Agence France-Presse: Scientists unveiled evidence yesterday to suggest global warming is affecting all of Antarctica, home to the world’s mightiest store of ice. The average temperature across the White Continent has been rising for the last half century and the finger of blame points at the greenhouse effect, they said. The research, published in the British journal Nature, takes a fresh look at one of the great unknowns – and dreads – in climate science. Any significant thaw of Antarctica …