Global warming is the long-term heating of the Earth's climate system experienced since the pre-industrial era (between 1850 and 1900) as a result of human activity, especially the combustion of fossil fuels, which raises high-temperature greenhouse gas levels in the Earth's environment.
The rate at which sea levels are rising globally is increasing. This is due to both glacier melting and ocean thermal expansion as a result of increased air heat generated by emissions. Global warming is exemplified by widespread reductions in the extent of snow and ice.
Thus Option C is not a manmade cause of global warming.
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