Bowerbirds, a yellow sub and measuring CO2

This week, Richard Hollingham finds out that bowerbirds are not just brilliant at making elaborate bowers, they're also good at mimicking other birds and pretty much most sounds they hear – including human voices.  He also goes to a Scottish forest to meet researchers from the University of Edinburgh who are using a 220-metre high TV tower to measure greenhouse gas concentrations from across Scotland and all the way to Ireland and even as far as Canada.  Lastly, during Richard's recent trip to the Arctic onboard the RRS James Clark Ross, he spoke to a scientist who explained how a small yellow submarine is helping scientists understand much more about Arctic ocean currents.