Do we know space better than our oceans?

Sam got in touch to ask if it's true that we know more about space than we do about our oceans. Chris Smith put this question to ecologist Danni Green from Anglia Ruskin University...

Danni - In short I'd say yes it is. Particularly if you're talking about understanding the topography and the shape of the oceans. So for example technically we have got 100 percent of the oceans mapped but the resolution is to 5000 metres whereas we've mapped 98 percent of Venus to 100 metres resolution.

Chris - So we do know quite a bit about quite a few places but not necessarily the bottom of the sea.

Danni - But there is actually a big movement in 2017, there's a group called the General Bathymetric Chart of the Ocean GEBCO, for short and they’re launching this huge effort to map everything in more detail by 2030. And this is a big collaborative thing which would mean that ships that are out doing things for fisheries or for recreation would also be mapping the oceans using multi-beam sonar which is obviously a lot quicker than just a single beam one at a time. So there's a huge collaborative effort to map the oceans in more detail. However some ecologists are concerned that this also may lead to a huge race to try to mine the oceans more. There's lots of precious minerals down there, there's diamonds, gold, obviously oil. We're already on the oil wagon. So there's an issue there that is this going to lead to conservation or exploitation.

Chris - I wondered if you were going to say something else when you mentioned the sonar and conservation issues because there is a question as well that one of the reasons we see things like giant mammals beaching, whales driving themselves onto beaches is because of distress caused by Marine noise and underwater sound pollution.

Danni - Yes exactly. So this is another big issue. It's also associated with oil rigs and the whole process of exploration of the sea as well as exploitation.

Chris - But is sonar of the kind used by shipping. Is that destructive and disturbing to the environment and the behavior of these animals?

Danni - Yes it is, yes. There's a lot of evidence that this is interfering with their navigation systems and causing them to beach.

Chris - So it's a bit of a worry that in order to understand the ocean we could actually be doing damage

Danni - It could be disrupting even more. Yeah.

Chris - Tim?

Tim -  Why is the ocean not mapped much better? you'd imagine it's much, much harder to map the surface of Venus. You know, millions of miles away than it is to map the ocean floor.

Danni - There's a lot of water in the way. Just in short, it makes it quite difficult.

And obviously there's some areas that are mapped in a lot more detail, so we've mapped about 10 to 15 percent, to 100 meters, because those are the shipping routes and the places we go to. But the areas that we rarely go to with really turbulent seas are going to be less well understood at this stage.

Chris - I spoke to a group of marine scientists at the University of Aberdeen a few years ago and one of them passed on the sobering fact that he ventured, not personally but with a probe, ventured to the bottom of the Pacific Ocean. It's about seven miles, 12 kilometers down, very long way down and the first thing he saw when he reached the sea bed was a plastic raincoat!

Danni - Plastic raincoat, yeah.