A new study suggests that ice sheets are melting faster than had previously been thought. But what does this mean for us, asks Chris Bond.
Aelfleda Terrace has been part of the Whitby skyline since the days of Queen Victoria reign. Until this week, that is.
This picturesque row of cottages is now set for demolition, following a landslide that swept away the gardens and 150 years of history. Torrential rain caused patios and a slab of rock and mud the size of a minibus to slide down the steep slope and crash into another terrace.
For the people who have now lost their homes it has been a devastating experience. They are among the victims of this latest flooding catastrophe that has wrought havoc across the UK and, according to the Environment Agency, left more than 1,600 properties inundated.
These floods raise concerns once again over our seemingly ever-changing climate – a climate which, if anything, looks as though it’s going to become increasingly volatile.
As families and communities up and down the country start to pick up the pieces and begin to rebuild their lives, a new study of satellite data just published in the journal Science shows the ice sheets covering Greenland and Antarctica are melting three times faster now than they were in the 1990s.
Scientists say that since 1992 melting ice sheets from these two areas have added 11.1 millimetres to global sea levels – about a fifth of the total rise. Until now, there has been confusion over what’s actually happening to the ice sheets, with estimates differing greatly. But the new survey is believed to be the most accurate assessment to date, ending 20 years of uncertainty.
It confirms that, with the exception of East Antarctica, both land masses are losing ice, although big differences in the pace of change were seen at each pole. So while the rate of ice loss from Greenland has increased almost five-fold since the mid-90s, it has remained fairly constant in Antarctica.
The project’s leader, Professor Andrew Shepherd of Leeds University, says the study brought the international scientific community together. “Without these efforts we would not be in a position to tell people with confidence how the Earth’s ice sheets have changed, and to end the uncertainty that has existed for many years.”
The scientists matched results from 10 satellite observations, using different techniques to identify changes on the Earth and to contrast these with earlier studies using similar geographical regions and time periods.
Rates of ice loss were calculated for Greenland, East Antarctica, West Antarctica and the Antarctic Peninsula, and although East Antarctica showed a net increase in ice mass, this was not enough to compensate for larger losses elsewhere.
US climate scientist Professor Richard Alley commented on the findings, calling the project a spectacular achievement. “The data will lead to a better understanding of how sea-level change may depend on the human decisions that influence global temperatures,” he said.
The huge polar ice sheets are important because of the vast amounts of water they lock up. The Antarctic ice sheet contains 30 million cubic kilometres of ice and holds about 90 per cent of all the fresh water on the surface of the Earth and were that to melt sea levels would rise by more than 60 metres. The Greenland ice sheet is much smaller, but would add seven metres to sea levels if it all melted.
Melting ice sheets are a consequence, rather than a cause, of climate change but what impact, if any, is this accelerated melting likely to have on Britain in the coming decades?
Professor Chris Clark, Sorby Chairman of Geoscience at Sheffield University, says even a small rise in sea level can have a detrimental effect. “Rivers drain at what we call a base level, sea level in other words, and Yorkshire has a lot of soft cliffs and a rise in sea level would cause problems to the infrastructure, to harbours and sea walls.”
In 2007, the Intergovernmental Panel on Climate Change (IPCC) estimated that by the end of the century there could be a rise in sea level by as much as half a metre, but already some climate experts are saying this figure could be exceeded.
“This probably doesn’t sound very much to the average person in the street, but when you think about all the pictures we’ve seen recently of people’s living rooms being flooded, then as little as 10 centimetres can mean a great deal. And if all the rivers drain out to a higher level then we are going to see increasing instances of flooding.”