And that’s still a conservative estimate; in reality, global light pollution may have increased by 270 percent(!) in a quarter of a century.

British researchers say so in the magazine Remote Sensing. They are based on images taken by satellites of the Earth’s surface between 1992 and 2017.

Effects

And those images reveal that the Earth’s surface is increasingly illuminated at night. It’s worrying. “The global spread of artificial light is affecting the nighttime environment,” said researcher Alejandro Sánchez. “The essence of the night is darkness. When we take away the darkness, we take away what protects many species from predation. We help hunters catch their prey, we disrupt the rest and reproductive systems of species. And at the moment we see the big and small consequences of that everywhere we research it.”

Significant increase

And light pollution appears to be a growing problem. According to Sánchez and colleagues, light pollution has increased by at least 49 percent in 25 years. In reality, however, the increase is much greater, Sánchez suspects. Because the numbers only refer to the light that satellites can see. This means that the rapidly emerging LED lighting is partly unaffected. Compared to traditional lamps, these LED lamps emit more blue light. And satellite sensors cannot see that blue light and probably underestimate the light emission considerably. Taking into account that flaw in the satellite view, Sánchez and colleagues think that light pollution has actually increased by 270 percent worldwide in 25 years. And in some areas possibly even by 400 percent.

Asia and Africa

Back to what the satellites can see: a worldwide increase in light pollution of no less than 49 percent. If we zoom in a bit further, we see that light pollution has increased significantly in Asia, South America, Oceania and Africa. We asked Sánchez about the cause of those rising light emissions. “It is a combination of economic growth and a misconception of development. From the western world we have created the image through our films and our policies that more light means more wealth. But that is a distorted picture. So you now see that Germany – one of the most developed countries in the world – is the least luminous. In addition, we in the west are also more critical when it comes to preserving darkness. In these regions (Asia, South America, Oceania and Africa, ed.) there are far fewer activists, so there is nothing to prevent companies from ‘overlighting’. We are also – as usual – dumping the technologies we no longer want here.”

Decrease

In addition to regions where light pollution has increased significantly, there are also areas where light pollution appears to have been reduced in 25 years. This is the case, for example, in North America. And the rising light emission is also leveling off in Europe. That seems like good news, but caution is in order. “The satellites are definitely giving us the wrong idea. Take Great Britain, for example.” According to the satellites, the light emission has decreased here. But we know that about 66 percent of outdoor lighting in Britain is now LEDs. “And that means that the amount of light pollution has skyrocketed, because traditional lighting has mainly been replaced by 4000K and 3000K LEDs. We see the same in Italy and Spain.”

The problem with LED lighting
In an effort to save energy, there is also a massive switch to LED lighting for outdoor lighting. Wrongly, according to Sánchez. “The most efficient and sustainable lighting (for outside, ed.) is still the low-pressure sodium lamp. But those lamps are much cheaper than LEDs and can only provide orange-yellow light, which is why they were quickly made redundant by the industry for commercial reasons.” LEDs are therefore not the most energy-efficient choice on the street. And to top it all off, in practice they are also more light-polluting than other types of lighting. “The LEDs are naturally no more polluting. We, or rather: the industry, chooses to make them more polluting. We can use LEDs of any color, but we opted for white LEDs. And those white LEDs are generally more light-polluting, because their light scatters much further into the atmosphere and has a greater impact on nature. This way the light attracts more insects. If we were to choose Amber LEDs (which are yellow/orange in color, ed.) or LEDs with a low color temperature, such as 2200K, we would reduce the light pollution in many places in Europe and America (with the switch to LED lighting, ed. .) have been pushed back.”

The researchers are still trying to clarify to what extent the light emissions observed by satellites differ from the actual light pollution. But the difference seems to be big. “In Milan, for example, satellites show a 50 percent decrease in light emissions, when in reality it has increased by at least 27 percent.” The good news, however, is that it is not very complicated to reduce the light emission with LEDs. “One of the advantages of LEDs is that you can dim them.”

government

When it comes to combating light pollution – and the resulting problems in nature – there is clearly an important task for the government. And it’s time for them to put their beloved LEDs to good use, says Sánchez. “LEDs are easy to dim, easier to aim and we can make them in any color.” It means that by making smarter choices we can significantly reduce light pollution. Many countries can take an example from France as far as Sánchez is concerned. “France is one of the leading countries when it comes to limiting light pollution. 12,000 municipalities in France turn off their lights and lights with a color temperature above 3000 K are banned.” It is at odds with what we see in the Netherlands. “The Netherlands is a bit special,” says Sánchez. “It is one of the few countries in the world where it gets lighter as it gets later in the evening. That’s because of the greenhouses. And it is the opposite of the 12,000 French municipalities that turn off the lights around midnight.”

Besides governments, citizens can also contribute to the fight against light pollution. “We can turn off the lights in our backyard, draw the curtains and buy cars with warm lights instead of bright ones. But the most important thing is to ask your representatives to do their job and buy quality products that protect the night.”