Global warming is the long-term rise in the average temperature of the Earth’s climate system. It is a major aspect of climate change. Global warming and climate change are often used interchangeably but important note, global warming is the main human-caused increase in global surface temperatures and its projected continuation. While there have been prehistoric periods of global warming, it is thought changes since the mid-20th century have been unprecedented.
Many physical impacts of global warming have already been observed, including extreme weather events, glacier retreat, changes in the timing of seasonal events (e.g. earlier flowering of plants), sea level rise, and declines in Arctic sea ice. The future impact of global warming depends on the extent to which nations implement prevention efforts and reduce greenhouse gas emissions.