The Problem With Light

Artificial light at night (or ALAN) is a global driver of significant environmental change and loss of biodiversity, affecting the behaviour, physiology, reproduction, and survival of many terrestrial, freshwater and marine organisms. Nevertheless, an estimated 23% of land surfaces world-wide (excluding the poles), and 22% of the world’s coastal regions are exposed to artificial light at night, with over 80% of the global population currently living under light-polluted skies. As human populations continue to grow, the spread of light pollution across all systems is continuing at a rate of 2% per year. 

The brighter nights caused by artificial light are a big problem, because nearly all organisms on Earth have evolved in stable day/night, light/dark cycles through evolutionary time scales. Because of the consistency in these natural light rhythms, many important biological events are highly attuned to changes in light. Unfortunately, the presence of human-made light at night can alter these natural light rhythms and interfere with the behaviour and physiology of individual organisms, with potential flow-on effects leading to whole ecosystems impacts.

Importantly, the type of light matters when it comes to impacts on organisms. In the last decade, there has been a global focus on replacing more traditional light sources, such as mercury vapour and halogen lamps, with more cost- and energy-efficient light-emitting diode (LED) lights. However, LEDs of all colours emit significant blue light, which has been identified as having the greatest impacts on humans and wildlife alike, through suppression of melatonin production that regulates sleep/wake cycles of many animals. This is also relevant when considering aquatic environments, since blue artificial light penetrates deeper in the water column due to faster attenuation of red light.

In Australia, very little is known on how light pollution impacts wildlife and interacts with other stressors, such as climate change and urbanisation. NERAL was formed to address these many research gaps and to better link research on ALAN to policy and management outcomes. We are planning to run experiments across Australia that will shed much needed light (pun intended) on this important global issue. Meanwhile, you can find some of the recent research and outreach articles from NERAL members here.