The massive Greenland ice sheet has subglacial lakes beneath it and scientists have noticed some significant changes in the lakes recently. It has been found that these subglacial lakes could increase the sensitivity of ice to climatic changes. A team of U.S. scientists has researched this, emphasizing that this discovery would help to gain a better understanding about the effect of global warming on the ice sheet’s basal ice layer. Basal ice layer is on the top of the island’s bedrock. Meltwater have a major contribution in the rising sea levels across the globe which is presently threatening coast cities all around the world. Rise in temperature results in the formation of meltwater and it acts as a lubricant to the basal layer of ice. This lubrication makes the layer of ice more likely to slide out to sea.
Previously the scientists had discovered the sudden draining of meltwater that had pooled on the surface of the glacier. It was assumed that these lakes, formed under the ice sheet, transfer heat to the basal layer. Study co-author Michael Bevis, of the School of Earth Sciences at Ohio State University in Columbus, said “If enough water is pouring down into the Greenland Ice Sheet for us to see the same subglacial lake empty and refill itself over and over, then there must be so much latent heat being released under the ice that we’d have to expect it to change the large-scale behavior of the ice sheet.”
Recently it has been found that two of the subglacial lakes have drained within a few weeks. One of the lakes, which contained more than 7 billion gallons of water (supplied by melting ice caps), is presently a cold and empty crater having a depth of 230 feet and length of some 1.2 miles. Greenland’s ice sheet is the second largest ice sheet in the world after Antarctica and it covers almost 80 percent of the island. The island has 2.8 million cubic kilometers volume of ice and at some spots the ice is about 3 kilometers thick.
Rise in global temperatures has caused melting of large sections of ice, resulting in the addition of billions of tons of water to the oceans. An alarming report also stated that Greenland’s ice sheet is melting at a faster rate than estimated and this implies that it is pouring an additional 10 billion tons of water into the oceans. According to the lead author of the new study and a researcher with Cornell University, Michael Willis, increasing amount of water draining into the subglacial lakes under the ice sheet results in the softening of surrounding ice due to the heat it releases. This could eventually increase the ice flow. Willis added “Each summer scientists see bright blue streams form on the surface of Greenland as warm air melts the ice sheet. What happens to this water when it disappears into cracks in the ice has remained a mystery.”