Breaking the ice

Has Antarctica been getting warmer? To the frustration of many environmentalists, it’s not an easy question. Manned weather stations have existed there for over 50 years, unmanned stations from 1980 onwards. Coverage is patchy both in space and time, with weather stations clustered in a few spots and records full of gaps from when sensors got buried in snow, breakdowns occurred or stations were closed. From 1982, satellites have measured the temperature over the continent but inaccurately, because of clouds and instrument inconsistencies.

So taking Antarctica’s temperature involves considerable mathematical skill and leaves much room for statistical disagreement. The disagreement has just became a lot less polite, as several scientists exchanged the blogosphere equivalents of declarations of war. What started out as a difference over methods and results has descended into character assassination and accusations of duplicity. Underlying all this, one side claims that Antarctica — a continent which holds 90 per cent of the world’s ice — is warming significantly. The other side claims this is not so. The battle has implications far beyond Antarctica. It has exposed a real problem of bias in scientific journals.

The story starts in 2009 when the prestigious journal Nature carried a cover story with an image of Antarctica glowing a warm pink. The paper inside used a relatively novel statistical reconstruction method to combine the detailed satellite data with the more accurate, but sparse, weather station data. It concluded that most of Antarctica — and particularly West Antarctica — had warmed significantly since 1957. This was worthy of a cover story because it contradicted the previous understanding: that only the most northerly part of this ice continent, the slender Antarctic peninsula, was warming.

The paper’s senior author was Eric Steig of the University of Washington. His work duly captured world headlines. Four days later, the editor of the famously pugnacious RealClimate blog, Gavin Schmidt, boasted that the sceptics were surprisingly silent.