease the consequences.
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