Climate change

Global ice loss increases at alarming pace over 23-year period

written by Oceanographic Staff

According to new research led by the University of Leeds, the rate of global ice loss has increased within the past three decades, from 0.8 trillion tons per year in the 1990s to 1.3 trillion tons per year by 2017.

Using satellite data, the researchers also found that the Earth lost 28 trillion tonnes of ice between 1994 and 2017, which is the equivalent to a sheet of ice 100 metres thick covering the whole of the UK.

Ice loss results in rising sea levels, which increases the risk of flooding to coastal communities, and threatens natural habitats that numerous species depend on for survival.

“Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most,” said lead author Dr Thomas Slater, a Research Fellow at Leeds’ Centre for Polar Observation and Modelling. “The ice sheets are now following the worst-case climate warming scenarios set out by the Intergovernmental Panel on Climate Change. Sea-level rise on this scale will have very serious impacts on coastal communities this century.”

global ice loss Greenland meltwater

The researchers concluded that there has been a 65% increase in the rate of global ice loss over the 23-year period surveyed, mainly due to steep rises in losses from the polar ice sheets in Antarctica and Greenland.

The increase in global ice loss has been triggered by the heating of the atmosphere and oceans, the temperatures of which have increased by 0.26°C and 0.12°C per decade since the 1980, respectively. The majority of all ice loss was driven by atmospheric melting (68%), while the remaining losses (32%) were driven by oceanic melting.

Rising atmospheric temperatures have been the main driver of the decline in Arctic sea ice and mountain glaciers across the globe, while rising ocean temperatures have increased the melting of the Antarctic ice sheet. For the Greenland ice sheet and Antarctic ice shelves, ice losses have been triggered by a combination of rising ocean and atmospheric temperatures.

“Sea ice loss doesn’t contribute directly to sea level rise but it does have an indirect influence,” said Dr Isobel Lawrence, a Research Fellow at Leeds’ Centre for Polar Observation and Modelling. “One of the key roles of Arctic sea ice is to reflect solar radiation back into space which helps keep the Arctic cool. As the sea ice shrinks, more solar energy is being absorbed by the oceans and atmosphere, causing the Arctic to warm faster than anywhere else on the planet. Not only is this speeding up sea ice melt, it’s also exacerbating the melting of glaciers and ice sheets which causes sea levels to rise.”

Their survey covers 215,000 mountain glaciers spread around the planet, the polar ice sheets in Greenland and Antarctica, the ice shelves floating around Antarctica, and sea ice drifting in the Arctic and Southern Oceans. During the survey period, every category lost ice, but the biggest losses were from Arctic Sea ice (7.6 trillion tons) and Antarctic ice shelves (6.5 trillion tons), both of which float on the polar oceans.

“Over the past three decades there’s been a huge international effort to understand what’s happening to individual components in Earth’s ice system,” added Dr Slater, “revolutionised by satellites which allow us to routinely monitor the vast and inhospitable regions where ice can be found. Our study is the first to combine these efforts and look at all the ice that is being lost from the entire planet.”

Half of all losses were from ice on land, and raised global sea levels by 35mm. This included 6.1 trillion tons lost from mountain glaciers, 3.8 trillion tons from the Greenland ice sheet, and 2.5 trillion tons from the Antarctic ice sheet. It has been estimated that for every centimetre of sea level rise, approximately one million people are in danger of being displaced.

Despite storing a mere 1% of the Earth’s total ice volume, glaciers have contributed to nearly one quarter of the global ice loss over the period studied. Every single glacier region around the world lost ice.

Funded by UK Natural Environment Research Council, the study was the first of its kind using satellite observations to examine all the ice that is disappearing on Earth.

Photography by Ian Joughin.

For information regarding co-authors and to read the full study, click here

For more from our Ocean Newsroom, click here.

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