Plastic lasts a long time, and the Coke bottle you just bought can exist for the next thousand years, taking 40 human generations to finally and fully degrade. The consequences of plastic’s wonton use on the environment, thanks in large part to that longevity, is as dire as one could imagine, perhaps more.

Using plastic so frivolously is obviously bad, but its ability to outlive us several times over also offers an opportunity to scribe letters to future generations on a medium that will likely remain intact. Project Letters to the Future is leveraging plastic’s persistence to preserve handwritten letters to great-great-great-great grandchildren from across the world.