# The Application of Satellite Image Analysis in Oil Spill Detection
## 4 Discussion  
A rapid response from rescue personnel is essential during oil spills and other natural disasters [52]. Oil spills are detectable using the spatial and spectral resolutions provided by the sensors used in this analysis. The proposed methodology is based on a long-term analysis to better understand climate change in the area studied. Analyses have been carried out to identify and analyze the possible causes of the collapse of the foundations under the fuel tank. Based on the results obtained, it can be concluded that May 2020 was a very warm period for Norilsk. This was confirmed by analysis using NDWI2, NDVI, SWM, and NDSII indices. Large water reservoir anomalies can be found by detecting water changes and multi-time analysis.  
The leakage tests were carried out with Sentinel-1 and Sentinel-2 missions to determine the thickness of the leak and actual water contamination. Moreover, Norilsk, due to its geographic location, is a complicated area to monitor by remote sensing methods due to year-round cloudiness and precipitation. For this reason, the first data after the leak are from 31 May 2020. According to the official statement of [PERSON], CEO of Norilsk Nickel, the main cause of the fuel tank failure was the heatwave in May 2020, which caused the ground under the plant to thaw [16]. Permafrost covers about 60% of the total area of Russia and 90% of Norilsk and its vicinity. According to reports by climatologists, since the mid-1970s the rate of temperature increase in northern parts of Russia has been more than five times greater than the value calculated for global warming, which is 0.18 \({}^{\circ}\)C. Moreover, since the 1980s, there has been a drastically rapid thawing of sea ice in the Arctic Ocean due to climate change. The volume of sea ice in 2019 decreased by more than 50% compared to the 1979-2019 average. Contemporary climate models confirm a more intense warming of Siberia, which will result in a significant loss and change in the extent of permafrost [49]. The May 2018 decree of the President of Russia, entitled \"On the Foundations of the State Policy of the Russian Federation in the Field of Industrial Safety\", states that \"60-70% of equipment used in hazardous production plants has reached the standard service life of the equipment. Under such conditions, the socio-economic damage caused by accidents can be estimated at 600-700 billion rubles annually, which will adversely affect the economic stability of the Russian Federation\" [53].  
According to the official website of Nornickel [54], by October 2020, the leak was: \"fully located and most of the fuel-water mixture collected\". By 28 September 2020, a total of 34,451 m\({}^{3}\) of mixture had been collected, and by 28 October 2020, \"more than 25,000 m\({}^{3}\) of mixture was pumped through newly installed pipelines from temporary tanks to storage for subsequent separation.\" A study published in Nature [49] found that almost half of all oil and gas fields in Siberia are located in areas with significant thawing and subsidence potential. Global warming can have a devastating effect not only on local nature and people living there, but also on the entire global climate system, e.g., by melting permafrost, reducing snow cover, and melting ice [55]. The Norilsk disaster shows how climate change puts a huge strain on the Arctic, its indigenous peoples, and local flora and fauna.  
Figure 12: NDSII Results (**a**) for the image taken 14 May 2020, (**b**) for the image taken 13 June 2020.