From hunting gear to shoes, ancient artefacts once covered by ice are being unearthed in Norway. Now scientists face a race against time to preserve them

Archaeologists have gained an unexpected benefit from global warming. They have discovered melting ice sheets and glaciers are exposing ancient artefacts that had been covered with thick layers of ice for millennia.

The discoveries are providing new insights into the behaviour of our ancestors – but they come at a price. So rapid is the rise in global temperatures, and so great is the rate of disintegration of the world's glaciers, that archaeologists risk losing precious relics freed from the icy tombs. Wood rots in a few years once freed from ice while rarer feathers used on arrows, wool or leather, crumble to dust in days unless stored in a freezer. As a result, archaeologists are racing against time to find and save these newly exposed wonders.

A perfect example is provided at Juvfonna in Norway, where reindeer hunting gear used by the Vikings' ancestors has been found littering the ground as the front edge of Juvfonna's ice sheet has retreated. A section more than 60ft wide has disappeared over the course of 12 months, exposing several hundred artefacts. "It's like a time machine... the ice has not been this small for many, many centuries," says Lars Piloe, the Dane heading a team of "snow patch archaeologists".

Bows and arrows, specialised hunting sticks – used to drive reindeer towards archers – and even a 3,400-year-old leather shoe have been found at the site in the Jotunheimen mountains, home of the "ice giants" of Norse mythology. These finds have been logged with a GPS satellite marker before being taken for examination. From these measurements, archaeologists reckon people using hunting sticks – each about a metre long with a flapping piece of wood attached by connecting thread – were set up about two metres apart. They then drove reindeer toward hunters who needed to get within 60ft of an animal to have a chance of hitting one with an iron-tipped arrow.

Such a hunt would require 15 to 20 people, Piloe adds, indicating that Norway had an organised society around the start of the dark ages, 1,500 years ago. "Our main focus is the rescue part," according to Piloe. "There are many ice patches. We can only cover a few. We know we are losing artefacts everywhere."

Similar discoveries have been made in glaciers or in permafrost from Alaska to Siberia. Italy's iceman "Ötzi", killed by an arrow wound approximately 5,000 years ago, was found in an Alpine glacier, for example.

Patrick Hunt, of Stanford University in California, who is trying to find where Carthaginian general Hannibal invaded Italy in 218BC with an army and elephants, says there is now an alarming rate of thaw in the Alps: "This is the first summer since 1994 when we began our field excavations above 8,000ft that we have not been inundated by even one day of rain, sleet and snow flurries. I expect we will see more ice patch archaeology discoveries."

Just how many others will be lost to science is difficult to assess, however.