Earth has Lost 28 Trillion Tonnes of Ice in Less Than 30 Years

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According to scientists at the University of Leeds, Edinburgh, and Imperial College London, Earth has lost 28 trillion tonnes of ice between 1994 and 2017. 

The study was led by Dr Tom Slater from the Centre of Polar Observation and Modelling at the University of Leeds. It combined numerical climate models and satellite observations from the Ice Sheet Mass Balance Intercomparison Exercise (IMBIE) to determine the rate that Earth’s ice is melting – and it is accelerating rapidly. 

Having researched mountain glaciers, the Greenland and Antarctic ice sheets, the Southern Ocean and Arctic Ocean ice, and finally the Antarctic ice shelves, they concluded that all areas had lost ice by the trillions of tonnes. 

The Arctic Ocean ice saw the greatest decrease of some 7.6 trillion, while the Southern Ocean ice witnessed the least – approximately 0.9 trillion tonnes. Just over 60% of the ice loss occurred in the southern hemisphere. Atmospheric melting has driven 68% of ice loss from mountain glaciers, Arctic Ocean ice, ice shelf calving and ice sheet surface mass balance. The remaining 32% that occurred via ice shelf thinning and ice sheet discharge.

There is now widespread evidence to suggest a reduction in the planet’s ice has occurred directly because of climate change. Burning fossil fuels, which creates greenhouse gases in the atmosphere, is believed to have influenced this. 

What is the scientific explanation for this loss of ice?

As annual surface temperatures increase, other alterations such as in the levels, temperatures, and salinity of the oceans and the distribution of ice, thereafter occur. When extra water from glaciers and ice sheets enters the ocean, the seas expand in volume. As seawater expands, it also gets warmer via the process of thermal expansion. 

According to the International Union for the Conservation of Nature (IUCN), coral bleaching and the loss of habitat are results of ocean warming, this greatly affects marine species and their ecosystems. Similarly, rising ocean temperatures affect humans by increasing the prospect of disease and threatening food security. 

What impact does the ice melting have on sea level rise?

Since the 1990s, melting of the Greenland ice sheets has increased the world’s oceans by 10.6mm. Meanwhile, Antarctic has added 7.2mm. Over our planet’s 4.6-billion-year history, sea levels have risen and subsequently fallen considerably. But latest measurements indicate that global sea levels are rising per year by 4mm which is far greater than the average rate of the past two to three thousand years. 

Results from the study show that in the last five years, melting ice from mountain glaciers and ice sheets has surpassed global warming as the main cause of rising sea levels. The study also concluded that compared to the 1990s, ice loss has increased by 49% over the last 24 years. To confirm the trend, the study examined satellite records of ice shelf range and in situ measurements of the changes in glacier mass which pre-date the survey.

Published thirty years after the Intergovernmental Panel on Climate Change (IPCC) outlined their predictions, the group’s research reveals that the level of ice loss which has occurred between 1994 and 2007 matches the worst-case scenario estimate by IPCC in August 1990. 

Additional consequences

Alongside this, the ice of the Antarctica and Greenland ice sheets coupled with mountain glaciers are freshwater. When they melt and drain into the oceans, the freshwater alters the delicate balance of salinity in the seas. 

A continuation, or at worse, growth in this trend could potentially cause disastrous consequences for the world’s coastlines and those that live among them. If sea levels increase by the predicted 17cm, up to 16 million people are going to be affected by annual coastal flooding