 Ward also criticised Lawson for repeating in a 2010 BBC radio debate that Antarctic ice volumes were unchanged even after his error was highlighted by his opponent, Professor Kevin Anderson.Ward said that Lawson provided no evidence to back his claim which is contrary to satellite measurements, and Lawson similarly incorrectly implied that the correlation between CO2 and sea levels was uncertain as sea levels were rising more slowly since 1950 than before it.The Charity Commission requires that statements by campaigning charities "must be factually accurate and have a legitimate evidence base".