Climate in crisis

Pledges to reduce greenhouse gas emissions are largely unachievable says a major audit of commitments to the Paris Climate Accord. Air pollution in Delhi is so bad, breathing the toxic particles has been likened to smoking. Can a scientific assessment of the multiple causes help provide a way forward?We examine a new way of making new plastic – from old plastic.And why sending some stem cells to the international space station might help astronauts travel further.(Image: Tourists wearing masks to protect themselves from smog in New Delhi, India. Credit: Sushil Kumar/Hindustan Times via Getty Images)Presenter: Roland Pease Producer: Julian Siddle