![]() ![]() ![]() View image in fullscreen Credits: OLI/Landsat-8/Nasa Scientists have also investigated other African lakes to see if the same phenomenon is possible elsewhere. In 2001, French scientists installed a degassing instrument – mostly a pipe and fountain that allows gas to escape at a consistent rate. The unpredictable and dangerous nature of the lake led scientists from around the world to propose solutions that would prevent another carbon dioxide eruption. The soil on and around the old volcano is rich and fertile, and even after the 1986 disaster people were eager to return to it. Though it is impossible to know for sure from this image, the small white dots may be villages and settlements amid the forests and brown, volcanic hills.Despite the inherent dangers of living so close to active volcanoes and dangerous lakes, roughly 10,000 people populate the area. The natural-color image above shows Lake Nyos as it appeared on 18 December 2014. Eventually the gas becomes too concentrated and a bubble of CO2 bursts from the lake. Carbon dioxide from that magma slowly percolates through Earth’s crust with the groundwater and accumulates in the bottom of the lake. A pocket of magma lies 80kks (50 miles) below the surface. Lake Nyos sits in a crater on the edge of an inactive volcano in the Oku volcanic field. The suffocating gas killed nearly 1,800 people, 3,500 livestock, and countless birds and insects. Scientists would discover months later, after much research, that a cloud of carbon dioxide rose out of the lake and rolled into a valley below at more than 100km (60 miles) per hour. On the evening of 21 August 1986, a silent, invisible killer raced down the hills around Lake Nyos in northwest Cameroon, taking the lives of nearly everything in its path. View image in fullscreen Credits: OLI/Landsat 8/Nasa Given that this is the correct time for the prescribed burns, and the pattern suggests a non-random event, it is possible that most of these fires have been set for fire-reduction purposes. The long line of fires presents an unusual distribution, and an uncommon one for wildfires. Most of the fires scattered across the landscape are most likely wildfires. Wildfires generally have a random pattern, and large wildfires can leave large burn scars. Thus the traditional Aboriginal technique of “fighting fire with fire” is returning.Īlthough it is not possible to determine the cause of a fire from a Modis image, clues such as time of year, pattern, and evidence of burn scars can help make educated guesses about what is occurring on the land. Since about 1997 projects such as the West Arnhem Land Fire Abatement (Walfa) have been created to re-institute early season prescribed burns. These fierce blazes destroy soil and biodiversity and emit tonnes of greenhouse gasses into the atmosphere each year. By 1997 about 40% of the region burned annually, with 32% of the fires occurring in the late dry season. This traditional method had been replaced with strict fire suppression in modern times, which resulted in fewer fires, but the fires that did ignite tended to be fierce. Traditional agricultural practices involved burning small sections of savannah early in the dry season, in order to prevent large fires later in the season. Lines of fires are seen as red hotspots across Arnhem Land on the northern tip of Australia, early in the dry season of 2015, on 4 July.Īrnhem Land is Aboriginal land, and culturally rich as well as biodiverse. View image in fullscreen Credits: Modis/Aqua/Nasa The system is expected to make ocean colour satellite imagery more easily available to environmental and water quality managers. In April 2015, Nasa and several partners announced a new multi-agency effort to develop an early warning indicator for harmful algal blooms in fresh water. Harmful algal blooms can lead to fish kills and make water unsafe for recreation and for consumption. The researchers noted that if land management practices and climate change trends continue, the lake is likely to see more blooms like the 2011 event. Algae in this basin thrive when there is an abundance of nutrients (many from agricultural runoff) and sunlight, as well as warm water temperatures. Earlier in the month National Oceanic and Atmospheric Administration (Noaa) scientists predicted that the 2015 season for harmful algal blooms would be severe in western Lake Erie, rivalling the blooms of 2011. ![]() Algal blooms around the Great Lakes are visible as swirls of green in this image of Lake St Clair and in western Lake Erie, 28 July. ![]()
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