Polluting shipwrecks are the ticking time-bomb at the bottom of our oceans

At the bottom of the oceans and seas lie more than 8,500 shipwrecks from two world wars. These wrecks have been estimated to contain as much as 6 billion gallons of oil, as well as munitions, toxic heavy metals and even chemical weapons.

For decades, these wrecks have largely lain out of sight and out of mind. But all this time, their structures have been degrading, inexorably increasing the chances of sudden releases of toxic substances into the marine environment.

In parts of the globe, climate change is exacerbating this risk.