Satellite images show growing darkness in Syria

During the four years that researcher Xi Li has watched Syria's civil war unfold through nighttime satellite imagery, he has seen the pinpricks of light fade to the point where 83 percent of the country's lights have gone out.

"Satellite data never tell lies," said the Chinese-born Li, a visiting scholar at the University of Maryland's Department of Geographic Sciences. "The Syrian people need help."

He has measured the levels of nighttime light across Syria since the conflict began in March 2011. His findings were published last year in the International Journal of Remote Sensing.

He said 97 percent of the lights in Aleppo, once the largest city, have gone out since the conflict started in March 2011.

The bright light of Aleppo shown in March 2011 is almost entirely gone by February of this year. Even the government-controlled capital, Damascus, is 35 percent dimmer. Raqqa, the new de facto capital of the Islamic State group, has 96 percent of its lights out, Li said.

Li blamed the displacement of people as the main factor behind the darkening, as about 3.8 million people have fled the country.