There might be 117,000,000 lakes on Earth, but only between 8 and 20 have been concretely identified as ancient. UNESCO Lake Ohrid is certainly in the club, but exactly how old is it and why does age matter?
To qualify as an ancient lake, an inland water must have been continuously in existence since before the last glacial period, 120,000 years ago. Such long life is highly unusual for a lake, because most transform into land via a process of sedimentation relatively quickly, while others are not here constantly, but flicker in and out of existence, depending on environmental factors.
Longevity brings special powers to these rare ancient lakes. Not only can they preserve species that perish when live-fast-die-young waters disappear, but they also have time to evolve completely new and unique plants and animals. This makes them very important for humankind to learn about both the world of the deep past and how that world transformed into the one we see today.
Estimates of Lake Ohrid’s age have varied from 1 to 10 million years, but the most recent studies seem to place it at about 2,000,000 (with deep water for about 1,200,000). Its ecosystems have the life-force to prove it too: Figures boast a mind-boggling 1,200 species right now. The more we research, the more that number will grow.