22 October 2015, Carbon Brief, Five charts that show how Arctic and Antarctic sea ice is faring in 2015. At this time of year, there are big differences in what’s going on with sea ice at either end of the world. September saw the Arctic hit its fourth lowest summer minimum on record, while over in Antarctica, the winter maximum finished just above average, ending a streak of record highs in the last three years. Carbon Brief takes a look at what’s happened this year and how it fits in with long term trends. Summer minimum Scientists have been using satellites to measure sea ice extent at the north and south poles since the late 1970s. They take measurements daily, and record the annual minimum and maximum as an indicator of how the poles are changing. In the Arctic, the end of the summer marks the point when sea ice is at its smallest extent, before it freezes up again as temperatures fall. Scientists keep a close eye around the time the low is normally reached – usually mid september – then look for signs of ice accumulating again in order to pinpoint exactly when the summer minimum is reached. According to the National Snow and Ice Data Center (NSIDC) in the US, the summer low occurred this year on 11 September. But because sea ice can throw in a late dip or surge, the NSIDC waited until 6 October before finally confirming this summer’s minimum of 4.41m square kilometers (sq km) – the fourth lowest on record. So how did the rest of the season shape up before this point? Read More here
Tag Archives: Antarctica
14 October 2015, Climate News Network, Antarctic ice shelf melting could double by 2050. Scientists find that the combination of global warming and powerful winds sweeping snow off the ice of Antarctica threatens to speed up sea level rise. Antarctica, the planet’s largest desert, is home to 90% of the world’s ice – enough to raise global sea levels by at least 60 metres. So what happens to its ice and snow is a matter of serious concern to all of us. One group has just predicted that, by 2050, the rate at which the ice shelves melt will double. Another reports that powerful winds are not just shifting Antarctica’s snow, but are also blowing 80 billion tonnes of it away, into the sea or the atmosphere. Both cases exemplify the challenges of climate research and the construction of projections for the future. Inland glaciers Ice shelves are already afloat: if they melt, that will make no difference to sea levels. But floating ice that is fixed to the continental shelf also serves as a brake on the flow of glaciers further inland. So without the ice shelf “doorstops”, these could start to shed ice ever faster, and accelerate sea level rise. Luke Trusel, postdoctoral scholar at the Woods Hole Oceanographic Institutionin the US, and colleagues report in Nature Geoscience that they foresee a doubling of surface melting of the ice shelves by 2050. If greenhouse gas emissions from fossil fuel combustion continue at the present rate, by 2100 the melting may surpass the levels associated with collapse of the shelves. Read More here
14 September 2015, Climate News Network, Southern Ocean starts to soak up carbon again. Scientists report that the great oceanic “lung” is again breathing in vast amounts of carbon dioxide from the atmosphere – but can’t say why or whether it will last. The high seas have begun to respond again to the changes in the atmosphere, with two new studies confirming that the Southern Ocean is absorbing more atmospheric carbon. Levels of carbon dioxide in the atmosphere have been steadily increasing as humans burn ever more fossil fuels, but climate scientists will probably hesitate before exhaling sighs of relief over the latest findings. Rising CO2 in the atmosphere means global warming, which means climate change, melting ice caps, rising sea levels − and even more global warming and climate change. So the discovery that one great stretch of hostile ocean is soaking up more of the stuff sounds like very good news. However, the celebrations are likely to be cautious, as there is no guarantee that the process is permanent. Read More here
26 August 2015, NASA The fingerprints of sea level rise. When you fill a sink, the water rises at the same rate to the same height in every corner. That’s not the way it works with our rising seas. According to the 23-year record of satellite data from NASA and its partners, the sea level is rising a few millimeters a year — a fraction of an inch. If you live on the U.S. East Coast, though, your sea level is rising two or three times faster than average. If you live in Scandinavia, it’s falling. Residents of China’s Yellow River delta are swamped by sea level rise of more than nine inches (25 centimeters) a year. These regional differences in sea level change will become even more apparent in the future, as ice sheets melt. For instance, when the Amundsen Sea sector of the West Antarctic Ice Sheet is totally gone, the average global sea level will rise four feet. But the East Coast of the United States will see an additional 14 to 15 inches above that average. Read More here