The dramatic melting of the world’s mountain glaciers – from the Alps to the Himalayas – is mostly the result of man-made global warming rather than natural variability in the climate, a study has found.
Scientists have laid to rest the idea that glaciers as far apart as Patagonia and Indonesia are melting primarily because of natural changes to the climate caused by such things as solar variability and volcanic eruptions.
An assessment of about 200,000 glaciers in the world, some of which have been monitored since the mid 19th century, has found that about two thirds of the current rate of glacial melting is due to human influences on the climate.
Scientists found that while much of the melting a century or more ago was most probably due to natural variability in the climate, it is now primarily caused by anthropogenic global warming resulting from industrial greenhouse gases.
“We can clearly detect an anthropogenic effect on glaciers and it’s been steadily rising over the last 100 years,” said Ben Marzeion, a climate scientist at the University of Innsbruck in Austria.
“In the 19th century and first half of the 20th century we observed that glacier mass loss attributable to human activity is hardly noticeable but since then it has steadily increased,” said Dr Marzeion, the lead author of the study published in the journal Science.
In pictures: Changing climate around the world
In pictures: Changing climate around the world
Calved icebergs from the nearby Twin Glaciers are seen floating on the water in Qaqortoq, Greenland
Oroumieh, one of the biggest saltwater lakes on Earth, has shrunk more than 80 percent to 1,000 square kilometers in the past decade. It shrinks mainly because of climate change, expanded irrigation for surrounding farms and the damming of rivers that feed the body of water
A boat navigates among calved icebergs from the nearby Twin Glaciers in Qaqortoq, Greenland. Boats are a crucial mode of transportation in the country that has few roads. As cities like Miami, New York and other vulnerable spots around the world strategize about how to respond to climate change, many Greenlanders simply do what theyve always done: adapt. 'Were used to change, said Greenlander Pilu Neilsen. 'We learn to adapt to whatever comes. If all the glaciers melt, well just get more land
The Svalbard Global Seed Vault is seen after being inaugurated in Longyearbyen, Norway. The 'doomsday' seed vault built to protect millions of food crops from climate change, wars and natural disasters opened deep within an Arctic mountain in the remote Norwegian archipelago of Svalbard
A technician preparing to drain a vast underground lake at the Tete Rousse glacier on the Mont Blanc Alpine mountain, to avert a potentially disatrous flood. Some 65,000 cubic metres (2.3 million cubic feet) of water have gathered in a cavity, dangerously raising the pressure beneath the mountain, a favourite spot for holiday makers in Saint-Gervais-les-Bains
Cracked mud is picture at sunrise in the dried shores of Lake Gruyere affected by continuous drought near the western Switzerland village of Avry-devant-Pont. A leading climate scientist warned that Europe should take action over increasing drought and floods, stressing that some climate change trends were clear despite variations in predictions
Cattle graze on grassland that remains dry and brown at the height of the rainy season in south of Bakersfield, California. Its third straight year of unprecedented drought, California is experiencing its driest year on record, dating back 119 years, and dating back as far as 500 years, according to some scientists who study tree rings
An aerial view shows tents of flood-displaced people surrounded by water in southern Sehwan town. United Nations Framework Convention on Climate Change (UNFCCC) executive secretary Christiana Figueres met with people displaced by last year's devastating floods. Catastrophic monsoon rains that swept through the country in 2010 and affected some 20 million people, destroyed 1.7 million homes and damaged 5.4 million acres of arable land
An aerial view of flooding in North Wagga Wagga. Climate change is amplifying risks from drought, floods, storm and rising seas, threatening all countries but small island states, poor nations and arid regions in particular, UN experts warned
Damages caused by a landslide on the Pan-American highway near La Moramulca, 55 Km south of Tegucigalpa. International highways have been washed out, villages isolated and thousands of families have lost homes and crops in a region that the United Nations has classified as one of the most affected by climate change
A resident sprays water on a peatland fire in Pekanbaru district in Riau province on Indonesia's Sumatra island. Indonesia, an archipelago of 17,000 islands, is one of the world's biggest carbon emitters because of rampant deforestation. US Secretary of State John Kerry Sunday issued a clarion call for nations to do to more to combat climate change, calling it 'the world's largest weapon of mass destruction'
An excavator clearing a peatland forest area for a palm oil plantations in Trumon subdistrict, Aceh province, on Indonesia's Sumatra island. As Southeast Asia's largest economy grows rapidly, swathes of biodiverse forests across the archipelago of 17,000 islands have been cleared to make way for paper and palm oil plantations, as well as for mining and agriculture. The destruction has ravaged biodiversity, placing animals such as orangutans and Sumatran tigers in danger of extinction, while also leading to the release of vast amounts of climate change-causing carbon dioxide
Stagnant rain water with tannery waste make the Hazaribagh area in Old Dhaka as well as Buriganga River the most polluted. Each year during the seven-month long dry season between October and April the Buriganga River becomes totally stagnant with its upstream region drying up and becoming polluted from toxic waste from city industries
Waste water from Dhaka city drained to the River Buriganga contributes to its pollutions. On the World Water Day observed in 2007 under the theme Coping with Water Scarcity, under the leadership of the Food and Agriculture Organization of the United Nations, DrikNEWS explores some of the images of the river. UN-Water has identified coping with water scarcity as part of the strategic issues and priorities requiring joint UN action. The theme highlights the significance of cooperation and importance of an integrated approach to water resource management of water at international, national and local levels
Heavy smog has been lingering in northern and eastern parts of China, disturbing the traffic, worsening air pollution and forcing the closure of schools. China's Environment Ministry said it will send inspection teams to provinces and cities most seriously affected by smog to ensure rules on fighting air pollution are being enforced
In comparison to anthropogenic warming caused carbon dioxide emissions, variations in solar radiation and the effects of volcanic eruptions, which can lower temperatures by blocking solar radiation, now play only a minor role in influencing whether a glacier recedes or expands, the scientists found.
The study found that about 25 per cent of the global loss of glacier ice that occurred between 1851 and 2010 could be attributable to human influences, but that this rose to about 69 per cent between 1991 and 2010, based on computer simulations of the climate that included natural and man-made effects.
“The influence of anthropogenic warming becomes robust around the middle of the 20th century. It seems obvious that if it gets warmer, glaciers will melt but no-one has actually shown that before – and it’s possible to say that now this is primarily caused by humans,” Dr Marzeion said.
“While we keep factors such as solar variability and volcanic eruptions unchanged, we are able to modify land use changes and greenhouse gas emissions in our models,” he said.
“In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss. What is happening in recent decades is not explicable by natural climate effects such as variations in solar radiation or volcanic activity,” he added.
It widely accepted that the global trend in glacier melting began in the mid 19th century, at the end of the “little ice age” when temperatures in some parts of the world were below average for many decades.
It can take decades or even centuries for glaciers to adjust to climate change and the real effects of the more recent human influences on the climate have not been clear until this study, Dr Marzeion said.
“There is a lag response of several decades which means that we are only seeing a fraction of the total anthropogenic effects on melting glaciers that we will eventually see as a result of the carbon dioxide in the atmosphere now,” he said.
Although mountain glaciers store less than one per cent of the total ice on earth, they are a major cause of global sea-level rise over the 20th century because they have melted so rapidly. The smaller glaciers of the Alps and Rocky Mountains are among the fastest disappearing masses of non-polar ice.