Gabrielle Walker

Climate change: the tipping point of the iceberg.

Could climate change run away with itself? Gabrielle Walker looks at the balance of evidence.Whats the point?The idea that passing a hidden threshold could drastically worsen man-made climate change has been current in the scientific literature for many years. Now it has a new name, a ‘tipping point’, and suddenly the news magazines and other media have picked up on it. Gabrielle Walker gets back to the science to ask whether the Arctic climate is really on the brink.

Geology: High on Antarctica

Gabrielle Walker enjoys a historic exploration of the frozen continents great mountain range.

Antarctic astronomy: seeing in the dark.

When darkness falls for Antarcticas long winter months, the sky becomes a spectacular canopy of stars. At one brand new base, astronomers are braving the extreme cold to build telescopes that they hope will rival space observatories. Gabrielle Walker investigates.Losing sight of the starsOptical astronomers had high hopes for the Concordia base in Antarctica as a cheaper alternative to space-based telescopes. There is little atmospheric water vapour there to distort the light, it is outside the normal region for aurora and theres little wind, which should avoid a problem found elsewhere in Antarctica, where distortion due to wind turbulence causes bad ‘seeing’. But it has not been plain sailing: Concordia has its own type of air turbulence caused by a steep temperature gradient between the snow and the air above it. Can the astronomers rise to this latest challenge?