Missing submarine on Titanic excursion: Sufficient oxygen until Thursday? |

A search and rescue operation is underway in the Atlantic Ocean for a small submarine that went missing while taking tourists to the wreckage of the Titanic. It's feared the vessel could be almost four kilometers under water. Several aircraft have been using sonar technology to try and pin-point its exact location, while a submarine team is hoping to launch a rescue attempt late on Tuesday. It's believed the submarine should have enough oxygen to keep its pilot and four passengers alive until Thursday.

Why Atlantic fish are invading the Arctic

Scientists are witnessing the upending of large parts of the Arctic ocean. As the sea ice recedes and temperatures rise, the warmer waters of the Atlantic are moving north and bringing with them new competitors that vie for the same rich resources. Journalist Eli Kintisch explores an ecosystem undergoing profound change.