Ice loss up

Study after study has shown that Earth is losing its glacial and polar ice. Previous research has focussed on specific areas, from mass loss of the Greenland ice sheet to warming in the South Pole.

Now, research led by the University of Leeds, UK, has found that global ice loss is increasing at a record rate.

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Key research points 

• Global ice loss increased from 0.8 trillion tonnes per year in the 1990s to 1.3 trillion tonnes in 2017
• 68% of ice loss was driven by atmospheric warming. The remaining 32% is due to warming oceans
• Every category – mountain glaciers, polar ice sheets, ice shelves and sea ice – lost ice 
• The biggest losses were from the Arctic Sea ice and ice shelves in Antarctica

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The findings, published in the journal The Cryosphere, reveals the Earth lost 28 trillion tonnes of ice between 1994 and 2017 – the equivalent to a sheet of ice 100 metres thick covering the whole of the UK (more than 240,000 square kilometres).

The rate of ice loss increased from 0.8 trillion tonnes per year in the 1990s to 1.3 trillion tonnes by 2017.

“Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most,” says lead author Thomas Slater, from 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.”

The study highlights the majority of ice loss (68%) was driven by warming of the atmosphere, which has increased temperature by 0.26°C per decade since 1980.

The remaining 32% was triggered by warming oceans, which have increased by 0.12°C over the same period. 

The survey covered 215,000 mountain glaciers, polar ice sheets in Greenland and Antarctica, ice shelves floating around Antarctica and sea ice in the Arctic and Southern oceans. 

Results showed the biggest losses were from the Arctic sea ice and ice shelves in Antarctica. However, it also highlights that every category lost ice.

Glaciers contributed to almost a quarter of the ice losses over the survey period, despite storying only 1% of the Earth’s total ice volume. Ice loss was greater in the Northern Hemisphere, which accounted for 58% of the global decline.

“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, revolutionised by satellites which allow us to routinely monitor the vast and inhospitable regions where ice can be found,” Slater says. 

“Our study is the first to combine these efforts and look at all the ice that is being lost from the entire planet.”

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Snapshot: ice melt impacts

• Entering warmer waters, very cold melt water slows ocean currents
• Polar vortexes, increased heatwaves and unpredictable weather patterns caused by ice loss cause significant damage to crops, affecting global food supply
• As sea ice melts, wildlife such as polar bears are spending more time on land, causing higher rates of human-animal conflicts

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Global ice melt has far-reaching ramifications. The melt raises sea levels, increases flooding risk to coastal communities and poses a threat to habitats. 

“As well as contributing to global mean sea level rise, mountain glaciers are critical as freshwater resource for local communities,” says co-author Inès Otosaka. 

“The retreat of glaciers around the world is therefore of crucial importance at both local and global scales.”