Satellite image of waterways

1. Satellite images reveal Earth’s Waterways cover much more of the planet than we thought: Earth is covered by more waterways than originally thought according to a study published in the journal Science. Satellite images reveal the Earth’s rivers and streams cover 45 percent more surface area traversing about 773,000 square kilometers (300,000 square miles) around the globe – and it could have major implications in how we understand climate change.

Rivers and streams are a major source of greenhouse gas emissions, making up as much as five times more than the world’s lakes and reservoirs combined. Organic matter in the soil and vegetation is converted by microbes living in the waterways, generating greenhouse gases like carbon dioxide and methane, which is 25 times more potent than carbon dioxide. A greater number of river and stream surface area means more contact between water and air and a greater rate of carbon exchange with the atmosphere, especially when humans pollute the waterways; more greenhouse gases are released when pollutants like fertilizers and sewage make their way to water systems. Source: IFL Science

2. World’s largest iceberg set to disappear after 18 year long journey: The largest iceberg ever recorded, that broke away from Antarctica’s Ross Ice Shelf 18 years ago, could be nearing the end of its voyage, according to NASA. When iceberg B-15 first broke away in March 2000, it measured about 296 km long and 37 km wide. B-15 has since fractured into numerous smaller bergs, and most have melted away. Just four pieces remain that meet the minimum size requirement – at least 37 km to be tracked by the U.S. National Ice Center. When astronauts aboard the ISS shot a photograph of the iceberg on May 22 this year, B-15Z measured about 18 km long and 9 km wide. However, the iceberg may not be tracked much longer if it splinters into smaller pieces. A large fracture is visible along the centre of the berg. Melting and breakup would not be surprising, given the berg’s long journey and northerly location. A previous image showed B-15Z farther south in October 2017, after it had ridden the coastal counter-current about three-quarters of the way around Antarctica bringing it to the Southern Ocean off the tip of the Antarctic Peninsula. Currents prevented the berg from continuing through the Drake Passage; instead, B-15Z cruised north into the southern Atlantic Ocean. When the May 2018 photograph was acquired, the berg was about 277 km northwest of the South Georgia islands. Icebergs that make it this far have been known to rapidly melt and end their life cycles here. Source: The Hindu



3. Hidden mountain ranges discovered under Antarctica Ice: Researchers have discovered mountain ranges and three huge, deep subglacial valleys hidden beneath the Antarctica ice. The findings, published in the journal Geophysical Research Letters, are the first to emerge from extensive ice penetrating radar data collected in Antarctica as part of the European Space Agency PolarGAP project. Although there are extensive satellite data that help image the surface of the Earth and its deep interior, there was a gap around the South Pole area, which is not covered by satellites due the inclination of their orbits. The PolarGAP project was therefore designed to fill in the gap in the satellite data coverage of the South Pole and in particular acquire the missing gravity data. Airborne radar data were also collected to enable mapping of the bedrock topography hidden beneath the ice sheet. The data reveals the topography which controls how quickly ice flows between the East and West Antarctic ice sheets.

The team, led by researchers from Northumbria University in the UK, has mapped for the first time three vast, subglacial valleys in West Antarctica. These valleys could be important in future as they help to channel the flow of ice from the centre of the continent towards the coast. If climate change causes the ice sheet to thin, these troughs could increase the speed at which ice flows from the centre of Antarctica to the sea, raising global sea levels. The largest valley, known as the Foundation Trough, is more than 350 kilometres long and 35 kilometres wide. Its length is equivalent to the distance from London to Manchester, while its width amounts to more than one and a half times the length of New York’s Manhattan Island. The two other troughs are equally vast. The Patuxent Trough is more than 300 kilometres long and over 15 kilometres wide, while the Offset Rift Basin is 150 kilometres long and 30 kilometres wide. Source: The Hindu

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