Italy was suffering from a heat wave for a while before an enormous chunk of the Alpine glacier burst and killed hikers. Experts believe that climate change will increase those dangerous, hot conditions.

Seven hikers were killed and many others remain unaccounted after large chunks ice- and rock-sized pieces from the Marmolada Glacier hurled down the mountain in an avalanche. Experts believe that the event may have been triggered by higher temperatures and below-average winter snowfall.

It is difficult to determine the exact role of climate changes in particular events. Large chunks of ice can also cause Alpine glaciers to melt naturally. Climate change is causing higher temperatures, which can lead to more snow melting and ice formation, according to Brian Menounos, a University of Northern British Columbia professor who studies climate change and glaciers.

Menounos stated that "Glaciers directly respond to a warmer climate and a warmer planet." They can respond to long-term climate changes but also to extreme events, such as heat waves.

The Marmolada glacier can be found in the Dolomite Mountains, which are a series of dramatic, steep peaks in northeast Italy. Climate change is already affecting the region. According to Copernicus (the European climate modeling group), temperatures in the Alps rose twice as fast as the global average between the late 19th century and the early 21st centuries. The U.N. identified the Mediterranean basin, which includes Italy, as a hot spot for climate change and prone to heat waves. In Italy, the Alps, and around the globe, glaciers are retreating.

According to the government's National Research Council, the Marmolada glacier is shrinking over decades and could disappear in 25-30 years.

The daytime temperatures at the glacier's elevation were 50F (10C) before the avalanche. They don't usually rise above freezing. Tobias Bolch, a researcher at the University of St. Andrews in Scotland, stated that prolonged hot weather at high altitudes created special circumstances.

Guglielmina Adele Diiolaiuti is a University of Milan professor who studies glaciers. She said that pictures of the ice remaining in the glacier tells a story about how it happened.

The top two-thirds of the ice face appear slightly dirty, which indicates that it was exposed to air.

She stated, "It's obvious that this section of the vertical icecliff was the interior part of a crevasse." A crevasse refers to a deep opening in a glacier.

According to Diolaiuti, the bottom is darker, which indicates that it was attached.

The glacier may have been under water pressure due to the accumulation of water in the crevasse. Experts believe it may have also helped loosen the glacier's grip over the steep rock on which it was sitting.

Richard Alley, Penn State's professor of ice sheets, stated that anyone who has ever tried to shovel ice from a driveway will know it sticks to the pavement. The ice will loosen its grip as the weather warms.

Alley stated, "All of the sudden, whoosh! You can get it off."

According to a local official, the area that was broken into is 220 yards (200m) wide, 85 yards (880m) high, and 65 yards (60.6 meters) deep. The mountain was rushed down at a speed of nearly 200 miles an hour (300 km per hour).

Most likely, the hikers were taken by surprise.

This winter, in addition to the heat and snowfall, was lower than normal. Northern Italy is experiencing its worst drought in 70-years. The glacier's surface can become darker due to the accumulation of impurities and snow. This causes more heat trapping, which makes it less stable. According to St. Andrews Bolch, the extra heat melts the snow and ice faster.

Rescue efforts found equipment and body parts on Tuesday. The sun returned on Tuesday after rain made rescue difficult Monday.

Climate change may reduce the likelihood of certain avalanches, according to Daniel Farinotti (ETH Zurich, WSL Birmensdorf). To grow glaciers, they need snowfall and cold weather. Glaciers that grow on steep slopes may experience avalanches when ice is pushed onto ledges. He said that glaciers recede with warmer temperatures and that smaller glaciers pose fewer dangers.

Experts believe that melting snow and ice is likely to be the culprit in Sunday's avalanche.

Roberta Paranuzio, who studies climate change at the National Research Council of Italy, said that "the ice, or the snow, are very sensitive to temperature increases."

Although there are some isolated avalanches, hikers love the Marmolada area.

Bolch stated that "the really warm weather was one reason why the event happened, but on the contrary, this really warm temperature made it attractive to mountaineers for them to climb it."

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