It takes the Russian icebreaker named '50 Years of Victory ' three and a half days to traverse the 2,400 kilometres (1,500 miles) to the North Pole from Murmansk, the base of Russia's Northern Fleet.  The journey is only possible in summer, when ice cover is at its lowest and climate change is making the journey gradually easier year by year. The Arctic ice cover is now "five to seven times" thinner than in the 1980s, Russia's meterological institute Rosgidromet said in a report in March, adding that in the summer months the waters are becoming increasingly free of ice.  The region is stuck in a vicious circle as the retreating ice cover allows the warmer waters of the Atlantic to enter the Arctic basin. STOCKSHOTS