Cancel
Advanced Search
KEYWORDS
CATEGORY
AUTHOR
MONTH

Please click here to take a brief survey

Light and the Bright Green City
Alex Steffen, 9 Feb 10
Article Photo

It's become a common slide at conferences: a map of the Earth at night, with the wealthier and denser areas shining brightly. Africa seen at night is largely dark, and this is often the point of the slide: look at how much energy some people have access to, and how little others do (which is true: almost 90% of Africans lack ready access to electricity, according to the World Bank), and, by inference, what gaps in economic prosperity persist.

But these maps don't actually display prosperity, or even energy use: instead, maps of brightness illustrate light pollution and energy waste. The blazing lights our satellites photograph while whizzing above us in their orbits, well, that's light that's serving no useful purpose (unless you want to think of our glowing cities as a form of art meant for distant eyes). Light seen from space is bouncing off illuminated surfaces, or being shone directly from bulbs aimed up. Neither is helping us on the ground see our cities better.

We could, we should, be treating light as precious, and getting clever about illuminating our lives with only the light we need. Using the minimum needed lumens would not only save a fair bit of energy, it would also bring the night sky back to our cities; it's the light bounced back by the atmosphere that hides the stars.

Seen from above, a bright green city would be only a smudge of light.

(PS: if you want to follow my twitter stream from TED, you can find me at @AlexSteffen.)

Bookmark and Share


Comments

If you look at the lights at night comparison maps, you'll see that many areas have gotten darker over time (the northeastern US falls into this group). Often (though not always) this is because of municipalities that have changed zoning so that lights have to point down, rather than send up to 90% of their light off in useless directions.

That light is not only waste, but also light pollution that interferes with our views of heavenly bodies.

You can explore the images over time at (amongst other places):

http://www.koshland-science-museum.org/exhib_lightsatnight/


Posted by: Gene on 9 Feb 10

Excellent insight, Alex. But of course, some of the light reaching surfaces would be reflected to the sky. What we see isn't all "wasted" light - but the point is well taken.


Posted by: David Foley on 10 Feb 10

Post A Comment

Please note that comments will remain open for only 14 days after the article is posted. While previous comments will remain visible, attempts to post new comments after this period will fail. This helps stop comment spam, so your forebearance is appreciated.

The Worldchanging comments are meant to be used for further exploration and evaluation of the ideas covered in our posts. Please note that, while constructive disagreement is fine, insults and abuse are not, and will result in the comment being deleted and a likely ban from commenting. We will also delete at will and without warning comments we believe are designed to disrupt a conversation rather than contribute to it. In short, we'll kill troll posts.

Finally, please note that comments which simply repost copyrighted works or commercial messages will be summarily deleted.

REMEMBER PERSONAL INFO?
Yes No

NAME


EMAIL ADDRESS


URL


COMMENTS



EMAIL THIS ENTRY TO:

YOUR EMAIL ADDRESS:


MESSAGE (optional):


Search Worldchanging

Worldchanging Newsletter Get good news for a change —
Click here to sign up!


Worldchanging2.0


Website Design by Eben Design | Logo Design by Egg Hosting | Hosted by Amazon AWS | Problems with the site? Send email to tech /at/ worldchanging.com
©2012
Architecture for Humanity - all rights reserved except where otherwise indicated.

Find_us_on_facebook_badge.gif twitter-logo.jpg