New research calculates the huge cost of 'negative emissions' technologies that will be required to avoid dangerous climate change.
Could sea levels really rise by several metres this century. Probably not, although this century's greenhouse emissions could potentially set the stage for large rises in centuries to come.
Former NASA climate scientist James Hansen has come to the Paris climate talks to push his radical alternative to current carbon pricing schemes.
Sea level rise represents one of the most worrying aspects of global warming, potentially displacing millions of people along coasts, low river valleys, deltas and islands.
NASA's former climate chief, James Hansen, is lead author on a paper that predicts rapidly rising seas this century, but not all climate scientists believe the study's models are convincing.