36 years ago today, the world welcomed its 5-billionth human. Now that the Earth's population has reached 8 billion and rising, the question continues to loom: Will we run out of space, food, and other necessary resources? Today is a day where we can reflect on just how much life the Earth is capable of sustaining and how our individual and collective lives impact our local, national, and global environments.

Pictured here is Hong Kong, a city recognised as one of the world's most densely populated areas with approximately 26,232 people per square kilometre. Though Hong Kong has a low birth rate, the density remains high due to a population that is living longer thanks to improvements in healthcare, which is a contributing factor to population increases worldwide. Though this crowded neon-lit night scene may be glamorous, it also represents light pollution at its most extreme—a prime example of humanity's impact on the environment.