Efforts to stall climate change
Compiled by Susan Ramsay and Timothy Chui
Climate change is set to warm the world by several degrees into the next century, so scientists are thinking about a variety of sun shade solutions to combat rising temperatures. This month's edition of National Geographic reports two novel solutions.
The cheaper solution is to launch tonnes of sulfate particles into the stratosphere by plane, balloon and battleship guns to cool the globe. The plan comes from the Carnegie Institution's Ken Calderia. He expects his plan to mirror the effects of massive volcanic eruptions - such as Mount Pinatubo's cloud of pumice and ash which cooled the world by a degree for a year - but would also require regular top-ups as the particles fell to earth.
University of Arizona astronomer and telescope designer Roger Angel has a longer-lasting but more expensive plan - to place trillions of silicon nitride discs between the earth and the sun.